Commitments and Contingencies - Schedule of Contractual Obligations (Parenthetical) (Details)	Dec. 31, 2017 Property
Commitments And Contingencies Disclosure [Abstract]
Number of properties	12

Number of properties on which minimum basic rent due for various office space the Company leases and fixed base rent due on ground leases.

No definition available.

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