CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	PREFERRED SHARES	General Partner [Member]	Limited Partner [Member]	ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME	Partially Owned Properties [Member]
Balance, beginning of year - Noncontrolling Interest at Dec. 31, 2011						$ 74,306
Balance, beginning of year at Dec. 31, 2011		200,000	5,665,733	119,536	(196,718)
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner			1,085	(1,085)
Issuance of OP Units			123,601
Exercise of EQR share options			18,938
EQR's Employee Share Purchase Plan (ESPP)			4,210
Share-based employee compensation expense:
EQR restricted shares			2,710
EQR share options			4,092
EQR ESPP discount			743
Offering costs			(1,887)
Net income available to Units - General Partner			141,833
OP Units - General Partner distributions			(101,404)
Supplemental Executive Retirement Plan (SERP)			(6,292)
Change in market value of Redeemable Limited Partners			(37,603)
Adjustment for Limited Partners ownership in Operating Partnership			(3,778)	3,778
Issuance of LTIP Units to Noncontrolling Interests				5
Equity compensation associated with Units - Limited Partners				2,163
Net income available to Units - Limited Partners				6,418
Units - Limited Partners distributions				(4,567)
Change in carrying value of Redeemable Limited Partners				(3,217)
Accumulated other comprehensive (loss) income - derivative instruments:
Unrealized holding gains arising during the year	3,218				3,218
Losses reclassified into earnings from other comprehensive income	(3,563)				3,563
Accumulated other comprehensive income (loss) - other instruments:
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	(36)				(36)
Net Income (Loss) Attributable to Noncontrolling Interest						450
Contributions by Noncontrolling Interests						921
Distributions to Noncontrolling Interests						(1,762)
Balance, end of period - Noncontrolling Interest at Mar. 31, 2012						73,915
Balance, end of period at Mar. 31, 2012		$ 200,000	$ 5,811,981	$ 123,031	$ (189,973)