CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - 6 months ended Jun. 30, 2016 - USD ($) $ in Thousands	Total	ERPOP [Member]	ERPOP [Member] PREFERENCE UNITS	ERPOP [Member] GENERAL PARTNER	ERPOP [Member] LIMITED PARTNERS	ERPOP [Member] ACCUMULATED OTHER COMPREHENSIVE (LOSS)	ERPOP [Member] NONCONTROLLING INTERESTS
Balance, beginning of year at Dec. 31, 2015			$ 37,280	$ 10,585,104	$ 221,379	$ (152,016)
Balance, beginning of year at Dec. 31, 2015							$ 4,608
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner				271	(271)
Exercise of EQR share options				26,141
EQR's Employee Share Purchase Plan (ESPP)				2,023
Share-based employee compensation expense:
EQR restricted shares				9,627
EQR share options				2,733
EQR ESPP discount				357
Net income available to Units – General Partner		$ 3,805,052		3,805,052
OP Units – General Partner distributions				(3,289,355)
Supplemental Executive Retirement Plan (SERP)				801
Change in market value of Redeemable Limited Partners		99,190		99,190
Adjustment for Noncontrolling Interests ownership in Operating Partnership				4,865	(4,865)
Limited Partners' Capital Account [Abstract]
Issuance of restricted units to Noncontrolling Interests					1
Equity compensation associated with Units – Limited Partners					13,903
Net income available to Units – Limited Partners		152,089			152,089
Units – Limited Partners distributions					(129,757)
Change in carrying value of Redeemable Limited Partners		(10,731)			(10,731)
Other comprehensive (loss) income – derivative instruments:
Unrealized holding (losses) gains arising during the period	$ (4,467)	(4,467)				(4,467)
Losses reclassified into earnings from other comprehensive income	(32,922)	(32,922)				32,922
Accumulated other comprehensive income – foreign currency:
Currency translation adjustments arising during the period	50	50				50
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	$ 1,545	$ 1,545					1,545
Distributions to Noncontrolling Interests							(27,714)
Other							25,839
Balance, end of period at Jun. 30, 2016			$ 37,280	$ 11,246,809	$ 241,748	$ (123,511)
Balance, end of period at Jun. 30, 2016							$ 4,278