Deposits - Restricted and Escrow Deposits - Mortgage - Additional Information (Details) $ in Millions	9 Months Ended
Sep. 30, 2017 USD ($)
Cash And Cash Equivalents [Abstract]
Proceeds from return of various mortgage principal reserves/sinking funds	$ 60.5

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