CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - 3 months ended Mar. 31, 2016 - 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, 2015			$ (152,016)	$ 37,280	$ 10,585,104	$ 221,379
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					144	(144)
Exercise of EQR share options					20,687
EQR's Employee Share Purchase Plan (ESPP)					982
Share-based employee compensation expense:
EQR restricted shares					5,134
EQR share options					810
EQR ESPP discount					173
Net income available to Units – General Partner		$ 3,586,985			3,586,985
OP Units – General Partner distributions					(3,105,215)
Supplemental Executive Retirement Plan (SERP)					1,341
Change in market value of Redeemable Limited Partners		55,478			55,478
Adjustment for Noncontrolling Interests ownership in Operating Partnership					1,062	(1,062)
Limited Partners' Capital Account [Abstract]
Issuance of restricted units to Noncontrolling Interests						1
Equity compensation associated with Units – Limited Partners						9,335
Net income available to Units – Limited Partners		143,309				143,309
Units – Limited Partners distributions						(122,499)
Change in carrying value of Redeemable Limited Partners		(9,775)				(9,775)
Other comprehensive income (loss) – derivative instruments:
Unrealized holding (losses) arising during the period	$ (2,906)	(2,906)	(2,906)
Losses reclassified into earnings from other comprehensive income	(28,654)	(28,654)	28,654
Accumulated other comprehensive income – foreign currency:
Currency translation adjustments arising during the period	75	75	75
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	$ 764	$ 764					764
Distributions to Noncontrolling Interests							(26,781)
Other							25,808
Balance, end of period at Mar. 31, 2016			$ (126,193)	$ 37,280	$ 11,152,685	$ 240,544
Balance, end of period at Mar. 31, 2016							$ 4,399