Equity, Capital and Other Interests EQR Common Shares (Details)	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Common Shares outstanding at January 1,	300,522,169	297,508,185
Common Shares Issued:
Conversion of OP Units	31,361
Issuance of Common Shares	2,078,310
Exercise of share options	690,340
Employee Share Purchase Plan (ESPP)	85,837
Restricted Share Grants Net	128,136
Units
Common Shares And Units Outstanding	314,053,586
Units Ownership Interest in Operating Partnership	4.30%
Limited Partner [Member]
Units
Total Units Outstanding	13,531,417	13,492,543
Issuance Of LTIPs	70,235
Shares Issued During Period Shares Conversion Of Units To Common Shares	(31,361)
Limited Partner [Member]
Units
Total Units Outstanding	13,531,417	13,492,543
Issuance Of LTIPs	70,235
Shares Issued During Period Shares Conversion Of Units To Common Shares	(31,361)