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Restricted Deposits - Additional Information (Details) | 12 Months Ended
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Dec. 31, 2017 USD ($)
Cash And Cash Equivalents [Abstract] |
Proceeds from return of various mortgage principal reserves/sinking funds | $ 60,500

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- Definition Proceeds from return of various mortgage principal reserves and sinking funds. + References No definition available. + Details
Name: | eqr_ProceedsFromReturnOfVariousMortgagePrincipalReservesAndSinkingFunds
Namespace Prefix: | eqr_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_CashAndCashEquivalentsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration