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			4,754	(4,754)
Issuance of OP Units			123,601
Exercise of EQR share options			31,281
EQR's Employee Share Purchase Plan (ESPP)			4,523
Share-based employee compensation expense:
EQR restricted shares			5,116
EQR share options			7,976
EQR ESPP discount			809
Offering costs			(1,907)
Net income available to Units - General Partner			241,630
OP Units - General Partner distributions			(202,967)
Supplemental Executive Retirement Plan (SERP)			(5,473)
Acquisition Noncontrolling Interests Partially Owned Properties			1,219			(1,306)
Change in market value of Redeemable Limited Partners			(32,391)
Adjustment for Limited Partners ownership in Operating Partnership			39,429	(39,429)
Issuance Of OP Units To Noncontrolling Interests	66,606			66,606
Issuance of LTIP Units to Noncontrolling Interests				5
Equity compensation associated with Units - Limited Partners				4,211
Net income available to Units - Limited Partners				11,150
Units - Limited Partners distributions				(9,396)
Change in carrying value of Redeemable Limited Partners				(3,408)
Accumulated other comprehensive (loss) income - derivative instruments:
Unrealized holding (losses) arising during the period	(8,642)				(8,642)
Losses reclassified into earnings from other comprehensive income	(7,203)				7,203
Accumulated other comprehensive income (loss) - other instruments:
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	82				82
Net Income (Loss) Attributable to Noncontrolling Interest						769
Contributions by Noncontrolling Interests						2,935
Distributions to Noncontrolling Interests						(2,258)
Balance, end of period - Noncontrolling Interest at Jun. 30, 2012						74,446
Balance, end of period at Jun. 30, 2012		$ 200,000	$ 5,883,333	$ 144,521	$ (198,075)