Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Income Statements, Captions [Line Items]
Total property revenues	$ 308,646	$ 302,522	$ 294,101	$ 280,229	$ 276,778	$ 268,512	$ 256,952	$ 159,349	$ 1,185,498	$ 961,591	$ 603,327
Net income	85,762	47,182	50,542	64,753	44,805	58,582	4,645	26,406	248,239	134,438	172,055
Net income available to common stockholders	$ 79,624	$ 42,323	$ 45,555	$ 59,363	$ 40,175	$ 53,565	$ 1,207	$ 21,912	$ 226,865	$ 116,859	$ 150,811
Net income:
Basic (in dollars per share)	$ 1.22	$ 0.65	$ 0.70	$ 0.92	$ 0.63	$ 0.85	$ 0.02	$ 0.58	$ 3.50	$ 2.07	$ 4.05
Diluted (in dollars per share)	1.22	0.65	0.70	0.92	0.63	0.85	0.02	0.58	$ 3.49	$ 2.06	$ 4.04
Market price:
High (in dollars per share)	244.71	232.20	231.90	243.17	214.43	196.08	185.99	173.01
Low (in dollars per share)	214.29	205.72	208.85	207.26	176.70	177.68	164.76	141.79
Close (in dollars per share)	239.41	223.42	212.50	229.90	206.60	178.75	184.91	170.05
Dividends declared (in dollars per share)	$ 1.44	$ 1.44	$ 1.44	$ 1.44	$ 1.30	$ 1.30	$ 1.30	$ 1.21
Essex Portfolio, L.P. [Member]
Condensed Income Statements, Captions [Line Items]
Total property revenues	$ 308,646	$ 302,522	$ 294,101	$ 280,229	$ 276,778	$ 268,512	$ 256,952	$ 159,349	$ 1,185,498	$ 961,591	$ 603,327
Net income	85,762	47,182	50,542	64,753	44,805	58,582	4,645	26,406	248,239	134,438	172,055
Net income available to common stockholders	$ 82,333	$ 43,794	$ 47,088	$ 61,474	$ 41,599	$ 55,382	$ 1,416	$ 23,329	$ 234,689	$ 121,726	$ 159,749
Net income:
Basic (in dollars per share)	$ 1.22	$ 0.65	$ 0.70	$ 0.93	$ 0.63	$ 0.85	$ 0.02	$ 0.58	$ 3.50	$ 2.07	$ 4.06
Diluted (in dollars per share)	1.22	0.65	0.70	0.92	0.63	0.85	0.02	0.58	$ 3.49	$ 2.07	$ 4.05
Market price:
Dividends declared (in dollars per share)	$ 1.44	$ 1.44	$ 1.44	$ 1.44	$ 1.3	$ 1.3	$ 1.3	$ 1.21