Net Income Per Common Share and Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Basic:
Net income available to common stockholders/unitholders	$ 118,858	$ 90,918
Weighted average number of shares/common units outstanding during the period (in shares)	65,702,788	66,044,022
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.81	$ 1.38
Diluted:
Net income available to common stockholders/unitholders	$ 118,858	$ 90,918
Net income available to common stockholders/unitholders, weighted average common shares (in shares)	65,783,869	66,082,517
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.81	$ 1.38
Essex Portfolio, L.P. [Member]
Basic:
Net income available to common stockholders/unitholders	$ 123,029	$ 94,050
Weighted average number of shares/common units outstanding during the period (in shares)	68,007,852	68,317,435
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.81	$ 1.38
Diluted:
Net income available to common stockholders/unitholders	$ 123,029	$ 94,050
Net income available to common stockholders/unitholders, weighted average common shares (in shares)	68,088,933	68,355,930
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.81	$ 1.38
Employee Stock Option [Member]
Basic:
Income effect of Dilutive Securities	$ 0	$ 0
Effect of dilutive securities (in shares)	81,081	38,495
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	106,029	364,068
Employee Stock Option [Member] | Essex Portfolio, L.P. [Member]
Basic:
Income effect of Dilutive Securities	$ 0	$ 0
Effect of dilutive securities (in shares)	81,081	38,495
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	106,029	364,068
Convertible Limited Partnership Units [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,305,064	2,273,413
Antidilutive securities excluded from computation of earnings per share, value	$ 4,200	$ 3,100