Net Income Per Common Share and Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic:
Net income available to common stockholders									$ 439,286	$ 390,153	$ 433,059
Income from continuing operations available to common stockholders (in shares)									65,840,422	66,041,058	65,829,155
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.95	$ 1.51	$ 1.40	$ 1.81	$ 1.78	$ 1.23	$ 1.52	$ 1.38	$ 6.67	$ 5.91	$ 6.58
Diluted:
Net income available to common stockholders									$ 439,286	$ 390,153	$ 433,059
Income from continuing operations available to common stockholders (in shares)									65,939,455	66,085,089	65,898,255
Net income available to common stockholders/unitholders (in dollars per share)	1.95	1.51	1.40	1.81	1.78	1.22	1.52	1.38	$ 6.66	$ 5.90	$ 6.57
Stock Options
Basic:
Effect of Dilutive Securities									$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)									99,033	44,031	69,100
Convertible Limited Partnership Units
Diluted:
Anti-dilutive securities (in shares)									2,300,478	2,274,941	2,252,575
Antidilutive securities excluded from computation of earnings per share									$ 15,300	$ 13,500	$ 14,800
Essex Portfolio, L.P.
Basic:
Net income available to common stockholders									$ 454,629	$ 403,605	$ 447,884
Income from continuing operations available to common stockholders (in shares)									68,140,900	68,315,999	68,081,730
Net income available to common stockholders/unitholders (in dollars per share)	1.95	1.51	1.40	1.81	1.78	1.23	1.52	1.38	$ 6.67	$ 5.91	$ 6.58
Diluted:
Net income available to common stockholders									$ 454,629	$ 403,605	$ 447,884
Income from continuing operations available to common stockholders (in shares)									68,239,933	68,360,030	68,150,830
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.95	$ 1.51	$ 1.40	$ 1.81	$ 1.78	$ 1.23	$ 1.52	$ 1.38	$ 6.66	$ 5.90	$ 6.57
Essex Portfolio, L.P. | Stock Options
Basic:
Effect of Dilutive Securities									$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)									99,033	44,031	69,100
Diluted:
Anti-dilutive securities (in shares)									115,066	160,039	154,793