Consolidated Statements of Capital - USD ($) shares in Thousands, $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	$ 124,440	$ 96,639	$ 109,662	$ 187,551	$ 413,599	$ 458,043	$ 438,410
Reversal of unrealized gains upon the sale of marketable securities					13	(1,909)	(4,848)
Change in fair value of derivatives and amortization of swap settlements					7,824	12,744	15,926
Change in fair value of marketable securities, net					(118)	3,284	(828)
Issuance of common stock under:
Sale of common stock by general partner, net					(919)	89,055	(384)
Retirement of common stock, net					(51,233)		(1,045)
Changes in the redemption value of redeemable noncontrolling interest					(1,164)	(65)	768
Changes in noncontrolling interest from acquisition					7,919	22,506
Distributions to noncontrolling interests					(29,233)	(27,051)	(25,854)
Redemptions					(1,333)	(28,580)	(2,511)
Preferred stock dividends ($0.45 per share)							(1,314)
ASU 2017-05 [Member]
Issuance of common stock under:
Cumulative adjustment to retained earnings			123,708			123,708
Essex Portfolio, L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		6,396,825		6,292,237	6,396,825	6,292,237	6,337,023
Net income	124,440	96,639	109,662	187,551	413,599	458,043	438,410
Reversal of unrealized gains upon the sale of marketable securities					13	(1,909)	(4,848)
Change in fair value of derivatives and amortization of swap settlements					7,824	12,744	15,926
Change in fair value of marketable securities, net					(118)	3,284	(828)
Issuance of common stock under:
General partner's stock based compensation, net					6,213	26,635	18,949
Sale of common stock by general partner, net					(919)	89,055	(384)
Equity based compensation costs					12,851	11,302	10,899
Redemption of Series H preferred units							(73,750)
Retirement of common stock, net					(51,233)		(1,045)
Changes in the redemption value of redeemable noncontrolling interest					(1,164)	(65)	768
Changes in noncontrolling interest from acquisition						22,506
Distributions to noncontrolling interests					(12,174)	(11,078)	(11,296)
Redemptions					(1,333)	(28,580)	(2,511)
Preferred stock dividends ($0.45 per share)							(1,314)
Distributions declared					(508,167)	(477,349)	(433,762)
Balances	6,393,844		6,396,825		6,393,844	6,396,825	6,292,237
Essex Portfolio, L.P. [Member] | ASU 2016-01 [Member]
Issuance of common stock under:
Cumulative adjustment to retained earnings			0			0
Essex Portfolio, L.P. [Member] | ASU 2017-05 [Member]
Issuance of common stock under:
Cumulative adjustment to retained earnings			123,708			123,708
Essex Portfolio, L.P. [Member] | Accumulated other comprehensive loss, net [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		(15,229)		(29,348)	(15,229)	(29,348)	(39,598)
Reversal of unrealized gains upon the sale of marketable securities					13	(1,909)	(4,848)
Change in fair value of derivatives and amortization of swap settlements					7,824	12,744	15,926
Change in fair value of marketable securities, net					(118)	3,284	(828)
Issuance of common stock under:
Balances	(9,738)		(15,229)		(9,738)	(15,229)	(29,348)
Essex Portfolio, L.P. [Member] | Accumulated other comprehensive loss, net [Member] | ASU 2016-01 [Member]
Issuance of common stock under:
Cumulative adjustment to retained earnings			(2,228)			(2,228)
Essex Portfolio, L.P. [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		66,410		47,873	66,410	47,873	49,642
Net income					9,994	10,159	9,342
Issuance of common stock under:
Changes in the redemption value of redeemable noncontrolling interest					68	(65)	596
Changes in noncontrolling interest from acquisition						22,506
Distributions to noncontrolling interests					(12,174)	(11,078)	(11,296)
Redemptions					(67)	(2,985)	(411)
Balances	64,231		66,410		64,231	66,410	47,873
Essex Portfolio, L.P. [Member] | General Partner [Member] | Common Equity [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		$ 6,295,852		$ 6,224,276	$ 6,295,852	$ 6,224,276	$ 6,208,535
Balances (in shares)		66,054		65,528	66,054	65,528	65,379
Net income					$ 390,153	$ 433,059	$ 411,124
Issuance of common stock under:
General partner's stock based compensation, net					$ 6,213	$ 26,635	$ 18,949
General partner's stock based compensation, net (in shares)					41	179	140
Sale of common stock by general partner, net					$ (919)	$ 89,055	$ (384)
Sale of common stock by general partner, net (in shares)					0	345
Equity based compensation costs					$ 11,651	$ 9,529	8,246
Retirement of common stock, net					$ (51,233)		$ (1,045)
Retirement of common stock, net (in shares)					(210)		(5)
Changes in the redemption value of redeemable noncontrolling interest					$ (1,143)	(136)	$ 172
Redemptions					$ (1,061)	$ (25,190)	$ (2,117)
Redemptions (in shares)					(5)	(2)	(14)
Distributions declared					$ (491,108)	$ (461,376)	$ (419,204)
Balances	$ 6,280,290		$ 6,295,852		$ 6,280,290	$ 6,295,852	$ 6,224,276
Balances (in shares)	65,890		66,054		65,890	66,054	65,528
Essex Portfolio, L.P. [Member] | General Partner [Member] | Common Equity [Member] | ASU 2016-01 [Member]
Issuance of common stock under:
Cumulative adjustment to retained earnings			$ 2,234			$ 2,234
Essex Portfolio, L.P. [Member] | General Partner [Member] | Common Equity [Member] | ASU 2017-05 [Member]
Issuance of common stock under:
Cumulative adjustment to retained earnings			119,651			119,651
Essex Portfolio, L.P. [Member] | General Partner [Member] | Preferred Equity [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		$ 0		$ 0	$ 0	0	$ 71,209
Net income							3,855
Issuance of common stock under:
Redemption of Series H preferred units							(73,750)
Preferred stock dividends ($0.45 per share)							(1,314)
Distributions declared							0
Balances	$ 0		0		0	0	0
Essex Portfolio, L.P. [Member] | Limited Partner [Member] | Common Equity [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		$ 49,792		$ 49,436	$ 49,792	$ 49,436	$ 47,235
Balances (in shares)		2,268		2,237	2,268	2,237	2,215
Net income					$ 13,452	$ 14,825	$ 14,089
Issuance of common stock under:
Equity based compensation costs					$ 1,200	$ 1,773	$ 2,653
Equity based compensation costs (in shares)					11	33	37
Changes in the redemption value of redeemable noncontrolling interest					$ (89)	$ 136
Changes in noncontrolling interest from acquisition					$ 7,919
Contributions from noncontrolling interest (in shares)					31
Redemptions					$ (205)	$ (405)	$ 17
Redemptions (in shares)					(5)	(2)	(15)
Distributions declared					$ (17,059)	$ (15,973)	$ (14,558)
Balances	$ 59,061		$ 49,792		$ 59,061	$ 49,792	$ 49,436
Balances (in shares)	2,305		2,268		2,305	2,268	2,237
Essex Portfolio, L.P. [Member] | Limited Partner [Member] | Common Equity [Member] | ASU 2016-01 [Member]
Issuance of common stock under:
Cumulative adjustment to retained earnings			$ (6)			$ (6)
Essex Portfolio, L.P. [Member] | Limited Partner [Member] | Common Equity [Member] | ASU 2017-05 [Member]
Issuance of common stock under:
Cumulative adjustment to retained earnings			$ 4,057			$ 4,057