Equity, Capital and Other Interests ERP Units (Details) - shares	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Capital Unit [Line Items]
Common Shares And Units Outstanding	378,595,767
Exercise of EQR share options	882,764
EQR’s Employee Share Purchase Plan (ESPP)	52,869
Restricted share grants, net	168,484
Conversion of restricted shares to restricted units	(1,284)
Conversion of Limited Partner OP Units to EQR Common Shares	181,753
Units Ownership Interest in Operating Partnership	3.80%
ERPOP [Member]
Capital Unit [Line Items]
Common Shares And Units Outstanding	378,595,767	377,154,145
Limited Partners' Capital Account, Units Outstanding	14,455,727	14,298,691
Exercise of EQR share options	882,764
EQR’s Employee Share Purchase Plan (ESPP)	52,869
Restricted share grants, net	168,484
Restricted units, net	337,505
Conversion of restricted shares to restricted units	1,284
Conversion of Limited Partner OP Units to EQR Common Shares	(181,753)
Units Ownership Interest in Operating Partnership	3.80%