CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - 9 months ended Sep. 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				3,680	(3,680)
Exercise of EQR share options				26,939
EQR's Employee Share Purchase Plan (ESPP)				2,778
Share-based employee compensation expense:
EQR restricted shares				12,333
EQR share options				3,084
EQR ESPP discount				490
Offering costs				(304)
Net income available to Units – General Partner		$ 4,012,595		4,012,595
OP Units – General Partner distributions				(4,570,234)
Supplemental Executive Retirement Plan (SERP)				748
Change in market value of Redeemable Limited Partners		113,308		113,308
Adjustment for Noncontrolling Interests ownership in Operating Partnership				6,434	(6,434)
Limited Partners' Capital Account [Abstract]
Issuance of restricted units to Noncontrolling Interests					1
Equity compensation associated with Units – Limited Partners					16,041
Net income available to Units – Limited Partners		160,442			160,442
Units – Limited Partners distributions					(180,230)
Change in carrying value of Redeemable Limited Partners		11,583			11,583
Other comprehensive (loss) income – derivative instruments:
Unrealized holding (losses) gains arising during the period	$ (4,240)	(4,240)				(4,240)
Losses reclassified into earnings from other comprehensive income	(37,262)	(37,262)				37,262
Accumulated other comprehensive income – foreign currency:
Currency translation adjustments arising during the period	264	264				264
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	$ 2,368	$ 2,368					2,368
Distributions to Noncontrolling Interests							(28,621)
Other							25,839
Balance, end of period at Sep. 30, 2016			$ 37,280	$ 10,196,955	$ 219,102	$ (118,730)
Balance, end of period at Sep. 30, 2016							$ 4,194