Leases - Summary of Residential and Non-Residential Accounts Receivable and Straight-Line Receivable Balances (Parenthetical) (Details)	Sep. 30, 2020
Leases [Abstract]
Holding percentage of residential security deposits of net receivable	31.30%

Holding percentage of residential security deposits of net receivable.

No definition available.

Name:	eqr_HoldingPercentageOfResidentialSecurityDepositsOfNetReceivable
Namespace Prefix:	eqr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant