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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Basic:
Net income available to common stockholders	$ 70,759	$ 72,013	$ 249,723	$ 149,994
Weighted average number of shares outstanding during the period (in shares)	65,729,074	65,451,110	65,639,775	65,428,382
Net income available to common stockholders (in dollars per share)	$ 1.08	$ 1.10	$ 3.80	$ 2.29
Diluted:
Income from continuing operations available to common stockholders	$ 70,759	$ 72,013	$ 250,461	$ 149,994
Adjusted income from continuing operations available to common stockholders (in shares)	65,819,694	65,575,378	65,942,018	65,558,811
Net income available to common stockholders (in dollars per share)	$ 1.08	$ 1.10	$ 3.80	$ 2.29
Essex Portfolio, L.P. [Member]
Basic:
Net income available to common stockholders	$ 73,181	$ 74,463	$ 258,291	$ 155,228
Weighted average number of shares outstanding during the period (in shares)	67,980,761	67,675,038	67,891,734	67,654,279
Net income available to common stockholders (in dollars per share)	$ 1.08	$ 1.10	$ 3.80	$ 2.29
Diluted:
Income from continuing operations available to common stockholders	$ 73,181	$ 74,463	$ 259,029	$ 155,228
Adjusted income from continuing operations available to common stockholders (in shares)	68,071,381	67,799,306	68,193,977	67,784,708
Net income available to common stockholders (in dollars per share)	$ 1.08	$ 1.10	$ 3.80	$ 2.29
Employee Stock Option [Member]
Basic:
Income effect of Dilutive Securities	$ 0	$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)	90,620	124,268	91,515	130,429
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	8,240	87,954	23,619	87,954
Employee Stock Option [Member] | Essex Portfolio, L.P. [Member]
Basic:
Income effect of Dilutive Securities	$ 0	$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)	90,620	124,268	91,515	130,429
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	8,240	87,954	23,619	87,954
DownREIT Units [Member]
Basic:
Income effect of Dilutive Securities			$ 738	$ 0
Effect of dilutive securities (in shares)			210,728	0
DownREIT Units [Member] | Essex Portfolio, L.P. [Member]
Basic:
Income effect of Dilutive Securities			$ 738	$ 0
Effect of dilutive securities (in shares)			210,728	0
Convertible Limited Partnership Units [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,251,687	2,223,928	2,251,959	2,225,897
Antidilutive securities excluded from computation of earnings per share, value	$ 2,500	$ 2,400	$ 8,600	$ 5,200