Equity and Redeemable Noncontrolling Interests of Equity Residential - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Common Stock, Shares, Outstanding January 1,	364,755,444	362,855,454	360,479,260	325,054,654
Common Shares Issued:
Conversion of OP Units	208,307	94,671	67,939
Stock Issued During Period, Shares, New Issues	0	0	34,468,085
Exercise of share options	1,456,363	2,086,380	586,017
Employee Share Purchase Plan (ESPP)	68,462	68,807	73,468
Restricted share grants, net	168,142	169,722	229,097
Common Shares Other:
Conversion of restricted shares to restricted units	(1,284)	(12,146)	0
Stock Repurchased and Retired During Period, Shares	0	(31,240)	0
Units
Units Ownership Interest in Operating Partnership	3.80%	3.80%	3.80%
Redeemable Noncontrolling Interests – Operating Partnership	$ 566,783	$ 500,733	$ 363,144	$ 398,372
Change in market value of Redeemable Noncontrolling Interests – Operating Partnership	$ 64,378	$ 139,818	$ (79,667)
Common Shares And Units Outstanding	379,182,608	377,154,145	374,659,636
Change in carrying value	$ 1,672	$ (2,229)	$ 44,439
ERPOP [Member]
Common Shares Other:
Conversion of restricted shares to restricted units	1,284	12,146	0
Stock Repurchased and Retired During Period, Shares		(31,240)
Units
Total Units Outstanding	14,427,164	14,298,691	14,180,376	13,968,758
Restricted unit grants, net	335,496	200,840	279,557
Shares Issued During Period Shares Conversion Of Units To Common Shares	(208,307)	(94,671)	(67,939)