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v3.20.4

Debt - Notes - Additional Information (Details) | 12 Months Ended
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Dec. 31, 2020
Debt Disclosure [Abstract] |
Shelf registration statement effective date | 2019-06
Shelf registration statement expiry date | 2022-06

X
- Definition Effective date of securities under the shelf registration statement. + References No definition available. + Details
Name: | eqr_EffectiveDateOfSecuritiesUnderShelfRegistrationStatement
Namespace Prefix: | eqr_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expiry date of securities remaining under the shelf registration statement. + References No definition available. + Details
Name: | eqr_ExpiryDateOfSecuritiesRemainingUnderShelfRegistrationStatement
Namespace Prefix: | eqr_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

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