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Deposits - Restricted and Escrow Deposits - Mortgage - Additional Information (Details) $ in Millions | 9 Months Ended
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Sep. 30, 2017 USD ($)
Cash And Cash Equivalents [Abstract] |
Proceeds from return of various mortgage principal reserves/sinking funds | $ 60.5

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- Definition Proceeds from return of various mortgage principal reserves and sinking funds. + References No definition available. + Details
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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