CONSOLIDATED STATEMENT OF CHANGES IN CAPITAL OF ERP OPERATING LIMITED PARTNERSHIP - USD ($) $ in Thousands	Total	Series K Preferred Stock [Member]	ERPOP [Member]	ERPOP [Member] Series K Preferred Stock [Member]	PREFERRED SHARES ERPOP [Member]	PREFERRED SHARES ERPOP [Member] Series K Preferred Stock [Member]	General Partner [Member] ERPOP [Member]	Limited Partner [Member] ERPOP [Member]	ACCUMULATED OTHER COMPREHENSIVE (LOSS) ERPOP [Member]	PARTIALLY OWNED PROPERTIES ERPOP [Member]
Balance, beginning of year at Dec. 31, 2013					$ 50,000		$ 10,612,363	$ 211,412	$ (155,162)
Balance, beginning of year at Dec. 31, 2013										$ 126,583
Preference Units
Partial redemption of 8.29% Series K Cumulative Redeemable					0
Preferred Stock Preference Units Dividend Rate Percentage		8.29%				8.29%
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner							2,365	(2,365)
Exercise of EQR share options							82,573
EQR's Employee Share Purchase Plan (ESPP)							3,392
Conversion of EQR restricted shares to restricted units							0	0
Share-based employee compensation expense:
EQR restricted shares							9,904
EQR share options							7,349
EQR ESPP discount							859
OP Units repurchased and retired							(1,777)
Net income available to Units – General Partner			$ 627,163				627,163
OP Units – General Partner distributions							(723,782)
Offering costs							(41)
Supplemental Executive Retirement Plan (SERP)							7,374
Acquisition of Noncontrolling Interests – Partially Owned Properties							(2,308)			(2,244)
Change in market value of Redeemable Limited Partners							(139,818)
Adjustment for Limited Partners ownership in Operating Partnership							4,992
LIMITED PARTNERS
Issuance of restricted units to Limited Partners								3
Conversion of OP Units held by Limited Partners into OP Units held by General Partner							2,365	(2,365)
Conversion of EQR restricted shares to restricted units							0	0
Equity compensation associated with Units – Limited Partners								11,969
Net income available to Units – Limited Partners			24,831					24,831
Units – Limited Partners distributions								(28,676)
Change in carrying value of Redeemable Limited Partners								2,229
Noncontrolling Interest, Period Increase (Decrease)								(4,992)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding (losses) gains arising during the year	$ (33,306)		(33,306)						(33,306)
Losses reclassified into earnings from other comprehensive income	(16,868)		(16,868)						16,868
Accumulated other comprehensive income (loss) – foreign currency:
Currency translation adjustments arising during the year	(552)		(552)						(552)
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	658,683		658,683							2,544
Contributions by Noncontrolling Interests	5,684		5,684							5,684
Distributions to Noncontrolling Interests										(7,827)
Acquisition of Noncontrolling Interests – Partially Owned Properties							(2,308)			(2,244)
Deconsolidation of previously consolidated Noncontrolling Interests										0
Other										169
Balance, end of year at Dec. 31, 2014					50,000		10,490,608	214,411	(172,152)
Balance, end of year at Dec. 31, 2014										124,909
Preference Units
Partial redemption of 8.29% Series K Cumulative Redeemable					(12,720)
Preferred Stock Preference Units Dividend Rate Percentage		8.29%		8.29%		0.00%
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner							4,966	(4,966)
Exercise of EQR share options							59,508
EQR's Employee Share Purchase Plan (ESPP)							4,404
Conversion of EQR restricted shares to restricted units							(70)	70
Share-based employee compensation expense:
EQR restricted shares							15,066
EQR share options							3,756
EQR ESPP discount							884
OP Units repurchased and retired							0
Net income available to Units – General Partner			863,277				863,277
OP Units – General Partner distributions							(804,825)
Offering costs							(79)
Supplemental Executive Retirement Plan (SERP)							1,380
Acquisition of Noncontrolling Interests – Partially Owned Properties							0			0
Change in market value of Redeemable Limited Partners							(64,378)
Adjustment for Limited Partners ownership in Operating Partnership							10,607
LIMITED PARTNERS
Issuance of restricted units to Limited Partners								3
Conversion of OP Units held by Limited Partners into OP Units held by General Partner							4,966	(4,966)
Conversion of EQR restricted shares to restricted units							(70)	70
Equity compensation associated with Units – Limited Partners								21,503
Net income available to Units – Limited Partners			34,241					34,241
Units – Limited Partners distributions								(31,604)
Change in carrying value of Redeemable Limited Partners								(1,672)
Noncontrolling Interest, Period Increase (Decrease)								(10,607)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding (losses) gains arising during the year	2,219		2,219						2,219
Losses reclassified into earnings from other comprehensive income	(18,244)		(18,244)						18,244
Accumulated other comprehensive income (loss) – foreign currency:
Currency translation adjustments arising during the year	(327)		(327)						(327)
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	908,018		908,018							3,657
Contributions by Noncontrolling Interests	0		0							0
Distributions to Noncontrolling Interests										(6,608)
Acquisition of Noncontrolling Interests – Partially Owned Properties							0			0
Deconsolidation of previously consolidated Noncontrolling Interests										(117,350)
Other										0
Balance, end of year at Dec. 31, 2015					37,280		10,585,104	221,379	(152,016)
Balance, end of year at Dec. 31, 2015										4,608
Preference Units
Partial redemption of 8.29% Series K Cumulative Redeemable					0
Preferred Stock Preference Units Dividend Rate Percentage		8.29%		8.29%		8.29%
OP Unit Issuance:
Conversion of OP Units held by Limited Partners into OP Units held by General Partner							3,726	(3,726)
Exercise of EQR share options							35,833
EQR's Employee Share Purchase Plan (ESPP)							3,686
Conversion of EQR restricted shares to restricted units							0	0
Share-based employee compensation expense:
EQR restricted shares							15,016
EQR share options							3,432
EQR ESPP discount							650
OP Units repurchased and retired							0
Net income available to Units – General Partner			4,289,072				4,289,072
OP Units – General Partner distributions							(4,754,537)
Offering costs							(314)
Supplemental Executive Retirement Plan (SERP)							748
Acquisition of Noncontrolling Interests – Partially Owned Properties							0			0
Change in market value of Redeemable Limited Partners							115,093
Adjustment for Limited Partners ownership in Operating Partnership							8,198
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							3,726	(3,726)
Conversion of EQR restricted shares to restricted units							0	0
Equity compensation associated with Units – Limited Partners								18,180
Net income available to Units – Limited Partners			171,511					171,511
Units – Limited Partners distributions								(187,448)
Change in carrying value of Redeemable Limited Partners								9,598
Noncontrolling Interest, Period Increase (Decrease)								(8,198)
Accumulated other comprehensive income (loss) – derivative instruments:
Unrealized holding (losses) gains arising during the year	(3,915)		(3,915)						(3,915)
Losses reclassified into earnings from other comprehensive income	(41,758)		(41,758)						41,758
Accumulated other comprehensive income (loss) – foreign currency:
Currency translation adjustments arising during the year	264		264						264
PARTIALLY OWNED PROPERTIES
Net income attributable to Noncontrolling Interests	4,480,104		4,480,104							16,430
Contributions by Noncontrolling Interests	$ 0		$ 0							0
Distributions to Noncontrolling Interests										(36,268)
Acquisition of Noncontrolling Interests – Partially Owned Properties							0			0
Deconsolidation of previously consolidated Noncontrolling Interests										0
Other										25,839
Balance, end of year at Dec. 31, 2016					$ 37,280		$ 10,305,707	$ 221,297	$ (113,909)
Balance, end of year at Dec. 31, 2016										$ 10,609