Net Income Per Common Share and Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Basic:
Net income available to common stockholders/unitholders	$ 315,006	$ 118,858
Weighted average common shares/units (in shares)	66,043,831	65,702,788
Net income available to common stockholders/unitholders (in dollars per share)	$ 4.77	$ 1.81
Effect of Dilutive Securities:
Stock options (in shares)	57,337	81,081
DownREIT units (in shares)	94,247	0
Diluted:
Net income available to common stockholders/unitholders	$ 315,202	$ 118,858
Weighted average common shares/units (in shares)	66,195,415	65,783,869
Net income available to common stockholders/unitholders (in dollars per share)	$ 4.76	$ 1.81
Essex Portfolio, L.P.
Basic:
Net income available to common stockholders/unitholders	$ 325,992	$ 123,029
Weighted average common shares/units (in shares)	68,344,012	68,007,852
Net income available to common stockholders/unitholders (in dollars per share)	$ 4.77	$ 1.81
Effect of Dilutive Securities:
Stock options (in shares)	57,337	81,081
Diluted:
Net income available to common stockholders/unitholders	$ 326,188	$ 123,029
Weighted average common shares/units (in shares)	68,495,596	68,088,933
Net income available to common stockholders/unitholders (in dollars per share)	$ 4.76	$ 1.81
Convertible units
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,300,181	2,305,064
Income allocated to convertible OP Units	$ 11,000	$ 4,200
Stock options
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	116,380	106,029
Stock options | Essex Portfolio, L.P.
Diluted:
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	116,380	106,029
Subsidiaries | DownREIT Units
Effect of Dilutive Securities:
Income effect of Dilutive Securities	$ 196	$ 0