Net Income Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic [Abstract]
Income from discontinued operations available to common stockholders	$ 42,323	$ 53,566	$ 147,241	$ 76,685
Weighted average number of shares outstanding during the period (in shares)	65,138,868	62,892,601	64,714,994	54,250,104
Net income available to common stockholders (in dollars per share)	$ 0.65	$ 0.85	$ 2.28	$ 1.41
Effect of dilutive securities	$ 0	$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)	158,682	177,171	177,776	193,123
Diluted [Abstract]
Income from continuing operations available to common stockholders	$ 42,323	$ 53,566	$ 147,241	$ 76,685
Adjusted income from continuing operations available to common stockholders (in shares)	65,297,550	63,069,772	64,892,770	54,443,227
Net income available to common stockholders (in dollars per share)	$ 0.65	$ 0.85	$ 2.27	$ 1.41
Essex Portfolio, L.P. [Member]
Basic [Abstract]
Income from discontinued operations available to common stockholders	$ 43,794	$ 55,382	$ 152,356	$ 80,127
Weighted average number of shares outstanding during the period (in shares)	67,316,498	65,057,157	66,896,293	56,484,589
Net income available to common stockholders (in dollars per share)	$ 0.65	$ 0.85	$ 2.28	$ 1.42
Effect of dilutive securities	$ 0	$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)	158,682	177,171	177,776	193,123
Diluted [Abstract]
Income from continuing operations available to common stockholders	$ 43,794	$ 55,382	$ 152,356	$ 80,127
Adjusted income from continuing operations available to common stockholders (in shares)	67,475,180	65,234,328	67,074,069	56,677,712
Net income available to common stockholders (in dollars per share)	$ 0.65	$ 0.85	$ 2.27	$ 1.41
Convertible Limited Partnership Units [Member]
Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	2,177,630	2,164,556	2,181,299	2,234,485
Antidilutive securities excluded from computation of earnings per share, value	$ 1,500	$ 1,800	$ 5,100	$ 3,400
Convertible Limited Partnership Units [Member] | Essex Portfolio, L.P. [Member]
Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	902,668		902,668	902,668
Employee Stock Option [Member]
Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	24,500	8,343	24,500	42,518
Employee Stock Option [Member] | Essex Portfolio, L.P. [Member]
Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	24,500	8,343	24,500	42,518