CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - 3 months ended Mar. 31, 2018 - USD ($) $ in Thousands	Total	ERPOP [Member]	PREFERRED SHARES ERPOP [Member]	General Partner [Member] ERPOP [Member]	Limited Partner [Member] ERPOP [Member]	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ERPOP [Member]	PARTIALLY OWNED PROPERTIES [Member] ERPOP [Member]
Balance, beginning of year at Dec. 31, 2017			$ 37,280	$ 10,293,796	$ 226,691	$ (88,612)
Balance, beginning of year at Dec. 31, 2017							$ 4,708
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner				134	(134)
Exercise of EQR share options				1,600
EQR's Employee Share Purchase Plan (ESPP)				1,681
Share-based employee compensation expense:
EQR restricted shares				2,623
EQR share options				7,338
EQR ESPP discount				297
Net income available to Units General Partner		$ 211,036		211,036
OP Units General Partner distributions				(198,928)
Offering costs				(26)
Supplemental Executive Retirement Plan (SERP)				83
Change in market value of Redeemable Limited Partners				12,831
Adjustment for Limited Partners ownership in Operating Partnership				(2,839)	2,839
LIMITED PARTNERS
Issuance of restricted units to Limited Partners					1
Conversion of OP Units held by Limited Partners into OP Units held by General Partner				134	(134)
Equity compensation associated with Units Limited Partners					4,803
Net income available to Units Limited Partners		8,059			8,059
Units Limited Partners distributions					(7,188)
Change in carrying value of Redeemable Limited Partners					(443)
Adjustment for Limited Partners ownership in Operating Partnership				(2,839)	2,839
Issuance of restricted units to Noncontrolling Interests					1
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding gains (losses) arising during the period	$ 6,087	6,087				6,087
Losses reclassified into earnings from other comprehensive income	(4,791)	(4,791)				4,791
NONCONTROLLING INTERESTS PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	$ 220,548	$ 220,548					680
Contributions by Noncontrolling Interests							125
Distributions to Noncontrolling Interests							(4,220)
Balance, end of period at Mar. 31, 2018			$ 37,280	$ 10,329,626	$ 234,628	$ (77,734)
Balance, end of period at Mar. 31, 2018							$ 1,293