Commitments to Acquire/Dispose of Real Estate - Separate Agreements to Dispose (Parenthetical) (Details)	3 Months Ended
Mar. 31, 2019
Discontinued Operations And Disposal Groups [Abstract]
Ownership percentage	20.00%

Percentage of ownership interest in unconsolidated entity.

No definition available.

Name:	eqr_PercentageOfOwnershipInterestInUnconsolidatedEntity
Namespace Prefix:	eqr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration