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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic:
Net income available to common stockholders/unitholders	$ 99,335	$ 80,975	$ 310,468	$ 272,333
Weighted average number of shares/common units outstanding during the period (in shares)	65,850,524	66,052,108	65,757,914	66,047,990
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.51	$ 1.23	$ 4.72	$ 4.12
Effect of Dilutive Securities: Stock options (in shares)	122,561	51,704	99,746	45,014
Diluted:
Net income available to common stockholders/unitholders	$ 99,335	$ 80,975	$ 310,468	$ 272,333
Net income available to common stockholders/unitholders, weighted average common shares (in shares)	65,973,085	66,103,812	65,857,660	66,093,004
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.51	$ 1.22	$ 4.71	$ 4.12
Essex Portfolio, L.P. [Member]
Basic:
Net income available to common stockholders/unitholders	$ 102,799	$ 83,764	$ 321,331	$ 281,714
Weighted average number of shares/common units outstanding during the period (in shares)	68,148,913	68,325,091	68,058,802	68,321,153
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.51	$ 1.23	$ 4.72	$ 4.12
Effect of Dilutive Securities: Stock options (in shares)	122,561	51,704	99,746	45,014
Diluted:
Net income available to common stockholders/unitholders	$ 102,799	$ 83,764	$ 321,331	$ 281,714
Net income available to common stockholders/unitholders, weighted average common shares (in shares)	68,271,474	68,376,795	68,158,548	68,366,167
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.51	$ 1.23	$ 4.71	$ 4.12
Convertible Limited Partnership Units [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,298,389	2,272,983	2,300,888	2,273,163
Income allocated to convertible OP Units	$ 3,500	$ 2,800	$ 10,900	$ 9,400
Share-based Payment Arrangement, Option [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	150,852	0	160,252
Share-based Payment Arrangement, Option [Member] | Essex Portfolio, L.P. [Member]
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	150,852	0	160,252