Net Income Per Common Share and Net Income Per Common Unit (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Basic:
Income from continuing operations available to common stockholders									$ 121,324		$ 108,532		$ 30,570
Income from continuing operations available to common stockholders (in shares)									37,248,960		35,032,491		32,541,792
Income from continuing operations available to common stockholders (in dollars per share)									$ 3.26		$ 3.10		$ 0.94
Income from discontinued operations available to common stockholders									29,487		11,280		9,798
Income from discontinued operations available to common stockholders (in shares)									37,248,960		35,032,491		32,541,792
Income from discontinued operations available to common stockholders (in dollars per share)									$ 0.79		$ 0.32		$ 0.30
Income available to common stockholders	31,874	68,788	24,946	25,203	43,793	16,219	37,078	22,722	150,811		119,812		40,368
Income available to common stockholders (in dollars per share)	$ 0.85	$ 1.84	$ 0.67	$ 0.68	$ 1.22	$ 0.46	$ 1.07	$ 0.67	$ 4.05		$ 3.42		$ 1.24
Effect of Dilutive Securities									0	[1]	0	[1]	0	[1]
Effect of Dilutive Securities (in shares)									86,335	[1]	92,430	[1]	86,922	[1]
Diluted:
Income from continuing operations available to common stockholders									121,324	[1]	108,532	[1]	30,570	[1]
Income from continuing operations available to common stockholders (in shares)									37,335,295	[1]	35,124,921	[1]	32,628,714	[1]
Income from continuing operations available to common stockholders (in dollars per share)									$ 3.25	[1]	$ 3.09	[1]	$ 0.94	[1]
Income from discontinued operations available to common stockholders									29,487		11,280		9,798
Income from discontinued operations available to common stockholders (in shares)									37,335,295		35,124,921		32,628,714
Income from discontinued operations available to common stockholders (in dollars per share)									$ 0.79		$ 0.32		$ 0.30
Total income (Diluted)									150,811		119,812		40,368
Total income per common share amount (in dollars per share)	$ 0.85	$ 1.84	$ 0.67	$ 0.68	$ 1.22	$ 0.45	$ 1.07	$ 0.67	$ 4.04		$ 3.41		$ 1.24
Convertible Limited Partnership Units [Member]
Diluted:
Anti-dilutive securities (in shares)									2,131,425		2,219,046		2,231,807
Stock Options [Member]
Diluted:
Anti-dilutive securities (in shares)									168,325		263,613		175,500
Essex Portfolio, L.P. [Member]
Basic:
Income from continuing operations available to common stockholders									128,576		115,834		33,035
Income from continuing operations available to common stockholders (in shares)									39,380,385		37,251,537		34,773,599
Income from continuing operations available to common stockholders (in dollars per share)									$ 3.27		$ 3.11		$ 0.95
Income from discontinued operations available to common stockholders									31,173		11,937		10,558
Income from discontinued operations available to common stockholders (in shares)									39,380,385		37,251,537		34,773,599
Income from discontinued operations available to common stockholders (in dollars per share)									$ 0.79		$ 0.32		$ 0.30
Income available to common stockholders	33,776	72,777	26,493	26,703	46,581	17,296	39,580	24,314	159,749		127,771		43,593
Income available to common stockholders (in dollars per share)	$ 0.87	$ 1.84	$ 0.67	$ 0.68	$ 1.23	$ 0.46	$ 1.08	$ 0.67	$ 4.06		$ 3.43		$ 1.25
Effect of Dilutive Securities									0	[2]	0	[2]	0	[2]
Effect of Dilutive Securities (in shares)									86,335	[2]	92,430	[2]	67,319	[2]
Diluted:
Income from continuing operations available to common stockholders									128,576		115,834		33,035
Income from continuing operations available to common stockholders (in shares)									39,466,720		37,343,967		34,860,521
Income from continuing operations available to common stockholders (in dollars per share)									$ 3.26		$ 3.10		$ 0.95
Income from discontinued operations available to common stockholders									31,173		11,937		10,558
Income from discontinued operations available to common stockholders (in shares)									39,466,720		37,343,967		34,860,521
Income from discontinued operations available to common stockholders (in dollars per share)									$ 0.79		$ 0.32		$ 0.30
Total income (Diluted)									$ 159,749		$ 127,771		$ 43,593
Total income per common share amount (in dollars per share)	$ 0.86	$ 1.84	$ 0.67	$ 0.68	$ 1.23	$ 0.45	$ 1.07	$ 0.67	$ 4.05		$ 3.42		$ 1.25
Essex Portfolio, L.P. [Member] | Convertible Limited Partnership Units [Member]
Diluted:
Anti-dilutive securities (in shares)									168,325		175,500
Essex Portfolio, L.P. [Member] | Stock Options [Member]
Diluted:
Anti-dilutive securities (in shares)									263,613

[1] Weighted average convertible limited partnership units of 2,131,425, 2,219,046, and 2,231,807, which include vested Series Z and Series Z-1 incentive units, for the years ended December 31, 2013, 2012 and 2011, respectively, were not included in the determination of diluted earnings per share calculation because they were 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. Stock options of 168,325; 263,613; and 175,500; for the years ended December 31, 2013, 2012, and 2011, respectively, were not included in the diluted earnings per share calculation because the exercise price of these options were greater than the average market price of the common shares for the years ended and, therefore, were anti-dilutive. All shares of cumulative convertible Series G preferred stock have been excluded from diluted earnings per share for the years ended 2013, 2012, and 2011 respectively, as the effect was anti-dilutive.

[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. Stock options of 168,325; 263,613; and 175,500; for the years ended December 31, 2013, 2012, and 2011, respectively, were not included in the diluted earnings per unit calculation because the exercise price of these units were greater than the average market price of the common units for the years ended and, therefore, were anti-dilutive. All units of cumulative convertible Series G preferred interest have been excluded from diluted earnings per unit for the years ended 2013, 2012, and 2011 respectively, as the effect was anti-dilutive.