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, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Basic:
Net income available to common stockholders/unitholders	$ 118,390	$ 73,661	$ 351,680	$ 473,125
Weighted average common shares/units (in shares)	65,048,486	65,232,837	65,013,477	65,561,820
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.82	$ 1.13	$ 5.41	$ 7.22
Effect of Dilutive Securities:
Stock options (in shares)	99,295	8,591	61,697	20,026
DownREIT units (in shares)			0	94,247
Diluted:
Net income available to common stockholders/unitholders	$ 118,390	$ 73,661	$ 351,680	$ 473,712
Weighted average common shares/units (in shares)	65,147,781	65,241,428	65,075,174	65,676,093
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.82	$ 1.13	$ 5.40	$ 7.21
Essex Portfolio, L.P.
Basic:
Net income available to common stockholders/unitholders	$ 122,558	$ 76,254	$ 364,083	$ 489,668
Weighted average common shares/units (in shares)	67,336,164	67,528,346	67,307,259	67,858,961
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.82	$ 1.13	$ 5.41	$ 7.22
Effect of Dilutive Securities:
Stock options (in shares)	99,295	8,591	61,697	20,026
DownREIT units (in shares)			0	94,247
Diluted:
Net income available to common stockholders/unitholders	$ 122,558	$ 76,254	$ 364,083	$ 490,255
Weighted average common shares/units (in shares)	67,435,459	67,536,937	67,368,956	67,973,234
Net income available to common stockholders/unitholders (in dollars per share)	$ 1.82	$ 1.13	$ 5.40	$ 7.21
DownREIT Units
Effect of Dilutive Securities:
Income effect of Dilutive Securities			$ 0	$ 587
DownREIT Units | Essex Portfolio, L.P.
Effect of Dilutive Securities:
Income effect of Dilutive Securities			$ 0	$ 587
Convertible units
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,287,678	2,295,510	2,291,725	2,297,141
Income allocated to convertible OP Units	$ 4,200	$ 2,600	$ 12,400	$ 16,500
Stock options
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	493,567	116,380	299,046
Stock options | Essex Portfolio, L.P.
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	0	493,567	116,380	299,046