Condensed Consolidated Statement of Capital (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2019
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	$ 125,002	$ 78,842	$ 371,566	$ 497,683
Cash flow hedge losses reclassified to earnings				3,282
Change in fair value of derivatives and amortization of swap settlements	728	1,884	5,607	(6,119)
Change in fair value of marketable debt securities, net	99	92	356	(178)
Issuance of common stock under:
Sale of common stock by general partner, net	(118)	(95)	(202)	(228)
Retirement of common units, net		(26,586)	(9,172)	(222,990)
Accounting standards update					Accounting Standards Update 2016-13 [Member]
Changes in the redemption value of redeemable noncontrolling interest	1,673	2,522	(4,922)	6,691
Contributions from noncontrolling interest			1,900
Changes in noncontrolling interest from acquisition				1,349
Distributions to noncontrolling interest	(7,257)	(7,677)	(22,114)	(23,689)
Redemptions	(6,089)	(1,268)	(8,407)	(2,971)
Essex Portfolio, L.P.
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning	6,136,703	6,352,881	6,183,192	6,403,504
Net income	125,002	78,842	371,566	497,683
Cash flow hedge losses reclassified to earnings				3,282
Change in fair value of derivatives and amortization of swap settlements	728	1,884	5,607	(6,119)
Change in fair value of marketable debt securities, net	99	92	356	(178)
Issuance of common stock under:
General partner's stock based compensation, net	15,572		12,402	9,201
Sale of common stock by general partner, net	(118)	(95)	(202)	(228)
Equity based compensation costs	1,628	2,361	9,495	9,294
Retirement of common units, net		(26,586)	(9,172)	(222,990)
Accounting standards update					Accounting Standards Update 2016-13 [Member]
Cumulative effect upon adoption of ASU No. 2016-13	6,131,899	6,267,482	6,131,899	6,267,482	$ 6,403,504
Changes in the redemption value of redeemable noncontrolling interest	1,673	2,522	(4,922)	6,691
Contributions from noncontrolling interest			1,900
Changes in noncontrolling interest from acquisition				1,349
Distributions to noncontrolling interest	(2,488)	(2,908)	(7,756)	(9,381)
Redemptions	(6,089)	(1,268)	(8,407)	(2,971)
Distributions declared	(140,811)	(140,243)	(422,160)	(421,465)
Balance at period end	$ 6,131,899	$ 6,267,482	$ 6,131,899	$ 6,267,482	6,403,504
Essex Portfolio, L.P. | Common Equity | General Partner
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning (in shares)	65,004	65,331	64,999	66,092
Balance at period beginning	$ 5,963,223	$ 6,184,784	$ 6,015,139	$ 6,234,315
Net income	$ 118,390	73,661	$ 351,680	$ 473,125
Issuance of common stock under:
General partner's stock based compensation, net (in shares)	68		112	95
General partner's stock based compensation, net	$ 15,572		$ 12,402	$ 9,201
Sale of common stock by general partner, net	(118)	(95)	(202)	(228)
Equity based compensation costs	1,573	$ 2,279	$ 9,172	$ 8,956
Retirement of common units, net (in shares)		(121)	(40)	(985)
Retirement of common units, net		$ (26,586)	$ (9,172)	$ (222,990)
Cumulative effect upon adoption of ASU No. 2016-13	5,958,200	6,099,797	5,958,200	6,099,797	$ 6,234,315
Changes in the redemption value of redeemable noncontrolling interest	$ 1,253	2,346	$ (5,499)	$ 6,888
Redemptions (in shares)	9		10	8
Redemptions	$ (5,651)	(1,118)	$ (7,518)	$ (2,123)
Distributions declared	$ (136,042)	$ (135,474)	$ (407,802)	$ (407,157)
Balance at period end (in shares)	65,081	65,210	65,081	65,210	66,092
Balance at period end	$ 5,958,200	$ 6,099,797	$ 5,958,200	$ 6,099,797	$ 6,234,315
Essex Portfolio, L.P. | Common Equity | Limited Partners
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning (in shares)	2,294	2,296	2,295	2,302
Balance at period beginning	$ 56,950	$ 61,437	$ 58,184	$ 57,359
Net income	4,168	2,593	12,403	$ 16,543
Issuance of common stock under:
Equity based compensation costs (in shares)				2
Equity based compensation costs	55	82	323	$ 338
Cumulative effect upon adoption of ASU No. 2016-13	56,385	59,441	56,385	59,441	$ 57,359
Changes in the redemption value of redeemable noncontrolling interest	$ 141	98	$ 129	$ (318)
Redemptions (in shares)	(12)		(13)	(8)
Redemptions	$ (160)		$ (296)	$ (173)
Distributions declared	$ (4,769)	$ (4,769)	$ (14,358)	$ (14,308)
Balance at period end (in shares)	2,282	2,296	2,282	2,296	2,302
Balance at period end	$ 56,385	$ 59,441	$ 56,385	$ 59,441	$ 57,359
Essex Portfolio, L.P. | Accumulated Other Comprehensive Loss
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning	(6,167)	(15,423)	(11,303)	(10,432)
Cash flow hedge losses reclassified to earnings				3,282
Change in fair value of derivatives and amortization of swap settlements	728	1,884	5,607	(6,119)
Change in fair value of marketable debt securities, net	99	92	356	(178)
Issuance of common stock under:
Cumulative effect upon adoption of ASU No. 2016-13	(5,340)	(13,447)	(5,340)	(13,447)	(10,432)
Balance at period end	(5,340)	(13,447)	(5,340)	(13,447)	(10,432)
Essex Portfolio, L.P. | Noncontrolling Interest
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning	122,697	122,083	121,172	122,262
Net income	2,444	2,588	7,483	8,015
Issuance of common stock under:
Cumulative effect upon adoption of ASU No. 2016-13	122,654	121,691	122,654	121,691	122,262
Changes in the redemption value of redeemable noncontrolling interest	279	78	448	121
Contributions from noncontrolling interest			1,900
Changes in noncontrolling interest from acquisition				1,349
Distributions to noncontrolling interest	(2,488)	(2,908)	(7,756)	(9,381)
Redemptions	(278)	(150)	(593)	(675)
Balance at period end	$ 122,654	$ 121,691	$ 122,654	121,691	122,262
Essex Portfolio, L.P. | Cumulative Effect, Period Of Adoption, Adjustment
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning				(190)
Issuance of common stock under:
Cumulative effect upon adoption of ASU No. 2016-13					(190)
Balance at period end					(190)
Essex Portfolio, L.P. | Cumulative Effect, Period Of Adoption, Adjustment | Common Equity | General Partner
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning				$ (190)
Issuance of common stock under:
Cumulative effect upon adoption of ASU No. 2016-13					(190)
Balance at period end					$ (190)