Equity, Capital and Other Interests EQR Common Shares (Details)	6 Months Ended		6 Months Ended			12 Months Ended	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Archstone Transaction [Member]	Jun. 30, 2013 Limited Partner [Member]	Dec. 31, 2012 Limited Partner [Member]	Dec. 31, 2012 Public Offering [Member]	Jun. 30, 2013 Limited Partner [Member]	Dec. 31, 2012 Limited Partner [Member]
Common Shares outstanding at January 1,	360,312,049	325,054,654
Common Shares Issued:
Conversion of OP Units	36,262
Issuance of Common Shares	34,468,085		34,468,085			21,850,000
Exercise of share options	468,203
Employee Share Purchase Plan (ESPP)	50,148
Restricted Share Grants Net	234,697
Units
Total Units Outstanding				14,214,427	13,968,758		14,214,427	13,968,758
Issuance Of LTIPs				281,931			281,931
Shares Issued During Period Shares Conversion Of Units To Common Shares				(36,262)			(36,262)
Common Shares And Units Outstanding	374,526,476
Units Ownership Interest in Operating Partnership	3.80%