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Real Estate and Accumulated Depreciation (Details) (USD $) | 12 Months Ended |  |  |
--- | --- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |
Fixtures and Equipment, Gross | $ 1,365,276,000 us-gaap_FixturesAndEquipmentGross |  | $ 1,214,220,000 us-gaap_FixturesAndEquipmentGross |  |
Land And Depreciable Property Net | 16,700,000,000 eqr_LandAndDepreciablePropertyNet |  | 15,200,000,000 eqr_LandAndDepreciablePropertyNet |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Accumulated Depreciation | (5,432,805,000)us-gaap_RealEstateAccumulatedDepreciation |  | (4,807,709,000)us-gaap_RealEstateAccumulatedDepreciation | (4,912,221,000)us-gaap_RealEstateAccumulatedDepreciation | (4,539,583,000)us-gaap_RealEstateAccumulatedDepreciation
Partially Owned Unconsolidated Properties | 3 eqr_PartiallyOwnedUnconsolidatedProperties |  |  |  |
Number Of Unconsolidated Projects | 1 eqr_NumberOfUnconsolidatedProjects |  |  |  |
Partially Owned Unconsolidated Units | 1,281 eqr_PartiallyOwnedUnconsolidatedUnits |  |  |  |
Military Housing Properties | 2 eqr_MilitaryHousingProperties |  |  |  |
Military Housing Units | 5,033 eqr_MilitaryHousingUnits |  |  |  |
100 K Street [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
Initial Cost to Company, Land | 15,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 1,949,701 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 1,949,701 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 17,549,701 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
Investment in Real Estate Net | 17,549,701 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A100KStreetMember |  |  |  |
1111 Belle Pre (fka The Madison) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Alexandria, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 360 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
Initial Cost to Company, Land | 18,937,702 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 92,495,595 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 17,838 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 18,937,702 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 92,513,433 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 111,451,135 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
Accumulated Depreciation | (3,422,538)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
Investment in Real Estate Net | 108,028,597 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1111BellePrefkaTheMadisonMember |  |  |  |
1210 Mass [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 144 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
Initial Cost to Company, Land | 9,213,512 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 36,559,189 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 610,534 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,213,512 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 37,169,723 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 46,383,235 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
Accumulated Depreciation | (12,689,430)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
Investment in Real Estate Net | 33,693,805 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Mass1210Member |  |  |  |
1401 E Madison [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
Initial Cost to Company, Land | 10,322,187 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 1,019,404 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,322,187 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 1,019,404 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 11,341,591 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
Investment in Real Estate Net | 11,341,591 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1401EMadisonMember |  |  |  |
1500 Mass Ave [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 556 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
Initial Cost to Company, Land | 54,638,298 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 40,361,702 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 13,296,439 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 54,638,298 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 53,658,141 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 108,296,439 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
Accumulated Depreciation | (14,670,887)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
Investment in Real Estate Net | 93,625,552 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1500MassAveMember |  |  |  |
170 Amsterdam [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 97,371,663 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 97,371,663 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 97,371,663 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
Investment in Real Estate Net | 97,371,663 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A170AmsterdamMember |  |  |  |
175 Kent [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Brooklyn, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 113 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
Initial Cost to Company, Land | 22,037,831 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 53,962,169 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,072,648 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 22,037,831 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 55,034,817 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 77,072,648 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
Accumulated Depreciation | (8,337,345)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
Investment in Real Estate Net | 68,735,303 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A175KentMember |  |  |  |
180 Montague (fka Brooklyn Heights) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Brooklyn, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 193 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
Initial Cost to Company, Land | 32,400,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 92,675,228 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 946,790 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 32,400,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 93,622,018 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 126,022,018 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
Accumulated Depreciation | (10,067,159)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
Investment in Real Estate Net | 115,954,859 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A180MontagueMember |  |  |  |
1800 Oak (fka Rosslyn) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 314 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
Initial Cost to Company, Land | 31,400,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 109,005,734 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,424,829 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 31,400,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 110,430,563 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 141,830,563 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
Accumulated Depreciation | (11,550,245)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
Investment in Real Estate Net | 130,280,318 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A1800OakMember |  |  |  |
200 N Lemon Street [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Anaheim, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
Initial Cost to Company, Land | 5,865,235 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 2,802,003 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,865,235 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 2,802,003 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 8,667,238 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
Investment in Real Estate Net | 8,667,238 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A200NLemonStreetMember |  |  |  |
204-206 Pine Street/1610 2nd Avenue [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
Initial Cost to Company, Land | 22,106,465 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,015,203 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 22,106,465 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,015,203 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 40,121,668 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
Investment in Real Estate Net | 40,121,668 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A204206PineStreet16102NdAvenueMember |  |  |  |
2201 Pershing Drive [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 188 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
Initial Cost to Company, Land | 11,321,198 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 49,316,482 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,018,023 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 11,321,198 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 51,334,505 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 62,655,703 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
Accumulated Depreciation | (4,704,104)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
Investment in Real Estate Net | 57,951,599 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201PershingDriveMember |  |  |  |
2201 Wilson [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 219 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
Initial Cost to Company, Land | 21,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 78,724,663 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,155,814 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 21,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 79,880,477 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 101,780,477 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
Accumulated Depreciation | (8,243,035)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
Investment in Real Estate Net | 93,537,442 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2201WilsonMember |  |  |  |
2400 M St [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 359 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
Initial Cost to Company, Land | 30,006,593 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 114,013,785 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,170,237 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 30,006,593 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 117,184,022 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 147,190,615 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
Accumulated Depreciation | (37,361,925)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
Investment in Real Estate Net | 109,828,690 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MSt2400Member |  |  |  |
340 Fremont [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
Initial Cost to Company, Land | 42,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 64,972,143 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 42,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 64,972,143 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 106,972,143 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
Investment in Real Estate Net | 106,972,143 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A340FremontMember |  |  |  |
420 East 80th Street [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 155 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
Initial Cost to Company, Land | 39,277,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,026,984 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,746,938 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 39,277,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 26,773,922 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 66,050,922 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
Accumulated Depreciation | (10,547,486)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
Investment in Real Estate Net | 55,503,436 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FourHundredAndTwentyEastEightiethStreetMember |  |  |  |
425 Mass [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 559 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
Initial Cost to Company, Land | 28,150,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 138,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,341,423 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 28,150,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 141,941,423 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 170,091,423 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
Accumulated Depreciation | (29,744,846)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
Investment in Real Estate Net | 140,346,577 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425MassMember |  |  |  |
443 - 459 Eye Street [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
Initial Cost to Company, Land | 12,671,446 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 7,660,628 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,671,446 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 7,660,628 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 20,332,074 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
Investment in Real Estate Net | 20,332,074 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A443459EyeStreetMember |  |  |  |
4885 Edgemoor Lane [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bethesda, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 520,879 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 520,879 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 520,879 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
Investment in Real Estate Net | 520,879 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4885EdgemoorLaneMember |  |  |  |
4th and Hill [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
Initial Cost to Company, Land | 13,131,456 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 1,242,358 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,131,456 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 1,242,358 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 14,373,814 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
Investment in Real Estate Net | 14,373,814 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4thandHillMember |  |  |  |
600 Washington [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 135 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
Initial Cost to Company, Land | 32,852,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 43,140,551 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 394,984 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 32,852,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 43,535,535 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 76,387,535 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
Accumulated Depreciation | (15,049,427)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
Investment in Real Estate Net | 61,338,108 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Washington600Member |  |  |  |
660 Washington (fka Boston Common) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boston, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 420 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
Initial Cost to Company, Land | 106,100,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 166,311,679 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 785,303 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 106,100,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 167,096,982 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 273,196,982 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
Accumulated Depreciation | (18,440,877)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
Investment in Real Estate Net | 254,756,105 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A660WashingtonMember |  |  |  |
70 Greene [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Jersey City, NJ |  |  |  |
Real Estate And Accumulated Depreciation Units | 480 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
Initial Cost to Company, Land | 28,108,899 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 236,941,402 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 648,362 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 28,108,899 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 237,589,764 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 265,698,663 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
Accumulated Depreciation | (41,945,093)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
Investment in Real Estate Net | 223,753,570 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Greene70Member |  |  |  |
71 Broadway [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 238 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
Initial Cost to Company, Land | 22,611,600 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 77,492,171 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 11,705,700 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 22,611,600 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 89,197,871 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 111,809,471 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
Accumulated Depreciation | (32,081,951)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
Investment in Real Estate Net | 79,727,520 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Broadway71Member |  |  |  |
77 Bluxome [Domain] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 102 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
Initial Cost to Company, Land | 5,249,124 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,609,876 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 91,584 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,249,124 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,701,460 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 23,950,584 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
Accumulated Depreciation | (2,715,377)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
Investment in Real Estate Net | 21,235,207 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77BluxomeDomain |  |  |  |
777 Sixth [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 294 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
Initial Cost to Company, Land | 65,352,706 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 65,747,294 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,569,464 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 65,352,706 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 67,316,758 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 132,669,464 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
Accumulated Depreciation | (19,832,874)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
Investment in Real Estate Net | 112,836,590 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A777SixthMember |  |  |  |
801 Brannan [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
Initial Cost to Company, Land | 42,367,171 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 10,605,097 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 42,367,171 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 10,605,097 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 52,972,268 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
Investment in Real Estate Net | 52,972,268 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A801BrannanMember |  |  |  |
A88 Hillside [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Daly City, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 95 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Initial Cost to Company, Land | 7,786,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 31,587,325 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,440,789 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,786,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 33,028,114 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 40,814,914 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Accumulated Depreciation | (4,524,720)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Investment in Real Estate Net | 36,290,194 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A88HillsideMember |  |  |  |
Abington Glen [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Abington, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 90 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Initial Cost to Company, Land | 553,105 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 3,697,396 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,640,482 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 553,105 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 6,337,878 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 6,890,983 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Accumulated Depreciation | (4,166,796)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Investment in Real Estate Net | 2,724,187 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AbingtonGlenMember |  |  |  |
Agoura Hills [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Agoura Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 178 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Initial Cost to Company, Land | 16,700,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 30,103,716 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 199,116 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 16,700,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,302,832 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 47,002,832 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Accumulated Depreciation | (4,124,770)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Investment in Real Estate Net | 42,878,062 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AgouraHillsMember |  |  |  |
Alban Towers [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 229 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Initial Cost to Company, Land | 18,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 89,794,201 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 209,270 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 18,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 90,003,471 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 108,903,471 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Accumulated Depreciation | (9,591,406)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Investment in Real Estate Net | 99,312,065 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlbanTowersMember |  |  |  |
Arbor Terrace [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Sunnyvale, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 175 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Initial Cost to Company, Land | 9,057,300 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,483,642 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,555,686 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,057,300 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 21,039,328 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,096,628 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Accumulated Depreciation | (12,373,084)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Investment in Real Estate Net | 17,723,544 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArborTerraceMember |  |  |  |
Arboretum (MA) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Canton, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 156 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Initial Cost to Company, Land | 4,685,900 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 10,992,751 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,419,397 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,685,900 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 14,412,148 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 19,098,048 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Accumulated Depreciation | (8,193,657)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Investment in Real Estate Net | 10,904,391 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArboretumMaMember |  |  |  |
Artisan on Second [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 118 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Initial Cost to Company, Land | 8,000,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 36,074,600 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 389,768 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,000,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 36,464,368 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 44,464,768 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Accumulated Depreciation | (6,430,450)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Investment in Real Estate Net | 38,034,318 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanOnSecondMember |  |  |  |
Artistry Emeryville (fka Emeryville) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Emeryville, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 261 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Initial Cost to Company, Land | 12,300,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 61,466,267 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,320,923 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,300,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 62,787,190 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 75,087,190 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Accumulated Depreciation | (7,113,391)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Investment in Real Estate Net | 67,973,799 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtistryEmeryvilleMember |  |  |  |
Ashton, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Corona Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 492 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Initial Cost to Company, Land | 2,594,264 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 33,042,397 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,987,399 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,594,264 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 40,029,796 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 42,624,060 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Accumulated Depreciation | (24,912,155)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Investment in Real Estate Net | 17,711,905 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AshtonMember |  |  |  |
Avenue Two [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redwood City, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 123 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Initial Cost to Company, Land | 7,995,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,005,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,462,589 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,995,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,467,589 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 27,462,589 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Accumulated Depreciation | (3,258,935)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Investment in Real Estate Net | 24,203,654 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenueTwoMember |  |  |  |
Azure (fka Mission Bay-Block 13) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Initial Cost to Company, Land | 32,855,115 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 113,753,727 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 32,855,115 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 113,753,727 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 146,608,842 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Investment in Real Estate Net | 146,608,842 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AzurefkaMissionBayBlock13Member |  |  |  |
Ball Park Lofts [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Denver, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 354 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Initial Cost to Company, Land | 5,481,556 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 51,658,741 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,682,528 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,481,556 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 56,341,269 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 61,822,825 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Accumulated Depreciation | (21,540,968)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Investment in Real Estate Net | 40,281,857 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BallParkLoftsMember |  |  |  |
Barrington Place [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Oviedo, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 233 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Initial Cost to Company, Land | 6,990,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 15,740,825 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,018,496 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,990,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,759,321 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 25,749,321 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Accumulated Depreciation | (9,212,819)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Investment in Real Estate Net | 16,536,502 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BarringtonPlaceMember |  |  |  |
Bay Hill [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Long Beach, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 160 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Initial Cost to Company, Land | 7,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 27,437,239 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 963,706 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 28,400,945 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 36,000,945 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Accumulated Depreciation | (10,977,611)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Investment in Real Estate Net | 25,023,334 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BayHillMember |  |  |  |
Beatrice, The [Domain] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 302 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Initial Cost to Company, Land | 114,351,405 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 165,648,595 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 593,292 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 114,351,405 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 166,241,887 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 280,593,292 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Accumulated Depreciation | (23,101,995)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Investment in Real Estate Net | 257,491,297 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BeatriceDomain |  |  |  |
Belle Terra [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Mukilteo, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 235 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Initial Cost to Company, Land | 5,686,861 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 26,070,540 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,142,423 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,686,861 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 27,212,963 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 32,899,824 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Accumulated Depreciation | (10,954,172)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Investment in Real Estate Net | 21,945,652 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleTerraMember |  |  |  |
Belle Arts Condominium Homes, LLC [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bellevue, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 1 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Initial Cost to Company, Land | 63,158 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 248,929 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | (5,320)eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 63,158 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 243,609 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 306,767 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Investment in Real Estate Net | 306,767 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BelleArtsCondominiumHomesLlcMember |  |  |  |
Bella Fontaine [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Marina Del Rey, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 102 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Initial Cost to Company, Land | 9,098,808 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 28,701,192 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 236,115 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,098,808 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 28,937,307 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 38,036,115 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Accumulated Depreciation | (4,398,214)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Investment in Real Estate Net | 33,637,901 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaFontaineMember |  |  |  |
Berkeley Land [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Berkeley, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Initial Cost to Company, Land | 13,908,910 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 8,409,958 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,908,910 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 8,409,958 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 22,318,868 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Investment in Real Estate Net | 22,318,868 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyLandMember |  |  |  |
Bradford Apartments [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Newington, CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 64 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Initial Cost to Company, Land | 401,091 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 2,681,210 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 904,877 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 401,091 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 3,586,087 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 3,987,178 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Accumulated Depreciation | (1,902,145)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Investment in Real Estate Net | 2,085,033 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BradfordApartmentsMember |  |  |  |
Breakwater at Marina Del Rey [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Marina Del Rey, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 224 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 73,040,897 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 390,829 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 73,431,726 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 73,431,726 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Accumulated Depreciation | (8,397,690)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Investment in Real Estate Net | 65,034,036 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BreakwateratMarinaDelReyMember |  |  |  |
Briar Knoll Apts [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Vernon, CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 150 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Initial Cost to Company, Land | 928,972 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 6,209,988 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,440,679 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 928,972 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 8,650,667 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 9,579,639 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Accumulated Depreciation | (4,376,105)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Investment in Real Estate Net | 5,203,534 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarKnollAptsMember |  |  |  |
Briarwood (CA) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Sunnyvale, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 192 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Initial Cost to Company, Land | 9,991,500 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 22,247,278 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,407,674 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,991,500 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 25,654,952 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 35,646,452 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Accumulated Depreciation | (13,931,009)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Investment in Real Estate Net | 21,715,443 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BriarwoodCAMember |  |  |  |
Bridford Lakes II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Greensboro, NC |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Initial Cost to Company, Land | 1,100,564 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 792,508 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,100,564 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 792,508 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 1,893,072 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Investment in Real Estate Net | 1,893,072 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BridfordLakesTwoMember |  |  |  |
Brooklyner (fka 111 Lawrence) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Brooklyn, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 490 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Initial Cost to Company, Land | 40,099,922 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 221,438,631 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 785,785 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 40,099,922 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 222,224,416 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 262,324,338 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Accumulated Depreciation | (30,934,466)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Investment in Real Estate Net | 231,389,872 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheBrooklynerfka111LawrenceMember |  |  |  |
Brookside (CO) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boulder, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 144 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Initial Cost to Company, Land | 3,600,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 10,211,159 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,708,411 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,600,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 12,919,570 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 16,519,970 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Accumulated Depreciation | (7,278,630)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Investment in Real Estate Net | 9,241,340 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BrooksideCoMember |  |  |  |
Cambridge Park [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Cambridge, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 312 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Initial Cost to Company, Land | 31,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 106,048,587 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,280,508 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 31,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 107,329,095 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 138,529,095 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Accumulated Depreciation | (11,557,359)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Investment in Real Estate Net | 126,971,736 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CambridgeParkMember |  |  |  |
Carlyle Mill [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Alexandria, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 317 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Initial Cost to Company, Land | 10,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 51,367,913 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,851,009 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 57,218,922 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 67,218,922 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Accumulated Depreciation | (23,791,982)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Investment in Real Estate Net | 43,426,940 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarlyleMillMember |  |  |  |
Cascade [Domain] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Initial Cost to Company, Land | 23,751,564 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 10,791,356 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 23,751,564 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 10,791,356 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 34,542,920 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Investment in Real Estate Net | 34,542,920 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CascadeDomain |  |  |  |
Centennial (fka Centennial Court & Centennial Tower) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 408 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Initial Cost to Company, Land | 9,700,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 70,080,378 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,937,805 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,700,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 77,018,183 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 86,718,183 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Accumulated Depreciation | (27,564,879)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Investment in Real Estate Net | 59,153,304 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentennialfkaCentennialCourtCentennialTowerMember |  |  |  |
Centre Club [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Ontario, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 312 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Initial Cost to Company, Land | 5,616,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,485,891 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,450,905 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,616,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 26,936,796 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 32,552,796 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Accumulated Depreciation | (13,897,951)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Investment in Real Estate Net | 18,654,845 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubMember |  |  |  |
Centre Club II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Ontario, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 100 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Initial Cost to Company, Land | 1,820,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 9,528,898 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 819,747 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,820,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 10,348,645 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 12,168,645 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Accumulated Depreciation | (4,700,524)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Investment in Real Estate Net | 7,468,121 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CentreClubIiMember |  |  |  |
Church Corner [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Cambridge, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 85 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Initial Cost to Company, Land | 5,220,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,744,643 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,800,805 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,220,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,545,448 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 23,765,448 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Accumulated Depreciation | (7,065,181)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Investment in Real Estate Net | 16,700,267 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChurchCornerMember |  |  |  |
Cierra Crest [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Denver, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 480 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
Initial Cost to Company, Land | 4,803,100 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 34,894,898 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,414,548 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,803,100 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 40,309,446 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 45,112,546 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
Accumulated Depreciation | (24,419,410)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
Investment in Real Estate Net | 20,693,136 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CierraCrestMember |  |  |  |
City Gate at Cupertino (fka Cupertino) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Cupertino, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 311 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
Initial Cost to Company, Land | 40,400,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 95,937,046 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,779,973 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 40,400,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 97,717,019 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 138,117,019 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
Accumulated Depreciation | (10,309,105)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
Investment in Real Estate Net | 127,807,914 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityGateatCupertinofkaCupertinoMember |  |  |  |
City Pointe [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Fullerton, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 183 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
Initial Cost to Company, Land | 6,863,792 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 36,476,208 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 721,681 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,863,792 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 37,197,889 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 44,061,681 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
Accumulated Depreciation | (9,178,639)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
Investment in Real Estate Net | 34,883,042 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityPointeMember |  |  |  |
City Square Bellevue (fka Bellevue) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bellevue, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 191 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Initial Cost to Company, Land | 15,100,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 41,876,257 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,050,569 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,100,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 43,926,826 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 59,026,826 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Accumulated Depreciation | (4,422,723)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Investment in Real Estate Net | 54,604,103 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitySquareBellevuefkaBellevueMember |  |  |  |
Cleo, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 92 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Initial Cost to Company, Land | 6,615,467 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 14,829,335 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,773,750 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,615,467 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,603,085 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 25,218,552 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Accumulated Depreciation | (7,103,987)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Investment in Real Estate Net | 18,114,565 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CleoMember |  |  |  |
Coconut Palm Club [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Coconut Creek, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 301 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Initial Cost to Company, Land | 3,001,700 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 17,678,928 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,041,006 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,001,700 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 21,719,934 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 24,721,634 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Accumulated Depreciation | (12,873,552)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Investment in Real Estate Net | 11,848,082 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoconutPalmClubMember |  |  |  |
Colorado Pointe [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Denver, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 193 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Initial Cost to Company, Land | 5,790,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 28,815,607 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 752,433 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,790,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 29,568,040 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 35,358,040 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Accumulated Depreciation | (10,517,365)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Investment in Real Estate Net | 24,840,675 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColoradoPointeMember |  |  |  |
Copper Canyon [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Highlands Ranch, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 222 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Initial Cost to Company, Land | 1,442,212 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,251,114 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,772,671 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,442,212 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,023,785 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 19,465,997 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Accumulated Depreciation | (9,990,871)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Investment in Real Estate Net | 9,475,126 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CopperCanyonMember |  |  |  |
Corcoran House at DuPont Circle (fka DuPont Circle) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 137 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Initial Cost to Company, Land | 13,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 26,913,113 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 791,502 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 27,704,615 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 41,204,615 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Accumulated Depreciation | (3,669,329)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Investment in Real Estate Net | 37,535,286 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CorcoranHouseatDuPontCirclefkaDuPontCircleMember |  |  |  |
Courthouse Plaza [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 396 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 87,386,024 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,025,937 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 90,411,961 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 90,411,961 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Accumulated Depreciation | (11,097,765)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Investment in Real Estate Net | 79,314,196 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CourthousePlazaMember |  |  |  |
Cove at Boynton Beach I [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boynton Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 252 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Initial Cost to Company, Land | 12,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 31,469,651 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,584,960 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 36,054,611 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 48,654,611 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Accumulated Depreciation | (15,408,055)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Investment in Real Estate Net | 33,246,556 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIMember |  |  |  |
Cove at Boynton Beach II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boynton Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 296 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Initial Cost to Company, Land | 14,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 37,874,719 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 37,874,719 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 52,674,719 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Accumulated Depreciation | (14,615,674)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Investment in Real Estate Net | 38,059,045 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CoveAtBoyntonBeachIiMember |  |  |  |
Creekside (San Mateo) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Mateo, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 192 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Initial Cost to Company, Land | 9,606,600 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 21,193,232 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,609,414 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,606,600 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,802,646 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 34,409,246 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Accumulated Depreciation | (13,787,401)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Investment in Real Estate Net | 20,621,845 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CreeksideSanMateoMember |  |  |  |
Cronins Landing [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Waltham, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 281 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Initial Cost to Company, Land | 32,300,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 85,119,324 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,108,920 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 32,300,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 86,228,244 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 118,528,244 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Accumulated Depreciation | (9,629,005)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Investment in Real Estate Net | 108,899,239 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CroninsLandingMember |  |  |  |
Crystal Place [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 181 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Initial Cost to Company, Land | 17,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 47,918,975 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 822,173 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 17,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 48,741,148 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 65,941,148 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Accumulated Depreciation | (5,368,053)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Investment in Real Estate Net | 60,573,095 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CrystalPlaceMember |  |  |  |
Dartmouth Woods [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Lakewood, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 201 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Initial Cost to Company, Land | 1,609,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 10,832,754 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,497,430 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,609,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 13,330,184 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 14,939,984 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Accumulated Depreciation | (8,473,402)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Investment in Real Estate Net | 6,466,582 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DartmouthWoodsMember |  |  |  |
Dean Estates [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Taunton, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 58 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Initial Cost to Company, Land | 498,080 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 3,329,560 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 809,096 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 498,080 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 4,138,656 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 4,636,736 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Accumulated Depreciation | (2,275,545)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Investment in Real Estate Net | 2,361,191 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeanEstatesMember |  |  |  |
Deerwood (Corona) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Corona, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 316 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Initial Cost to Company, Land | 4,742,200 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 20,272,892 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,430,978 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,742,200 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,703,870 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 29,446,070 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Accumulated Depreciation | (15,468,543)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Investment in Real Estate Net | 13,977,527 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodCoronaMember |  |  |  |
Eagle Canyon [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Chino Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 252 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Initial Cost to Company, Land | 1,808,900 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,274,361 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,553,015 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,808,900 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 23,827,376 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 25,636,276 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Accumulated Depreciation | (15,121,257)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Investment in Real Estate Net | 10,515,019 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EagleCanyonMember |  |  |  |
Edgemont at Bethesda Metro [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bethesda, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 122 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Initial Cost to Company, Land | 13,092,552 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 43,907,448 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 525,086 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,092,552 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 44,432,534 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 57,525,086 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Accumulated Depreciation | (6,807,362)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Investment in Real Estate Net | 50,717,724 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EdgemontAtBethesdaMetroMember |  |  |  |
Elevé [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Glendale, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 208 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Initial Cost to Company, Land | 14,080,560 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 56,419,440 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 79,091 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,080,560 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 56,498,531 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 70,579,091 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Accumulated Depreciation | (2,964,122)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Investment in Real Estate Net | 67,614,969 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ElevMember |  |  |  |
Emerson Place [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boston, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 444 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Initial Cost to Company, Land | 14,855,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 57,566,636 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 16,797,224 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,855,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 74,363,860 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 89,218,860 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Accumulated Depreciation | (47,115,657)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Investment in Real Estate Net | 42,103,203 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EmersonPlaceMember |  |  |  |
Encinitas Heights (fka Encinitas) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Encinitas, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 120 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Initial Cost to Company, Land | 12,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 29,207,497 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 211,769 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 29,419,266 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 41,419,266 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Accumulated Depreciation | (3,528,264)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Investment in Real Estate Net | 37,891,002 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncinitasHeightsfkaEncinitasMember |  |  |  |
Enclave at Waterways [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Deerfield Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 300 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Initial Cost to Company, Land | 15,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 33,194,576 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,023,348 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 35,217,924 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 50,217,924 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Accumulated Depreciation | (13,576,836)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Investment in Real Estate Net | 36,641,088 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWaterwaysMember |  |  |  |
Enclave at Winston Park [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Coconut Creek, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 278 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Initial Cost to Company, Land | 5,560,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 19,939,324 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,124,830 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,560,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 25,064,154 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,624,154 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Accumulated Depreciation | (11,489,835)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Investment in Real Estate Net | 19,134,319 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EnclaveAtWinstonParkMember |  |  |  |
Encore at Sherman Oaks, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Sherman Oaks, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 174 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Initial Cost to Company, Land | 8,700,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 25,446,003 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 985,534 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,700,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 26,431,537 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 35,131,537 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Accumulated Depreciation | (5,201,465)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Investment in Real Estate Net | 29,930,072 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EncoreAtShermanOaksMember |  |  |  |
Estates at Tanglewood [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Westminster, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 504 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Initial Cost to Company, Land | 7,560,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 51,256,538 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,870,210 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,560,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 54,126,748 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 61,686,748 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Accumulated Depreciation | (20,000,446)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Investment in Real Estate Net | 41,686,302 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtTanglewoodMember |  |  |  |
Estates at Wellington Green [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Wellington, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 400 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Initial Cost to Company, Land | 20,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 64,790,850 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,415,710 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 20,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 67,206,560 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 87,206,560 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Accumulated Depreciation | (24,828,948)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Investment in Real Estate Net | 62,377,612 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstatesAtWellingtonGreenMember |  |  |  |
Fountains at Emerald Park (fka Emerald Park) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Dublin, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 324 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Initial Cost to Company, Land | 25,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 83,986,217 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 329,083 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 25,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 84,315,300 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 110,215,300 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Accumulated Depreciation | (9,418,800)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Investment in Real Estate Net | 100,796,500 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FountainsatEmeraldParkfkaEmeraldParkMember |  |  |  |
Fox Hill Apartments [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Enfield, CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 168 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Initial Cost to Company, Land | 1,129,018 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 7,547,256 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,038,591 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,129,018 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 9,585,847 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 10,714,865 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Accumulated Depreciation | (5,061,024)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Investment in Real Estate Net | 5,653,841 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxHillApartmentsMember |  |  |  |
Fremont Center [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Fremont, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 322 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Initial Cost to Company, Land | 25,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 78,753,114 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,138,054 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 25,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 79,891,168 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 105,691,168 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Accumulated Depreciation | (8,436,511)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Investment in Real Estate Net | 97,254,657 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FremontCenterMember |  |  |  |
Gables Grand Plaza [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Coral Gables, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 195 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 44,601,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,243,495 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 51,844,495 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 51,844,495 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Accumulated Depreciation | (20,895,735)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Investment in Real Estate Net | 30,948,760 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GablesGrandPlazaMember |  |  |  |
Gallery, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Hermosa Beach, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 169 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Initial Cost to Company, Land | 18,144,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 46,567,941 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,170,023 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 18,144,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 48,737,964 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 66,881,964 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Accumulated Depreciation | (16,524,852)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Investment in Real Estate Net | 50,357,112 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GalleryMember |  |  |  |
Gatehouse at Pine Lake [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pembroke Pines, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 296 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Initial Cost to Company, Land | 1,896,600 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 17,070,795 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,050,209 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,896,600 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,121,004 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 26,017,604 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Accumulated Depreciation | (14,398,441)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Investment in Real Estate Net | 11,619,163 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseAtPineLakeMember |  |  |  |
Gatehouse on the Green [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Plantation, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 312 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Initial Cost to Company, Land | 2,228,200 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 20,056,270 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 8,529,397 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,228,200 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 28,585,667 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,813,867 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Accumulated Depreciation | (17,655,268)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Investment in Real Estate Net | 13,158,599 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatehouseOnGreenMember |  |  |  |
Gates of Redmond [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redmond, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 180 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Initial Cost to Company, Land | 2,306,100 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 12,064,015 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,008,026 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,306,100 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 17,072,041 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 19,378,141 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Accumulated Depreciation | (10,668,500)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Investment in Real Estate Net | 8,709,641 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatesOfRedmondMember |  |  |  |
Geary Court Yard [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 164 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Initial Cost to Company, Land | 1,722,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 15,471,429 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,464,405 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,722,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,935,834 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 20,658,234 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Accumulated Depreciation | (11,005,136)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Investment in Real Estate Net | 9,653,098 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GearyCourtYardMember |  |  |  |
Glen Meadow [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Franklin, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 288 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Initial Cost to Company, Land | 2,339,330 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,133,588 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,991,967 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,339,330 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 20,125,555 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 22,464,885 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Accumulated Depreciation | (11,374,011)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Investment in Real Estate Net | 11,090,874 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GlenMeadowMember |  |  |  |
Governors Green [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bowie, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 478 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Initial Cost to Company, Land | 19,845,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 73,335,916 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,412,260 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 19,845,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 74,748,176 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 94,593,176 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Accumulated Depreciation | (23,032,994)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Investment in Real Estate Net | 71,560,182 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GovernorsGreenMember |  |  |  |
Greenfield Village [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Rocky Hill , CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 151 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Initial Cost to Company, Land | 911,534 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 6,093,418 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 773,225 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 911,534 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 6,866,643 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 7,778,177 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Accumulated Depreciation | (3,622,365)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Investment in Real Estate Net | 4,155,812 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenfieldVillageMember |  |  |  |
Greenwood Park [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Centennial, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 291 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Initial Cost to Company, Land | 4,365,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 38,372,440 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,833,754 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,365,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 41,206,194 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 45,571,194 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Accumulated Depreciation | (13,229,764)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Investment in Real Estate Net | 32,341,430 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodParkMember |  |  |  |
Greenwood Plaza [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Centennial, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 266 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Initial Cost to Company, Land | 3,990,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 35,846,708 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,744,839 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,990,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 38,591,547 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 42,581,547 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Accumulated Depreciation | (12,762,175)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Investment in Real Estate Net | 29,819,372 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GreenwoodPlazaMember |  |  |  |
Hammocks Place [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Miami, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 296 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Initial Cost to Company, Land | 319,180 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 12,513,467 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,338,503 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 319,180 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 17,851,970 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 18,171,150 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Accumulated Depreciation | (12,636,539)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Investment in Real Estate Net | 5,534,611 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HammocksPlaceMember |  |  |  |
Hampshire Place [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 259 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Initial Cost to Company, Land | 10,806,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 30,335,330 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,447,199 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,806,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 33,782,529 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 44,588,529 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Accumulated Depreciation | (12,995,633)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Investment in Real Estate Net | 31,592,896 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HampshirePlaceMember |  |  |  |
Harbor Steps [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 758 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Initial Cost to Company, Land | 59,387,158 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 158,829,432 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 14,399,390 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 59,387,158 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 173,228,822 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 232,615,980 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Accumulated Depreciation | (59,958,870)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Investment in Real Estate Net | 172,657,110 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarborStepsMember |  |  |  |
Heritage at Stone Ridge [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Burlington, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 180 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Initial Cost to Company, Land | 10,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 31,808,335 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,240,736 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 33,049,071 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 43,849,071 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Accumulated Depreciation | (11,857,633)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Investment in Real Estate Net | 31,991,438 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageAtStoneRidgeMember |  |  |  |
Heritage Ridge [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Lynwood, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 197 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Initial Cost to Company, Land | 6,895,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,983,597 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 885,040 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,895,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,868,637 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 26,763,637 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Accumulated Depreciation | (8,025,318)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Investment in Real Estate Net | 18,738,319 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeritageRidgeMember |  |  |  |
Heron Pointe [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boynton Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 192 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Initial Cost to Company, Land | 1,546,700 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 7,774,676 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,523,556 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,546,700 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 10,298,232 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 11,844,932 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Accumulated Depreciation | (6,663,332)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Investment in Real Estate Net | 5,181,600 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronPointeMember |  |  |  |
Hesby [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | North Hollywood, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 308 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
Initial Cost to Company, Land | 23,299,892 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 102,700,108 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 53,278 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 23,299,892 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 102,753,386 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 126,053,278 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
Accumulated Depreciation | (3,116,198)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
Investment in Real Estate Net | 122,937,080 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HesbyMember |  |  |  |
High Meadow [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Ellington, CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 100 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Initial Cost to Company, Land | 583,679 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 3,901,774 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,204,674 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 583,679 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 5,106,448 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 5,690,127 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Accumulated Depreciation | (2,657,575)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Investment in Real Estate Net | 3,032,552 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighMeadowMember |  |  |  |
Highland Glen [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Westwood, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 180 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Initial Cost to Company, Land | 2,229,095 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,828,153 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,784,639 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,229,095 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,612,792 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,841,887 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Accumulated Depreciation | (10,224,890)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Investment in Real Estate Net | 11,616,997 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenMember |  |  |  |
Highland Glen II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Westwood, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 102 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 19,875,857 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 168,257 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 20,044,114 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 20,044,114 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Accumulated Depreciation | (5,731,936)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Investment in Real Estate Net | 14,312,178 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandGlenTwoMember |  |  |  |
Highlands at Cherry Hill [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Cherry Hills, NJ |  |  |  |
Real Estate And Accumulated Depreciation Units | 170 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Initial Cost to Company, Land | 6,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 21,459,108 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 908,619 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 22,367,727 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 29,167,727 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Accumulated Depreciation | (8,000,482)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Investment in Real Estate Net | 21,167,245 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtCherryHillMember |  |  |  |
Highlands At South Plainfield [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | South Plainfield, NJ |  |  |  |
Real Estate And Accumulated Depreciation Units | 252 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Initial Cost to Company, Land | 10,080,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 37,526,912 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,066,617 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,080,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 38,593,529 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 48,673,529 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Accumulated Depreciation | (13,169,823)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Investment in Real Estate Net | 35,503,706 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HighlandsAtSouthPlainfieldMember |  |  |  |
Hikari [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 128 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Initial Cost to Company, Land | 9,435,760 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 32,564,240 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 226,353 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,435,760 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 32,790,593 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 42,226,353 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Accumulated Depreciation | (5,483,065)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Investment in Real Estate Net | 36,743,288 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HikariMember |  |  |  |
Hudson Crossing [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 259 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Initial Cost to Company, Land | 23,420,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 69,977,699 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,911,448 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 23,420,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 71,889,147 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 95,309,147 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Accumulated Depreciation | (25,933,022)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Investment in Real Estate Net | 69,376,125 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingMember |  |  |  |
Hudson Crossing II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Initial Cost to Company, Land | 10,599,286 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 361,404 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,599,286 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 361,404 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 10,960,690 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Investment in Real Estate Net | 10,960,690 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonCrossingTwoMember |  |  |  |
Hudson Pointe [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Jersey City, NJ |  |  |  |
Real Estate And Accumulated Depreciation Units | 182 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Initial Cost to Company, Land | 5,350,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 41,114,074 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,675,247 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,350,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 43,789,321 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 49,139,321 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Accumulated Depreciation | (16,766,304)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Investment in Real Estate Net | 32,373,017 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HudsonPointeMember |  |  |  |
Hunt Club II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Charlotte, NC |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Initial Cost to Company, Land | 100,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 100,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 100,000 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Investment in Real Estate Net | 100,000 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntClubTwoMember |  |  |  |
Huntington Park [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Everett, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 381 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Initial Cost to Company, Land | 1,597,500 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 14,367,864 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,321,606 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,597,500 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,689,470 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,286,970 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Accumulated Depreciation | (14,109,888)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Investment in Real Estate Net | 7,177,082 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HuntingtonParkMember |  |  |  |
Jia [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 280 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Initial Cost to Company, Land | 14,791,831 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 74,818,783 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 92,185 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,791,831 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 74,910,968 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 89,702,799 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Accumulated Depreciation | (3,493,876)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Investment in Real Estate Net | 86,208,923 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JiaMember |  |  |  |
Junction 47 (fka West Seattle) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Initial Cost to Company, Land | 11,726,305 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 32,787,325 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 11,726,305 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 32,787,325 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 44,513,630 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Investment in Real Estate Net | 44,513,630 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Junction47fkaWestSeattleMember |  |  |  |
Kenwood Mews [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Burbank, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 141 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Initial Cost to Company, Land | 14,100,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 24,662,883 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,139,424 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,100,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 27,802,307 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 41,902,307 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Accumulated Depreciation | (9,416,490)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Investment in Real Estate Net | 32,485,817 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KenwoodMewsMember |  |  |  |
Kings Colony (FL) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Miami, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 480 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Initial Cost to Company, Land | 19,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 48,379,586 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,959,307 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 19,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 54,338,893 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 73,538,893 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Accumulated Depreciation | (20,308,990)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Investment in Real Estate Net | 53,229,903 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KingsColonyFlMember |  |  |  |
Landings at Pembroke Lakes [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pembroke Pines, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 358 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Initial Cost to Company, Land | 17,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 24,460,989 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,417,847 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 17,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 29,878,836 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 47,778,836 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Accumulated Depreciation | (13,049,614)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Investment in Real Estate Net | 34,729,222 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPembrokeLakesMember |  |  |  |
Landings at Port Imperial [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | W. New York, NJ |  |  |  |
Real Estate And Accumulated Depreciation Units | 276 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Initial Cost to Company, Land | 27,246,045 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 37,741,050 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,383,017 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 27,246,045 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 45,124,067 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 72,370,112 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Accumulated Depreciation | (23,206,569)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Investment in Real Estate Net | 49,163,543 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LandingsAtPortImperialMember |  |  |  |
Legacy at Highlands Ranch [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Highlands Ranch, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 422 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Initial Cost to Company, Land | 6,330,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 37,557,013 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,638,356 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,330,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 40,195,369 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 46,525,369 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Accumulated Depreciation | (15,555,886)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Investment in Real Estate Net | 30,969,483 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LegacyAtHighlandsRanchMember |  |  |  |
Lincoln Heights [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Quincy, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 336 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Initial Cost to Company, Land | 5,928,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 33,595,262 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 11,650,955 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,928,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 45,246,217 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 51,174,617 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Accumulated Depreciation | (27,775,700)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Investment in Real Estate Net | 23,398,917 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LincolnHeightsMember |  |  |  |
Loft 590 [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 212 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Initial Cost to Company, Land | 20,100,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 67,909,023 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 103,786 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 20,100,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 68,012,809 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 88,112,809 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Accumulated Depreciation | (6,942,600)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Investment in Real Estate Net | 81,170,209 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Loft590Member |  |  |  |
Lofts at Kendall Square (fka Kendall Square) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Cambridge, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 186 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Initial Cost to Company, Land | 23,300,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 78,445,657 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,018,131 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 23,300,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 80,463,788 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 103,763,788 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Accumulated Depreciation | (8,212,576)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Investment in Real Estate Net | 95,551,212 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LoftsatKendallSquarefkaKendallSquareMember |  |  |  |
Longacre House [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 293 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Initial Cost to Company, Land | 73,170,045 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 53,962,510 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,359,584 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 73,170,045 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 55,322,094 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 128,492,139 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Accumulated Depreciation | (17,329,569)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Investment in Real Estate Net | 111,162,570 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongacreHouseMember |  |  |  |
Longfellow Place [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boston, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 710 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Initial Cost to Company, Land | 53,164,160 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 186,182,421 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 79,837,257 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 53,164,160 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 266,019,678 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 319,183,838 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Accumulated Depreciation | (143,763,840)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Investment in Real Estate Net | 175,419,998 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongfellowPlaceMember |  |  |  |
Mantena [Domain] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 98 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Initial Cost to Company, Land | 22,346,513 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 61,501,158 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 261,029 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 22,346,513 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 61,762,187 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 84,108,700 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Accumulated Depreciation | (6,972,870)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Investment in Real Estate Net | 77,135,830 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MantenaDomain |  |  |  |
Marina 41 (fka Marina Del Rey) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Marina Del Rey, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 623 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 168,842,442 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,512,278 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 172,354,720 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 172,354,720 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Accumulated Depreciation | (20,885,949)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Investment in Real Estate Net | 151,468,771 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Marina41fkaMarinaDelReyMember |  |  |  |
Mariposa at Playa Del Rey (fka Playa Del Rey) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Playa Del Rey, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 354 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Initial Cost to Company, Land | 60,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 89,311,482 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,751,781 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 60,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 92,063,263 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 152,963,263 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Accumulated Depreciation | (10,307,910)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Investment in Real Estate Net | 142,655,353 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MariposaatPlayaDelReyfkaPlayaDelReyMember |  |  |  |
Marquessa [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Corona Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 336 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Initial Cost to Company, Land | 6,888,500 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 21,604,584 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,638,093 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,888,500 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 25,242,677 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 32,131,177 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Accumulated Depreciation | (15,261,218)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Investment in Real Estate Net | 16,869,959 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarquessaMember |  |  |  |
Martine, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bellevue, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 67 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Initial Cost to Company, Land | 3,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 9,616,264 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,168,293 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 12,784,557 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 15,984,557 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Accumulated Depreciation | (4,645,681)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Investment in Real Estate Net | 11,338,876 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MartineMember |  |  |  |
Milano Lofts [Domain] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 99 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Initial Cost to Company, Land | 8,125,216 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 27,378,784 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 337,583 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,125,216 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 27,716,367 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 35,841,583 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Accumulated Depreciation | (3,549,329)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Investment in Real Estate Net | 32,292,254 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MilanoLoftsDomain |  |  |  |
Millikan [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Irvine, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Initial Cost to Company, Land | 11,049,027 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 30,318,032 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 11,049,027 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,318,032 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 41,367,059 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Investment in Real Estate Net | 41,367,059 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillikanMember |  |  |  |
Miramar Lakes [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Miramar, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 344 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Initial Cost to Company, Land | 17,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 51,487,235 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,246,702 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 17,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 53,733,937 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 70,933,937 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Accumulated Depreciation | (19,418,255)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Investment in Real Estate Net | 51,515,682 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MiramarLakesMember |  |  |  |
Mosaic at Largo Station [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Hyattsville, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 242 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Initial Cost to Company, Land | 4,120,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 42,477,297 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 543,227 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,120,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 43,020,524 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 47,141,324 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Accumulated Depreciation | (11,883,141)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Investment in Real Estate Net | 35,258,183 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtLargoStationMember |  |  |  |
Mozaic at Union Station [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 272 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Initial Cost to Company, Land | 8,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 52,529,446 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,415,603 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 53,945,049 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 62,445,049 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Accumulated Depreciation | (16,666,145)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Investment in Real Estate Net | 45,778,904 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MozaicAtUnionStationMember |  |  |  |
Murray Hill Tower (fka Murray Hill) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 270 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Initial Cost to Company, Land | 75,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 102,705,401 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,298,858 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 75,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 105,004,259 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 180,804,259 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Accumulated Depreciation | (14,081,429)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Investment in Real Estate Net | 166,722,830 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MurrayHillTowerfkaMurrayHillMember |  |  |  |
Northglen [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Valencia, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 234 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Initial Cost to Company, Land | 9,360,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 20,778,553 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,130,660 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,360,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 22,909,213 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 32,269,213 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Accumulated Depreciation | (11,564,178)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Investment in Real Estate Net | 20,705,035 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthglenMember |  |  |  |
Northlake (MD) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Germantown, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 304 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Initial Cost to Company, Land | 15,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,142,302 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 10,324,900 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 33,467,202 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 48,467,202 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Accumulated Depreciation | (16,634,313)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Investment in Real Estate Net | 31,832,889 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthlakeMdMember |  |  |  |
Northridge [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pleasant Hill, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 221 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Initial Cost to Company, Land | 5,527,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 14,691,705 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 10,017,139 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,527,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,708,844 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,236,644 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Accumulated Depreciation | (14,954,766)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Investment in Real Estate Net | 15,281,878 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthridgeMember |  |  |  |
Oak Mill One [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Germantown, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 208 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Initial Cost to Company, Land | 10,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 13,155,522 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,666,964 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 20,822,486 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,822,486 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Accumulated Depreciation | (10,690,161)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Investment in Real Estate Net | 20,132,325 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillOneMember |  |  |  |
Oak Park North [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Agoura Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 220 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Initial Cost to Company, Land | 1,706,900 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 15,362,666 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,313,705 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,706,900 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,676,371 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,383,271 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Accumulated Depreciation | (12,773,791)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Investment in Real Estate Net | 8,609,480 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkNorthMember |  |  |  |
Oak Park South [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Agoura Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 224 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Initial Cost to Company, Land | 1,683,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 15,154,608 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,367,145 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,683,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,521,753 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,205,553 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Accumulated Depreciation | (12,723,696)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Investment in Real Estate Net | 8,481,857 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakParkSouthMember |  |  |  |
Oaks at Falls Church [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Falls Church, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 176 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Initial Cost to Company, Land | 20,240,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 20,152,616 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,918,112 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 20,240,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,070,728 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 44,310,728 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Accumulated Depreciation | (9,576,777)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Investment in Real Estate Net | 34,733,951 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksAtFallsChurchMember |  |  |  |
Oakwood Boston [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boston, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 94 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Initial Cost to Company, Land | 22,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 28,672,979 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 803,040 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 22,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 29,476,019 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 51,676,019 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Accumulated Depreciation | (3,687,255)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Investment in Real Estate Net | 47,988,764 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodBostonMember |  |  |  |
Oakwood Crystal City [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 162 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Initial Cost to Company, Land | 15,400,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 35,474,336 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 320,085 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,400,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 35,794,421 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 51,194,421 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Accumulated Depreciation | (4,189,805)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Investment in Real Estate Net | 47,004,616 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodCrystalCityMember |  |  |  |
Oakwood Marina Del Rey [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Marina Del Rey, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 597 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 120,795,359 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,287,912 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 122,083,271 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 122,083,271 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Accumulated Depreciation | (14,413,937)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Investment in Real Estate Net | 107,669,334 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakwoodMarinaDelReyMember |  |  |  |
Oasis at Delray Beach I [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Delray Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 196 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Initial Cost to Company, Land | 5,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 25,150,766 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 793,145 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 25,943,911 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 31,843,911 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Accumulated Depreciation | (3,587,721)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Investment in Real Estate Net | 28,256,190 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIMember |  |  |  |
Oasis at Delray Beach II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Delray Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 128 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Initial Cost to Company, Land | 3,840,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,144,377 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,844 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,840,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,146,221 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,986,221 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Accumulated Depreciation | (1,077,031)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Investment in Real Estate Net | 20,909,190 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OasisatDelrayBeachIIMember |  |  |  |
Ocean Crest [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Solana Beach, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 146 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Initial Cost to Company, Land | 5,111,200 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 11,910,438 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,935,597 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,111,200 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 14,846,035 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 19,957,235 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Accumulated Depreciation | (8,670,106)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Investment in Real Estate Net | 11,287,129 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OceanCrestMember |  |  |  |
Olde Redmond Place [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redmond, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 192 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
Initial Cost to Company, Land | 4,807,100 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 14,126,038 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,477,139 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,807,100 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,603,177 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 23,410,277 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
Accumulated Depreciation | (11,824,788)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
Investment in Real Estate Net | 11,585,489 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OldeRedmondPlaceMember |  |  |  |
One Henry Adams [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Initial Cost to Company, Land | 30,952,393 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 8,970,233 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 30,952,393 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 8,970,233 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 39,922,626 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Investment in Real Estate Net | 39,922,626 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OneHenryAdamsMember |  |  |  |
Orchard Ridge [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Lynnwood, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 104 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Initial Cost to Company, Land | 480,600 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 4,372,033 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,640,650 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 480,600 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 6,012,683 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 6,493,283 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Accumulated Depreciation | (4,200,950)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Investment in Real Estate Net | 2,292,333 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OrchardRidgeMember |  |  |  |
Pacific Place [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 430 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Initial Cost to Company, Land | 32,250,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 110,750,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 572,991 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 32,250,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 111,322,991 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 143,572,991 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Accumulated Depreciation | (9,391,616)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Investment in Real Estate Net | 134,181,375 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PacificPlaceMember |  |  |  |
Palm Trace Landings [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Davie, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 768 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Initial Cost to Company, Land | 38,400,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 105,693,432 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,412,321 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 38,400,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 110,105,753 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 148,505,753 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Accumulated Depreciation | (39,754,320)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Investment in Real Estate Net | 108,751,433 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PalmTraceLandingsMember |  |  |  |
Parc 77 [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 137 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Initial Cost to Company, Land | 40,504,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,025,679 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,211,253 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 40,504,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 23,236,932 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 63,740,932 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Accumulated Depreciation | (9,380,110)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Investment in Real Estate Net | 54,360,822 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Parc77Member |  |  |  |
Parc Cameron [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 166 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Initial Cost to Company, Land | 37,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 9,855,597 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,069,564 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 37,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 15,925,161 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 53,525,161 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Accumulated Depreciation | (7,957,659)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Investment in Real Estate Net | 45,567,502 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcCameronMember |  |  |  |
Parc Coliseum [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 177 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Initial Cost to Company, Land | 52,654,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,045,751 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,981,026 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 52,654,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 31,026,777 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 83,680,777 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Accumulated Depreciation | (12,833,483)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Investment in Real Estate Net | 70,847,294 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcColiseumMember |  |  |  |
Parc East Towers [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 324 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Initial Cost to Company, Land | 102,163,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 108,989,402 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,888,302 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 102,163,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 116,877,704 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 219,040,704 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Accumulated Depreciation | (35,905,223)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Investment in Real Estate Net | 183,135,481 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParcEastTowersMember |  |  |  |
Parc on Powell (fka Parkside at Emeryville) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Emeryville, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Initial Cost to Company, Land | 16,657,467 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 55,107,488 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 16,657,467 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 55,107,488 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 71,764,955 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Investment in Real Estate Net | 71,764,955 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParconPowellfkaParksideatEmeryvilleMember |  |  |  |
Park Aire [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Wellington, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 268 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Initial Cost to Company, Land | 8,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 40,917,239 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,790 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 40,925,029 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 48,925,029 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Accumulated Depreciation | (1,877,464)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Investment in Real Estate Net | 47,047,565 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAireMember |  |  |  |
Park at Pentagon Row (fka Pentagon City) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 298 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Initial Cost to Company, Land | 28,300,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 78,838,184 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 313,935 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 28,300,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 79,152,119 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 107,452,119 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Accumulated Depreciation | (8,734,530)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Investment in Real Estate Net | 98,717,589 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkatPentagonRowfkaPentagonCityMember |  |  |  |
Park at Turtle Run The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Coral Springs, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 257 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Initial Cost to Company, Land | 15,420,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 36,064,629 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,328,323 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,420,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 37,392,952 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 52,812,952 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Accumulated Depreciation | (14,395,758)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Investment in Real Estate Net | 38,417,194 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkAtTurtleRunMember |  |  |  |
Park Connecticut [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 142 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Initial Cost to Company, Land | 13,700,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 59,087,519 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 438,263 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,700,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 59,525,782 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 73,225,782 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Accumulated Depreciation | (5,926,288)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Investment in Real Estate Net | 67,299,494 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkConnecticutMember |  |  |  |
Park Hacienda (fka Hacienda) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pleasanton, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 540 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Initial Cost to Company, Land | 43,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 128,753,359 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 418,551 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 43,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 129,171,910 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 172,371,910 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Accumulated Depreciation | (15,002,224)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Investment in Real Estate Net | 157,369,686 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkHaciendafkaHaciendaMember |  |  |  |
Park West (CA) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 444 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Initial Cost to Company, Land | 3,033,500 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 27,302,383 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 8,693,445 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,033,500 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 35,995,828 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 39,029,328 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Accumulated Depreciation | (23,298,739)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Investment in Real Estate Net | 15,730,589 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkWestCaMember |  |  |  |
Parkfield [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Denver, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 476 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Initial Cost to Company, Land | 8,330,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 28,667,618 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,305,900 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,330,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 31,973,518 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 40,303,518 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Accumulated Depreciation | (16,037,171)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Investment in Real Estate Net | 24,266,347 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkfieldMember |  |  |  |
Parkside [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Union City, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 208 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Initial Cost to Company, Land | 6,246,700 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 11,827,453 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,900,616 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,246,700 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 15,728,069 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,974,769 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Accumulated Depreciation | (10,008,760)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Investment in Real Estate Net | 11,966,009 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParksideMember |  |  |  |
Pegasus [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 322 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Initial Cost to Company, Land | 18,094,052 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 81,905,948 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,301,007 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 18,094,052 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 84,206,955 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 102,301,007 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Accumulated Depreciation | (16,114,037)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Investment in Real Estate Net | 86,186,970 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PegasusMember |  |  |  |
Phillips Park [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Wellesley, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 49 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Initial Cost to Company, Land | 816,922 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 5,460,955 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,092,085 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 816,922 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 6,553,040 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 7,369,962 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Accumulated Depreciation | (3,527,505)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Investment in Real Estate Net | 3,842,457 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PhillipsParkMember |  |  |  |
Playa Pacifica [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Hermosa Beach, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 285 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Initial Cost to Company, Land | 35,100,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 33,473,822 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 8,205,881 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 35,100,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 41,679,703 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 76,779,703 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Accumulated Depreciation | (18,071,577)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Investment in Real Estate Net | 58,708,126 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PlayaPacificaMember |  |  |  |
Portofino [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Chino Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 176 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Initial Cost to Company, Land | 3,572,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 14,660,994 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,469,722 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,572,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,130,716 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,703,116 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Accumulated Depreciation | (10,641,056)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Investment in Real Estate Net | 11,062,060 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoMember |  |  |  |
Portofino (Val) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Valencia, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 216 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Initial Cost to Company, Land | 8,640,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 21,487,126 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,770,117 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,640,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,257,243 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 32,897,243 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Accumulated Depreciation | (12,417,735)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Investment in Real Estate Net | 20,479,508 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortofinoValMember |  |  |  |
Portside Towers [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Jersey City, NJ |  |  |  |
Real Estate And Accumulated Depreciation Units | 527 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Initial Cost to Company, Land | 22,487,006 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 96,842,913 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 19,411,866 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 22,487,006 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 116,254,779 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 138,741,785 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Accumulated Depreciation | (66,421,447)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Investment in Real Estate Net | 72,320,338 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortsideTowersMember |  |  |  |
Potrero [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Initial Cost to Company, Land | 40,830,011 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 31,523,663 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 40,830,011 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 31,523,663 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 72,353,674 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Investment in Real Estate Net | 72,353,674 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PotreroMember |  |  |  |
Prado (fka Glendale) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Glendale, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 264 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 67,977,313 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,102,967 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 69,080,280 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 69,080,280 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Accumulated Depreciation | (7,364,217)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Investment in Real Estate Net | 61,716,063 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PradofkaGlendaleMember |  |  |  |
Preserve at Deer Creek [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Deerfield Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 540 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Initial Cost to Company, Land | 13,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 60,011,208 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 11,156,351 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 71,167,559 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 84,667,559 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Accumulated Depreciation | (27,613,392)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Investment in Real Estate Net | 57,054,167 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PreserveAtDeerCreekMember |  |  |  |
Prime, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 256 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Initial Cost to Company, Land | 32,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 64,436,539 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,229,561 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 32,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 65,666,100 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 97,666,100 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Accumulated Depreciation | (21,188,390)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Investment in Real Estate Net | 76,477,710 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PrimeMember |  |  |  |
Promenade at Aventura [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Aventura, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 296 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Initial Cost to Company, Land | 13,320,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 30,353,748 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,987,572 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,320,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 37,341,320 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 50,661,320 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Accumulated Depreciation | (18,578,470)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Investment in Real Estate Net | 32,082,850 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtAventuraMember |  |  |  |
Promenade at Town Center I [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Valencia, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 294 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Initial Cost to Company, Land | 14,700,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 35,390,279 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,630,025 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,700,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 38,020,304 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 52,720,304 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Accumulated Depreciation | (15,471,823)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Investment in Real Estate Net | 37,248,481 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTownCenterIMember |  |  |  |
Promenade at Tower Center II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Valencia, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 270 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Initial Cost to Company, Land | 13,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 34,405,636 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,374,656 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 36,780,292 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 50,280,292 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Accumulated Depreciation | (14,862,278)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Investment in Real Estate Net | 35,418,014 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtTowerCenterIiMember |  |  |  |
Promenade at Wyndham Lakes [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Coral Springs, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 332 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Initial Cost to Company, Land | 6,640,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 26,743,760 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,169,866 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,640,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 31,913,626 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 38,553,626 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Accumulated Depreciation | (16,302,998)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Investment in Real Estate Net | 22,250,628 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeAtWyndhamLakesMember |  |  |  |
Promenade Terrace [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Corona, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 330 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Initial Cost to Company, Land | 2,272,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 20,546,289 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,975,907 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,272,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 26,522,196 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 28,794,996 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Accumulated Depreciation | (17,641,430)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Investment in Real Estate Net | 11,153,566 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PromenadeTerraceMember |  |  |  |
Quarry Hills [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Quincy, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 316 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Initial Cost to Company, Land | 26,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 84,411,162 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 417,784 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 26,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 84,828,946 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 111,728,946 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Accumulated Depreciation | (9,818,230)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Investment in Real Estate Net | 101,910,716 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_QuarryHillsMember |  |  |  |
Red 160 (fka Redmond Way) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redmond, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 250 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Initial Cost to Company, Land | 15,546,376 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 65,320,010 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 761,676 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,546,376 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 66,081,686 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 81,628,062 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Accumulated Depreciation | (8,975,666)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Investment in Real Estate Net | 72,652,396 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Red160Member |  |  |  |
Red Road Commons [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Miami, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 404 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Initial Cost to Company, Land | 27,383,547 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 99,656,440 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,120,113 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 27,383,547 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 101,776,553 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 129,160,100 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Accumulated Depreciation | (18,087,040)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Investment in Real Estate Net | 111,073,060 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedRoadCommonsMember |  |  |  |
Redmond Court [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bellevue, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 206 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Initial Cost to Company, Land | 10,300,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 33,488,745 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 607,648 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,300,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 34,096,393 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 44,396,393 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Accumulated Depreciation | (3,981,275)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Investment in Real Estate Net | 40,415,118 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RedmondCourtMember |  |  |  |
Regency Palms [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Huntington Beach, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 310 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Initial Cost to Company, Land | 1,857,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,713,254 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,435,303 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,857,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 22,148,557 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 24,005,957 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Accumulated Depreciation | (15,007,785)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Investment in Real Estate Net | 8,998,172 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RegencyPalmsMember |  |  |  |
Renaissance Villas [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Berkeley, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 34 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Initial Cost to Company, Land | 2,458,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 4,542,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 140,950 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,458,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 4,682,950 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 7,140,950 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Accumulated Depreciation | (1,389,449)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Investment in Real Estate Net | 5,751,501 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RenaissanceVillasMember |  |  |  |
Reserve at Ashley Lake [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boynton Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 440 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Initial Cost to Company, Land | 3,520,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,332,494 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,923,362 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,520,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,255,856 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 33,776,256 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Accumulated Depreciation | (18,742,933)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Investment in Real Estate Net | 15,033,323 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtAshleyLakeMember |  |  |  |
Reserve at Mountain View (fka Mountain View) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Mountain View, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 180 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Initial Cost to Company, Land | 27,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 33,029,605 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 242,910 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 27,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 33,272,515 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 60,272,515 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Accumulated Depreciation | (4,243,783)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Investment in Real Estate Net | 56,028,732 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatMountainViewfkaMountainViewMember |  |  |  |
Reserve At Town Center II (WA) Member |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Mill Creek, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 100 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Initial Cost to Company, Land | 4,310,417 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 17,165,142 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 84,183 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,310,417 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 17,249,325 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,559,742 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Accumulated Depreciation | (3,154,760)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Investment in Real Estate Net | 18,404,982 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiWaMember |  |  |  |
Reserve at Town Center III [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Mill Creek, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 95 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Initial Cost to Company, Land | 2,089,388 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 19,174,300 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,431 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,089,388 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,175,731 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,265,119 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Accumulated Depreciation | (736,100)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Investment in Real Estate Net | 20,529,019 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtTownCenterIiiMember |  |  |  |
Residences at Bayview [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pompano Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 225 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Initial Cost to Company, Land | 5,783,545 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 39,334,455 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,213,792 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,783,545 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 40,548,247 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 46,331,792 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Accumulated Depreciation | (9,079,046)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Investment in Real Estate Net | 37,252,746 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesAtBayviewMember |  |  |  |
Residences at Westgate I (fka Westage II) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pasadena, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 252 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Initial Cost to Company, Land | 17,859,785 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 106,746,558 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 17,859,785 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 106,746,558 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 124,606,343 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Accumulated Depreciation | (1,278,424)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Investment in Real Estate Net | 123,327,919 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIfkaWestageIIMember |  |  |  |
Residences at Westgate II (fka Westgage III) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pasadena, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Initial Cost to Company, Land | 12,118,061 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 33,542,963 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,118,061 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 33,542,963 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 45,661,024 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Investment in Real Estate Net | 45,661,024 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ResidencesatWestgateIIfkaWestgageIIIMember |  |  |  |
Reunion at Redmond Ridge (fka Redmond Ridge) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redmond, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 321 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Initial Cost to Company, Land | 6,975,705 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 46,175,001 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 300,070 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,975,705 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 46,475,071 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 53,450,776 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Accumulated Depreciation | (11,417,545)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Investment in Real Estate Net | 42,033,231 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReunionAtRedmondRidgeMember |  |  |  |
Rianna I [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 78 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Initial Cost to Company, Land | 2,268,160 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 14,864,482 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 425,331 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,268,160 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 15,289,813 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 17,557,973 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Accumulated Depreciation | (3,897,325)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Investment in Real Estate Net | 13,660,648 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIMember |  |  |  |
Ridgewood Village I&II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Diego, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 408 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Initial Cost to Company, Land | 11,809,500 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 34,004,048 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,650,898 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 11,809,500 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 38,654,946 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 50,464,446 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Accumulated Depreciation | (19,997,912)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Investment in Real Estate Net | 30,466,534 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RidgewoodVillageIAndIIMember |  |  |  |
Riva Terra I (fka Redwood Shores) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redwood City, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 304 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Initial Cost to Company, Land | 34,963,355 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 84,587,658 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 957,762 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 34,963,355 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 85,545,420 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 120,508,775 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Accumulated Depreciation | (9,986,376)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Investment in Real Estate Net | 110,522,399 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIMember |  |  |  |
Riva Terra II (fka Harborside) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redwood City, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 149 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
Initial Cost to Company, Land | 17,136,645 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 40,536,531 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,331,562 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 17,136,645 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 41,868,093 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 59,004,738 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
Accumulated Depreciation | (4,516,747)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
Investment in Real Estate Net | 54,487,991 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RivaTerraIIMember |  |  |  |
River Tower [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 323 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Initial Cost to Company, Land | 118,669,441 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 98,880,559 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,781,678 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 118,669,441 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 104,662,237 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 223,331,678 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Accumulated Depreciation | (28,053,948)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Investment in Real Estate Net | 195,277,730 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverTowerMember |  |  |  |
Riverpark [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redmond, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 319 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Initial Cost to Company, Land | 14,355,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 80,894,049 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 625,094 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,355,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 81,519,143 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 95,874,143 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Accumulated Depreciation | (11,733,102)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Investment in Real Estate Net | 84,141,041 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverparkMember |  |  |  |
Rivers Bend (CT) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Windsor, CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 373 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Initial Cost to Company, Land | 3,325,517 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 22,573,826 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,186,964 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,325,517 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 25,760,790 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 29,086,307 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Accumulated Depreciation | (13,537,132)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Investment in Real Estate Net | 15,549,175 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiversBendCTMember |  |  |  |
Riverview Condominiums [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Norwalk, CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 92 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Initial Cost to Company, Land | 2,300,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 7,406,730 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,467,328 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,300,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 9,874,058 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 12,174,058 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Accumulated Depreciation | (5,541,526)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Investment in Real Estate Net | 6,632,532 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiverviewCondominiumsMember |  |  |  |
Rolling Green (Milford) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Milford, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 304 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Initial Cost to Company, Land | 2,012,350 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 13,452,150 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,922,309 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,012,350 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,374,459 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,386,809 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Accumulated Depreciation | (10,707,965)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Investment in Real Estate Net | 10,678,844 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RollingGreenMilfordMember |  |  |  |
Rosecliff II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Quincy, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 130 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Initial Cost to Company, Land | 4,922,840 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 30,202,160 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 477,564 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,922,840 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,679,724 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 35,602,564 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Accumulated Depreciation | (5,256,770)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Investment in Real Estate Net | 30,345,794 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffIiMember |  |  |  |
Sabal Pointe [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Coral Springs, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 276 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Initial Cost to Company, Land | 1,951,600 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 17,570,508 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,140,842 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,951,600 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,711,350 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 26,662,950 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Accumulated Depreciation | (15,728,545)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Investment in Real Estate Net | 10,934,405 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SabalPointeMember |  |  |  |
Sage Condominium Homes, LLC [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Everett, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 123 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Initial Cost to Company, Land | 2,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 12,021,256 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 632,845 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 12,654,101 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 15,154,101 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Accumulated Depreciation | (4,686,644)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Investment in Real Estate Net | 10,467,457 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SageCondominiumHomesLlcMember |  |  |  |
Sakura Crossing [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 230 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Initial Cost to Company, Land | 14,641,990 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 42,858,010 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 445,099 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,641,990 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 43,303,109 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 57,945,099 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Accumulated Depreciation | (8,084,997)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Investment in Real Estate Net | 49,860,102 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SakuraCrossingMember |  |  |  |
Savoy at Dayton Station I & II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Aurora, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 444 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Initial Cost to Company, Land | 5,450,295 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 38,765,670 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,405,215 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,450,295 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 42,170,885 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 47,621,180 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Accumulated Depreciation | (17,320,767)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Investment in Real Estate Net | 30,300,413 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyAtDaytonStationIIiMember |  |  |  |
Savoy at Dayton Station III (fka Savoy III) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Aurora, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 168 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Initial Cost to Company, Land | 659,165 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 21,274,302 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 79,142 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 659,165 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 21,353,444 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 22,012,609 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Accumulated Depreciation | (2,539,418)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Investment in Real Estate Net | 19,473,191 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SavoyatDaytonStationIIIfkaSavoyIIIMember |  |  |  |
Scarborough Square [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Rockville, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 121 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Initial Cost to Company, Land | 1,815,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 7,608,126 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,968,824 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,815,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 10,576,950 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 12,391,950 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Accumulated Depreciation | (6,577,786)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Investment in Real Estate Net | 5,814,164 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ScarboroughSquareMember |  |  |  |
Seventh & James [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 96 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Initial Cost to Company, Land | 663,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 5,974,803 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,665,212 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 663,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 9,640,015 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 10,303,815 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Accumulated Depreciation | (6,286,805)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Investment in Real Estate Net | 4,017,010 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SeventhJamesMember |  |  |  |
Shadow Creek [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Winter Springs, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 280 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Initial Cost to Company, Land | 6,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 21,719,768 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,299,111 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,018,879 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,018,879 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Accumulated Depreciation | (9,913,377)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Investment in Real Estate Net | 20,105,502 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ShadowCreekMember |  |  |  |
Sheffield Court [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 597 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Initial Cost to Company, Land | 3,342,381 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 31,337,332 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 13,400,936 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,342,381 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 44,738,268 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 48,080,649 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Accumulated Depreciation | (29,786,965)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Investment in Real Estate Net | 18,293,684 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheffieldCourtMember |  |  |  |
Sheridan Lake Club [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Dania Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 240 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Initial Cost to Company, Land | 12,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,170,580 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,964,151 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 25,134,731 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 37,134,731 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Accumulated Depreciation | (9,437,897)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Investment in Real Estate Net | 27,696,834 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanLakeClubMember |  |  |  |
Sheridan Ocean Club Combined [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Dania Beach, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 648 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Initial Cost to Company, Land | 18,313,414 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 47,091,594 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 17,651,928 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 18,313,414 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 64,743,522 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 83,056,936 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Accumulated Depreciation | (32,954,888)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Investment in Real Estate Net | 50,102,048 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SheridanOceanClubCombinedMember |  |  |  |
Skycrest [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Valencia, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 264 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Initial Cost to Company, Land | 10,560,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 25,574,457 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,362,878 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,560,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 27,937,335 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 38,497,335 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Accumulated Depreciation | (14,051,911)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Investment in Real Estate Net | 24,445,424 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkycrestMember |  |  |  |
Skylark [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Union City, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 174 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Initial Cost to Company, Land | 1,781,600 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,731,916 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,659,208 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,781,600 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,391,124 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,172,724 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Accumulated Depreciation | (10,873,674)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Investment in Real Estate Net | 10,299,050 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylarkMember |  |  |  |
Skyline Terrace [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Burlingame, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 138 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Initial Cost to Company, Land | 16,836,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 35,414,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,187,335 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 16,836,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 39,601,335 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 56,437,335 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Accumulated Depreciation | (8,225,224)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Investment in Real Estate Net | 48,212,111 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTerraceMember |  |  |  |
Skyline Towers [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Falls Church, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 939 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Initial Cost to Company, Land | 78,278,200 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 91,485,591 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 32,273,806 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 78,278,200 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 123,759,397 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 202,037,597 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Accumulated Depreciation | (54,795,726)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Investment in Real Estate Net | 147,241,871 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkylineTowersMember |  |  |  |
Sonterra at Foothill Ranch [Domain] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Foothill Ranch, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 300 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
Initial Cost to Company, Land | 7,503,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 24,048,507 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,564,362 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,503,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 26,612,869 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 34,116,269 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
Accumulated Depreciation | (15,189,055)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
Investment in Real Estate Net | 18,927,214 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SonterraatFoothillRanchDomain |  |  |  |
South City Station (fka South San Francisco) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 360 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
Initial Cost to Company, Land | 68,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 79,476,861 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,392,508 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 68,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 80,869,369 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 149,769,369 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
Accumulated Depreciation | (9,849,234)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
Investment in Real Estate Net | 139,920,135 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthCityStationfkaSouthSanFranciscoMember |  |  |  |
South Winds [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Fall River, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 404 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Initial Cost to Company, Land | 2,481,821 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,780,359 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,195,897 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,481,821 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 21,976,256 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 24,458,077 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Accumulated Depreciation | (12,085,135)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Investment in Real Estate Net | 12,372,942 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthWindsMember |  |  |  |
Southwood [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Palo Alto, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 100 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Initial Cost to Company, Land | 6,936,600 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 14,324,069 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,085,293 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,936,600 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 17,409,362 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 24,345,962 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Accumulated Depreciation | (10,084,791)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Investment in Real Estate Net | 14,261,171 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SouthwoodMember |  |  |  |
Springbrook Estates [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Riverside, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Initial Cost to Company, Land | 18,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 18,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 18,200,000 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Investment in Real Estate Net | 18,200,000 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SpringbrookEstatesMember |  |  |  |
Square One [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 112 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
Initial Cost to Company, Land | 7,222,544 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 26,277,456 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | (4)eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,222,544 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 26,277,452 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 33,499,996 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
Accumulated Depreciation | (93,215)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
Investment in Real Estate Net | 33,406,781 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SquareOneMember |  |  |  |
St. Andrews at Winston Park [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Coconut Creek, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 284 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Initial Cost to Company, Land | 5,680,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 19,812,090 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,167,806 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,680,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,979,896 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,659,896 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Accumulated Depreciation | (11,483,152)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Investment in Real Estate Net | 19,176,744 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StAndrewsAtWinstonParkMember |  |  |  |
Summerset Village II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Chatsworth, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Initial Cost to Company, Land | 260,646 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 260,646 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 260,646 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Investment in Real Estate Net | 260,646 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageIiMember |  |  |  |
Summit And Birch Hill [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Farmington, CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 186 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Initial Cost to Company, Land | 1,757,438 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 11,748,112 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,477,936 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,757,438 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 15,226,048 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 16,983,486 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Accumulated Depreciation | (8,409,730)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Investment in Real Estate Net | 8,573,756 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAndBirchHillMember |  |  |  |
Summit at Lake Union [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 150 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Initial Cost to Company, Land | 1,424,700 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 12,852,461 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,489,502 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,424,700 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 17,341,963 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 18,766,663 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Accumulated Depreciation | (10,565,888)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Investment in Real Estate Net | 8,200,775 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitAtLakeUnionMember |  |  |  |
Summit at Sausalito (fka Sausalito) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Sausalito, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 198 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Initial Cost to Company, Land | 26,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 28,435,024 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,373,534 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 26,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 29,808,558 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 55,808,558 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Accumulated Depreciation | (4,476,616)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Investment in Real Estate Net | 51,331,942 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummitatSausalitofkaSausalitoMember |  |  |  |
Tallman [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Initial Cost to Company, Land | 16,842,249 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 38,951,437 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 16,842,249 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 38,951,437 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 55,793,686 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Investment in Real Estate Net | 55,793,686 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TallmanMember |  |  |  |
Tasman (fka Vista Montana - Residential) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Jose, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Initial Cost to Company, Land | 27,709,329 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 91,844,910 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 27,709,329 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 91,844,910 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 119,554,239 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Investment in Real Estate Net | 119,554,239 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TasmanfkaVistaMontanaResidentialMember |  |  |  |
Ten23 (fka 500 West 23rd Street) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 111 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 58,856,293 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 109,788 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 58,966,081 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 58,966,081 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Accumulated Depreciation | (6,036,550)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Investment in Real Estate Net | 52,929,531 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Ten23Fka500West23RdStreetMember |  |  |  |
Terraces, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 117 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Initial Cost to Company, Land | 14,087,610 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,314,151 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 698,702 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,087,610 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 17,012,853 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 31,100,463 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Accumulated Depreciation | (3,403,077)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Investment in Real Estate Net | 27,697,386 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TerracesMember |  |  |  |
Third Square [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Cambridge, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 471 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Initial Cost to Company, Land | 26,767,171 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 218,822,728 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,859,006 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 26,767,171 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 222,681,734 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 249,448,905 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Accumulated Depreciation | (46,866,757)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Investment in Real Estate Net | 202,582,148 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ThirdSquareMember |  |  |  |
Three20 [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 134 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Initial Cost to Company, Land | 7,030,766 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 29,078,811 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 324,200 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,030,766 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 29,403,011 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 36,433,777 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Accumulated Depreciation | (1,679,563)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Investment in Real Estate Net | 34,754,214 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Three20Member |  |  |  |
Tortuga Bay [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Orlando, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 314 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Initial Cost to Company, Land | 6,280,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 32,121,779 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,652,231 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,280,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 33,774,010 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 40,054,010 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Accumulated Depreciation | (12,539,818)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Investment in Real Estate Net | 27,514,192 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TortugaBayMember |  |  |  |
Town Center South Commercial Tract [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | St. Charles, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Initial Cost to Company, Land | 1,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 5,499 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 5,499 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 1,505,499 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Investment in Real Estate Net | 1,505,499 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownCenterSouthCommercialMember |  |  |  |
Town Square at Mark Center II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Alexandria, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 272 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Initial Cost to Company, Land | 15,568,464 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 55,029,607 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 674,851 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,568,464 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 55,704,458 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 71,272,922 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Accumulated Depreciation | (12,914,649)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Investment in Real Estate Net | 58,358,273 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownsquareatmarkcenterphaseIIMember |  |  |  |
Trump Place, 140 Riverside [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 354 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Initial Cost to Company, Land | 103,539,100 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 94,082,725 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,343,151 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 103,539,100 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 98,425,876 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 201,964,976 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Accumulated Depreciation | (33,587,819)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Investment in Real Estate Net | 168,377,157 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace140RiversideMember |  |  |  |
Trump Place, 160 Riverside [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 455 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Initial Cost to Company, Land | 139,933,500 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 190,964,745 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 10,315,504 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 139,933,500 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 201,280,249 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 341,213,749 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Accumulated Depreciation | (67,180,501)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Investment in Real Estate Net | 274,033,248 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace160RiversideMember |  |  |  |
Trump Place, 180 Riverside [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 516 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Initial Cost to Company, Land | 144,968,250 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 138,346,681 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 8,758,301 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 144,968,250 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 147,104,982 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 292,073,232 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Accumulated Depreciation | (50,963,924)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Investment in Real Estate Net | 241,109,308 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TrumpPlace180RiversideMember |  |  |  |
Urbana (fka Market Street Landing) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 287 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Initial Cost to Company, Land | 12,542,418 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 74,247,060 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 592,913 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,542,418 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 74,839,973 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 87,382,391 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Accumulated Depreciation | (2,706,973)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Investment in Real Estate Net | 84,675,418 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UrbanafkaMarketStreetLandingMember |  |  |  |
Uwajimaya Village [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 176 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Initial Cost to Company, Land | 8,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 22,188,288 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 463,663 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 22,651,951 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 31,451,951 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Accumulated Depreciation | (8,690,210)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Investment in Real Estate Net | 22,761,741 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UwajimayaVillageMember |  |  |  |
Vantage Pointe [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Diego, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 679 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Initial Cost to Company, Land | 9,403,960 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 190,596,040 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,068,618 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,403,960 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 196,664,658 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 206,068,618 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Accumulated Depreciation | (37,027,336)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Investment in Real Estate Net | 169,041,282 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VantagePointeMember |  |  |  |
Veloce [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redmond, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 322 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Initial Cost to Company, Land | 15,322,724 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 76,176,594 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 253,112 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,322,724 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 76,429,706 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 91,752,430 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Accumulated Depreciation | (7,951,300)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Investment in Real Estate Net | 83,801,130 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeloceMember |  |  |  |
Verde Condominium Homes (fka Mission Verde, LLC) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Jose, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 108 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Initial Cost to Company, Land | 5,190,700 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 9,679,109 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,659,737 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,190,700 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 13,338,846 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 18,529,546 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Accumulated Depreciation | (8,271,659)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Investment in Real Estate Net | 10,257,887 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VerdeCondominiumHomesfkaMissionVerdeLLCMember |  |  |  |
Veridian (fka Silver Spring) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Silver Spring, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 457 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Initial Cost to Company, Land | 18,539,817 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 130,407,365 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,187,628 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 18,539,817 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 131,594,993 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 150,134,810 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Accumulated Depreciation | (25,425,869)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Investment in Real Estate Net | 124,708,941 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VeridianfkaSilverSpringMember |  |  |  |
Villa Solana [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Laguna Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 272 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Initial Cost to Company, Land | 1,665,100 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 14,985,678 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 9,004,790 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,665,100 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 23,990,468 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 25,655,568 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Accumulated Depreciation | (16,477,170)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Investment in Real Estate Net | 9,178,398 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillaSolanaMember |  |  |  |
Village at Bear Creek [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Lakewood, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 472 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Initial Cost to Company, Land | 4,519,700 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 40,676,390 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,730,669 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,519,700 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 46,407,059 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 50,926,759 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Accumulated Depreciation | (28,337,074)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Investment in Real Estate Net | 22,589,685 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageAtBearCreekMember |  |  |  |
Village at Del Mar Heights, The (fka Del Mar Heights) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Diego, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 168 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Initial Cost to Company, Land | 15,100,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 40,859,396 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 252,027 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,100,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 41,111,423 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 56,211,423 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Accumulated Depreciation | (4,661,947)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Investment in Real Estate Net | 51,549,476 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TheVillageatDelMarHeightsfkaDelMarHeightsMember |  |  |  |
Village at Howard Hughes (Lots 1&2) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Initial Cost to Company, Land | 43,783,485 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 42,858,234 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 43,783,485 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 42,858,234 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 86,641,719 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Investment in Real Estate Net | 86,641,719 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VillageatHowardHughesLots12Member |  |  |  |
Virginia Square [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 231 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 85,940,003 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,862,631 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 87,802,634 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 87,802,634 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Accumulated Depreciation | (9,021,044)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Investment in Real Estate Net | 78,781,590 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirginiaSquareMember |  |  |  |
Vista Del Lago [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Mission Viejo, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 608 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Initial Cost to Company, Land | 4,525,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 40,736,293 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 15,509,600 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,525,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 56,245,893 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 60,771,693 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Accumulated Depreciation | (39,353,877)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Investment in Real Estate Net | 21,417,816 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaDelLagoMember |  |  |  |
Walden Park [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Cambridge, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 232 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Initial Cost to Company, Land | 12,448,888 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 52,044,448 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,585,931 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,448,888 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 55,630,379 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 68,079,267 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Accumulated Depreciation | (10,279,717)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Investment in Real Estate Net | 57,799,550 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaldenParkMember |  |  |  |
Waterford Place (CO) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Thornton, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 336 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Initial Cost to Company, Land | 5,040,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 29,946,419 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,892,852 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,040,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 31,839,271 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 36,879,271 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Accumulated Depreciation | (13,850,610)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Investment in Real Estate Net | 23,028,661 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterfordPlaceCOMember |  |  |  |
Watertown Square [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Watertown, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 134 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Initial Cost to Company, Land | 16,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 34,074,056 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 273,661 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 16,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 34,347,717 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 51,147,717 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Accumulated Depreciation | (3,888,131)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Investment in Real Estate Net | 47,259,586 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WatertownSquareMember |  |  |  |
Webster Green [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Needham, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 77 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Initial Cost to Company, Land | 1,418,893 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 9,485,006 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,311,268 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,418,893 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 10,796,274 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 12,215,167 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Accumulated Depreciation | (5,513,744)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Investment in Real Estate Net | 6,701,423 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WebsterGreenMember |  |  |  |
Welleby Lake Club [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Sunrise, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 304 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
Initial Cost to Company, Land | 3,648,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 17,620,879 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,006,733 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,648,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 23,627,612 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 27,275,612 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
Accumulated Depreciation | (13,651,141)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
Investment in Real Estate Net | 13,624,471 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WellebyLakeClubMember |  |  |  |
West 96th [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 207 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
Initial Cost to Company, Land | 84,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 67,055,502 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,691,019 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 84,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 68,746,521 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 153,546,521 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
Accumulated Depreciation | (10,502,306)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
Investment in Real Estate Net | 143,044,215 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West96thMember |  |  |  |
West End Apartments (fka Emerson Place/ CRP II) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boston, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 310 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Initial Cost to Company, Land | 469,546 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 163,123,022 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,657,912 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 469,546 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 164,780,934 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 165,250,480 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Accumulated Depreciation | (38,899,184)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Investment in Real Estate Net | 126,351,296 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestEndApartmentsMember |  |  |  |
Westchester at Pavilions [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Waldorf, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 491 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Initial Cost to Company, Land | 11,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 89,612,465 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 454,376 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 11,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 90,066,841 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 101,966,841 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Accumulated Depreciation | (8,949,050)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Investment in Real Estate Net | 93,017,791 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratPavilionsMember |  |  |  |
Westchester at Rockville [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Rockville, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 192 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Initial Cost to Company, Land | 10,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 44,135,207 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 277,296 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 44,412,503 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 55,012,503 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Accumulated Depreciation | (5,009,486)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Investment in Real Estate Net | 50,003,017 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestchesteratRockvilleMember |  |  |  |
Westmont [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 163 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Initial Cost to Company, Land | 64,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 61,143,259 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 761,971 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 64,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 61,905,230 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 126,805,230 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Accumulated Depreciation | (7,967,408)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Investment in Real Estate Net | 118,837,822 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestmontMember |  |  |  |
Westside [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 204 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Initial Cost to Company, Land | 34,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 56,962,630 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,269,381 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 34,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 58,232,011 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 92,432,011 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Accumulated Depreciation | (6,264,171)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Investment in Real Estate Net | 86,167,840 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideMember |  |  |  |
Westside Villas I [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 21 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Initial Cost to Company, Land | 1,785,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 3,233,254 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 357,453 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,785,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 3,590,707 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 5,375,707 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Accumulated Depreciation | (1,813,481)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Investment in Real Estate Net | 3,562,226 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIMember |  |  |  |
Westside Villas II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 23 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Initial Cost to Company, Land | 1,955,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 3,541,435 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 250,691 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,955,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 3,792,126 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 5,747,126 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Accumulated Depreciation | (1,850,426)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Investment in Real Estate Net | 3,896,700 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiMember |  |  |  |
Westside Villas III [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 36 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Initial Cost to Company, Land | 3,060,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 5,538,871 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 377,157 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,060,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 5,916,028 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 8,976,028 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Accumulated Depreciation | (2,880,318)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Investment in Real Estate Net | 6,095,710 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIiiMember |  |  |  |
Westside Villas IV [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 36 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Initial Cost to Company, Land | 3,060,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 5,539,390 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 385,604 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,060,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 5,924,994 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 8,984,994 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Accumulated Depreciation | (2,887,551)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Investment in Real Estate Net | 6,097,443 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasIvMember |  |  |  |
Westside Villas V [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 60 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Initial Cost to Company, Land | 5,100,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 9,224,485 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 657,592 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,100,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 9,882,077 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 14,982,077 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Accumulated Depreciation | (4,823,944)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Investment in Real Estate Net | 10,158,133 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasVMember |  |  |  |
Westside Villas VI [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 18 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Initial Cost to Company, Land | 1,530,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 3,023,523 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 318,754 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,530,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 3,342,277 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 4,872,277 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Accumulated Depreciation | (1,665,408)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Investment in Real Estate Net | 3,206,869 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViMember |  |  |  |
Westside Villas VII [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 53 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Initial Cost to Company, Land | 4,505,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 10,758,900 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 616,684 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,505,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 11,375,584 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 15,880,584 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Accumulated Depreciation | (4,960,551)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Investment in Real Estate Net | 10,920,033 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestsideVillasViiMember |  |  |  |
Westwood Glen [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Westwood, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 156 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Initial Cost to Company, Land | 1,616,505 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 10,806,004 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,225,649 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,616,505 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 13,031,653 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 14,648,158 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Accumulated Depreciation | (6,710,710)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Investment in Real Estate Net | 7,937,448 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestwoodGlenMember |  |  |  |
Windridge (CA) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Laguna Niguel, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 344 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Initial Cost to Company, Land | 2,662,900 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,985,497 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 8,684,076 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,662,900 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 32,669,573 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 35,332,473 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Accumulated Depreciation | (21,637,211)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Investment in Real Estate Net | 13,695,262 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WindridgeCaMember |  |  |  |
Winston, The (FL) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pembroke Pines, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 464 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Initial Cost to Company, Land | 18,561,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 49,527,569 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,852,872 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 18,561,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 52,380,441 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 70,941,441 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Accumulated Depreciation | (18,475,139)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Investment in Real Estate Net | 52,466,302 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WinstonFLMember |  |  |  |
Wood Creek I [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pleasant Hill, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 256 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Initial Cost to Company, Land | 9,729,900 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,009,768 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,555,668 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,729,900 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 29,565,436 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 39,295,336 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Accumulated Depreciation | (17,862,164)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Investment in Real Estate Net | 21,433,172 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekICAMember |  |  |  |
Woodbridge (CT) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Newington, CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 73 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodbridgeCTMember |  |  |  |
Initial Cost to Company, Land | 498,377 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodbridgeCTMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 3,331,548 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodbridgeCTMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,266,343 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodbridgeCTMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 498,377 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodbridgeCTMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 4,597,891 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodbridgeCTMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 5,096,268 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodbridgeCTMember |  |  |  |
Accumulated Depreciation | (2,465,999)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodbridgeCTMember |  |  |  |
Investment in Real Estate Net | 2,630,269 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodbridgeCTMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | 0 |  |  |  |
Woodlake (WA) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Kirkland, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 288 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Initial Cost to Company, Land | 6,631,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,735,484 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,790,078 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,631,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 20,525,562 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 27,156,962 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Accumulated Depreciation | (12,057,883)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Investment in Real Estate Net | 15,099,079 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlakeWaMember |  |  |  |
Woodland Park [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | East Palo Alto, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 1,809 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Initial Cost to Company, Land | 72,627,418 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 57,649,069 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 9,382,472 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 72,627,418 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 67,031,541 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 139,658,959 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Accumulated Depreciation | (24,058,784)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Investment in Real Estate Net | 115,600,175 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodlandParkMember |  |  |  |
Management Business [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Chicago, IL |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 103,392,322 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 103,392,322 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 103,392,322 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Accumulated Depreciation | (79,507,853)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Investment in Real Estate Net | 23,884,469 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = us-gaap_ManagementMember |  |  |  |
Operating Partnership [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Chicago, IL |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 1,434,910 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 1,434,910 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 1,434,910 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Investment in Real Estate Net | 1,434,910 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OperatingPartnershipMember |  |  |  |
Wholly Owned Unencumbered [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Units | 69,217 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
Initial Cost to Company, Land | 4,798,437,902 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 12,737,799,082 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,002,255,162 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,798,437,902 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 13,740,054,244 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 18,538,492,146 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
Accumulated Depreciation | (3,650,524,741)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
Investment in Real Estate Net | 14,887,967,405 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedUnencumberedMember |  |  |  |
101 West End [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 506 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
Initial Cost to Company, Land | 190,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 131,374,708 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,868,722 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 190,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 133,243,430 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 323,843,430 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
Accumulated Depreciation | (19,903,961)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
Investment in Real Estate Net | 303,939,469 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
Encumbrances | 104,781,651 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A101WestEndMember |  |  |  |
1401 Joyce On Pentagon Row [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 326 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
Initial Cost to Company, Land | 9,780,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 89,668,165 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 793,393 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,780,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 90,461,558 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 100,241,558 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
Accumulated Depreciation | (22,366,104)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
Investment in Real Estate Net | 77,875,454 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
Encumbrances | 57,428,472 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_JoyceOnPentagonRow1401Member |  |  |  |
2501 Porter [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 202 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2501PorterMember |  |  |  |
Initial Cost to Company, Land | 13,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2501PorterMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 75,271,179 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2501PorterMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,555,253 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2501PorterMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2501PorterMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 76,826,432 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2501PorterMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 89,826,432 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2501PorterMember |  |  |  |
Accumulated Depreciation | (7,789,697)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2501PorterMember |  |  |  |
Investment in Real Estate Net | 82,036,735 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A2501PorterMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
300 East 39th (fka East 39th) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 254 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
Initial Cost to Company, Land | 48,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 96,174,639 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 868,920 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 48,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 97,043,559 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 145,943,559 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
Accumulated Depreciation | (11,236,211)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
Investment in Real Estate Net | 134,707,348 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
Encumbrances | 59,449,107 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A300East39thMember |  |  |  |
3003 Van Ness (fka Van Ness) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 625 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A3003VanNessMember |  |  |  |
Initial Cost to Company, Land | 56,300,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A3003VanNessMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 141,191,580 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A3003VanNessMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,514,645 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A3003VanNessMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 56,300,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A3003VanNessMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 143,706,225 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A3003VanNessMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 200,006,225 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A3003VanNessMember |  |  |  |
Accumulated Depreciation | (16,968,210)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A3003VanNessMember |  |  |  |
Investment in Real Estate Net | 183,038,015 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A3003VanNessMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (K) | [1] |  |  |
303 East 83rd (fka Camargue) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 261 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A303East83rdfkaCamargueMember |  |  |  |
Initial Cost to Company, Land | 79,400,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A303East83rdfkaCamargueMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 79,122,624 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A303East83rdfkaCamargueMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 738,175 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A303East83rdfkaCamargueMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 79,400,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A303East83rdfkaCamargueMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 79,860,799 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A303East83rdfkaCamargueMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 159,260,799 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A303East83rdfkaCamargueMember |  |  |  |
Accumulated Depreciation | (10,706,970)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A303East83rdfkaCamargueMember |  |  |  |
Investment in Real Estate Net | 148,553,829 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A303East83rdfkaCamargueMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
425 Broadway [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Santa Monica, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 101 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425BroadwayMember |  |  |  |
Initial Cost to Company, Land | 12,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425BroadwayMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 34,394,772 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425BroadwayMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 680,943 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425BroadwayMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425BroadwayMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 35,075,715 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425BroadwayMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 47,675,715 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425BroadwayMember |  |  |  |
Accumulated Depreciation | (3,569,288)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425BroadwayMember |  |  |  |
Investment in Real Estate Net | 44,106,427 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A425BroadwayMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
4701 Willard [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Chevy Chase, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 513 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
Initial Cost to Company, Land | 76,921,130 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 153,947,682 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 20,688,968 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 76,921,130 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 174,636,650 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 251,557,780 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
Accumulated Depreciation | (24,386,428)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
Investment in Real Estate Net | 227,171,352 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
Encumbrances | 98,427,692 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A4701WillardAveMember |  |  |  |
55 West Fifth I & II (fka Townhouse Plaza and Gardens) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Mateo, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 241 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
Initial Cost to Company, Land | 21,041,710 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 71,931,323 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 8,114,511 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 21,041,710 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 80,045,834 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 101,087,544 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
Accumulated Depreciation | (9,767,221)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
Investment in Real Estate Net | 91,320,323 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
Encumbrances | 29,128,487 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A55WestFifthIIiMember |  |  |  |
77 Park Avenue (fka Hoboken) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Hoboken, NJ |  |  |  |
Real Estate And Accumulated Depreciation Units | 301 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77ParkAvenuefkaHobokenMember |  |  |  |
Initial Cost to Company, Land | 27,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77ParkAvenuefkaHobokenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 168,992,440 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77ParkAvenuefkaHobokenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,559,417 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77ParkAvenuefkaHobokenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 27,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77ParkAvenuefkaHobokenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 170,551,857 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77ParkAvenuefkaHobokenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 198,451,857 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77ParkAvenuefkaHobokenMember |  |  |  |
Accumulated Depreciation | (16,271,604)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77ParkAvenuefkaHobokenMember |  |  |  |
Investment in Real Estate Net | 182,180,253 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A77ParkAvenuefkaHobokenMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (K) | [1] |  |  |
800 Sixth Ave (fka Chelsea) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 266 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
Initial Cost to Company, Land | 59,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 155,861,605 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 218,240 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 59,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 156,079,845 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 215,979,845 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
Accumulated Depreciation | (16,645,847)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
Investment in Real Estate Net | 199,333,998 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
Encumbrances | 76,680,282 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A800SixthAvefkaChelseaMember |  |  |  |
929 House [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Cambridge, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 127 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Initial Cost to Company, Land | 3,252,993 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 21,745,595 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,861,409 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,252,993 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 27,607,004 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,859,997 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Accumulated Depreciation | (13,677,315)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Investment in Real Estate Net | 17,182,682 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Encumbrances | 1,784,337 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_House929Member |  |  |  |
Academy Village [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | North Hollywood, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 248 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Initial Cost to Company, Land | 25,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,593,194 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,244,947 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 25,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,838,141 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 55,838,141 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Accumulated Depreciation | (14,131,888)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Investment in Real Estate Net | 41,706,253 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Encumbrances | 20,000,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcademyVillageMember |  |  |  |
Acappella [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pasadena, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 143 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Initial Cost to Company, Land | 5,839,548 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 29,360,452 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 902,132 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,839,548 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,262,584 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 36,102,132 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Accumulated Depreciation | (6,456,855)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Investment in Real Estate Net | 29,645,277 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Encumbrances | 19,842,607 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AcappellaMember |  |  |  |
Acton Courtyard [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Berkeley, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 71 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Initial Cost to Company, Land | 5,550,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 15,785,509 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 174,547 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,550,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 15,960,056 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,510,056 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Accumulated Depreciation | (5,066,680)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Investment in Real Estate Net | 16,443,376 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Encumbrances | 9,920,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ActonCourtyardMember |  |  |  |
Alborada [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Fremont, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 442 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlboradaMember |  |  |  |
Initial Cost to Company, Land | 24,310,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlboradaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 59,214,129 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlboradaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,040,631 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlboradaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 24,310,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlboradaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 62,254,760 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlboradaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 86,564,760 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlboradaMember |  |  |  |
Accumulated Depreciation | (31,791,543)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlboradaMember |  |  |  |
Investment in Real Estate Net | 54,773,217 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlboradaMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (I) | [1] |  |  |
Alcyone [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 161 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Initial Cost to Company, Land | 11,379,497 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 49,360,503 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | (9)eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 11,379,497 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 49,360,494 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 60,739,991 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Investment in Real Estate Net | 60,739,991 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Encumbrances | 28,910,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AlcyoneMember |  |  |  |
Arches, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Sunnyvale, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 410 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArchesMember |  |  |  |
Initial Cost to Company, Land | 26,650,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArchesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 62,850,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArchesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 851,025 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArchesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 26,650,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArchesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 63,701,025 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArchesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 90,351,025 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArchesMember |  |  |  |
Accumulated Depreciation | (12,837,616)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArchesMember |  |  |  |
Investment in Real Estate Net | 77,513,409 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArchesMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Artech Building [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Berkeley, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 21 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Initial Cost to Company, Land | 1,642,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 9,152,518 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 260,646 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,642,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 9,413,164 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 11,055,164 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Accumulated Depreciation | (2,729,697)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Investment in Real Estate Net | 8,325,467 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Encumbrances | 3,200,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtechBuildingMember |  |  |  |
Artisan Square [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Northridge, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 140 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Initial Cost to Company, Land | 7,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 20,537,359 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,064,325 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 21,601,684 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 28,601,684 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Accumulated Depreciation | (9,217,575)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Investment in Real Estate Net | 19,384,109 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Encumbrances | 22,779,715 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ArtisanSquareMember |  |  |  |
Avanti [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Anaheim, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 162 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Initial Cost to Company, Land | 12,960,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,497,683 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,314,548 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,960,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,812,231 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 32,772,231 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Accumulated Depreciation | (7,174,217)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Investment in Real Estate Net | 25,598,014 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Encumbrances | 18,169,458 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvantiMember |  |  |  |
Avenir [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boston, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 241 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 114,321,619 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 551,758 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 114,873,377 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 114,873,377 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Accumulated Depreciation | (12,259,457)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Investment in Real Estate Net | 102,613,920 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Encumbrances | 94,465,696 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_AvenirMember |  |  |  |
Bachenheimer Building [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Berkeley, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 44 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Initial Cost to Company, Land | 3,439,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 13,866,379 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 124,166 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,439,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 13,990,545 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 17,429,545 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Accumulated Depreciation | (4,228,536)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Investment in Real Estate Net | 13,201,009 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Encumbrances | 8,585,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BachenheimerBuildingMember |  |  |  |
Bella Vista I, II, III Combined [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Woodland Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 579 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Initial Cost to Company, Land | 31,682,754 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 121,095,786 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,885,108 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 31,682,754 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 123,980,894 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 155,663,648 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Accumulated Depreciation | (40,957,341)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Investment in Real Estate Net | 114,706,307 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Encumbrances | 58,055,099 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellaVistaApartmentsAtBocaDelMarMember |  |  |  |
Berkeleyan [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Berkeley, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 56 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Initial Cost to Company, Land | 4,377,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,022,110 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 321,597 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,377,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 16,343,707 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 20,720,707 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Accumulated Depreciation | (5,080,620)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Investment in Real Estate Net | 15,640,087 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Encumbrances | 8,290,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BerkeleyanMember |  |  |  |
Calvert Woodley [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 136 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CalvertWoodleyMember |  |  |  |
Initial Cost to Company, Land | 12,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CalvertWoodleyMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 43,527,379 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CalvertWoodleyMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 733,195 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CalvertWoodleyMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CalvertWoodleyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 44,260,574 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CalvertWoodleyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 56,860,574 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CalvertWoodleyMember |  |  |  |
Accumulated Depreciation | (5,010,638)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CalvertWoodleyMember |  |  |  |
Investment in Real Estate Net | 51,849,936 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CalvertWoodleyMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
Canterbury [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Germantown, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 544 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Initial Cost to Company, Land | 2,781,300 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 32,942,531 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 15,098,222 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,781,300 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 48,040,753 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 50,822,053 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Accumulated Depreciation | (33,408,506)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Investment in Real Estate Net | 17,413,547 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Encumbrances | 31,680,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanterburyMember |  |  |  |
Carmel Terrace [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Diego, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 384 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarmelTerraceMember |  |  |  |
Initial Cost to Company, Land | 2,288,300 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarmelTerraceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 20,596,281 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarmelTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 10,568,110 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarmelTerraceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,288,300 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarmelTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 31,164,391 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarmelTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 33,452,691 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarmelTerraceMember |  |  |  |
Accumulated Depreciation | (22,658,333)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarmelTerraceMember |  |  |  |
Investment in Real Estate Net | 10,794,358 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CarmelTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Chelsea Square [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Redmond, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 113 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Initial Cost to Company, Land | 3,397,100 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 9,289,074 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,788,938 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,397,100 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 11,078,012 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 14,475,112 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Accumulated Depreciation | (6,337,147)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Investment in Real Estate Net | 8,137,965 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Encumbrances | 9,270,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ChelseaSquareMember |  |  |  |
Citrus Suites [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Santa Monica, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 70 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitrusSuitesMember |  |  |  |
Initial Cost to Company, Land | 9,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitrusSuitesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,950,326 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitrusSuitesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 123,388 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitrusSuitesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitrusSuitesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 17,073,714 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitrusSuitesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 26,073,714 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitrusSuitesMember |  |  |  |
Accumulated Depreciation | (1,867,465)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitrusSuitesMember |  |  |  |
Investment in Real Estate Net | 24,206,249 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CitrusSuitesMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
CityView at Longwood [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Boston, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 295 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Initial Cost to Company, Land | 14,704,898 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 79,195,102 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 9,272,973 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,704,898 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 88,468,075 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 103,172,973 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Accumulated Depreciation | (17,874,351)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Investment in Real Estate Net | 85,298,622 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Encumbrances | 23,780,076 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CityviewAtLongwoodMember |  |  |  |
Clarendon, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 292 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Initial Cost to Company, Land | 30,400,340 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 103,824,660 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,980,446 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 30,400,340 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 105,805,106 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 136,205,446 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Accumulated Depreciation | (18,582,643)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Investment in Real Estate Net | 117,622,803 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Encumbrances | 40,376,421 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClarendonMember |  |  |  |
Cleveland House [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 214 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClevelandHouseMember |  |  |  |
Initial Cost to Company, Land | 18,300,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClevelandHouseMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 66,392,414 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClevelandHouseMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,085,128 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClevelandHouseMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 18,300,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClevelandHouseMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 67,477,542 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClevelandHouseMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 85,777,542 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClevelandHouseMember |  |  |  |
Accumulated Depreciation | (7,336,935)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClevelandHouseMember |  |  |  |
Investment in Real Estate Net | 78,440,607 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ClevelandHouseMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
Columbia Crossing [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 247 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColumbiaCrossingMember |  |  |  |
Initial Cost to Company, Land | 23,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColumbiaCrossingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 53,045,073 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColumbiaCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,524,626 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColumbiaCrossingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 23,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColumbiaCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 54,569,699 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColumbiaCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 78,069,699 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColumbiaCrossingMember |  |  |  |
Accumulated Depreciation | (6,390,653)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColumbiaCrossingMember |  |  |  |
Investment in Real Estate Net | 71,679,046 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ColumbiaCrossingMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
Connecticut Heights [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 518 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ConnecticutHeightsMember |  |  |  |
Initial Cost to Company, Land | 27,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ConnecticutHeightsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 114,002,295 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ConnecticutHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 523,868 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ConnecticutHeightsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 27,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ConnecticutHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 114,526,163 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ConnecticutHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 142,126,163 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ConnecticutHeightsMember |  |  |  |
Accumulated Depreciation | (12,120,961)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ConnecticutHeightsMember |  |  |  |
Investment in Real Estate Net | 130,005,202 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ConnecticutHeightsMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (K) | [1] |  |  |
Deerwood (SD) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Diego, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 316 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodSdMember |  |  |  |
Initial Cost to Company, Land | 2,082,095 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodSdMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,739,815 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodSdMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 14,095,827 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodSdMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,082,095 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodSdMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 32,835,642 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodSdMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 34,917,737 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodSdMember |  |  |  |
Accumulated Depreciation | (23,757,806)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodSdMember |  |  |  |
Investment in Real Estate Net | 11,159,931 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DeerwoodSdMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Del Mar Ridge [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Diego, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 181 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Initial Cost to Company, Land | 7,801,824 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 36,948,176 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,108,004 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,801,824 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 40,056,180 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 47,858,004 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Accumulated Depreciation | (10,328,077)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Investment in Real Estate Net | 37,529,927 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Encumbrances | 23,789,381 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_DelmarridgeMember |  |  |  |
Estancia at Santa Clara (fka Santa Clara) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Santa Clara, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 450 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstanciaatSantaClarafkaSantaClaraMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstanciaatSantaClarafkaSantaClaraMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 123,759,804 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstanciaatSantaClarafkaSantaClaraMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 526,676 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstanciaatSantaClarafkaSantaClaraMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstanciaatSantaClarafkaSantaClaraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 124,286,480 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstanciaatSantaClarafkaSantaClaraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 124,286,480 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstanciaatSantaClarafkaSantaClaraMember |  |  |  |
Accumulated Depreciation | (13,537,262)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstanciaatSantaClarafkaSantaClaraMember |  |  |  |
Investment in Real Estate Net | 110,749,218 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_EstanciaatSantaClarafkaSantaClaraMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
Fairchase [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Fairfax, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 392 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairchaseMember |  |  |  |
Initial Cost to Company, Land | 23,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairchaseMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 87,722,321 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairchaseMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 269,692 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairchaseMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 23,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairchaseMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 87,992,013 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairchaseMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 111,492,013 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairchaseMember |  |  |  |
Accumulated Depreciation | (9,395,216)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairchaseMember |  |  |  |
Investment in Real Estate Net | 102,096,797 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairchaseMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
Fairfield [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Stamford, CT |  |  |  |
Real Estate And Accumulated Depreciation Units | 263 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Initial Cost to Company, Land | 6,510,200 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 39,690,120 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,459,297 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,510,200 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 46,149,417 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 52,659,617 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Accumulated Depreciation | (27,466,826)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Investment in Real Estate Net | 25,192,791 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Encumbrances | 34,595,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FairfieldMember |  |  |  |
Fine Arts Building [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Berkeley, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 100 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Initial Cost to Company, Land | 7,817,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 26,462,772 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 302,689 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,817,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 26,765,461 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 34,582,461 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Accumulated Depreciation | (8,237,485)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Investment in Real Estate Net | 26,344,976 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Encumbrances | 16,215,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FineArtsBuildingMember |  |  |  |
Flats at DuPont Circle [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Washington, D.C. |  |  |  |
Real Estate And Accumulated Depreciation Units | 306 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FlatsatDuPontCircleMember |  |  |  |
Initial Cost to Company, Land | 35,200,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FlatsatDuPontCircleMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 108,768,198 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FlatsatDuPontCircleMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 504,057 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FlatsatDuPontCircleMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 35,200,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FlatsatDuPontCircleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 109,272,255 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FlatsatDuPontCircleMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 144,472,255 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FlatsatDuPontCircleMember |  |  |  |
Accumulated Depreciation | (11,204,638)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FlatsatDuPontCircleMember |  |  |  |
Investment in Real Estate Net | 133,267,617 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FlatsatDuPontCircleMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
Gaia Building [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Berkeley, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 91 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Initial Cost to Company, Land | 7,113,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 25,623,826 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 225,339 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,113,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 25,849,165 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 32,962,165 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Accumulated Depreciation | (7,962,885)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Investment in Real Estate Net | 24,999,280 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Encumbrances | 14,630,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaiaBuildingMember |  |  |  |
Gaithersburg Station [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Gaithersburg, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 389 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Initial Cost to Company, Land | 17,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 74,556,144 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 231,854 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 17,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 74,787,998 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 92,287,998 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Accumulated Depreciation | (6,934,203)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Investment in Real Estate Net | 85,353,795 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Encumbrances | 98,884,291 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GaithersburgStationMember |  |  |  |
Gateway at Malden Center [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Malden, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 203 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Initial Cost to Company, Land | 9,209,780 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 25,722,666 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 12,495,969 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,209,780 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 38,218,635 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 47,428,415 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Accumulated Depreciation | (17,530,227)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Investment in Real Estate Net | 29,898,188 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Encumbrances | 14,970,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GatewayAtMaldenCenterMember |  |  |  |
Glo [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 201 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Initial Cost to Company, Land | 16,047,023 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 48,650,963 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 394,064 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 16,047,023 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 49,045,027 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 65,092,050 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Accumulated Depreciation | (8,010,461)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Investment in Real Estate Net | 57,081,589 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Encumbrances | 31,938,525 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_GloMember |  |  |  |
Hathaway [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Long Beach, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 385 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Initial Cost to Company, Land | 2,512,500 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 22,611,912 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,849,296 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,512,500 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,461,208 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 32,973,708 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Accumulated Depreciation | (20,670,436)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Investment in Real Estate Net | 12,303,272 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Encumbrances | 46,517,800 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HathawayMember |  |  |  |
Heights on Capitol Hill [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 104 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Initial Cost to Company, Land | 5,425,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 21,138,028 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 265,813 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,425,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 21,403,841 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 26,828,841 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Accumulated Depreciation | (6,924,808)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Investment in Real Estate Net | 19,904,033 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Encumbrances | 28,180,585 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeightsOnCapitolHillMember |  |  |  |
Heronfield [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Kirkland, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 202 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronfieldMember |  |  |  |
Initial Cost to Company, Land | 9,245,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronfieldMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 27,017,749 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,262,931 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronfieldMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,245,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 29,280,680 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronfieldMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 38,525,680 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronfieldMember |  |  |  |
Accumulated Depreciation | (9,728,197)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronfieldMember |  |  |  |
Investment in Real Estate Net | 28,797,483 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HeronfieldMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Ivory Wood [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bothell, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 144 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Initial Cost to Company, Land | 2,732,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 13,888,282 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 751,887 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,732,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 14,640,169 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 17,372,969 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Accumulated Depreciation | (5,844,211)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Investment in Real Estate Net | 11,528,758 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Encumbrances | 8,020,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IvoryWoodMember |  |  |  |
Kelvin Court (fka Alta Pacific) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Irvine, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 132 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
Initial Cost to Company, Land | 10,752,145 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 34,649,929 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 248,840 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,752,145 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 34,898,769 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 45,650,914 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
Accumulated Depreciation | (8,359,653)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
Investment in Real Estate Net | 37,291,261 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
Encumbrances | 26,495,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_KelvinCourtMember |  |  |  |
La Terrazza at Colma Station [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Colma, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 153 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 41,251,044 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 642,535 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 41,893,579 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 41,893,579 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Accumulated Depreciation | (12,830,190)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Investment in Real Estate Net | 29,063,389 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Encumbrances | 25,175,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LaTerrazzaAtColmaStationMember |  |  |  |
Laguna Clara [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Santa Clara, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 264 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LagunaClaraMember |  |  |  |
Initial Cost to Company, Land | 13,642,420 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LagunaClaraMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 29,707,475 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LagunaClaraMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,256,707 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LagunaClaraMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,642,420 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LagunaClaraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 33,964,182 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LagunaClaraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 47,606,602 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LagunaClaraMember |  |  |  |
Accumulated Depreciation | (14,568,252)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LagunaClaraMember |  |  |  |
Investment in Real Estate Net | 33,038,350 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LagunaClaraMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Liberty Park [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Braintree, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 202 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Initial Cost to Company, Land | 5,977,504 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 26,749,111 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,730,323 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,977,504 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,479,434 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 36,456,938 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Accumulated Depreciation | (13,021,186)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Investment in Real Estate Net | 23,435,752 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Encumbrances | 24,980,280 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyParkMember |  |  |  |
Liberty Tower [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 235 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Initial Cost to Company, Land | 16,382,822 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 83,817,078 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,124,478 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 16,382,822 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 84,941,556 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 101,324,378 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Accumulated Depreciation | (17,478,810)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Investment in Real Estate Net | 83,845,568 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Encumbrances | 46,865,218 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LibertyTowerMember |  |  |  |
Lindley Apartments [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Encino, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 129 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Initial Cost to Company, Land | 5,805,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 25,705,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 681,636 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,805,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 26,386,636 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 32,191,636 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Accumulated Depreciation | (5,246,707)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Investment in Real Estate Net | 26,944,929 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Encumbrances | 20,382,643 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LindleyMember |  |  |  |
Longview Place [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Waltham, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 348 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Initial Cost to Company, Land | 20,880,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 90,255,509 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,770,380 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 20,880,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 94,025,889 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 114,905,889 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Accumulated Depreciation | (31,602,144)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Investment in Real Estate Net | 83,303,745 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Encumbrances | 60,073,423 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LongviewPlaceMember |  |  |  |
Market Street Village [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Diego, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 229 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarketStreetVillageMember |  |  |  |
Initial Cost to Company, Land | 13,740,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarketStreetVillageMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 40,757,301 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarketStreetVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,480,272 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarketStreetVillageMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 13,740,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarketStreetVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 42,237,573 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarketStreetVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 55,977,573 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarketStreetVillageMember |  |  |  |
Accumulated Depreciation | (13,620,631)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarketStreetVillageMember |  |  |  |
Investment in Real Estate Net | 42,356,942 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarketStreetVillageMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Marks [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Englewood, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 616 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Initial Cost to Company, Land | 4,928,500 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 44,622,314 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 11,548,101 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,928,500 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 56,170,415 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 61,098,915 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Accumulated Depreciation | (34,206,804)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Investment in Real Estate Net | 26,892,111 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Encumbrances | 19,195,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MarksMember |  |  |  |
Metro on First [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 102 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Initial Cost to Company, Land | 8,540,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 12,209,981 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 452,229 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,540,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 12,662,210 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,202,210 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Accumulated Depreciation | (4,480,929)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Investment in Real Estate Net | 16,721,281 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Encumbrances | 22,843,410 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MetroOnFirstMember |  |  |  |
Midtown 24 [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Plantation, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 247 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Midtown24Member |  |  |  |
Initial Cost to Company, Land | 10,129,900 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Midtown24Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 58,770,100 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Midtown24Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,401,853 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Midtown24Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,129,900 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Midtown24Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 60,171,953 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Midtown24Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 70,301,853 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Midtown24Member |  |  |  |
Accumulated Depreciation | (10,913,036)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Midtown24Member |  |  |  |
Investment in Real Estate Net | 59,388,817 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Midtown24Member |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Mill Creek [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Milpitas, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 516 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Initial Cost to Company, Land | 12,858,693 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 57,168,503 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,442,026 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,858,693 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 62,610,529 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 75,469,222 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Accumulated Depreciation | (25,958,217)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Investment in Real Estate Net | 49,511,005 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Encumbrances | 69,312,259 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MillCreekMember |  |  |  |
Moda [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 251 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ModaMember |  |  |  |
Initial Cost to Company, Land | 12,649,228 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ModaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 36,842,012 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ModaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 751,889 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ModaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,649,228 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ModaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 37,593,901 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ModaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 50,243,129 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ModaMember |  |  |  |
Accumulated Depreciation | (7,947,470)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ModaMember |  |  |  |
Investment in Real Estate Net | 42,295,659 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ModaMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (M) | [1] |  |  |
Monte Viejo [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Phoenix, AZ |  |  |  |
Real Estate And Accumulated Depreciation Units | 480 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Initial Cost to Company, Land | 12,700,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 45,926,784 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,356,649 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,700,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 47,283,433 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 59,983,433 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Accumulated Depreciation | (18,448,547)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Investment in Real Estate Net | 41,534,886 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Encumbrances | 38,998,007 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonteViejoMember |  |  |  |
Montierra (CA) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Diego, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 272 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MontierraMember |  |  |  |
Initial Cost to Company, Land | 8,160,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MontierraMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 29,360,938 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MontierraMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 7,349,217 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MontierraMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,160,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MontierraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 36,710,155 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MontierraMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 44,870,155 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MontierraMember |  |  |  |
Accumulated Depreciation | (20,207,547)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MontierraMember |  |  |  |
Investment in Real Estate Net | 24,662,608 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MontierraMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Mosaic at Metro [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Hyattsville, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 260 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 59,580,898 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 396,392 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 59,977,290 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 59,977,290 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
Accumulated Depreciation | (13,426,350)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
Investment in Real Estate Net | 46,550,940 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
Encumbrances | 43,349,098 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MosaicAtMetroMember |  |  |  |
New River Cove [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Davie, FL |  |  |  |
Real Estate And Accumulated Depreciation Units | 316 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NewRiverCoveMember |  |  |  |
Initial Cost to Company, Land | 15,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NewRiverCoveMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 46,142,895 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NewRiverCoveMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,112,295 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NewRiverCoveMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NewRiverCoveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 48,255,190 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NewRiverCoveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 64,055,190 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NewRiverCoveMember |  |  |  |
Accumulated Depreciation | (17,348,296)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NewRiverCoveMember |  |  |  |
Investment in Real Estate Net | 46,706,894 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NewRiverCoveMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
North Pier at Harborside [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Jersey City, NJ |  |  |  |
Real Estate And Accumulated Depreciation Units | 297 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthPierAtHarborsideMember |  |  |  |
Initial Cost to Company, Land | 4,000,159 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthPierAtHarborsideMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 94,290,590 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthPierAtHarborsideMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,508,073 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthPierAtHarborsideMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,000,159 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthPierAtHarborsideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 96,798,663 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthPierAtHarborsideMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 100,798,822 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthPierAtHarborsideMember |  |  |  |
Accumulated Depreciation | (35,934,228)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthPierAtHarborsideMember |  |  |  |
Investment in Real Estate Net | 64,864,594 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthPierAtHarborsideMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (I) | [1] |  |  |
Northpark [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Burlingame, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 510 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Initial Cost to Company, Land | 38,607,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 77,477,449 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 11,535,799 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 38,607,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 89,013,248 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 127,620,248 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Accumulated Depreciation | (21,086,248)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Investment in Real Estate Net | 106,534,000 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Encumbrances | 62,833,873 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_NorthparkMember |  |  |  |
Oak Mill II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Germantown, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 192 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Initial Cost to Company, Land | 854,133 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 10,233,947 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,614,557 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 854,133 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 16,848,504 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 17,702,637 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Accumulated Depreciation | (11,657,281)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Investment in Real Estate Net | 6,045,356 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Encumbrances | 9,600,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OakMillTwoMember |  |  |  |
Oaks [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Santa Clarita, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 520 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Initial Cost to Company, Land | 23,400,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 61,020,438 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,140,268 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 23,400,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 65,160,706 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 88,560,706 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Accumulated Depreciation | (27,139,584)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Investment in Real Estate Net | 61,421,122 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Encumbrances | 37,159,525 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OaksMember |  |  |  |
Olympus Towers [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 328 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Initial Cost to Company, Land | 14,752,034 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 73,335,425 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,446,206 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 14,752,034 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 78,781,631 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 93,533,665 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Accumulated Depreciation | (30,519,078)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Investment in Real Estate Net | 63,014,587 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Encumbrances | 49,875,780 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_OlympusTowersMember |  |  |  |
Park Place at San Mateo (fka San Mateo) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Mateo, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 575 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkPlaceatSanMateofkaSanMateoMember |  |  |  |
Initial Cost to Company, Land | 71,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkPlaceatSanMateofkaSanMateoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 211,907,141 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkPlaceatSanMateofkaSanMateoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,736,590 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkPlaceatSanMateofkaSanMateoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 71,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkPlaceatSanMateofkaSanMateoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 214,643,731 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkPlaceatSanMateofkaSanMateoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 286,543,731 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkPlaceatSanMateofkaSanMateoMember |  |  |  |
Accumulated Depreciation | (22,552,999)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkPlaceatSanMateofkaSanMateoMember |  |  |  |
Investment in Real Estate Net | 263,990,732 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ParkPlaceatSanMateofkaSanMateoMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
Providence [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bothell, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 200 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ProvidenceMember |  |  |  |
Initial Cost to Company, Land | 3,573,621 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ProvidenceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 19,055,505 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ProvidenceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 908,245 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ProvidenceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,573,621 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ProvidenceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 19,963,750 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ProvidenceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 23,537,371 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ProvidenceMember |  |  |  |
Accumulated Depreciation | (8,060,429)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ProvidenceMember |  |  |  |
Investment in Real Estate Net | 15,476,942 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ProvidenceMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (I) | [1] |  |  |
Reserve at Clarendon Centre, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 252 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtClarendonCentreMember |  |  |  |
Initial Cost to Company, Land | 10,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtClarendonCentreMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 52,812,935 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtClarendonCentreMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,852,271 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtClarendonCentreMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtClarendonCentreMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 56,665,206 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtClarendonCentreMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 67,165,206 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtClarendonCentreMember |  |  |  |
Accumulated Depreciation | (22,423,199)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtClarendonCentreMember |  |  |  |
Investment in Real Estate Net | 44,742,007 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtClarendonCentreMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Reserve at Eisenhower, The [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Alexandria, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 226 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEisenhowerMember |  |  |  |
Initial Cost to Company, Land | 6,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEisenhowerMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 34,585,060 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEisenhowerMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,407,205 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEisenhowerMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEisenhowerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 35,992,265 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEisenhowerMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 42,492,265 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEisenhowerMember |  |  |  |
Accumulated Depreciation | (15,227,463)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEisenhowerMember |  |  |  |
Investment in Real Estate Net | 27,264,802 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEisenhowerMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Reserve at Empire Lakes [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Rancho Cucamonga, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 467 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEmpireLakesMember |  |  |  |
Initial Cost to Company, Land | 16,345,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEmpireLakesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 73,080,670 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEmpireLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,097,816 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEmpireLakesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 16,345,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEmpireLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 75,178,486 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEmpireLakesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 91,523,486 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEmpireLakesMember |  |  |  |
Accumulated Depreciation | (25,847,398)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEmpireLakesMember |  |  |  |
Investment in Real Estate Net | 65,676,088 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtEmpireLakesMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (I) | [1] |  |  |
Reserve at Fairfax Corners [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Fairfax, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 652 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Initial Cost to Company, Land | 15,804,057 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 63,129,050 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,733,306 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,804,057 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 69,862,356 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 85,666,413 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Accumulated Depreciation | (29,870,640)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Investment in Real Estate Net | 55,795,773 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Encumbrances | 84,778,876 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtFairfaxCornersMember |  |  |  |
Reserve at Potomac Yard [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Alexandria, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 588 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Initial Cost to Company, Land | 11,918,917 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 68,862,641 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,341,718 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 11,918,917 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 75,204,359 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 87,123,276 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Accumulated Depreciation | (28,902,316)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Investment in Real Estate Net | 58,220,960 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Encumbrances | 66,470,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveAtPotomacYardMember |  |  |  |
Reserve at Town Center (WA) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Mill Creek, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 389 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Initial Cost to Company, Land | 10,369,400 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 41,172,081 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,404,316 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,369,400 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 43,576,397 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 53,945,797 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Accumulated Depreciation | (17,140,399)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Investment in Real Estate Net | 36,805,398 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Encumbrances | 29,160,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ReserveatTownCenterWAMember |  |  |  |
Rianna II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 78 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Initial Cost to Company, Land | 2,161,840 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 14,433,614 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 219,336 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,161,840 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 14,652,950 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 16,814,790 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Accumulated Depreciation | (3,719,806)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Investment in Real Estate Net | 13,094,984 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Encumbrances | 9,664,461 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RiannaIiMember |  |  |  |
Rockingham Glen [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | West Roxbury, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 143 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Initial Cost to Company, Land | 1,124,217 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 7,515,160 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,127,798 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,124,217 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 9,642,958 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 10,767,175 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Accumulated Depreciation | (5,189,711)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Investment in Real Estate Net | 5,577,464 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Encumbrances | 732,326 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RockinghamGlenMember |  |  |  |
Siena Terrace [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Lake Forest, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 356 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Initial Cost to Company, Land | 8,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 24,083,024 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,513,124 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,596,148 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 39,496,148 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Accumulated Depreciation | (16,196,382)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Investment in Real Estate Net | 23,299,766 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Encumbrances | 38,440,808 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SienaTerraceMember |  |  |  |
Skyview [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Rancho Santa Margarita, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 260 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
Initial Cost to Company, Land | 3,380,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 21,952,863 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,762,747 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,380,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 24,715,610 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 28,095,610 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
Accumulated Depreciation | (13,314,866)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
Investment in Real Estate Net | 14,780,744 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
Encumbrances | 30,889,928 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SkyviewMember |  |  |  |
SoMa Square Apartments (fka South Market) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Francisco, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 410 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SoMaSquareApartmentsfkaSouthMarketMember |  |  |  |
Initial Cost to Company, Land | 79,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SoMaSquareApartmentsfkaSouthMarketMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 177,316,977 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SoMaSquareApartmentsfkaSouthMarketMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,711,818 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SoMaSquareApartmentsfkaSouthMarketMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 79,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SoMaSquareApartmentsfkaSouthMarketMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 180,028,795 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SoMaSquareApartmentsfkaSouthMarketMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 259,928,795 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SoMaSquareApartmentsfkaSouthMarketMember |  |  |  |
Accumulated Depreciation | (19,032,108)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SoMaSquareApartmentsfkaSouthMarketMember |  |  |  |
Investment in Real Estate Net | 240,896,687 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SoMaSquareApartmentsfkaSouthMarketMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
Stonegate (CO) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Broomfield, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 350 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StonegateCOMember |  |  |  |
Initial Cost to Company, Land | 8,750,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StonegateCOMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 32,950,375 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StonegateCOMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,208,246 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StonegateCOMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,750,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StonegateCOMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 36,158,621 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StonegateCOMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 44,908,621 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StonegateCOMember |  |  |  |
Accumulated Depreciation | (13,931,379)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StonegateCOMember |  |  |  |
Investment in Real Estate Net | 30,977,242 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StonegateCOMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (I) | [1] |  |  |
Stoney Ridge [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Dale City, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 264 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Initial Cost to Company, Land | 8,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 24,147,091 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,813,599 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 29,960,690 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 37,960,690 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Accumulated Depreciation | (13,117,254)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Investment in Real Estate Net | 24,843,436 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Encumbrances | 13,414,254 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StoneyRidgeMember |  |  |  |
Summerset Village [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Chatsworth, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 280 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Initial Cost to Company, Land | 2,629,804 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,670,889 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,735,640 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,629,804 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 30,406,529 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 33,036,333 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Accumulated Depreciation | (18,638,374)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Investment in Real Estate Net | 14,397,959 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Encumbrances | 38,039,912 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SummersetVillageMember |  |  |  |
Talleyrand [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Tarrytown, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 300 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Initial Cost to Company, Land | 12,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 49,838,160 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,373,570 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 54,211,730 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 66,211,730 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Accumulated Depreciation | (25,824,997)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Investment in Real Estate Net | 40,386,733 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Encumbrances | 35,000,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TalleyrandMember |  |  |  |
Teresina [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Chula Vista, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 440 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Initial Cost to Company, Land | 28,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 61,916,670 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,524,216 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 28,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 64,440,886 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 93,040,886 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Accumulated Depreciation | (23,028,983)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Investment in Real Estate Net | 70,011,903 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Encumbrances | 41,153,983 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TeresinaMember |  |  |  |
Toscana [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Irvine, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 563 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Initial Cost to Company, Land | 39,410,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 50,806,072 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 8,065,576 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 39,410,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 58,871,648 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 98,281,648 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Accumulated Depreciation | (30,358,453)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Investment in Real Estate Net | 67,923,195 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Encumbrances | 71,243,194 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ToscanaMember |  |  |  |
Touriel Building [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Berkeley, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 35 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Initial Cost to Company, Land | 2,736,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 7,810,027 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 173,049 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,736,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 7,983,076 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 10,719,076 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Accumulated Depreciation | (2,537,090)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Investment in Real Estate Net | 8,181,986 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Encumbrances | 5,050,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TourielBuildingMember |  |  |  |
Town Square at Mark Center I (fka Millbrook I) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Alexandria, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 406 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Initial Cost to Company, Land | 24,360,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 86,178,714 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,101,186 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 24,360,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 89,279,900 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 113,639,900 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Accumulated Depreciation | (31,779,511)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Investment in Real Estate Net | 81,860,389 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Encumbrances | 77,353,222 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TownSquareAtMarkCenteriMember |  |  |  |
Uptown Square [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Denver, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 696 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Initial Cost to Company, Land | 17,492,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 100,696,541 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,323,125 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 17,492,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 105,019,666 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 122,511,666 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Accumulated Depreciation | (38,387,874)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Investment in Real Estate Net | 84,123,792 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Encumbrances | 99,190,116 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_UptownSquareMember |  |  |  |
Versailles [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Woodland Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 253 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Initial Cost to Company, Land | 12,650,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 33,656,292 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,439,447 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 12,650,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 39,095,739 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 51,745,739 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Accumulated Depreciation | (16,887,476)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Investment in Real Estate Net | 34,858,263 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Encumbrances | 30,372,953 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesMember |  |  |  |
Versailles (K-Town) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 225 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Initial Cost to Company, Land | 10,590,975 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 44,409,025 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,089,480 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,590,975 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 45,498,505 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 56,089,480 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Accumulated Depreciation | (10,851,277)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Investment in Real Estate Net | 45,238,203 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Encumbrances | 29,826,475 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VersaillesKTownMember |  |  |  |
Victor on Venice [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 115 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VictorOnVeniceMember |  |  |  |
Initial Cost to Company, Land | 10,350,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VictorOnVeniceMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 35,433,437 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VictorOnVeniceMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 493,945 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VictorOnVeniceMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 10,350,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VictorOnVeniceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 35,927,382 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VictorOnVeniceMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 46,277,382 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VictorOnVeniceMember |  |  |  |
Accumulated Depreciation | (11,164,686)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VictorOnVeniceMember |  |  |  |
Investment in Real Estate Net | 35,112,696 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VictorOnVeniceMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (J) | [1] |  |  |
Vintage [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Ontario, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 300 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Initial Cost to Company, Land | 7,059,230 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 47,677,762 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 418,205 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,059,230 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 48,095,967 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 55,155,197 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Accumulated Depreciation | (15,673,129)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Investment in Real Estate Net | 39,482,068 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Encumbrances | 33,000,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VintageMember |  |  |  |
Vintage at 425 Broadway (fka Promenade) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Santa Monica, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 58 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Vintageat425BroadwayfkaPromenadeMember |  |  |  |
Initial Cost to Company, Land | 9,000,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Vintageat425BroadwayfkaPromenadeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 13,961,523 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Vintageat425BroadwayfkaPromenadeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 354,858 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Vintageat425BroadwayfkaPromenadeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 9,000,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Vintageat425BroadwayfkaPromenadeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 14,316,381 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Vintageat425BroadwayfkaPromenadeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 23,316,381 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Vintageat425BroadwayfkaPromenadeMember |  |  |  |
Accumulated Depreciation | (1,915,005)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Vintageat425BroadwayfkaPromenadeMember |  |  |  |
Investment in Real Estate Net | 21,401,376 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Vintageat425BroadwayfkaPromenadeMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (L) | [1] |  |  |
Vista on Courthouse [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 220 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Initial Cost to Company, Land | 15,550,260 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 69,449,740 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,100,172 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 15,550,260 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 70,549,912 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 86,100,172 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Accumulated Depreciation | (16,370,415)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Investment in Real Estate Net | 69,729,757 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Encumbrances | 31,380,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VistaOnCourthouseMember |  |  |  |
Water Park Towers [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Arlington, VA |  |  |  |
Real Estate And Accumulated Depreciation Units | 362 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterParkTowersMember |  |  |  |
Initial Cost to Company, Land | 34,400,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterParkTowersMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 108,485,859 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterParkTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,570,221 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterParkTowersMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 34,400,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterParkTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 112,056,080 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterParkTowersMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 146,456,080 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterParkTowersMember |  |  |  |
Accumulated Depreciation | (12,141,171)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterParkTowersMember |  |  |  |
Investment in Real Estate Net | 134,314,909 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WaterParkTowersMember |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (K) | [1] |  |  |
West 54th [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 222 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Initial Cost to Company, Land | 60,900,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 48,193,837 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 320,475 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 60,900,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 48,514,312 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 109,414,312 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Accumulated Depreciation | (7,362,247)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Investment in Real Estate Net | 102,052,065 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Encumbrances | 46,859,227 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_West54thMember |  |  |  |
Westgate (fka Westgate I) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pasadena, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 480 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Initial Cost to Company, Land | 22,898,848 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 133,553,692 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 348,871 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 22,898,848 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 133,902,563 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 156,801,411 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Accumulated Depreciation | (18,556,819)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Investment in Real Estate Net | 138,244,592 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Encumbrances | 96,935,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WestgatefkaWestgateIMember |  |  |  |
Woodleaf [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Campbell, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 178 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Initial Cost to Company, Land | 8,550,600 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 16,988,183 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,312,027 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,550,600 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 21,300,210 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 29,850,810 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Accumulated Depreciation | (11,452,912)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Investment in Real Estate Net | 18,397,898 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Encumbrances | 17,858,854 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodleafMember |  |  |  |
Wholly Owned Encumbered [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Units | 29,923 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedEncumberedMember |  |  |  |
Initial Cost to Company, Land | 1,889,558,099 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedEncumberedMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 5,894,004,795 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedEncumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 330,213,229 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedEncumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 6,224,218,024 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedEncumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 8,113,776,123 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedEncumberedMember |  |  |  |
Accumulated Depreciation | 1,587,799,207 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedEncumberedMember |  |  |  |
Investment in Real Estate Net | 6,525,976,916 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedEncumberedMember |  |  |  |
Encumbrances | 4,726,035,749 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WhollyOwnedEncumberedMember |  |  |  |
2300 Elliott [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 92 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
Initial Cost to Company, Land | 796,800 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 7,173,725 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,244,167 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 796,800 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 13,417,892 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 14,214,692 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
Accumulated Depreciation | (9,635,532)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
Investment in Real Estate Net | 4,579,160 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_Elliott2300Member |  |  |  |
400 Park Aveue South (Toll) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Initial Cost to Company, Land | 58,090,357 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 55,679,496 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 0 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 58,090,357 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 55,679,496 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 113,769,853 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Investment in Real Estate Net | 113,769,853 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_A400ParkAveueSouthTollMemberMember |  |  |  |
Canyon Ridge [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Diego, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 162 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Initial Cost to Company, Land | 4,869,448 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 11,955,064 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,794,600 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,869,448 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 14,749,664 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 19,619,112 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Accumulated Depreciation | (8,662,269)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Investment in Real Estate Net | 10,956,843 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonRidgeMember |  |  |  |
Country Oaks [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Agoura Hills, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 256 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Initial Cost to Company, Land | 6,105,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 29,561,865 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,053,877 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,105,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 33,615,742 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 39,720,742 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Accumulated Depreciation | (15,662,969)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Investment in Real Estate Net | 24,057,773 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CountryOaksMember |  |  |  |
Fox Ridge [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Englewood, CO |  |  |  |
Real Estate And Accumulated Depreciation Units | 300 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Initial Cost to Company, Land | 2,490,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 17,522,114 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,601,407 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,490,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 22,123,521 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 24,613,521 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Accumulated Depreciation | (11,718,055)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Investment in Real Estate Net | 12,895,466 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_FoxRidgeMember |  |  |  |
Monterra in Mill Creek [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Mill Creek, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 139 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Initial Cost to Company, Land | 2,800,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 13,255,123 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 670,037 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 2,800,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 13,925,160 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 16,725,160 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Accumulated Depreciation | (5,104,802)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Investment in Real Estate Net | 11,620,358 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_MonterraInMillCreekMember |  |  |  |
Prism at Park Avenue South (fka 400 Park Aveue South (EQR)) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | New York, NY |  |  |  |
Real Estate And Accumulated Depreciation Units | 0 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Initial Cost to Company, Land | 76,292,169 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 150,666,648 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 11,603 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 76,292,169 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 150,678,251 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 226,970,420 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Accumulated Depreciation | 0 us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Investment in Real Estate Net | 226,970,420 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_APrismatParkAvenueSouthfka400ParkAveueSouthEQRMember |  |  |  |
Strayhorse at Arrowhead Ranch [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Glendale, AZ |  |  |  |
Real Estate And Accumulated Depreciation Units | 136 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Initial Cost to Company, Land | 4,400,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 12,968,002 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 443,437 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,400,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 13,411,439 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 17,811,439 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Accumulated Depreciation | (4,853,154)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Investment in Real Estate Net | 12,958,285 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_StrayhorseAtArrowheadRanchMember |  |  |  |
Via Ventura (CA) (fka Ventura) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Ventura, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 192 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Initial Cost to Company, Land | 8,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 44,308,202 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 406,230 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 8,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 44,714,432 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 53,314,432 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Accumulated Depreciation | (5,214,735)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Investment in Real Estate Net | 48,099,697 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_ViaVenturaMember |  |  |  |
Wood Creek II (fka Willow Brook (CA)) |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Pleasant Hill, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 228 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Initial Cost to Company, Land | 5,055,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 38,388,672 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,889,178 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,055,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 43,277,850 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 48,332,850 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Accumulated Depreciation | (16,682,842)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Investment in Real Estate Net | 31,650,008 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WoodCreekIIfkaWillowBrookCAMember |  |  |  |
Partially Owned Unencumbered [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Units | 1,505 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Initial Cost to Company, Land | 169,498,774 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 381,478,911 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 24,114,536 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 169,498,774 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 405,593,447 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 575,092,221 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Accumulated Depreciation | (77,534,358)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Investment in Real Estate Net | 497,557,863 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Encumbrances | 0 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedUnencumberedMember |  |  |  |
Bellevue Meadows [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bellevue, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 180 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Initial Cost to Company, Land | 4,507,100 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 12,574,814 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,524,770 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,507,100 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 17,099,584 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 21,606,684 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Accumulated Depreciation | (10,473,761)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Investment in Real Estate Net | 11,132,923 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Encumbrances | 16,538,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_BellevueMeadowsMember |  |  |  |
Canyon Creek (CA) [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | San Ramon, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 268 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Initial Cost to Company, Land | 5,425,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,812,121 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 6,427,590 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,425,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 25,239,711 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,664,711 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Accumulated Depreciation | (12,764,001)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Investment in Real Estate Net | 17,900,710 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Encumbrances | 28,200,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_CanyonCreekCMember |  |  |  |
Harrison Square (fka Elliot Bay) [Domain] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Seattle, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 166 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarrisonSquarefkaElliotBayDomain |  |  |  |
Initial Cost to Company, Land | 7,600,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarrisonSquarefkaElliotBayDomain |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 35,844,345 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarrisonSquarefkaElliotBayDomain |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 3,159,773 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarrisonSquarefkaElliotBayDomain |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 7,600,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarrisonSquarefkaElliotBayDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 39,004,118 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarrisonSquarefkaElliotBayDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 46,604,118 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarrisonSquarefkaElliotBayDomain |  |  |  |
Accumulated Depreciation | (3,837,725)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarrisonSquarefkaElliotBayDomain |  |  |  |
Investment in Real Estate Net | 42,766,393 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_HarrisonSquarefkaElliotBayDomain |  |  |  |
Real Estate And Accumulated Depreciation, Encumbrances Reference | (K) | [1] |  |  |
Isle at Arrowhead Ranch [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Glendale, AZ |  |  |  |
Real Estate And Accumulated Depreciation Units | 256 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Initial Cost to Company, Land | 1,650,237 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 19,593,123 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,216,333 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 1,650,237 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 21,809,456 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 23,459,693 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Accumulated Depreciation | (13,005,000)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Investment in Real Estate Net | 10,454,693 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Encumbrances | 17,700,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_IsleAtArrowheadRanchMember |  |  |  |
Lantern Cove [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Foster City, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 232 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Initial Cost to Company, Land | 6,945,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 23,064,976 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 5,705,946 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,945,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 28,770,922 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 35,715,922 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Accumulated Depreciation | (13,736,832)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Investment in Real Estate Net | 21,979,090 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Encumbrances | 36,455,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_LanternCoveMember |  |  |  |
Rosecliff [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Quincy, MA |  |  |  |
Real Estate And Accumulated Depreciation Units | 156 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Initial Cost to Company, Land | 5,460,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 15,721,570 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,561,718 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,460,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 18,283,288 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 23,743,288 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Accumulated Depreciation | (9,854,030)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Investment in Real Estate Net | 13,889,258 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Encumbrances | 17,400,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_RosecliffMember |  |  |  |
Schooner Bay I [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Foster City, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 168 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Initial Cost to Company, Land | 5,345,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 20,390,618 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,756,784 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,345,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 25,147,402 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 30,492,402 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Accumulated Depreciation | (12,000,181)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Investment in Real Estate Net | 18,492,221 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Encumbrances | 28,870,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayOneMember |  |  |  |
Schooner Bay II [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Foster City, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 144 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Initial Cost to Company, Land | 4,550,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 18,064,764 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 4,275,408 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 4,550,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 22,340,172 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 26,890,172 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Accumulated Depreciation | (10,806,797)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Investment in Real Estate Net | 16,083,375 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Encumbrances | 26,175,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SchoonerBayTwoMember |  |  |  |
Surrey Downs [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Bellevue, WA |  |  |  |
Real Estate And Accumulated Depreciation Units | 122 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Initial Cost to Company, Land | 3,057,100 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 7,848,618 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,407,669 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 3,057,100 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 10,256,287 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 13,313,387 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Accumulated Depreciation | (6,009,471)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Investment in Real Estate Net | 7,303,916 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Encumbrances | 9,829,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_SurreyDownsMember |  |  |  |
Virgil Square [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Los Angeles, CA |  |  |  |
Real Estate And Accumulated Depreciation Units | 142 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Initial Cost to Company, Land | 5,500,000 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 15,216,613 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 2,175,257 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 5,500,000 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 17,391,870 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 22,891,870 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Accumulated Depreciation | (6,559,144)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Investment in Real Estate Net | 16,332,726 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Encumbrances | 9,900,000 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_VirgilSquareMember |  |  |  |
Wisconsin Place [Domain] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Description Of Location | Chevy Chase, MD |  |  |  |
Real Estate And Accumulated Depreciation Units | 432 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Initial Cost to Company, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 172,089,355 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 550,832 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 0 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 172,640,187 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 172,640,187 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Accumulated Depreciation | (17,900,087)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Investment in Real Estate Net | 154,740,100 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Encumbrances | 144,571,681 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_WisconsinPlaceDomain |  |  |  |
Partially Owned Encumbered [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Units | 2,266 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Initial Cost to Company, Land | 50,039,437 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 359,220,917 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 38,762,080 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 50,039,437 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 397,982,997 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 448,022,434 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Accumulated Depreciation | (116,947,029)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Investment in Real Estate Net | 331,075,405 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Encumbrances | 360,479,262 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PartiallyOwnedEncumberedMember |  |  |  |
Portfolio Entity Encumbrances [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Encumbrances | 2,124,179,543 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_PortfolioEntityEncumbrancesMember |  |  |  |
Total Consolidated Investment in Real Estate [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Real Estate And Accumulated Depreciation Units | 102,911 eqr_RealEstateAndAccumulatedDepreciationUnits / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Initial Cost to Company, Land | 6,907,534,212 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements | 19,372,503,705 us-gaap_RealEstateAndAccumulatedDepreciationInitialCostOfBuildingsAndImprovements / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Real Estate And Accumulated Depreciation Costs Capitalized Subsequent To Acquisition Building And Fixtures | 1,395,345,007 eqr_RealEstateAndAccumulatedDepreciationCostsCapitalizedSubsequentToAcquisitionBuildingAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Gross Amount Carried at close of period 12/31/2013, Land | 6,907,534,212 us-gaap_RealEstateAndAccumulatedDepreciationCarryingAmountOfLand / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Buildings And Improvements And Furnitures And Fixtures | 20,767,848,712 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Real Estate And Accumulated Depreciation Carrying Amount Of Land And Buildings And Improvements And Furnitures And Fixtures | 27,675,382,924 eqr_RealEstateAndAccumulatedDepreciationCarryingAmountOfLandAndBuildingsAndImprovementsAndFurnituresAndFixtures / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Accumulated Depreciation | (5,432,805,335)us-gaap_RealEstateAccumulatedDepreciation / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Investment in Real Estate Net | 22,242,577,589 eqr_InvestmentInRealEstateNet / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Encumbrances | 5,086,515,011 us-gaap_RealEstateAndAccumulatedDepreciationAmountOfEncumbrances / us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis = eqr_TotalConsolidatedInvestmentInRealEstateMember |  |  |  |
Unconsolidated Operating [Domain] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Partially Owned Unconsolidated Properties | 3 eqr_PartiallyOwnedUnconsolidatedProperties / us-gaap_StatementScenarioAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Partially Owned Unconsolidated Units | 1,281 eqr_PartiallyOwnedUnconsolidatedUnits / us-gaap_StatementScenarioAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Depreciable Property [Member] |  |  |  |  |
Real Estate and Accumulated Depreciation [Line Items] |  |  |  |  |
Fixtures and Equipment, Gross | $ 1,365,276,528 us-gaap_FixturesAndEquipmentGross / us-gaap_PropertyPlantAndEquipmentByTypeAxis = eqr_DepreciablePropertyMember |  |  |  |
Building [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 30 |  |  |  |
Renovations and Improvements Minimum [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 5 |  |  |  |
Renovations and Improvements Maximum [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 15 |  |  |  |
Replacements Minimum [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 5 |  |  |  |
Replacements Maximum [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 10 |  |  |  |
Management Business Renovations and Improvements Minimum [Member] [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 3 |  |  |  |
Management Business Renovations and Improvements Maximum [Member] [Member] |  |  |  |  |
Real Estates And Accumulated Depreciation Abstract |  |  |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 7 |  |  |  |
[1] | (I)through (L) See Encumbrances Reconciliation schedule.

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