Consolidated Statements of Capital (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Net income	$ 44,805	$ 26,406	$ 36,903	$ 29,702	$ 134,438		$ 172,055		$ 139,590
Reversal of unrealized gains upon the sale of marketable securities					(886)		(1,767)		(1,082)
Changes in fair value of cash flow hedges and amortization of gain on settlement of swap					4,168		12,614		3,402
Changes in fair value of marketable securities					6,302		(1,556)		1,411
Issuance of common stock under:
Sale of common stock					532,670		138,366		357,720
Reclassification Of Noncontrolling Interest To Redeemable Noncontrolling Interest					20,890
Changes in the redemption value of redeemable noncontrolling interest					312
Conversion of Series G preferred stock					4,349
Contributions from noncontrolling interest					1,419,816	[1]	0	[1]	0	[1]
Retirement of noncontrolling interest					(1,419,816)	[1]	0	[1]	0	[1]
Distributions to noncontrolling interests					17,069		(18,488)		(16,691)
Essex Portfolio, L.P. [Member]
Balances		1,998,238		1,880,116	1,998,238		1,880,116		1,553,728
Net income	44,805	26,406	36,903	29,702	134,438		172,055		139,590
Reversal of unrealized gains upon the sale of marketable securities					(886)		(1,767)		(1,082)
Changes in fair value of cash flow hedges and amortization of gain on settlement of swap					4,168		12,614		3,402
Changes in fair value of marketable securities					6,302		(1,556)		1,411
Stock Issued During Period, Value, Acquisitions					3,774,087
Issuance of common stock under:
Stock and unit based compensation plans					11,024		7,244		4,675
Sale of common stock					532,670		138,366		357,720
Stock and unit based compensation costs					11,872		1,608		1,801
Reclassification Of Noncontrolling Interest To Redeemable Noncontrolling Interest					(20,890)
Changes in the redemption value of redeemable noncontrolling interest					312
Conversion of Series G preferred stock					4,349
Contributions from noncontrolling interest					1,419,816	[1]	0	[1]	0	[1]
Retirement of noncontrolling interest					(1,419,816)	[1]	0	[1]	0	[1]
Capital contributions									4,232
Redemptions					(5,497)		(5,711)		(6,986)
Distributions to noncontrolling interests					(4,890)		(8,016)		(6,957)
Distributions declared					(309,229)		(196,715)		(171,418)
Balances	6,136,068		1,998,238		6,136,068		1,998,238		1,880,116
Essex Portfolio, L.P. [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Balances		(58,940)		(68,231)	(58,940)		(68,231)		(71,962)
Reversal of unrealized gains upon the sale of marketable securities					(886)		(1,767)		(1,082)
Changes in fair value of cash flow hedges and amortization of gain on settlement of swap					4,168		12,614		3,402
Changes in fair value of marketable securities					6,302		(1,556)		1,411
Issuance of common stock under:
Balances	(49,356)		(58,940)		(49,356)		(58,940)		(68,231)
Essex Portfolio, L.P. [Member] | Noncontrolling Interest [Member]
Balances		66,130		68,689	66,130		68,689		66,814
Net income					7,421		6,834		6,347
Issuance of common stock under:
Reclassification Of Noncontrolling Interest To Redeemable Noncontrolling Interest					(5,084)
Capital contributions									4,232
Redemptions					(942)		(1,377)		(1,747)
Distributions to noncontrolling interests					(4,890)		(8,016)		(6,957)
Balances	62,635		66,130		62,635		66,130		68,689
Essex Portfolio, L.P. [Member] | General Partner [Member] | Common Equity [Member]
Balances		1,873,882		1,762,856	1,873,882		1,762,856		1,439,089
Balances (in shares)		37,421,000		36,443,000	37,421,000		36,443,000		33,888,000
Net income					116,859		150,811		119,812
Stock Issued During Period, Shares, Acquisitions					23,067,000
Stock Issued During Period, Value, Acquisitions					3,774,087
Issuance of common stock under:
Stock and unit based compensation plans					11,024		7,244		4,675
Stock and unit based compensation plan (in shares)					218,000		65,000		151,000
Sale of common stock					532,670		138,366		357,720
Sale of common stock (in shares)					2,943,000		913,000		2,404,000
Stock and unit based compensation costs					5,719		(907)		(430)
Reclassification Of Noncontrolling Interest To Redeemable Noncontrolling Interest					(19,823)
Changes in the redemption value of redeemable noncontrolling interest					312
Conversion of Series G preferred stock					4,349
Stock Issued During Period, Shares, Conversion of Convertible Securities					34,000
Redemptions					(3,374)		(3,717)		(1,798)
Distributions to noncontrolling interests					0
Distributions declared					(292,790)		(180,771)		(156,212)
Balances	6,002,915		1,873,882		6,002,915		1,873,882		1,762,856
Balances (in shares)	63,683,000		37,421,000		63,683,000		37,421,000		36,443,000
Essex Portfolio, L.P. [Member] | General Partner [Member] | Preferred Equity [Member]
Balances		71,209		71,209	71,209		71,209		71,209
Net income					5,291		5,472		5,472
Issuance of common stock under:
Distributions declared					(5,291)		(5,472)		(5,472)
Balances	71,209		71,209		71,209		71,209		71,209
Essex Portfolio, L.P. [Member] | Limited Partner [Member] | Common Equity [Member]
Balances		45,957		45,593	45,957		45,593		48,578
Balances (in shares)		2,150,000		2,122,000	2,150,000		2,122,000		2,229,000
Net income					4,867		8,938		7,959
Issuance of common stock under:
Stock and unit based compensation costs					6,153		2,515		2,231
Stock and unit based compensation costs (in shares)					(62,000)		28,000		107,000
Reclassification Of Noncontrolling Interest To Redeemable Noncontrolling Interest					4,017
Reclassification Of Noncontrolling Interest To Redeemable Noncontrolling Interest In Units					(10,000)
Contributions from noncontrolling interest					1,419,816
Noncontrolling Interest, Increase From Non-cash Transaction, Shares					8,561,000
Retirement of noncontrolling interest					(1,419,816)
Treasury Stock, Shares, Retired					(8,561,000)
Redemptions					(1,181)		(617)		(3,441)
Distributions to noncontrolling interests					0
Distributions declared					(11,148)		(10,472)		(9,734)
Balances	48,665		45,957		48,665		45,957		45,593
Balances (in shares)	2,202,000		2,150,000		2,202,000		2,150,000		2,122,000
Essex Portfolio, L.P. [Member] | Limited Partner [Member] | Preferred Equity [Member]
Balances									0
Net income									0
Issuance of common stock under:
Distributions declared									0
Balances	$ 0		$ 0		$ 0		$ 0		$ 0

[1] See note 2(r) for details of noncash investing and financing activities related to the BRE merger.