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CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (USD $)
In Thousands, unless otherwise specified
Total
USD ($)
Preferred Stock [Member]
USD ($)
General Partner [Member]
USD ($)
Limited Partner [Member]
USD ($)
Accumulated Other Comprehensive Income (Loss) [Member]
USD ($)
Partially Owned Properties [Member]
USD ($)
Series N Preferred Stock [Member]
USD ($)
Series N Preferred Stock [Member]
Preferred Stock [Member]
Balance, beginning of year at Dec. 31, 2011   $ 200,000eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
$ 5,665,733eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
$ 119,536eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
$ (196,718)eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
$ 74,306eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Preference Units                
Redemption of 6.48% Series N Cumulative Redeemable 150,000us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock (150,000)us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
        150,000us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock
/ us-gaap_StatementClassOfStockAxis
= eqr_SeriesNPreferredStockMember
 
Preferred Stock Preference Units Dividend Rate Percentage             6.48%eqr_PreferredStockPreferenceUnitsDividendRatePercentage
/ us-gaap_StatementClassOfStockAxis
= eqr_SeriesNPreferredStockMember
6.48%eqr_PreferredStockPreferenceUnitsDividendRatePercentage
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
/ us-gaap_StatementClassOfStockAxis
= eqr_SeriesNPreferredStockMember
OP Unit Issuance:                
Conversion of OP Units held by Limited Partners into OP Units held by General Partner     18,929eqr_ExchangeOfOPUnitsBetweenLimitedPartnerAndGeneralPartner
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
(18,929)eqr_ExchangeOfOPUnitsBetweenLimitedPartnerAndGeneralPartner
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Issuance of OP Units     1,388,583eqr_IssuanceOfOpUnits
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Exercise of EQR share options     49,039us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
EQR's Employee Share Purchase Plan (ESPP)     5,399us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Share-based employee compensation expense:                
EQR restricted shares     8,936us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
EQR share options     11,752us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
EQR ESPP discount     965us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployeeStockPurchaseProgramRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
OP Units repurchased and retired     0eqr_PaymentsForRepurchaseOfOpUnits
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Offering costs     (39,359)us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Premium on redemption of Preferred Shares - original issuance costs     5,129eqr_PremiumOnRedemptionOfPreferredSharesPreferenceUnitsOriginalIssuance
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
      5,100eqr_PremiumOnRedemptionOfPreferredSharesPreferenceUnitsOriginalIssuance
/ us-gaap_StatementClassOfStockAxis
= eqr_SeriesNPreferredStockMember
 
Net income available to Units - General Partner     826,212us-gaap_NetIncomeLossAllocatedToGeneralPartners
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
OP Units - General Partner distributions     (554,429)eqr_GeneralPartnerDistribution
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Supplemental Executive Retirement Plan (SERP)     282eqr_SupplementalExecutiveRetirementPlanSerp
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Acquisition of Noncontrolling Interests - Partially Owned Properties 13eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties   1,293eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
    (1,306)eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Change in market value of Redeemable Limited Partners     38,734eqr_LimitedPartnersRedemptions
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Adjustment for Limited Partners ownership in Operating Partnership     5,763eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
(5,763)eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Limited Partners' Capital Account [Abstract]                
Issuance of OP Units to Noncontrolling Interests       66,606eqr_IssuanceOfOpUnitsToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Issuance restricted units to Limited Partners       5eqr_IssuanceOfLongTermIncentivePlanUnitsIntoNoncontrollingInterest
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Equity compensation associated with Units - Limited Partners       5,307us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationOtherLongtermIncentivePlansRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Net income available to Units - Limited Partners       38,641us-gaap_NetIncomeLossAllocatedToLimitedPartners
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Units - Limited Partners distributions       (25,095)eqr_UnitsLimitedPartnersDistributions
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Change in carrying value of Redeemable Limited Partners       (20,702)eqr_ChangeInCarryingValueOfRedeemableLimitedPartners
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Adjustment For Limited Partners Ownership In Operating Partnership     5,763eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
(5,763)eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Accumulated other comprehensive (loss) income - derivative instruments:                
Unrealized holding (losses) gains arising during the year (11,772)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax       (11,772)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Losses reclassified into earnings from other comprehensive income (14,678)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax       14,678us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Accumulated other comprehensive income (loss) - other instruments:                
Unrealized holding gains arising during the year 664us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax       664us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
(Gains) on Sale of Securities, Net 0us-gaap_GainLossOnSaleOfSecuritiesNet       0us-gaap_GainLossOnSaleOfSecuritiesNet
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Currency translation adjustments arising during the year 0us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax       0us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Noncontrolling Interest [Abstract]                
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 881,204us-gaap_ProfitLoss         844us-gaap_ProfitLoss
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Contributions - Noncontrolling Interests 8,221us-gaap_ProceedsFromMinorityShareholders         8,221us-gaap_ProceedsFromMinorityShareholders
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Distributions to Noncontrolling Interests           (5,131)us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Archstone of Archstone           0eqr_ArchstoneAcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Acquisition Noncontrolling Interests - Partially Owned Properties 13eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties   1,293eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
    (1,306)eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Other           754us-gaap_StockholdersEquityOther
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Balance, end of period at Dec. 31, 2012   50,000eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
7,432,961eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
159,606eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
(193,148)eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
77,688eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Preference Units                
Redemption of 6.48% Series N Cumulative Redeemable 0us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock 0us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
           
Preferred Stock Preference Units Dividend Rate Percentage             6.48%eqr_PreferredStockPreferenceUnitsDividendRatePercentage
/ us-gaap_StatementClassOfStockAxis
= eqr_SeriesNPreferredStockMember
0.00%eqr_PreferredStockPreferenceUnitsDividendRatePercentage
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
/ us-gaap_StatementClassOfStockAxis
= eqr_SeriesNPreferredStockMember
OP Unit Issuance:                
Conversion of OP Units held by Limited Partners into OP Units held by General Partner     1,699eqr_ExchangeOfOPUnitsBetweenLimitedPartnerAndGeneralPartner
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
(1,699)eqr_ExchangeOfOPUnitsBetweenLimitedPartnerAndGeneralPartner
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Issuance of OP Units     1,929,868eqr_IssuanceOfOpUnits
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Exercise of EQR share options     17,252us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
EQR's Employee Share Purchase Plan (ESPP)     3,401us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Share-based employee compensation expense:                
EQR restricted shares     13,264us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
EQR share options     10,514us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
EQR ESPP discount     632us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployeeStockPurchaseProgramRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
OP Units repurchased and retired     0eqr_PaymentsForRepurchaseOfOpUnits
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Offering costs     (1,047)us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Premium on redemption of Preferred Shares - original issuance costs     0eqr_PremiumOnRedemptionOfPreferredSharesPreferenceUnitsOriginalIssuance
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Net income available to Units - General Partner     1,826,468us-gaap_NetIncomeLossAllocatedToGeneralPartners
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
OP Units - General Partner distributions     (666,565)eqr_GeneralPartnerDistribution
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Supplemental Executive Retirement Plan (SERP)     (422)eqr_SupplementalExecutiveRetirementPlanSerp
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Acquisition of Noncontrolling Interests - Partially Owned Properties 0eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties   0eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
    0eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Change in market value of Redeemable Limited Partners     79,667eqr_LimitedPartnersRedemptions
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Adjustment for Limited Partners ownership in Operating Partnership     (35,329)eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
35,329eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Limited Partners' Capital Account [Abstract]                
Issuance of OP Units to Noncontrolling Interests       0eqr_IssuanceOfOpUnitsToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Issuance restricted units to Limited Partners       5eqr_IssuanceOfLongTermIncentivePlanUnitsIntoNoncontrollingInterest
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Equity compensation associated with Units - Limited Partners       13,609us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationOtherLongtermIncentivePlansRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Net income available to Units - Limited Partners       75,278us-gaap_NetIncomeLossAllocatedToLimitedPartners
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Units - Limited Partners distributions       (26,277)eqr_UnitsLimitedPartnersDistributions
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Change in carrying value of Redeemable Limited Partners       (44,439)eqr_ChangeInCarryingValueOfRedeemableLimitedPartners
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Adjustment For Limited Partners Ownership In Operating Partnership     (35,329)eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
35,329eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Accumulated other comprehensive (loss) income - derivative instruments:                
Unrealized holding (losses) gains arising during the year 18,771us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax       18,771us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Losses reclassified into earnings from other comprehensive income (20,141)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax       20,141us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Accumulated other comprehensive income (loss) - other instruments:                
Unrealized holding gains arising during the year 583us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax       583us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
(Gains) on Sale of Securities, Net (2,122)us-gaap_GainLossOnSaleOfSecuritiesNet       (2,122)us-gaap_GainLossOnSaleOfSecuritiesNet
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Currency translation adjustments arising during the year 613us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax       613us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Noncontrolling Interest [Abstract]                
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 1,905,353us-gaap_ProfitLoss         (538)us-gaap_ProfitLoss
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Contributions - Noncontrolling Interests 27,660us-gaap_ProceedsFromMinorityShareholders         27,660us-gaap_ProceedsFromMinorityShareholders
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Distributions to Noncontrolling Interests           (6,490)us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Archstone of Archstone           28,263eqr_ArchstoneAcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Acquisition Noncontrolling Interests - Partially Owned Properties 0eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties   0eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
    0eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Other           0us-gaap_StockholdersEquityOther
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Balance, end of period at Dec. 31, 2013   50,000eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
10,612,363eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
211,412eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
(155,162)eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
126,583eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Preference Units                
Redemption of 6.48% Series N Cumulative Redeemable 0us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock 0us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
           
Preferred Stock Preference Units Dividend Rate Percentage             6.48%eqr_PreferredStockPreferenceUnitsDividendRatePercentage
/ us-gaap_StatementClassOfStockAxis
= eqr_SeriesNPreferredStockMember
6.48%eqr_PreferredStockPreferenceUnitsDividendRatePercentage
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
/ us-gaap_StatementClassOfStockAxis
= eqr_SeriesNPreferredStockMember
OP Unit Issuance:                
Conversion of OP Units held by Limited Partners into OP Units held by General Partner     2,365eqr_ExchangeOfOPUnitsBetweenLimitedPartnerAndGeneralPartner
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
(2,365)eqr_ExchangeOfOPUnitsBetweenLimitedPartnerAndGeneralPartner
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Issuance of OP Units     0eqr_IssuanceOfOpUnits
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Exercise of EQR share options     82,573us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
EQR's Employee Share Purchase Plan (ESPP)     3,392us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Share-based employee compensation expense:                
EQR restricted shares     9,904us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
EQR share options     7,349us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
EQR ESPP discount     859us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationEmployeeStockPurchaseProgramRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
OP Units repurchased and retired     (1,777)eqr_PaymentsForRepurchaseOfOpUnits
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Offering costs     (41)us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Premium on redemption of Preferred Shares - original issuance costs     0eqr_PremiumOnRedemptionOfPreferredSharesPreferenceUnitsOriginalIssuance
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Net income available to Units - General Partner     627,163us-gaap_NetIncomeLossAllocatedToGeneralPartners
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
OP Units - General Partner distributions     (723,782)eqr_GeneralPartnerDistribution
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Supplemental Executive Retirement Plan (SERP)     7,374eqr_SupplementalExecutiveRetirementPlanSerp
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Acquisition of Noncontrolling Interests - Partially Owned Properties 5,501eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties   (2,308)eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
    (2,244)eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Change in market value of Redeemable Limited Partners     (139,818)eqr_LimitedPartnersRedemptions
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
         
Adjustment for Limited Partners ownership in Operating Partnership     4,992eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
(4,992)eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Limited Partners' Capital Account [Abstract]                
Issuance of OP Units to Noncontrolling Interests       0eqr_IssuanceOfOpUnitsToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Issuance restricted units to Limited Partners       3eqr_IssuanceOfLongTermIncentivePlanUnitsIntoNoncontrollingInterest
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Equity compensation associated with Units - Limited Partners       11,969us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationOtherLongtermIncentivePlansRequisiteServicePeriodRecognition
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Net income available to Units - Limited Partners       24,831us-gaap_NetIncomeLossAllocatedToLimitedPartners
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Units - Limited Partners distributions       (28,676)eqr_UnitsLimitedPartnersDistributions
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Change in carrying value of Redeemable Limited Partners       2,229eqr_ChangeInCarryingValueOfRedeemableLimitedPartners
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Adjustment For Limited Partners Ownership In Operating Partnership     4,992eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
(4,992)eqr_AdjustmentForLimitedPartnersOwnershipInOperatingPartnership
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
       
Accumulated other comprehensive (loss) income - derivative instruments:                
Unrealized holding (losses) gains arising during the year (33,306)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax       (33,306)us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Losses reclassified into earnings from other comprehensive income (16,868)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax       16,868us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Accumulated other comprehensive income (loss) - other instruments:                
Unrealized holding gains arising during the year 0us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax       0us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
(Gains) on Sale of Securities, Net 0us-gaap_GainLossOnSaleOfSecuritiesNet       0us-gaap_GainLossOnSaleOfSecuritiesNet
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Currency translation adjustments arising during the year (552)us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax       (552)us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
     
Noncontrolling Interest [Abstract]                
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 658,683us-gaap_ProfitLoss         2,544us-gaap_ProfitLoss
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Contributions - Noncontrolling Interests 5,684us-gaap_ProceedsFromMinorityShareholders         5,684us-gaap_ProceedsFromMinorityShareholders
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Distributions to Noncontrolling Interests           (7,827)us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Archstone of Archstone           0eqr_ArchstoneAcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Acquisition Noncontrolling Interests - Partially Owned Properties 5,501eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties   (2,308)eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
    (2,244)eqr_AcquisitionNoncontrollingInterestsPartiallyOwnedProperties
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Other           169us-gaap_StockholdersEquityOther
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember
   
Balance, end of period at Dec. 31, 2014   $ 50,000eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PreferredStockMember
$ 10,490,608eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_GeneralPartnerMember
$ 214,411eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_LimitedPartnerMember
$ (172,152)eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_AccumulatedOtherComprehensiveIncomeMember
$ 124,909eqr_PartnersCapitalIncludingPortionAttributableToNoncontrollingInterests
/ us-gaap_PartnerCapitalComponentsAxis
= us-gaap_PartiallyOwnedPropertiesMember