Net Income Per Common Share and Net Income Per Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic:
Net income available to common stockholders	$ 433,059	$ 411,124	$ 226,865
Income from continuing operations available to common stockholders (in shares)	65,829,155	65,471,540	64,871,717
Income from continuing operations available to common stockholders (in dollars per share)	$ 6.58	$ 6.28	$ 3.50
Diluted:
Income from continuing operations available to common stockholders	$ 433,059	$ 411,124	$ 226,865
Income from continuing operations available to common stockholders (in shares)	65,898,255	65,587,816	65,061,685
Income from continuing operations available to common stockholders (in dollars per share)	$ 6.57	$ 6.27	$ 3.49
Convertible Limited Partnership Units [Member]
Diluted:
Anti-dilutive securities (in shares)	2,252,575	2,224,100	2,182,467
Antidilutive securities excluded from computation of earnings per share	$ 14,800	$ 14,100	$ 7,800
Stock Options [Member]
Basic:
Effect of Dilutive Securities	$ 0	$ 0	$ 0
Effect of Dilutive Securities (in shares)	69,100	116,276	189,968
Essex Portfolio, L.P. [Member]
Basic:
Net income available to common stockholders	$ 447,884	$ 425,213	$ 234,689
Income from continuing operations available to common stockholders (in shares)	68,081,730	67,695,640	67,054,184
Income from continuing operations available to common stockholders (in dollars per share)	$ 6.58	$ 6.28	$ 3.50
Diluted:
Income from continuing operations available to common stockholders	$ 447,884	$ 425,213	$ 234,689
Income from continuing operations available to common stockholders (in shares)	68,150,830	67,811,916	67,244,152
Income from continuing operations available to common stockholders (in dollars per share)	$ 6.57	$ 6.27	$ 3.49
Essex Portfolio, L.P. [Member] | Stock Options [Member]
Basic:
Effect of Dilutive Securities	$ 0	$ 0	$ 0
Effect of Dilutive Securities (in shares)	69,100	116,276	189,968
Diluted:
Anti-dilutive securities (in shares)	154,793	252,334	54,100