Net Income Per Common Share and Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Basic [Abstract]
Income from discontinued operations available to common stockholders	$ 72,013	$ 45,555	$ 149,994	$ 104,918
Weighted average number of shares outstanding during the period (in shares)	65,451,110	64,810,184	65,428,382	64,499,545
Net income available to common stockholders (in dollars per share)	$ 1.10	$ 0.70	$ 2.29	$ 1.63
Effect of dilutive securities	$ 0	$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)	124,268	162,668	130,429	177,976
Diluted [Abstract]
Income from continuing operations available to common stockholders	$ 72,013	$ 45,555	$ 149,994	$ 104,918
Adjusted income from continuing operations available to common stockholders (in shares)	65,575,378	64,972,852	65,558,811	64,677,521
Net income available to common stockholders (in dollars per share)	$ 1.10	$ 0.70	$ 2.29	$ 1.62
Essex Portfolio, L.P. [Member]
Basic [Abstract]
Income from discontinued operations available to common stockholders	$ 74,463	$ 47,088	$ 155,228	$ 108,514
Weighted average number of shares outstanding during the period (in shares)	67,675,038	66,992,209	67,654,279	66,682,708
Net income available to common stockholders (in dollars per share)	$ 1.10	$ 0.70	$ 2.29	$ 1.63
Effect of dilutive securities	$ 0	$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)	124,268	162,668	130,429	177,976
Diluted [Abstract]
Income from continuing operations available to common stockholders	$ 74,463	$ 47,088	$ 155,228	$ 108,514
Adjusted income from continuing operations available to common stockholders (in shares)	67,799,306	67,154,877	67,784,708	66,860,684
Net income available to common stockholders (in dollars per share)	$ 1.10	$ 0.70	$ 2.29	$ 1.62
Convertible Limited Partnership Units [Member]
Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	2,223,928	2,182,025	2,225,897	2,183,163
Antidilutive securities excluded from computation of earnings per share, value	$ 2,400	$ 1,600	$ 5,200	$ 3,600
DownREIT Units [Member] [Member]
Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	953,006
DownREIT Units [Member] [Member] | Essex Portfolio, L.P. [Member]
Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	953,006
Employee Stock Option [Member]
Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	87,954	24,500	87,954	36,956
Employee Stock Option [Member] | Essex Portfolio, L.P. [Member]
Diluted [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount	87,954	24,500	87,954	36,956