Subsequent Events - Additional Information (Details) $ in Millions		6 Months Ended
Jul. 01, 2022 USD ($) Property ApartmentUnit	Jun. 30, 2022
Subsequent Event [Line Items]
Debt instrument, redemption, description		The redemption is expected to occur in the third quarter of 2022 and will be funded from disposition proceeds
Subsequent Events [Member]
Subsequent Event [Line Items]
Number of properties disposed \| Property	1
Number of property units disposed \| ApartmentUnit	455
Sales Price	$ 415.0
Forward starting swaps to hedge changes in interest rates	200.0
Subsequent Events [Member] \| Unsecured Notes Due In 2023 [Member]
Subsequent Event [Line Items]
Debt instrument redemption, principal amount	$ 500.0

Debt Instrument redemption, principal amount to be redeemed.

No definition available.

Name:	eqr_DebtInstrumentRedemptionPrincipalAmountToBeRedeemed
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Forward starting swaps to hedge changes in interest rates.

+ References

No definition available.

+ Details

Name:	eqr_ForwardStartingSwapsToHedgeChangesInInterestRates
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of properties disposed.

+ References

No definition available.

+ Details

Name:	eqr_NumberOfPropertiesDisposed
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of property units disposed.

+ References

No definition available.

+ Details

Name:	eqr_NumberOfPropertyUnitsDisposed
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of debt redemption features under terms of the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI https://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentRedemptionDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash received for the sale of real estate that is not part of an investing activity during the current period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromSaleOfRealEstate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=eqr_UnsecuredNotesDueInTwoThousandAndTwentyThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: