Equity, Capital and Other Interests ERP Units (Details)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Capital Unit [Line Items]
Common Shares And Units Outstanding	374,596,335
Issuance of OP Units	34,468,085
Exercise of EQR share options	530,847
EQR's Employee Share Purchase Plan (ESPP)	63,788
Restricted Share Grants Net	230,646
Units Ownership Interest in Operating Partnership	3.80%
General And Limited Partner [Member]
Capital Unit [Line Items]
Common Shares And Units Outstanding	374,596,335	339,023,412
Issuance of OP Units	34,468,085
Exercise of EQR share options	530,847
EQR's Employee Share Purchase Plan (ESPP)	63,788
Restricted Share Grants Net	230,646
Issuance Of LTIPs	279,557
Limited Partner [Member]
Capital Unit [Line Items]
Issuance Of LTIPs	279,557
Shares Issued During Period Shares Conversion Of Units To Common Shares	(47,939)
Total Units Outstanding	14,200,376	13,968,758