Leases - Summary of Residential and Non-Residential Accounts Receivable and Straight-Line Receivable Balances (Parenthetical) (Details)	Sep. 30, 2021
Leases [Abstract]
Holding percentage of residential security deposits of net receivable	58.40%

Holding percentage of residential security deposits of net receivable.

No definition available.

Name:	eqr_HoldingPercentageOfResidentialSecurityDepositsOfNetReceivables
Namespace Prefix:	eqr_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant