Consolidated Statements of Capital - USD ($) shares in Thousands, $ in Thousands	3 Months Ended				12 Months Ended
	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	$ 85,762	$ 64,753	$ 44,805	$ 26,406	$ 248,239	$ 134,438	$ 172,055
Reversal of unrealized gains upon the sale of marketable securities					0	(886)	(1,767)
Changes in fair value of cash flow hedges and amortization of gain on settlement of swap					7,893	4,168	12,614
Changes in fair value of marketable securities					1,865	6,302	(1,556)
Issuance of common stock under:
Sale of common stock					332,137	532,670	138,366
Reclassification of noncontrolling interest to redeemable noncontrolling interest					(19,772)	(20,890)
Changes in the redemption value of redeemable noncontrolling interest					(2,615)	312
Conversion of Series G preferred stock						4,349
Contributions from noncontrolling interest					0	(1,419,816)	0
Retirement of noncontrolling interest					0	(1,419,816)	0
Distributions to noncontrolling interests					(21,705)	(17,069)	(18,488)
Essex Portfolio, L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		6,136,068		1,998,238	6,136,068	1,998,238	1,880,116
Net income	85,762	64,753	44,805	26,406	248,239	134,438	172,055
Reversal of unrealized gains upon the sale of marketable securities					0	(886)	(1,767)
Changes in fair value of cash flow hedges and amortization of gain on settlement of swap					7,893	4,168	12,614
Changes in fair value of marketable securities					1,865	6,302	(1,556)
Common stock issued as consideration by general partner in merger						3,774,087
Issuance of common stock under:
Stock and unit based compensation plans					26,540	11,024	7,244
Sale of common stock					332,137	532,670	138,366
Stock and unit based compensation costs					9,646	11,872	1,608
Reclassification of noncontrolling interest to redeemable noncontrolling interest					(19,772)	(20,890)
Changes in the redemption value of redeemable noncontrolling interest					(2,615)	312
Conversion of Series G preferred stock						4,349
Contributions from noncontrolling interest					0	(1,419,816)	0
Retirement of noncontrolling interest					0	(1,419,816)	0
Redemptions					(2,621)	(5,497)	(5,711)
Distributions to noncontrolling interests					(8,751)	(4,890)	(8,016)
Distributions declared					(391,606)	(309,229)	(196,715)
Balances	6,337,023		6,136,068		6,337,023	6,136,068	1,998,238
Essex Portfolio, L.P. [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		(49,356)		(58,940)	(49,356)	(58,940)	(68,231)
Reversal of unrealized gains upon the sale of marketable securities						(886)	(1,767)
Changes in fair value of cash flow hedges and amortization of gain on settlement of swap					7,893	4,168	12,614
Changes in fair value of marketable securities					1,865	6,302	(1,556)
Issuance of common stock under:
Balances	(39,598)		(49,356)		(39,598)	(49,356)	(58,940)
Essex Portfolio, L.P. [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		62,635		66,130	62,635	66,130	68,689
Net income					8,295	7,421	6,834
Issuance of common stock under:
Reclassification of noncontrolling interest to redeemable noncontrolling interest					(12,115)	(5,084)
Redemptions					(422)	(942)	(1,377)
Distributions to noncontrolling interests					(8,751)	(4,890)	(8,016)
Balances	49,642		62,635		49,642	62,635	66,130
Essex Portfolio, L.P. [Member] | General Partner [Member] | Common Equity [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		$ 6,002,915		$ 1,873,882	$ 6,002,915	$ 1,873,882	$ 1,762,856
Balances (in shares)		63,683		37,421	63,683	37,421	36,443
Net income					$ 226,865	$ 116,859	$ 150,811
Common stock issued as consideration by general partner in merger						$ 3,774,087
Common stock issued as consideration by general partner in merger (in shares)						23,067
Issuance of common stock under:
Stock and unit based compensation plans					$ 26,540	$ 11,024	$ 7,244
Stock and unit based compensation plan (in shares)					207	218	65
Sale of common stock					$ 332,137	$ 532,670	$ 138,366
Sale of common stock (in shares)					1,482	2,943	913
Stock and unit based compensation costs					$ 5,946	$ 5,719	$ (907)
Reclassification of noncontrolling interest to redeemable noncontrolling interest					(7,657)	(19,823)
Changes in the redemption value of redeemable noncontrolling interest					(2,615)	312
Conversion of Series G preferred stock						$ 4,349
Conversion of Series G preferred stock (in shares)						34
Redemptions					$ (2,199)	$ (3,374)	(3,717)
Redemptions (in shares)					7
Distributions to noncontrolling interests						0
Distributions declared					$ (373,397)	(292,790)	(180,771)
Balances	$ 6,208,535		$ 6,002,915		$ 6,208,535	$ 6,002,915	$ 1,873,882
Balances (in shares)	65,379		63,683		65,379	63,683	37,421
Essex Portfolio, L.P. [Member] | General Partner [Member] | Preferred Equity [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		$ 71,209		$ 71,209	$ 71,209	$ 71,209	$ 71,209
Net income					5,255	5,291	5,472
Issuance of common stock under:
Distributions declared					(5,255)	(5,291)	(5,472)
Balances	$ 71,209		$ 71,209		71,209	71,209	71,209
Essex Portfolio, L.P. [Member] | Limited Partner [Member] | Common Equity [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		$ 48,665		$ 45,957	$ 48,665	$ 45,957	$ 45,593
Balances (in shares)		2,168		2,150	2,168	2,150	2,122
Net income					$ 7,824	$ 4,867	$ 8,938
Issuance of common stock under:
Stock and unit based compensation costs					$ 3,700	$ 6,153	$ 2,515
Stock and unit based compensation costs (in shares)					54	28	28
Reclassification of noncontrolling interest to redeemable noncontrolling interest					$ 0	$ 4,017
Reclassification of noncontrolling interest to redeemable noncontrolling interest (in units)						(10)
Contributions from noncontrolling interest						$ (1,419,816)
Contributions from noncontrolling interest (in shares)						8,561
Retirement of noncontrolling interest						$ (1,419,816)
Retirement of noncontrolling interest (in shares)						(8,561)
Redemptions					$ 0	$ (1,181)	$ (617)
Redemptions (in shares)					(7)
Distributions to noncontrolling interests						0
Distributions declared					$ (12,954)	(11,148)	(10,472)
Balances	$ 47,235		$ 48,665		$ 47,235	$ 48,665	$ 45,957
Balances (in shares)	2,215		2,168		2,215	2,168	2,150
Essex Portfolio, L.P. [Member] | Limited Partner [Member] | Preferred Equity [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balances		$ 0		$ 0	$ 0	$ 0	$ 0
Issuance of common stock under:
Balances	$ 0		$ 0		$ 0	$ 0	$ 0