Net Income Per Common Share and Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic:
Net income available to common stockholders	$ 568,870	$ 439,286	$ 390,153
Income from continuing operations available to common stockholders (in shares)	65,454,057	65,840,422	66,041,058
Net income available to common stockholders/unitholders (in dollars per share)	$ 8.69	$ 6.67	$ 5.91
Diluted:
Net income available to common stockholders	$ 569,653	$ 439,286	$ 390,153
Income from continuing operations available to common stockholders (in shares)	65,564,982	65,939,455	66,085,089
Net income available to common stockholders/unitholders (in dollars per share)	$ 8.69	$ 6.66	$ 5.90
Stock Options
Basic:
Income effect of dilutive securities	$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)	16,678	99,033	44,031
Convertible Limited Partnership Units
Diluted:
Anti-dilutive securities (in shares)	2,296,608	2,300,478	2,274,941
Antidilutive securities excluded from computation of earnings per share	$ 20,000	$ 15,300	$ 13,500
DownREIT units
Basic:
Income effect of dilutive securities	$ 783	$ 0	$ 0
Effect of dilutive securities (in shares)	94,247	0	0
Essex Portfolio, L.P.
Basic:
Net income available to common stockholders	$ 588,782	$ 454,629	$ 403,605
Income from continuing operations available to common stockholders (in shares)	67,750,665	68,140,900	68,315,999
Net income available to common stockholders/unitholders (in dollars per share)	$ 8.69	$ 6.67	$ 5.91
Diluted:
Net income available to common stockholders	$ 589,565	$ 454,629	$ 403,605
Income from continuing operations available to common stockholders (in shares)	67,861,590	68,239,933	68,360,030
Net income available to common stockholders/unitholders (in dollars per share)	$ 8.69	$ 6.66	$ 5.90
Essex Portfolio, L.P. | Stock Options
Basic:
Income effect of dilutive securities	$ 0	$ 0	$ 0
Effect of dilutive securities (in shares)	16,678	99,033	44,031
Diluted:
Anti-dilutive securities (in shares)	403,458	115,066	160,039
Essex Portfolio, L.P. | DownREIT units
Basic:
Income effect of dilutive securities	$ 783	$ 0	$ 0
Effect of dilutive securities (in shares)	94,247	0	0