Reportable Segments - NOI from Our Rental Real Estate for Each Segment Specific to Continuing Operations (Parenthetical) (Details) - Property	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Disclosure Of Entitys Reportable Segments [Abstract]
Units in same store properties	74,077	74,077	73,585

Total number of units associated with properties acquired or completed and stabilized two or more fiscal years ago, less properties subsequently sold.

No definition available.

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