Net Income Per Common Share (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Basic [Abstract]
Income from continuing operations available to common stockholders	$ 53,668,000		$ 56,347,000		$ 76,364,000		$ 105,421,000
Income from continuing operations available to common stockholders (in shares)	62,892,601		37,320,562		54,250,104		37,206,895
Income from continuing operations available to common stockholders (in dollars per share)	$ 0.85		$ 1.51		$ 1.41		$ 2.84
Income from discontinued operations available to common stockholders	0		12,441,000		0		13,516,000
Income from discontinued operations available to common stockholders (in shares)	62,893,000		37,321,000		54,250,000		37,207,000
Income from discontinued operations available to common stockholders (in dollars per share)	$ 0		$ 0.33		$ 0		$ 0.36
Income available to common stockholders	53,668,000		68,788,000		76,364,000		118,937,000
Income available to common stockholders (in dollars per share)	$ 0.85		$ 1.84		$ 1.41		$ 3.20
Effect of dilutive securities	0	[1]	54,000	[1]	0	[1]	0	[1]
Effect of dilutive securities (in shares)	177,000	[1]	116,000	[1]	193,000	[1]	89,000	[1]
Diluted [Abstract]
Income from continuing operations available to common stockholders	53,668,000		56,347,000		76,364,000	[1]	105,421,000	[1]
Adjusted income from continuing operations available to common stockholders (in shares)	63,070,000		37,437,000		54,443,000	[1]	37,296,000	[1]
Adjusted income from continuing operations available to common stockholders (in dollars per share)	$ 0.85		$ 1.51		$ 1.40	[1]	$ 2.83	[1]
Adjusted income from discontinued operations available to common stockholders	0		12,441,000		0		13,516,000
Adjusted income from discontinued operations available to common stockholders (in shares)	63,070,000		37,437,000		54,443,000		37,296,000
Adjusted income from discontinued operations available to common stockholders (in dollars per share)	$ 0		$ 0.33		$ 0		$ 0.36
Total income (Diluted)	53,668,000		68,842,000		76,364,000		118,937,000
Total income per common share amount (in dollars per share)	$ 0.85		$ 1.84		$ 1.40		$ 3.19
Convertible Limited Partnership Units [Member]
Diluted [Abstract]
Anti-dilutive securities (in shares)	2,572,111		2,146,929
Net income (loss) allocated to Limited Partners	1,800,000		4,000,000		3,400,000		7,000,000
Stock Options [Member]
Diluted [Abstract]
Anti-dilutive securities (in shares)	8,343		38,825		42,518		38,825
Essex Portfolio, L.P. [Member]
Basic [Abstract]
Income from continuing operations available to common stockholders	55,484,000		59,620,000		79,806,000		111,685,000
Income from continuing operations available to common stockholders (in shares)	65,057,157		39,467,492		56,484,589		39,333,100
Income from continuing operations available to common stockholders (in dollars per share)	$ 0.85		$ 1.51		$ 1.41		$ 2.84
Income from discontinued operations available to common stockholders	0		13,157,000		0		14,289,000
Income from discontinued operations available to common stockholders (in shares)	65,057,000		39,467,000		56,485,000		39,333,000
Income from discontinued operations available to common stockholders (in dollars per share)	$ 0		$ 0.33		$ 0		$ 0.36
Income available to common stockholders	55,484,000		72,777,000		79,806,000		125,974,000
Income available to common stockholders (in dollars per share)	$ 0.85		$ 1.84		$ 1.41		$ 3.20
Effect of dilutive securities	0	[2]	54,000	[2]	0	[2]	0	[2]
Effect of dilutive securities (in shares)	177,000	[2]	116,000	[2]	193,000	[2]	89,000	[2]
Diluted [Abstract]
Income from continuing operations available to common stockholders	55,484,000	[2]	59,674,000	[2]	79,806,000	[2]	111,685,000	[2]
Adjusted income from continuing operations available to common stockholders (in shares)	65,234,000	[2]	39,583,000	[2]	56,678,000	[2]	39,422,000	[2]
Adjusted income from continuing operations available to common stockholders (in dollars per share)	$ 0.85	[2]	$ 1.51	[2]	$ 1.41	[2]	$ 2.84	[2]
Adjusted income from discontinued operations available to common stockholders	0		13,157,000		0		14,289,000
Adjusted income from discontinued operations available to common stockholders (in shares)	65,234,000		39,583,000		56,678,000		39,422,000
Adjusted income from discontinued operations available to common stockholders (in dollars per share)	$ 0		$ 0.33		$ 0		$ 0.36
Total income (Diluted)	$ 55,484,000		$ 72,831,000		$ 79,806,000		$ 125,974,000
Total income per common share amount (in dollars per share)	$ 0.85		$ 1.84		$ 1.41		$ 3.20
Essex Portfolio, L.P. [Member] | Stock Options [Member]
Diluted [Abstract]
Anti-dilutive securities (in shares)	8,343		38,825		42,518		38,825

[1] Weighted average convertible limited partnership units of 2,164,556 and 2,146,929 which include vested Series Z-1 incentive units, for the three months ended September 30, 2014, and 2013, respectively, were not included in the determination of diluted EPS because they were anti-dilutive. Income allocated to convertible limited partnership units, which includes vested Series Z-1 units, aggregating $1.8 million and $4.0 million for the three months ended September 30, 2014 and 2013, respectively, and $3.4 million and $7.0 million for the nine months ended September 30, 2014 and 2013, respectively have been excluded from income available to common stockholders for the calculation of diluted income per common share since these units are excluded from the diluted weighted average common shares for the period as the effect was anti-dilutive. The Company has the ability to redeem DownREIT limited partnership units for cash and does not consider them to be potentially dilutive securities.

[2] The Operating Partnership has the ability to redeem DownREIT limited partnership units for cash and does not consider them to be potentially dilutive securities.