Net Income Per Common Share and Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Basic:
Net income available to common stockholders	$ 79,723	$ 65,561	$ 329,446	$ 215,555
Weighted average number of shares/common units outstanding during the period (in shares)	65,994,896	65,507,669	65,759,450	65,455,004
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.21	$ 1.00	$ 5.01	$ 3.29
Diluted:
Income from continuing operations available to common stockholders	$ 79,723	$ 65,561	$ 329,446	$ 215,555
Adjusted income from continuing operations available to common stockholders (in shares)	66,078,283	65,617,551	65,836,965	65,578,661
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.21	$ 1.00	$ 5.00	$ 3.29
Essex Portfolio, L.P. [Member]
Basic:
Net income available to common stockholders	$ 82,444	$ 67,784	$ 340,735	$ 223,012
Weighted average number of shares/common units outstanding during the period (in shares)	68,246,008	67,728,621	68,011,123	67,679,240
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.21	$ 1.00	$ 5.01	$ 3.30
Diluted:
Income from continuing operations available to common stockholders	$ 82,444	$ 67,784	$ 340,735	$ 223,012
Adjusted income from continuing operations available to common stockholders (in shares)	68,329,395	67,838,503	68,088,638	67,802,897
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.21	$ 1.00	$ 5.00	$ 3.29
Employee Stock Option [Member]
Basic:
Income effect of Dilutive Securities	$ 0	$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)	83,387	109,882	77,515	123,657
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	40,900	2,352	76,054
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)	83,387	109,882	77,515	123,657
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	40,900	2,352	76,054
Convertible Limited Partnership Units [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,251,112	2,220,952	2,251,673	2,224,236
Antidilutive securities excluded from computation of earnings per share, value	$ 2,700	$ 2,200	$ 11,300	$ 7,500