CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (Unaudited) - Class of Stock [Domain] - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Total	PREFERRED SHARES	COMMON SHARES, $0.01 PAR VALUE	Additional Paid-in Capital [Member]	RETAINED EARNINGS	Accumulated Other Comprehensive (Loss)	OPERATING PARTNERSHIP	Partially Owned Properties [Member]
Beginning Balance, Parent at Dec. 31, 2014	$ 10,368,456	$ 50,000	$ 3,629	$ 8,536,340	$ 1,950,639	$ (172,152)
Beginning Balance, Noncontrolling Interest at Dec. 31, 2014	339,320						$ 214,411	$ 124,909
Preferred Shares [Abstract]
Partial redemption of 8.29% Series K Cumulative Redeemable	(9,820)	(9,820)
Common Share Issuance:
Conversion of OP Units into Common Shares			2	4,117			(4,119)
Exercise of share options			8	33,976
EQR's Employee Share Purchase Plan (ESPP)				2,610
Conversion of restricted shares to restricted units				(70)			70
Share-based employee compensation expense:
Restricted Shares			2	10,343
Share options				2,028
ESPP discount				533
Offering costs				(40)
Supplemental Executive Retirement Plan (SERP)				(2,227)
Change in market value of Redeemable Noncontrolling Interests - Operating Partnership	(13,966)			13,966
Adjustment for Noncontrolling Interests ownership in Operating Partnership				6,313			(6,313)
Net income attributable to controlling interests	468,942				468,942
Common Share distributions					(402,159)
Preferred Share distributions					(1,724)
Premium on redemption of Preferred Shares	(2,789)				(2,789)
Other comprehensive (loss) income – derivative instruments:
Unrealized holding (losses) arising during the period	(112)					(112)
Losses reclassified into earnings from other comprehensive income	(8,911)					8,911
Currency translation adjustments arising during the period	(502)					(502)
Issuance of restricted units to Noncontrolling Interests							1
Equity Compensation associated with Noncontrolling Interests							16,368
Net (income) attributable to Noncontrolling Interests - Operating Partnership	(18,413)						18,413
Distributions to Noncontrolling Interests							(15,819)	(4,028)
Change in carrying value	1,411						(1,411)
Net (income) attributable to Noncontrolling Interests – Partially Owned Properties	1,487							1,487
Ending Balance, Parent at Jun. 30, 2015	10,500,764	$ 40,180	$ 3,641	$ 8,607,889	$ 2,012,909	$ (163,855)
Ending Balance, Noncontrolling Interest at Jun. 30, 2015	$ 343,969						$ 221,601	$ 122,368