Net Income Per Common Share and Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Basic:
Net income available to common stockholders	$ 178,964	$ 77,981
Weighted average number of shares outstanding during the period (in shares)	65,549,484	65,405,654
Net income available to common stockholders (in dollars per share)	$ 2.73	$ 1.19
Diluted:
Income from continuing operations available to common stockholders	$ 179,337	$ 77,981
Adjusted income from continuing operations available to common stockholders (in shares)	65,859,490	65,557,639
Net income available to common stockholders (in dollars per share)	$ 2.72	$ 1.19
Essex Portfolio, L.P. [Member]
Basic:
Net income available to common stockholders	$ 185,110	$ 80,765
Weighted average number of shares outstanding during the period (in shares)	67,801,718	67,633,519
Net income available to common stockholders (in dollars per share)	$ 2.73	$ 1.19
Diluted:
Income from continuing operations available to common stockholders	$ 185,483	$ 80,765
Adjusted income from continuing operations available to common stockholders (in shares)	68,111,724	67,785,504
Net income available to common stockholders (in dollars per share)	$ 2.72	$ 1.19
Convertible Limited Partnership Units [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,252,234	2,227,865
Antidilutive securities excluded from computation of earnings per share, value	$ 6,100	$ 2,800
Employee Stock Option [Member]
Basic:
Income effect of Dilutive Securities	$ 0	$ 0
Effect of dilutive securities (in shares)	96,778	151,985
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	225,895	77,200
Employee Stock Option [Member] | Essex Portfolio, L.P. [Member]
Basic:
Income effect of Dilutive Securities	$ 0	$ 0
Effect of dilutive securities (in shares)	96,778	151,985
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	225,895	77,200
DownREIT Units [Member]
Basic:
Income effect of Dilutive Securities	$ 373	$ 0
Effect of dilutive securities (in shares)	213,228	0
DownREIT Units [Member] | Essex Portfolio, L.P. [Member]
Basic:
Income effect of Dilutive Securities	$ 373	$ 0
Effect of dilutive securities (in shares)	213,228	0