Investments in Partially Owned Entities - Summary of Company's Investment in Unconsolidated Entities (Parenthetical) (Details) - Entity	Dec. 31, 2021	Dec. 31, 2020
Operating Property [Member]
Variable Interest Entity [Line Items]
Number of unconsolidated interest in entity owns land on consolidated joint venture properties owns and operates a related parking facility	1	1

Number of unconsolidated interest in entity owns land on consolidated joint venture properties, operates a related parking facility.

No definition available.

Name:	eqr_NumberOfUnconsolidatedInterestInEntityOwnsLandOnConsolidatedJointVenturePropertiesOperatesRelatedParkingFacility
Namespace Prefix:	eqr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant