CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - 9 months ended Sep. 30, 2015 - USD ($) $ in Thousands	Total	ERPOP [Member]	ERPOP [Member] Accumulated Other Comprehensive (Loss)	ERPOP [Member] Preferred Partner [Member]	ERPOP [Member] General Partner [Member]	ERPOP [Member] Limited Partner [Member]	ERPOP [Member] Noncontrolling Interest [Member]
Balance, beginning of year at Dec. 31, 2014			$ (172,152)	$ 50,000	$ 10,490,608	$ 214,411
Balance, beginning of year at Dec. 31, 2014							$ 124,909
Partial redemption of 8.29% Series K Cumulative Redeemable	$ 9,820	$ 9,820		(9,820)
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner					4,378	(4,378)
Exercise of EQR share options					37,047
EQR's Employee Share Purchase Plan (ESPP)		(3,376)			3,376
Conversion of EQR restricted shares to restricted units					(70)	70
Share-based employee compensation expense:
EQR restricted shares					12,691
EQR share options					2,887
EQR ESPP discount					692
Net income available to Units – General Partner		660,288			660,288
OP Units – General Partner distributions					(603,337)
Offering costs					(69)
Supplemental Executive Retirement Plan (SERP)					(1,325)
Change in market value of Redeemable Limited Partners		(20,262)			(20,262)
Adjustment for Noncontrolling Interests ownership in Operating Partnership					8,470	(8,470)
Issuance of restricted units to Noncontrolling Interests						3
Equity compensation associated with Units – Limited Partners						18,969
Net income available to Units – Limited Partners		26,191				26,191
Units – Limited Partners distributions						(23,719)
Change in carrying value of Redeemable Limited Partners		(1,590)				(1,590)
Other comprehensive income (loss) – derivative instruments:
Unrealized holding gains arising during the period	1,796	1,796	1,796
Losses reclassified into earnings from other comprehensive income	(13,647)	(13,647)	13,647
Currency translation adjustments arising during the period	(311)	(311)	(311)
Net income attributable to Noncontrolling Interests	$ 2,473	$ 2,473					2,473
Distributions to Noncontrolling Interests							(5,389)
Deconsolidation of previously consolidated Noncontrolling Interests							(117,350)
Balance, end of period at Sep. 30, 2015			$ (157,020)	$ 40,180	$ 10,595,374	$ 221,487
Balance, end of period at Sep. 30, 2015							$ 4,643