Equity, Capital and Other Interests EQR Common Shares (Details)	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Common Shares outstanding at January 1,	300,961,645	297,508,185
Common Shares Issued:
Conversion of OP Units	135,823
Issuance of Common Shares	2,078,310
Exercise of share options	1,014,585
Employee Share Purchase Plan (ESPP)	91,872
Restricted Share Grants Net	132,870
Units
Units Issued To Noncontrolling Interests	1,081,797
Common Shares And Units Outstanding	315,470,397
Units Ownership Interest in Operating Partnership	4.60%
Limited Partner [Member]
Units
Total Units Outstanding	14,508,752	13,492,543
Issuance Of LTIPs	70,235
Units Issued To Noncontrolling Interests	1,081,797
Shares Issued During Period Shares Conversion Of Units To Common Shares	(135,823)
Limited Partner [Member]
Units
Total Units Outstanding	14,508,752	13,492,543
Issuance Of LTIPs	70,235
Units Issued To Noncontrolling Interests	1,081,797
Shares Issued During Period Shares Conversion Of Units To Common Shares	(135,823)