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Summary of Significant Accounting Policies Text (Details) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Partially Owned Unconsolidated Properties | 3 eqr_PartiallyOwnedUnconsolidatedProperties |  |
Value of furniture and fixtures minimum range | $ 3,000 eqr_ValueOfFurnitureAndFixturesMinimumRange |  |
Value of furniture and fixtures maximum range | 13,000 eqr_ValueOfFurnitureAndFixturesMaximumRange |  |
Lease Intangibles, Average Term | 6 eqr_LeaseIntangiblesAverageTerm |  |
Capitalized Costs Development and Renovation | 22,400,000 eqr_CapitalizedCostsDevelopmentAndRenovation | 16,500,000 eqr_CapitalizedCostsDevelopmentAndRenovation | 14,300,000 eqr_CapitalizedCostsDevelopmentAndRenovation
Accumulated Amortization, Deferred Finance Costs | 37,700,000 us-gaap_AccumulatedAmortizationDeferredFinanceCosts | 33,400,000 us-gaap_AccumulatedAmortizationDeferredFinanceCosts |
Partially Owned Consolidated Properties | 19 eqr_PartiallyOwnedConsolidatedProperties |  |
Partially Owned Consolidated Units | 3,771 eqr_PartiallyOwnedConsolidatedUnits |  |
Noncontrolling Interests - Partially Owned Properties | 124,909,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties | 126,583,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties |
Furniture and Fixtures [Member] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 5 |  |
Furniture and Fixtures Maximum [Member] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 10 |  |
Building [Member] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 30 |  |
Building Improvements [Member] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 8 |  |
Replacements Minimum [Member] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 5 |  |
Replacements Maximum [Member] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 10 |  |
Renovations and Improvements Minimum [Member] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 5 |  |
Renovations and Improvements Maximum [Member] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | 15 |  |
Minimum [Member] |  |  |
Retail/Commercial Leases Term | 5 eqr_RetailCommercialLeasesTerm / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_MinimumMember |  |
Maximum [Member] |  |  |
Retail/Commercial Leases Term | 10 eqr_RetailCommercialLeasesTerm / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_MaximumMember |  |
Limited Life Partnership Properties [Member] |  |  |
Partially Owned Limited Life Partnership Properties | 6 eqr_PartiallyOwnedLimitedLifePartnershipProperties / eqr_PartiallyOwnedAxis = eqr_LimitedLifePartnershipPropertiesMember |  |
Noncontrolling Interest Balance Limited Life Partnerships | (10,900,000)eqr_NoncontrollingInterestBalanceLimitedLifePartnerships / eqr_PartiallyOwnedAxis = eqr_LimitedLifePartnershipPropertiesMember |  |
Noncontrolling Interests Settlement Value | $ 62,900,000 eqr_NoncontrollingInterestsSettlementValue / eqr_PartiallyOwnedAxis = eqr_LimitedLifePartnershipPropertiesMember |  |
Unconsolidated Operating [Domain] |  |  |
Partially Owned Unconsolidated Properties | 3 eqr_PartiallyOwnedUnconsolidatedProperties / us-gaap_StatementScenarioAxis = eqr_UnconsolidatedOperatingDomain |  |

X
- Definition Represents payroll and associated costs of employees directly responsible for and who spend their time on the supervision of development activities as well as major capital and/or renovation projects that are capitalized on the balance sheet + References No definition available. + Details
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- Definition Represents the average term in months of In-place lease intangibles over which the asset is amortized. + References No definition available. + Details
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- Definition Carrying amount of equity interests owned by the noncontrolling partners in partially owned limited life partnerships. + References No definition available. + Details
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- Definition Carrying amount of equity interests owned by noncontrolling partners in partially owned properties. + References No definition available. + Details
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- Definition Represents the value of Noncontrolling Interest distributions had the Company's partnership agreements been liquidated through the sale of their assets upon reaching the date specified in each respective partnership agreement. The Company, as controlling partner, has an obligation to cause the property owning partnerships to distribute the proceeds of liquidation to the Noncontrolling Interests in these Partially Owned Properties. + References No definition available. + Details
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- Definition Total number of rental properties that are partially owned and consolidated by the Company. + References No definition available. + Details
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- Definition Total number of units associated with rental properties that are partially owned and consolidated by the Company. + References No definition available. + Details
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- Definition Total number of properties that contain provisions in their respective partnership agreements that require liquidation through the sale of assets upon reaching the date specified within their agreements. + References No definition available. + Details
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- Definition Total number of rental properties that are partially owned and not consolidated by the Company. + References No definition available. + Details
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- Definition Represents the average term in years of retail/commercial leases. + References No definition available. + Details
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- Definition Value of the maximum amount applied on a per apartment unit basis to estimate the fair value of furniture and fixtures inside the unit for newly acquired properties that have an age of 10 years or less. + References No definition available. + Details
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- Definition Value of the minimum amount applied on a per apartment unit basis to estimate the fair value of furniture and fixtures inside the unit for newly acquired properties that have an age of 11 years or more. + References No definition available. + Details
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