Equity, Capital and Other Interests ERP Units (Details)	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Capital Unit [Line Items]
Common Shares And Units Outstanding	314,053,586
Issuance of OP Units	2,078,310
Exercise of EQR share options	690,340
EQR's Employee Share Purchase Plan (ESPP)	85,837
Restricted Share Grants Net	128,136
Units Ownership Interest in Operating Partnership	4.30%
General And Limited Partner [Member]
Capital Unit [Line Items]
Common Shares And Units Outstanding	314,053,586	311,000,728
Issuance of OP Units	2,078,310
Exercise of EQR share options	690,340
EQR's Employee Share Purchase Plan (ESPP)	85,837
Restricted Share Grants Net	128,136
Issuance Of LTIPs	70,235
Limited Partner [Member]
Capital Unit [Line Items]
Issuance Of LTIPs	70,235
Total Units Outstanding	13,531,417	13,492,543
Shares Issued During Period Shares Conversion Of Units To Common Shares	(31,361)