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Commitments and Contingencies - Schedule of Contractual Obligations (Parenthetical) (Details) | Dec. 31, 2018 Property
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Commitments And Contingencies Disclosure [Abstract] |
Number of properties | 12

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- Definition Number of properties on which minimum basic rent due for various office space the Company leases and fixed base rent due on ground leases. + References No definition available. + Details
Name: | eqr_NumberOfPropertiesOnWhichMinimumBasicRentAndFixedBaseRentDue
Namespace Prefix: | eqr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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