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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic:
Net income available to common stockholders									$ 390,153	$ 433,059	$ 411,124
Income from continuing operations available to common stockholders (in shares)									66,041,058	65,829,155	65,471,540
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.78	$ 1.23	$ 1.52	$ 1.38	$ 1.57	$ 1.21	$ 1.08	$ 2.73	$ 5.91	$ 6.58	$ 6.28
Diluted:
Income from continuing operations available to common stockholders									$ 390,153	$ 433,059	$ 411,124
Income from continuing operations available to common stockholders (in shares)									66,085,089	65,898,255	65,587,816
Net income available to common stockholders/unitholders (in dollars per share)	1.78	1.22	1.52	1.38	1.57	1.21	1.08	2.72	$ 5.90	$ 6.57	$ 6.27
Stock Options [Member]
Basic:
Effect of Dilutive Securities									$ 0	$ 0	$ 0
Effect of Dilutive Securities (in shares)									44,031	69,100	116,276
Convertible Limited Partnership Units [Member]
Diluted:
Anti-dilutive securities (in shares)									2,274,941	2,252,575	2,224,100
Antidilutive securities excluded from computation of earnings per share									$ 13,500	$ 14,800	$ 14,100
Essex Portfolio, L.P. [Member]
Basic:
Net income available to common stockholders									$ 403,605	$ 447,884	$ 425,213
Income from continuing operations available to common stockholders (in shares)									68,315,999	68,081,730	67,695,640
Net income available to common stockholders/unitholders (in dollars per share)	1.78	1.23	1.52	1.38	1.57	1.21	1.08	2.73	$ 5.91	$ 6.58	$ 6.28
Diluted:
Income from continuing operations available to common stockholders									$ 403,605	$ 447,884	$ 425,213
Income from continuing operations available to common stockholders (in shares)									68,360,030	68,150,830	67,811,916
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.78	$ 1.23	$ 1.52	$ 1.38	$ 1.57	$ 1.21	$ 1.08	$ 2.72	$ 5.90	$ 6.57	$ 6.27
Essex Portfolio, L.P. [Member] | Stock Options [Member]
Basic:
Effect of Dilutive Securities									$ 0	$ 0	$ 0
Effect of Dilutive Securities (in shares)									44,031	69,100	116,276
Diluted:
Anti-dilutive securities (in shares)									160,039	154,793	252,334