Condensed Consolidated Statement of Capital (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	$ 47,182	$ 162,477
Change in fair value of derivatives and amortization of swap settlements		1,675
Change in fair value of marketable securities		(543)
Issuance of common stock under:
Sale of common stock by general partner		307,835
Reclassification of noncontrolling interest to redeemable noncontrolling interest		(144)
Distributions to noncontrolling interest		(16,327)
Redemptions		(2,621)
Essex Portfolio, L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning		6,136,068
Net income	47,182	162,477
Change in fair value of derivatives and amortization of swap settlements		1,675
Change in fair value of marketable securities		(543)
Issuance of common stock under:
General partner's stock based compensation		22,173
Sale of common stock by general partner		307,835
Equity based compensation costs		5,511
Changes in redemption value of redeemable noncontrolling interest		(1,095)
Reclassification of noncontrolling interest to redeemable noncontrolling interest		(144)
Distributions to noncontrolling interest		(6,393)
Redemptions		(2,621)
Distributions declared		(293,120)
Balance at period end	6,331,823	6,331,823
Essex Portfolio, L.P. [Member] | Common Equity [Member] | General Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning		$ 6,002,915
Balance at period beginning (in shares)		63,683
Net income		$ 147,241
Issuance of common stock under:
General partner's stock based compensation		$ 22,173
General partner's stock based compensation (in shares)		170
Sale of common stock by general partner		$ 307,835
Sale of common stock by general partner (in shares)		1,375
Equity based compensation costs		$ 2,564
Changes in redemption value of redeemable noncontrolling interest		(1,095)
Redemptions		$ (2,199)
Redemptions (in shares)		7
Distributions declared		$ (279,245)
Balance at period end	$ 6,200,189	$ 6,200,189
Balance at period end (in shares)	65,235	65,235
Essex Portfolio, L.P. [Member] | Common Equity [Member] | Limited Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning		$ 48,665
Balance at period beginning (in shares)		2,168
Net income		$ 5,115
Issuance of common stock under:
General partner's stock based compensation		$ 0
General partner's stock based compensation (in shares)		0
Equity based compensation costs		$ 2,947
Equity based compensation costs (in shares)		16
Redemptions		$ 0
Redemptions (in shares)		(7)
Distributions declared		$ (9,934)
Balance at period end	$ 46,793	$ 46,793
Balance at period end (in shares)	2,177	2,177
Essex Portfolio, L.P. [Member] | Preferred Equity [Member] | General Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning		$ 71,209
Net income		3,941
Issuance of common stock under:
Distributions declared		(3,941)
Balance at period end	$ 71,209	71,209
Essex Portfolio, L.P. [Member] | AOCI Attributable to Parent [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning		(49,356)
Change in fair value of derivatives and amortization of swap settlements		1,675
Change in fair value of marketable securities		(543)
Issuance of common stock under:
Balance at period end	(48,224)	(48,224)
Essex Portfolio, L.P. [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning		62,635
Net income		6,180
Issuance of common stock under:
Reclassification of noncontrolling interest to redeemable noncontrolling interest		(144)
Distributions to noncontrolling interest		(6,393)
Redemptions		422
Balance at period end	$ 61,856	$ 61,856