CONSOLIDATED STATEMENTS OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP (Unaudited) - USD ($) $ in Thousands	Total	ERPOP [Member]	Preferred Stock [Member] ERPOP [Member]	GENERAL PARTNER [Member] ERPOP [Member]	LIMITED PARTNERS [Member] ERPOP [Member]	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) [Member] ERPOP [Member]	DISTRIBUTIONS [Member] ERPOP [Member]	PARTIALLY OWNED PROPERTIES [Member] ERPOP [Member]
Balance, beginning of year at Dec. 31, 2021			$ 37,280	$ 10,951,940	$ 214,094	$ (34,272)
Balance, beginning of year at Dec. 31, 2021								$ 18,166
Conversion of OP Units held by Limited Partners into OP Units held by General Partner				1,680	(1,680)
Exercise of EQR share options				21,021
EQR's Employee Share Purchase Plan (ESPP)				3,280
EQR restricted shares				9,526	1
EQR share options				1,856
EQR ESPP discount				637
Net income available to Units - General Partner		$ 615,573		615,573
OP Units General Partner distributions				(705,529)
Offering costs				(739)
Supplemental Executive Retirement Plan (SERP)				(269)
Acquisition of Noncontrolling Interests – Partially Owned Properties				(27,383)
Change in market value of Redeemable Limited Partners				127,570
Adjustment for Limited Partners ownership in Operating Partnership				9,156	(9,156)
Equity compensation associated with Units - Limited Partners					16,502
Net income available to Units - Limited Partners		21,024			21,024
Units - Limited Partners distributions					(23,078)
Change in carrying value of Redeemable Limited Partners					870
Unrealized holding gains (losses) arising during the period	$ 23,413	23,413				23,413
Losses reclassified into earnings from other comprehensive income	9,987	9,987				9,987
Distributions declared per Unit outstanding							$ 1.875
Net income attributable to Noncontrolling Interests	641,641	641,641						2,726
Contributions by Noncontrolling Interests								603
Distributions to Noncontrolling Interests								(18,267)
Acquisitions of Noncontrolling Interests - Partially Owned Properties								(4,795)
Balance, end of period at Sep. 30, 2022			37,280	11,008,319	218,577	(872)
Balance, end of period at Sep. 30, 2022								(1,567)
Balance, beginning of year at Jun. 30, 2022			37,280	10,883,459	216,326	(30,650)
Balance, beginning of year at Jun. 30, 2022								(1,734)
Conversion of OP Units held by Limited Partners into OP Units held by General Partner				196	(196)
Exercise of EQR share options				2,093
EQR's Employee Share Purchase Plan (ESPP)				902
EQR restricted shares				2,165
EQR share options				466
EQR ESPP discount				217
Net income available to Units - General Partner		322,252		322,252
OP Units General Partner distributions				(235,105)
Offering costs				(252)
Acquisition of Noncontrolling Interests – Partially Owned Properties				(28)
Change in market value of Redeemable Limited Partners				29,430
Adjustment for Limited Partners ownership in Operating Partnership				2,524	(2,524)
Equity compensation associated with Units - Limited Partners					3,343
Net income available to Units - Limited Partners		10,997			10,997
Units - Limited Partners distributions					(7,590)
Change in carrying value of Redeemable Limited Partners					(1,779)
Unrealized holding gains (losses) arising during the period	24,672	24,672				24,672
Losses reclassified into earnings from other comprehensive income	5,106	5,106				5,106
Distributions declared per Unit outstanding							0.625
Net income attributable to Noncontrolling Interests	335,165	335,165						1,143
Distributions to Noncontrolling Interests								(1,004)
Acquisitions of Noncontrolling Interests - Partially Owned Properties								28
Balance, end of period at Sep. 30, 2022			37,280	11,008,319	218,577	(872)
Balance, end of period at Sep. 30, 2022								(1,567)
Balance, beginning of year at Dec. 31, 2022			37,280	11,138,706	209,961	(2,547)
Balance, beginning of year at Dec. 31, 2022								(721)
Conversion of OP Units held by Limited Partners into OP Units held by General Partner				13,916	(13,916)
Exercise of EQR share options				11,474
EQR's Employee Share Purchase Plan (ESPP)				2,591
EQR restricted shares				10,294	1
EQR share options				3,904
EQR ESPP discount				481
Net income available to Units - General Partner		521,428		521,428
OP Units General Partner distributions				(753,633)
Supplemental Executive Retirement Plan (SERP)				32,078
Acquisition of Noncontrolling Interests – Partially Owned Properties				(900)
Change in market value of Redeemable Limited Partners				18,613
Adjustment for Limited Partners ownership in Operating Partnership				20,534	(20,534)
Equity compensation associated with Units - Limited Partners					14,205
Net income available to Units - Limited Partners		17,174			17,174
Units - Limited Partners distributions					(22,924)
Change in carrying value of Redeemable Limited Partners					21,878
Unrealized holding gains (losses) arising during the period	4,514	4,514				4,514
Losses reclassified into earnings from other comprehensive income	3,132	3,132				3,132
Distributions declared per Unit outstanding							1.9875
Net income attributable to Noncontrolling Interests	546,219	546,219						5,299
Contributions by Noncontrolling Interests								9
Distributions to Noncontrolling Interests								(3,573)
Acquisitions of Noncontrolling Interests - Partially Owned Properties								(2,837)
Balance, end of period at Sep. 30, 2023			37,280	11,019,486	205,845	5,099
Balance, end of period at Sep. 30, 2023								(1,823)
Balance, beginning of year at Jun. 30, 2023			37,280	10,982,878	207,405	3,708
Balance, beginning of year at Jun. 30, 2023								(4,728)
Conversion of OP Units held by Limited Partners into OP Units held by General Partner				9,257	(9,257)
Exercise of EQR share options				116
EQR's Employee Share Purchase Plan (ESPP)				467
EQR restricted shares				2,349
EQR share options				779
EQR ESPP discount				83
Net income available to Units - General Partner		171,735		171,735
OP Units General Partner distributions				(251,563)
Supplemental Executive Retirement Plan (SERP)				31,930
Change in market value of Redeemable Limited Partners				57,736
Adjustment for Limited Partners ownership in Operating Partnership				13,719	(13,719)
Equity compensation associated with Units - Limited Partners					3,338
Net income available to Units - Limited Partners		5,561			5,561
Units - Limited Partners distributions					(7,284)
Change in carrying value of Redeemable Limited Partners					19,801
Unrealized holding gains (losses) arising during the period	460	460				460
Losses reclassified into earnings from other comprehensive income	931	931				931
Distributions declared per Unit outstanding							$ 0.6625
Net income attributable to Noncontrolling Interests	$ 181,286	$ 181,286						3,217
Distributions to Noncontrolling Interests								(312)
Balance, end of period at Sep. 30, 2023			$ 37,280	$ 11,019,486	$ 205,845	$ 5,099
Balance, end of period at Sep. 30, 2023								$ (1,823)