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Investments in Partially Owned Entities (Details) (USD $) | 12 Months Ended | 22 Months Ended |
--- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2014 | Dec. 31, 2011
Partially Owned Property Balance Sheet Schedule |  |  |  |  |
Partially Owned Consolidated Properties | 19 eqr_PartiallyOwnedConsolidatedProperties |  |  | 19 eqr_PartiallyOwnedConsolidatedProperties |
Partially Owned Unconsolidated Properties | 3 eqr_PartiallyOwnedUnconsolidatedProperties |  |  | 3 eqr_PartiallyOwnedUnconsolidatedProperties |
Partially Owned Consolidated Units | 3,771 eqr_PartiallyOwnedConsolidatedUnits |  |  | 3,771 eqr_PartiallyOwnedConsolidatedUnits |
Partially Owned Unconsolidated Units | 1,281 eqr_PartiallyOwnedUnconsolidatedUnits |  |  | 1,281 eqr_PartiallyOwnedUnconsolidatedUnits |
ASSETS |  |  |  |  |
Investment in real estate | $ 27,675,383,000 us-gaap_RealEstateInvestmentPropertyAtCost | $ 26,800,948,000 us-gaap_RealEstateInvestmentPropertyAtCost |  | $ 27,675,383,000 us-gaap_RealEstateInvestmentPropertyAtCost |
Accumulated depreciation | 5,432,805,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation | 4,807,709,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation |  | 5,432,805,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation |
Investment in real estate, net | 22,242,578,000 us-gaap_RealEstateInvestmentPropertyNet | 21,993,239,000 us-gaap_RealEstateInvestmentPropertyNet |  | 22,242,578,000 us-gaap_RealEstateInvestmentPropertyNet |
Cash and cash equivalents | 40,080,000 us-gaap_CashAndCashEquivalentsAtCarryingValue | 53,534,000 us-gaap_CashAndCashEquivalentsAtCarryingValue | 612,590,000 us-gaap_CashAndCashEquivalentsAtCarryingValue | 40,080,000 us-gaap_CashAndCashEquivalentsAtCarryingValue | 383,921,000 us-gaap_CashAndCashEquivalentsAtCarryingValue
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures | 105,434,000 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures | 178,526,000 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures |  | 105,434,000 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures |
Restricted Cash and Cash Equivalents | 72,303,000 us-gaap_RestrictedCashAndCashEquivalents | 103,567,000 us-gaap_RestrictedCashAndCashEquivalents |  | 72,303,000 us-gaap_RestrictedCashAndCashEquivalents |
Deferred financing costs, net | 58,380,000 us-gaap_DeferredFinanceCostsNet | 58,486,000 us-gaap_DeferredFinanceCostsNet |  | 58,380,000 us-gaap_DeferredFinanceCostsNet |
Other assets | 383,754,000 us-gaap_OtherAssets | 404,557,000 us-gaap_OtherAssets |  | 383,754,000 us-gaap_OtherAssets |
Total assets | 22,950,614,000 us-gaap_Assets | 22,834,545,000 us-gaap_Assets |  | 22,950,614,000 us-gaap_Assets |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt | 5,086,515,000 us-gaap_SecuredDebt | 5,174,166,000 us-gaap_SecuredDebt |  | 5,086,515,000 us-gaap_SecuredDebt |
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable | 153,590,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable | 118,791,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable |  | 153,590,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable |
Accrued interest payable | 89,540,000 us-gaap_InterestPayableCurrentAndNoncurrent | 78,309,000 us-gaap_InterestPayableCurrentAndNoncurrent |  | 89,540,000 us-gaap_InterestPayableCurrentAndNoncurrent |
Other liabilities | 389,915,000 us-gaap_OtherLiabilities | 347,748,000 us-gaap_OtherLiabilities |  | 389,915,000 us-gaap_OtherLiabilities |
Security Deposit Liability | 75,633,000 us-gaap_SecurityDepositLiability | 71,592,000 us-gaap_SecurityDepositLiability |  | 75,633,000 us-gaap_SecurityDepositLiability |
Total liabilities | 11,742,105,000 us-gaap_Liabilities | 11,626,205,000 us-gaap_Liabilities |  | 11,742,105,000 us-gaap_Liabilities |
Noncontrolling Interests - Partially Owned Properties | 124,909,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties | 126,583,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties |  | 124,909,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties |
Total liabilities and equity | 22,950,614,000 us-gaap_LiabilitiesAndStockholdersEquity | 22,834,545,000 us-gaap_LiabilitiesAndStockholdersEquity |  | 22,950,614,000 us-gaap_LiabilitiesAndStockholdersEquity |
Partially Owned Property Income Statement Schedule |  |  |  |  |
Operating revenue | 2,614,748,000 us-gaap_Revenues | 2,387,702,000 us-gaap_Revenues | 1,747,502,000 us-gaap_Revenues |  |
Depreciation | 758,861,000 us-gaap_Depreciation | 978,973,000 us-gaap_Depreciation | 560,669,000 us-gaap_Depreciation |  |
General and administrative/other | 50,948,000 us-gaap_GeneralAndAdministrativeExpense | 62,179,000 us-gaap_GeneralAndAdministrativeExpense | 47,233,000 us-gaap_GeneralAndAdministrativeExpense |  |
Operating (loss) income | 921,375,000 us-gaap_OperatingIncomeLoss | 512,322,000 us-gaap_OperatingIncomeLoss | 514,093,000 us-gaap_OperatingIncomeLoss |  |
Interest and other income | 4,462,000 us-gaap_InterestAndOtherIncome | 5,283,000 us-gaap_InterestAndOtherIncome | 151,060,000 us-gaap_InterestAndOtherIncome |  |
Interest: |  |  |  |  |
Expense incurred, net | 457,191,000 us-gaap_InterestExpenseDebt | 586,854,000 us-gaap_InterestExpenseDebt | 455,236,000 us-gaap_InterestExpenseDebt |  |
Amortization of deferred financing costs | (11,088,000)us-gaap_AmortizationOfFinancingCosts | (22,197,000)us-gaap_AmortizationOfFinancingCosts | (21,295,000)us-gaap_AmortizationOfFinancingCosts |  |
(Loss) income before income and other taxes and (loss) from investments in unconsolidated entities | 448,485,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments | (121,076,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments | 160,826,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments |  |
Income and other tax (expense) benefit | (1,394,000)us-gaap_IncomeTaxExpenseBenefit | (1,169,000)us-gaap_IncomeTaxExpenseBenefit | (514,000)us-gaap_IncomeTaxExpenseBenefit |  |
(Loss) from investments in unconsolidated entities | (7,952,000)us-gaap_IncomeLossFromEquityMethodInvestments | (58,156,000)us-gaap_IncomeLossFromEquityMethodInvestments | (14,000)us-gaap_IncomeLossFromEquityMethodInvestments |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest | 658,683,000 us-gaap_ProfitLoss | 1,905,353,000 us-gaap_ProfitLoss | 881,204,000 us-gaap_ProfitLoss |  |
Joint Venture Partner Ownership Percentage | 80.00%eqr_JointVenturePartnerOwnershipPercentage |  |  | 80.00%eqr_JointVenturePartnerOwnershipPercentage |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Disposed Properties | 11 eqr_DisposedProperties | 94 eqr_DisposedProperties |  |  |
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax | 179,000 us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax | 2,036,505,000 us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax | 548,278,000 us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax |  |
Disposed Units | 3,480 eqr_DisposedUnits | 29,180 eqr_DisposedUnits |  |  |
Equity Method Investment, Ownership Percentage | 20.00%us-gaap_EquityMethodInvestmentOwnershipPercentage |  |  | 20.00%us-gaap_EquityMethodInvestmentOwnershipPercentage |
Debt Instrument, Maturity Date |  | Sep. 01, 2014 |  |  |
Distributions from unconsolidated entities – return of capital | 103,793,000 eqr_ProceedsFromDistributionsReceivedFromUnconsolidatedSubsidiaries | 25,471,000 eqr_ProceedsFromDistributionsReceivedFromUnconsolidatedSubsidiaries | 0 eqr_ProceedsFromDistributionsReceivedFromUnconsolidatedSubsidiaries |  |
Preferred Interests |  | 65,000,000 eqr_PreferredInterests |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets | 498,640,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets | 108,000,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets |  | 498,640,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets |
Investment in Joint Venture | 336,900,000 eqr_InvestmentInJointVenture |  |  | 336,900,000 eqr_InvestmentInJointVenture |
Number of Joint Ventures | 2 eqr_NumberOfJointVentures |  |  | 2 eqr_NumberOfJointVentures |
Partners Payments To Acquire Equity Method Investments | 40,100,000 eqr_PartnersPaymentsToAcquireEquityMethodInvestments |  |  |  |
Consolidated Development Projects Held for and or Under Development [Member] |  |  |  |  |
Partially Owned Property Balance Sheet Schedule |  |  |  |  |
Partially Owned Consolidated Properties | 0 eqr_PartiallyOwnedConsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 0 eqr_PartiallyOwnedConsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Partially Owned Consolidated Units | 0 eqr_PartiallyOwnedConsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 0 eqr_PartiallyOwnedConsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
ASSETS |  |  |  |  |
Investment in real estate | 340,740,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 340,740,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Accumulated depreciation | 0 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 0 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Investment in real estate, net | 340,740,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 340,740,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Cash and cash equivalents | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 0 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Restricted Cash and Cash Equivalents | 22,706,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 22,706,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Deferred financing costs, net | 0 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 0 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Other assets | 6,658,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 6,658,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Total assets | 370,104,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 370,104,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt | 0 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 0 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable | 13,307,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 13,307,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Accrued interest payable | 0 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 0 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Other liabilities | 69,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 69,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Security Deposit Liability | 25,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 25,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Total liabilities | 13,401,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 13,401,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Noncontrolling Interests - Partially Owned Properties | 117,350,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 117,350,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Parent Equity Interest | 239,353,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 239,353,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Total Equity Interest | 356,703,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 356,703,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Total liabilities and equity | 370,104,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  | 370,104,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |
Partially Owned Property Income Statement Schedule |  |  |  |  |
Operating revenue | 22,000 us-gaap_Revenues / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Operating Expenses | 91,000 eqr_RealEstateOperatingExpenses / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Net operating (loss) income | (69,000)us-gaap_GrossProfit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Depreciation | 0 us-gaap_Depreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
General and administrative/other | 1,000 us-gaap_GeneralAndAdministrativeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Operating (loss) income | (70,000)us-gaap_OperatingIncomeLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Interest and other income | 0 us-gaap_InterestAndOtherIncome / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Other expenses | 0 us-gaap_OtherNonoperatingIncomeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Interest: |  |  |  |  |
Expense incurred, net | 0 us-gaap_InterestExpenseDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Amortization of deferred financing costs | 0 us-gaap_AmortizationOfFinancingCosts / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
(Loss) income before income and other taxes and (loss) from investments in unconsolidated entities | (70,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Income and other tax (expense) benefit | 0 us-gaap_IncomeTaxExpenseBenefit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
(Loss) from investments in unconsolidated entities | 0 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest | (70,000)us-gaap_ProfitLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedDevelopmentProjectsHeldForAndOrUnderDevelopmentMember |  |  |  |
Consolidated Operating [Domain] |  |  |  |  |
Partially Owned Property Balance Sheet Schedule |  |  |  |  |
Partially Owned Consolidated Properties | 19 eqr_PartiallyOwnedConsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 19 eqr_PartiallyOwnedConsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Partially Owned Consolidated Units | 3,771 eqr_PartiallyOwnedConsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 3,771 eqr_PartiallyOwnedConsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
ASSETS |  |  |  |  |
Investment in real estate | 682,374,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 682,374,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Accumulated depreciation | 194,481,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 194,481,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Investment in real estate, net | 487,893,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 487,893,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Cash and cash equivalents | 19,338,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 19,338,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures | 51,979,000 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 51,979,000 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Restricted Cash and Cash Equivalents | 300,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 300,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Deferred financing costs, net | 2,141,000 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 2,141,000 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Other assets | 26,609,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 26,609,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Total assets | 588,260,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 588,260,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt | 360,479,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 360,479,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable | 1,611,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 1,611,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Accrued interest payable | 1,283,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 1,283,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Other liabilities | 885,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 885,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Security Deposit Liability | 1,954,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 1,954,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Total liabilities | 366,212,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 366,212,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Noncontrolling Interests - Partially Owned Properties | 7,559,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 7,559,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Parent Equity Interest | 214,489,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 214,489,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Total Equity Interest | 222,048,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 222,048,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Total liabilities and equity | 588,260,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  | 588,260,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |
Partially Owned Property Income Statement Schedule |  |  |  |  |
Operating revenue | 88,157,000 us-gaap_Revenues / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Operating Expenses | 25,674,000 eqr_RealEstateOperatingExpenses / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Net operating (loss) income | 62,483,000 us-gaap_GrossProfit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Depreciation | 21,679,000 us-gaap_Depreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
General and administrative/other | 116,000 us-gaap_GeneralAndAdministrativeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Operating (loss) income | 40,688,000 us-gaap_OperatingIncomeLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Interest and other income | 11,000 us-gaap_InterestAndOtherIncome / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Other expenses | (54,000)us-gaap_OtherNonoperatingIncomeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Interest: |  |  |  |  |
Expense incurred, net | (15,626,000)us-gaap_InterestExpenseDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Amortization of deferred financing costs | 355,000 us-gaap_AmortizationOfFinancingCosts / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
(Loss) income before income and other taxes and (loss) from investments in unconsolidated entities | 24,664,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Income and other tax (expense) benefit | (36,000)us-gaap_IncomeTaxExpenseBenefit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
(Loss) from investments in unconsolidated entities | (1,593,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest | 23,035,000 us-gaap_ProfitLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedOperatingDomain |  |  |  |
Consolidated Total [Domain] |  |  |  |  |
Partially Owned Property Balance Sheet Schedule |  |  |  |  |
Partially Owned Consolidated Properties | 19 eqr_PartiallyOwnedConsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 19 eqr_PartiallyOwnedConsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Partially Owned Consolidated Units | 3,771 eqr_PartiallyOwnedConsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 3,771 eqr_PartiallyOwnedConsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
ASSETS |  |  |  |  |
Investment in real estate | 1,023,114,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 1,023,114,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Accumulated depreciation | 194,481,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 194,481,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Investment in real estate, net | 828,633,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 828,633,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Cash and cash equivalents | 19,338,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 19,338,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures | 51,979,000 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 51,979,000 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Restricted Cash and Cash Equivalents | 23,006,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 23,006,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Deferred financing costs, net | 2,141,000 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 2,141,000 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Other assets | 33,267,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 33,267,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Total assets | 958,364,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 958,364,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt | 360,479,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 360,479,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable | 14,918,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 14,918,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Accrued interest payable | 1,283,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 1,283,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Other liabilities | 954,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 954,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Security Deposit Liability | 1,979,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 1,979,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Total liabilities | 379,613,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 379,613,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Noncontrolling Interests - Partially Owned Properties | 124,909,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 124,909,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Parent Equity Interest | 453,842,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 453,842,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Total Equity Interest | 578,751,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 578,751,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Total liabilities and equity | 958,364,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  | 958,364,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |
Partially Owned Property Income Statement Schedule |  |  |  |  |
Operating revenue | 88,179,000 us-gaap_Revenues / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Operating Expenses | 25,765,000 eqr_RealEstateOperatingExpenses / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Net operating (loss) income | 62,414,000 us-gaap_GrossProfit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Depreciation | 21,679,000 us-gaap_Depreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
General and administrative/other | 117,000 us-gaap_GeneralAndAdministrativeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Operating (loss) income | 40,618,000 us-gaap_OperatingIncomeLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Interest and other income | 11,000 us-gaap_InterestAndOtherIncome / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Other expenses | (54,000)us-gaap_OtherNonoperatingIncomeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Interest: |  |  |  |  |
Expense incurred, net | (15,626,000)us-gaap_InterestExpenseDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Amortization of deferred financing costs | 355,000 us-gaap_AmortizationOfFinancingCosts / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
(Loss) income before income and other taxes and (loss) from investments in unconsolidated entities | 24,594,000 us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Income and other tax (expense) benefit | (36,000)us-gaap_IncomeTaxExpenseBenefit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
(Loss) from investments in unconsolidated entities | (1,593,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest | 22,965,000 us-gaap_ProfitLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_ConsolidatedTotalDomain |  |  |  |
Unconsolidated Completed, Not Stabilized [Domain] |  |  |  |  |
Partially Owned Property Balance Sheet Schedule |  |  |  |  |
Partially Owned Unconsolidated Properties | 1 eqr_PartiallyOwnedUnconsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 1 eqr_PartiallyOwnedUnconsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Partially Owned Unconsolidated Units | 444 eqr_PartiallyOwnedUnconsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 444 eqr_PartiallyOwnedUnconsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
ASSETS |  |  |  |  |
Investment in real estate | 155,376,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 155,376,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Accumulated depreciation | 6,921,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 6,921,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Investment in real estate, net | 148,455,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 148,455,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Cash and cash equivalents | 2,684,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 2,684,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Restricted Cash and Cash Equivalents | 0 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 0 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Deferred financing costs, net | 0 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 0 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Other assets | 529,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 529,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Total assets | 151,668,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 151,668,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt | 96,793,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 96,793,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable | 769,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 769,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Accrued interest payable | 464,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 464,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Other liabilities | 294,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 294,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Security Deposit Liability | 173,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 173,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Total liabilities | 98,493,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 98,493,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Noncontrolling Interests - Partially Owned Properties | 47,223,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 47,223,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Parent Equity Interest | 5,952,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 5,952,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Total Equity Interest | 53,175,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 53,175,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Total liabilities and equity | 151,668,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  | 151,668,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |
Partially Owned Property Income Statement Schedule |  |  |  |  |
Operating revenue | 10,182,000 us-gaap_Revenues / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Operating Expenses | 3,781,000 eqr_RealEstateOperatingExpenses / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Net operating (loss) income | 6,401,000 us-gaap_GrossProfit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Depreciation | 6,512,000 us-gaap_Depreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
General and administrative/other | 1,000 us-gaap_GeneralAndAdministrativeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Operating (loss) income | (112,000)us-gaap_OperatingIncomeLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Interest and other income | 0 us-gaap_InterestAndOtherIncome / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Other expenses | 0 us-gaap_OtherNonoperatingIncomeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Interest: |  |  |  |  |
Expense incurred, net | (5,296,000)us-gaap_InterestExpenseDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Amortization of deferred financing costs | 0 us-gaap_AmortizationOfFinancingCosts / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
(Loss) income before income and other taxes and (loss) from investments in unconsolidated entities | (5,408,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Income and other tax (expense) benefit | (7,000)us-gaap_IncomeTaxExpenseBenefit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
(Loss) from investments in unconsolidated entities | 0 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest | (5,415,000)us-gaap_ProfitLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedCompletedNotStabilizedDomain |  |  |  |
Unconsolidated Operating [Domain] |  |  |  |  |
Partially Owned Property Balance Sheet Schedule |  |  |  |  |
Partially Owned Unconsolidated Properties | 2 eqr_PartiallyOwnedUnconsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 2 eqr_PartiallyOwnedUnconsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Partially Owned Unconsolidated Units | 837 eqr_PartiallyOwnedUnconsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 837 eqr_PartiallyOwnedUnconsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
ASSETS |  |  |  |  |
Investment in real estate | 134,669,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 134,669,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Accumulated depreciation | 11,391,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 11,391,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Investment in real estate, net | 123,278,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 123,278,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Cash and cash equivalents | 3,172,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 3,172,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Restricted Cash and Cash Equivalents | 214,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 214,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Deferred financing costs, net | 8,000 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 8,000 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Other assets | 691,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 691,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Total assets | 127,363,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 127,363,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt | 78,628,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 78,628,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable | 259,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 259,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Accrued interest payable | 227,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 227,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Other liabilities | 671,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 671,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Security Deposit Liability | 300,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 300,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Total liabilities | 80,085,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 80,085,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Noncontrolling Interests - Partially Owned Properties | 43,655,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 43,655,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Parent Equity Interest | 3,623,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 3,623,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Total Equity Interest | 47,278,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 47,278,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Total liabilities and equity | 127,363,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  | 127,363,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |
Partially Owned Property Income Statement Schedule |  |  |  |  |
Operating revenue | 15,160,000 us-gaap_Revenues / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Operating Expenses | 6,818,000 eqr_RealEstateOperatingExpenses / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Net operating (loss) income | 8,342,000 us-gaap_GrossProfit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Depreciation | 5,800,000 us-gaap_Depreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
General and administrative/other | 209,000 us-gaap_GeneralAndAdministrativeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Operating (loss) income | 2,333,000 us-gaap_OperatingIncomeLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Interest and other income | 0 us-gaap_InterestAndOtherIncome / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Other expenses | 0 us-gaap_OtherNonoperatingIncomeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Interest: |  |  |  |  |
Expense incurred, net | (3,831,000)us-gaap_InterestExpenseDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Amortization of deferred financing costs | 2,000 us-gaap_AmortizationOfFinancingCosts / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
(Loss) income before income and other taxes and (loss) from investments in unconsolidated entities | (1,500,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Income and other tax (expense) benefit | 0 us-gaap_IncomeTaxExpenseBenefit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
(Loss) from investments in unconsolidated entities | 0 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest | (1,500,000)us-gaap_ProfitLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedOperatingDomain |  |  |  |
Unconsolidated Total [Domain] |  |  |  |  |
Partially Owned Property Balance Sheet Schedule |  |  |  |  |
Partially Owned Unconsolidated Properties | 3 eqr_PartiallyOwnedUnconsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 3 eqr_PartiallyOwnedUnconsolidatedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Partially Owned Unconsolidated Units | 1,281 eqr_PartiallyOwnedUnconsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 1,281 eqr_PartiallyOwnedUnconsolidatedUnits / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
ASSETS |  |  |  |  |
Investment in real estate | 290,045,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 290,045,000 us-gaap_RealEstateInvestmentPropertyAtCost / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Accumulated depreciation | 18,312,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 18,312,000 us-gaap_RealEstateInvestmentPropertyAccumulatedDepreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Investment in real estate, net | 271,733,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 271,733,000 us-gaap_RealEstateInvestmentPropertyNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Cash and cash equivalents | 5,856,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 5,856,000 us-gaap_CashAndCashEquivalentsAtCarryingValue / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 0 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Restricted Cash and Cash Equivalents | 214,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 214,000 us-gaap_RestrictedCashAndCashEquivalents / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Deferred financing costs, net | 8,000 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 8,000 us-gaap_DeferredFinanceCostsNet / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Other assets | 1,220,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 1,220,000 us-gaap_OtherAssets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Total assets | 279,031,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 279,031,000 us-gaap_Assets / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt | 175,421,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 175,421,000 us-gaap_SecuredDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Accounts Payable And Accrued Liabilities Current And Noncurrent Other Than Interest And Dividend Payable | 1,028,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 1,028,000 eqr_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrentOtherThanInterestAndDividendPayable / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Accrued interest payable | 691,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 691,000 us-gaap_InterestPayableCurrentAndNoncurrent / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Other liabilities | 965,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 965,000 us-gaap_OtherLiabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Security Deposit Liability | 473,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 473,000 us-gaap_SecurityDepositLiability / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Total liabilities | 178,578,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 178,578,000 us-gaap_Liabilities / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Noncontrolling Interests - Partially Owned Properties | 90,878,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 90,878,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Parent Equity Interest | 9,575,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 9,575,000 eqr_ParentEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Total Equity Interest | 100,453,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 100,453,000 eqr_TotalEquityInterest / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Total liabilities and equity | 279,031,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  | 279,031,000 us-gaap_LiabilitiesAndStockholdersEquity / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |
Partially Owned Property Income Statement Schedule |  |  |  |  |
Operating revenue | 25,342,000 us-gaap_Revenues / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Operating Expenses | 10,599,000 eqr_RealEstateOperatingExpenses / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Net operating (loss) income | 14,743,000 us-gaap_GrossProfit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Depreciation | 12,312,000 us-gaap_Depreciation / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
General and administrative/other | 210,000 us-gaap_GeneralAndAdministrativeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Operating (loss) income | 2,221,000 us-gaap_OperatingIncomeLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Interest and other income | 0 us-gaap_InterestAndOtherIncome / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Other expenses | 0 us-gaap_OtherNonoperatingIncomeExpense / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Interest: |  |  |  |  |
Expense incurred, net | (9,127,000)us-gaap_InterestExpenseDebt / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Amortization of deferred financing costs | 2,000 us-gaap_AmortizationOfFinancingCosts / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
(Loss) income before income and other taxes and (loss) from investments in unconsolidated entities | (6,908,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Income and other tax (expense) benefit | (7,000)us-gaap_IncomeTaxExpenseBenefit / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
(Loss) from investments in unconsolidated entities | 0 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest | (6,915,000)us-gaap_ProfitLoss / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = eqr_UnconsolidatedTotalDomain |  |  |  |
Archstone Transaction [Member] |  |  |  |  |
Interest: |  |  |  |  |
Liquidation Value Preferred Interests | 74,600,000 eqr_LiquidationValuePreferredInterests / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_ArchstoneTransactionMember |  |  | 74,600,000 eqr_LiquidationValuePreferredInterests / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_ArchstoneTransactionMember |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Distributions from unconsolidated entities – return of capital | 79,600,000 eqr_ProceedsFromDistributionsReceivedFromUnconsolidatedSubsidiaries / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_ArchstoneTransactionMember |  |  | 98,500,000 eqr_ProceedsFromDistributionsReceivedFromUnconsolidatedSubsidiaries / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_ArchstoneTransactionMember |
Residual JV [Domain] |  |  |  |  |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Initial Basis of Real Estate, Unconsolidated |  | (147,600,000)eqr_InitialBasisOfRealEstateUnconsolidated / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_ResidualJvDomain |  |  |
Joint Venture Partner [Member] |  |  |  |  |
LIABILITIES AND EQUITY |  |  |  |  |
Noncontrolling Interests - Partially Owned Properties | 117,400,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_JointVenturePartnerMember |  |  | 117,400,000 eqr_NoncontrollingInterestsPartiallyOwnedProperties / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_JointVenturePartnerMember |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Land purchase price | 57,900,000 eqr_LandPurchasePrice / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_JointVenturePartnerMember |  |  | 57,900,000 eqr_LandPurchasePrice / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_JointVenturePartnerMember |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets | 75,700,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_JointVenturePartnerMember |  |  | 75,700,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_JointVenturePartnerMember |
Company's Portion [Member] |  |  |  |  |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Land purchase price | 76,100,000 eqr_LandPurchasePrice / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_CompanysPortionMember |  |  | 76,100,000 eqr_LandPurchasePrice / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_CompanysPortionMember |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets | 102,500,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_CompanysPortionMember |  |  | 102,500,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_CompanysPortionMember |
Nexus Sawgrass [Member] |  |  |  |  |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt | 48,600,000 us-gaap_SecuredDebt / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_NexusSawgrassMember |  |  | 48,600,000 us-gaap_SecuredDebt / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_NexusSawgrassMember |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.60%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_NexusSawgrassMember |  |  | 5.60%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_NexusSawgrassMember |
Debt Instrument, Maturity Date | Jan. 01, 2021 |  |  |  |
Project Cost | 78,600,000 eqr_ProjectCost / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_NexusSawgrassMember |  |  | 78,600,000 eqr_ProjectCost / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_NexusSawgrassMember |
Maximum Debt Commitment | 48,700,000 eqr_MaximumDebtCommitment / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_NexusSawgrassMember |  |  | 48,700,000 eqr_MaximumDebtCommitment / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_NexusSawgrassMember |
Domain [Member] |  |  |  |  |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt | 96,800,000 us-gaap_SecuredDebt / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_DomainMember |  |  | 96,800,000 us-gaap_SecuredDebt / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_DomainMember |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 5.75%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_DomainMember |  |  | 5.75%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_DomainMember |
Debt Instrument, Maturity Date | Jan. 01, 2022 |  |  |  |
Project Cost | 155,800,000 eqr_ProjectCost / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_DomainMember |  |  | 155,800,000 eqr_ProjectCost / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_DomainMember |
Maximum Debt Commitment | 98,600,000 eqr_MaximumDebtCommitment / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_DomainMember |  |  | 98,600,000 eqr_MaximumDebtCommitment / us-gaap_SignificantAcquisitionsAndDisposalsByTransactionAxis = eqr_DomainMember |
Unconsolidated Properties [Member] |  |  |  |  |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Disposed Properties | 1 eqr_DisposedProperties / us-gaap_StatementScenarioAxis = us-gaap_UnconsolidatedPropertiesMember |  |  |  |
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax | 4,900,000 us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax / us-gaap_StatementScenarioAxis = us-gaap_UnconsolidatedPropertiesMember |  |  |  |
Archstone Transaction [Member] |  |  |  |  |
Interest: |  |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired | 60.00%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired / us-gaap_StatementScenarioAxis = eqr_ArchstoneTransactionMember |  |  | 60.00%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired / us-gaap_StatementScenarioAxis = eqr_ArchstoneTransactionMember |
Joint Venture Partner Ownership Percentage | 40.00%eqr_JointVenturePartnerOwnershipPercentage / us-gaap_StatementScenarioAxis = eqr_ArchstoneTransactionMember |  |  | 40.00%eqr_JointVenturePartnerOwnershipPercentage / us-gaap_StatementScenarioAxis = eqr_ArchstoneTransactionMember |
Company's Portion [Member] |  |  |  |  |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Preferred Interests |  | 39,000,000 eqr_PreferredInterests / us-gaap_StatementScenarioAxis = eqr_CompanysPortionMember |  |  |
Wisconsin Place [Domain] |  |  |  |  |
Partially Owned Property Balance Sheet Schedule |  |  |  |  |
Partially Owned Consolidated Units |  | 432 eqr_PartiallyOwnedConsolidatedUnits / us-gaap_StatementScenarioAxis = eqr_WisconsinPlaceDomain |  |  |
ASSETS |  |  |  |  |
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures |  | 56,500,000 us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures / us-gaap_StatementScenarioAxis = eqr_WisconsinPlaceDomain |  |  |
Interest: |  |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired |  | 75.00%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired / us-gaap_StatementScenarioAxis = eqr_WisconsinPlaceDomain |  |  |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Initial Basis of Real Estate, Consolidated |  | 198,500,000 eqr_InitialBasisOfRealEstateConsolidated / us-gaap_StatementScenarioAxis = eqr_WisconsinPlaceDomain |  |  |
Waterton Tenside [Domain] |  |  |  |  |
Partially Owned Property Balance Sheet Schedule |  |  |  |  |
Partially Owned Unconsolidated Units |  | 336 eqr_PartiallyOwnedUnconsolidatedUnits / us-gaap_StatementScenarioAxis = eqr_WatertonTensideDomain |  |  |
LIABILITIES AND EQUITY |  |  |  |  |
Secured Debt |  | 30,000,000 us-gaap_SecuredDebt / us-gaap_StatementScenarioAxis = eqr_WatertonTensideDomain |  |  |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Equity Method Investment, Ownership Percentage |  | 20.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_StatementScenarioAxis = eqr_WatertonTensideDomain |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 3.66%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_StatementScenarioAxis = eqr_WatertonTensideDomain |  |  |
Debt Instrument, Maturity Date |  | Dec. 01, 2018 |  |  |
Initial Basis of Real Estate, Unconsolidated |  | 5,100,000 eqr_InitialBasisOfRealEstateUnconsolidated / us-gaap_StatementScenarioAxis = eqr_WatertonTensideDomain |  |  |
Joint Venture Partner [Member] |  |  |  |  |
Investments In Partially Owned Entities (Textuals) [Abstract] |  |  |  |  |
Disposed Properties | 1 eqr_DisposedProperties / us-gaap_StatementScenarioAxis = eqr_JointVenturePartnerMember |  | 2 eqr_DisposedProperties / us-gaap_StatementScenarioAxis = eqr_JointVenturePartnerMember |  |
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax | $ 1,100,000 us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax / us-gaap_StatementScenarioAxis = eqr_JointVenturePartnerMember |  | $ 21,300,000 us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax / us-gaap_StatementScenarioAxis = eqr_JointVenturePartnerMember |  |
Disposed Units | 388 eqr_DisposedUnits / us-gaap_StatementScenarioAxis = eqr_JointVenturePartnerMember |  | 441 eqr_DisposedUnits / us-gaap_StatementScenarioAxis = eqr_JointVenturePartnerMember |  |

X
- Definition Carrying value as of the balance sheet date of obligations incurred and payable pertaining to goods and services received from vendors, are incurred in connection with contractual obligations or accumulate over time and for which invoices have not yet been received or will not be rendered. + References No definition available. + Details
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- Definition The total number of rental properties that the Company disposed of to unaffiliated parties during the period. + References No definition available. + Details
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- Definition Total number of rental units associated with rental properties that the company disposed of to unaffiliated third parties during the period. + References No definition available. + Details
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- Definition Represents the initial basis at fair value of the Company's interests in a property acquired as part of a joint venture. The investment is consolidated. + References No definition available. + Details
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- Definition The Company's and the Joint Venture partner's total combined investment in the project. + References No definition available. + Details
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- Definition The aggregate liquidation preference of preferred interests acquired in conjunction with the Archstone transaction. + References No definition available. + Details
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- Definition The unfunded portion of the loan that may be drawn down or is due to be contractually funded in the future. + 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 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 rental properties that are partially owned and not consolidated by the Company. + References No definition available. + Details
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- Definition The cash inflow to the Company associated with a partner's purchase of or advances to an equity method investment, which is an investment in a joint venture or an entity. + References No definition available. + Details
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- Definition Represents preferred interests acquired in conjunction with the Archstone transaction that the Company and its joint venture partner purchased during the year. + References No definition available. + Details
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- Definition The cash inflow from distributions of capital received from unconsolidated joint ventures ( i.e proportionate share of proceeds and/or gain/loss from property sales). + References No definition available. + Details
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- Definition Represents total project costs for the development of land parcels to residential apartment communities. + References No definition available. + Details
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- Definition Total property and maintenance expense, real estate taxes and insurance expense and property management expense. + References No definition available. + Details
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- Definition Percentage of voting equity interests acquired at the acquisition date in the business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463 + Details
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
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- Definition The amount of interest income and other income recognized during the period. Included in this element is interest derived from investments in debt securities, cash and cash equivalents, and other investments which reflect the time value of money or transactions in which the payments are for the use or forbearance of money and other income from ancillary business-related activities (that is, excluding major activities considered part of the normal operations of the business). + References No definition available. + Details
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- Definition Amount of the cost of borrowed funds accounted for as interest expense for debt. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.8) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 8 -Article 5 + Details
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- Definition The cumulative amount of depreciation for real estate property held for investment purposes. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(3)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Article 7 + Details
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