Condensed Consolidated Statement of Capital - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Partners' Capital [Roll Forward]
Net income	$ 96,639
Reversal of unrealized gains upon the sale of marketable debt securities	(1)
Change in fair value of derivatives and amortization of swap settlements	6,254
Change in fair value of marketable debt securities, net	(77)
Issuance of common stock under:
Sale of common stock by general partner, net	(67)
Retirement of common units, net	(3,774)
Changes in the redemption value of redeemable noncontrolling interest	(1,953)
Distributions to noncontrolling interest	(6,297)
ASU 2016-01 [Member]
Issuance of common stock under:
Cumulative effect upon adoption		$ 0
ASU 2017-05 [Member]
Issuance of common stock under:
Cumulative effect upon adoption		123,708
Essex Portfolio, L.P. [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning	6,396,825
Net income	96,639
Reversal of unrealized gains upon the sale of marketable debt securities	(1)
Change in fair value of derivatives and amortization of swap settlements	6,254
Change in fair value of marketable debt securities, net	(77)
Issuance of common stock under:
General partner's stock based compensation, net	1,222
Sale of common stock by general partner, net	(67)
Equity based compensation costs	2,530
Retirement of common units, net	(3,774)
Changes in the redemption value of redeemable noncontrolling interest	(1,953)
Distributions to noncontrolling interest	(2,044)
Distributions declared	(127,103)
Balance at period end	6,492,159
Essex Portfolio, L.P. [Member] | ASU 2016-01 [Member]
Issuance of common stock under:
Cumulative effect upon adoption		0
Essex Portfolio, L.P. [Member] | ASU 2017-05 [Member]
Issuance of common stock under:
Cumulative effect upon adoption		123,708
Essex Portfolio, L.P. [Member] | Common Equity [Member] | General Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning	$ 6,295,852
Balance at period beginning (in units)	66,054
Net income	$ 90,918
Issuance of common stock under:
General partner's stock based compensation, net	$ 1,222
General partner's stock based compensation, net (in units)	7
Sale of common stock by general partner, net	$ (67)
Sale of common stock by general partner, net (in units)	0
Equity based compensation costs	$ 2,253
Retirement of common units, net	$ (3,774)
Retirement of common units, net (in shares)	(17)
Changes in the redemption value of redeemable noncontrolling interest	$ (1,957)
Distributions declared	(122,850)
Balance at period end	$ 6,383,482
Balance at period end (in units)	66,044
Essex Portfolio, L.P. [Member] | Common Equity [Member] | General Partner [Member] | ASU 2016-01 [Member]
Issuance of common stock under:
Cumulative effect upon adoption		2,234
Essex Portfolio, L.P. [Member] | Common Equity [Member] | General Partner [Member] | ASU 2017-05 [Member]
Issuance of common stock under:
Cumulative effect upon adoption		119,651
Essex Portfolio, L.P. [Member] | Common Equity [Member] | Limited Partner [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning	$ 49,792
Balance at period beginning (in units)	2,268
Net income	$ 3,132
Issuance of common stock under:
Equity based compensation costs	$ 277
Equity based compensation costs (in units)	5
Changes in the redemption value of redeemable noncontrolling interest	$ 4
Distributions declared	(4,253)
Balance at period end	$ 53,003
Balance at period end (in units)	2,273
Essex Portfolio, L.P. [Member] | Common Equity [Member] | Limited Partner [Member] | ASU 2016-01 [Member]
Issuance of common stock under:
Cumulative effect upon adoption		(6)
Essex Portfolio, L.P. [Member] | Common Equity [Member] | Limited Partner [Member] | ASU 2017-05 [Member]
Issuance of common stock under:
Cumulative effect upon adoption		4,057
Essex Portfolio, L.P. [Member] | Accumulated Other Comprehensive Loss [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning	$ (15,229)
Reversal of unrealized gains upon the sale of marketable debt securities	(1)
Change in fair value of derivatives and amortization of swap settlements	6,254
Change in fair value of marketable debt securities, net	(77)
Issuance of common stock under:
Cumulative effect upon adoption		(2,228)
Balance at period end	(11,281)
Essex Portfolio, L.P. [Member] | Accumulated Other Comprehensive Loss [Member] | ASU 2016-01 [Member]
Issuance of common stock under:
Cumulative effect upon adoption		$ (2,228)
Essex Portfolio, L.P. [Member] | Noncontrolling Interest [Member]
Increase (Decrease) in Partners' Capital [Roll Forward]
Balance at period beginning	66,410
Net income	2,589
Issuance of common stock under:
Changes in the redemption value of redeemable noncontrolling interest	0
Distributions to noncontrolling interest	(2,044)
Balance at period end	$ 66,955