Restricted Deposits - Additional Information (Details)	12 Months Ended
Dec. 31, 2017 USD ($)
Cash And Cash Equivalents [Abstract]
Proceeds from return of various mortgage principal reserves/sinking funds	$ 60,500

Proceeds from return of various mortgage principal reserves and sinking funds.

No definition available.

Name:	eqr_ProceedsFromReturnOfVariousMortgagePrincipalReservesAndSinkingFunds
Namespace Prefix:	eqr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration