Subsequent Events - Additional Information (Details) $ in Thousands		3 Months Ended
Apr. 01, 2022 USD ($) Property ApartmentUnit	Mar. 31, 2022 USD ($) Property ApartmentUnit
Subsequent Event [Line Items]
Properties acquired \| Property		1
Property Units acquired \| ApartmentUnit		172
Purchase Price		$ 113,000
Subsequent Events [Member]
Subsequent Event [Line Items]
Properties acquired \| Property	1
Property Units acquired \| ApartmentUnit	354
Purchase Price	$ 265,700
Percentage interest in consolidated operating property	25.00%
Payments to acquired interest in consolidated operating property	$ 32,200

Payments to acquired interest in consolidated operating property.

No definition available.

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

- Definition

Percentage interest acquired in consolidated operating property.

+ References

No definition available.

+ Details

Name:	eqr_PercentageInterestAcquiredInConsolidatedOperatingProperty
Namespace Prefix:	eqr_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Total number of property or properties acquired from unaffiliated third parties during the period.

+ References

No definition available.

+ Details

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

- Definition

Total number of units associated with the property or properties acquired from unaffiliated third parties during the period.

+ References

No definition available.

+ Details

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

- Definition

Amount of assets acquired at the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123413009&loc=d3e4845-128472

+ Details

Name:	us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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: