Equity, Capital and Other Interests ERP Units (Details)	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Capital Unit [Line Items]
Common Shares And Units Outstanding	315,470,397
Issuance of OP Units	2,078,310
Exercise of EQR share options	1,014,585
EQR's Employee Share Purchase Plan (ESPP)	91,872
Restricted Share Grants Net	132,870
Units Issued To Noncontrolling Interests	1,081,797
Units Ownership Interest in Operating Partnership	4.60%
General And Limited Partner [Member]
Capital Unit [Line Items]
Common Shares And Units Outstanding	315,470,397	311,000,728
Issuance of OP Units	2,078,310
Exercise of EQR share options	1,014,585
EQR's Employee Share Purchase Plan (ESPP)	91,872
Restricted Share Grants Net	132,870
Issuance Of LTIPs	70,235
Units Issued To Noncontrolling Interests	1,081,797
Limited Partner [Member]
Capital Unit [Line Items]
Issuance Of LTIPs	70,235
Units Issued To Noncontrolling Interests	1,081,797
Total Units Outstanding	14,508,752	13,492,543
Shares Issued During Period Shares Conversion Of Units To Common Shares	(135,823)
Limited Partner [Member]
Capital Unit [Line Items]
Issuance Of LTIPs	70,235
Units Issued To Noncontrolling Interests	1,081,797
Total Units Outstanding	14,508,752	13,492,543
Shares Issued During Period Shares Conversion Of Units To Common Shares	(135,823)