Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Total property revenues	$ 276,209	$ 268,118	$ 256,614	$ 159,017	$ 155,986	$ 152,177	$ 148,783	$ 145,057	$ 959,958	$ 602,003	$ 526,696
Income before discontinued operations	44,805	58,582	4,645	26,406	20,020	62,718	28,983	29,161	134,438	140,882	127,653
Net income	44,805us-gaap_ProfitLoss	58,582us-gaap_ProfitLoss	4,645us-gaap_ProfitLoss	26,406us-gaap_ProfitLoss	36,903us-gaap_ProfitLoss	75,875us-gaap_ProfitLoss	29,575us-gaap_ProfitLoss	29,702us-gaap_ProfitLoss	134,438us-gaap_ProfitLoss	172,055us-gaap_ProfitLoss	139,590us-gaap_ProfitLoss
Net income available to common stockholders	40,175	53,565	1,207	21,912	31,874	68,788	24,946	25,203	116,859	150,811	119,812
Net income:
Basic (in dollars per share)	$ 0.63us-gaap_EarningsPerShareBasic	$ 0.85us-gaap_EarningsPerShareBasic	$ 0.02us-gaap_EarningsPerShareBasic	$ 0.58us-gaap_EarningsPerShareBasic	$ 0.85us-gaap_EarningsPerShareBasic	$ 1.84us-gaap_EarningsPerShareBasic	$ 0.67us-gaap_EarningsPerShareBasic	$ 0.68us-gaap_EarningsPerShareBasic	$ 2.07us-gaap_EarningsPerShareBasic	$ 4.05us-gaap_EarningsPerShareBasic	$ 3.42us-gaap_EarningsPerShareBasic
Diluted (in dollars per share)	$ 0.63us-gaap_EarningsPerShareDiluted	$ 0.85us-gaap_EarningsPerShareDiluted	$ 0.02us-gaap_EarningsPerShareDiluted	$ 0.58us-gaap_EarningsPerShareDiluted	$ 0.85us-gaap_EarningsPerShareDiluted	$ 1.84us-gaap_EarningsPerShareDiluted	$ 0.67us-gaap_EarningsPerShareDiluted	$ 0.68us-gaap_EarningsPerShareDiluted	$ 2.06us-gaap_EarningsPerShareDiluted	$ 4.04us-gaap_EarningsPerShareDiluted	$ 3.41us-gaap_EarningsPerShareDiluted
Market price:
High (in dollars per share)	$ 211.91ess_CommonStockMarketPricePerShareHigh	$ 180.65ess_CommonStockMarketPricePerShareHigh	$ 185.66ess_CommonStockMarketPricePerShareHigh	$ 171.70ess_CommonStockMarketPricePerShareHigh	$ 165.44ess_CommonStockMarketPricePerShareHigh	$ 172.16ess_CommonStockMarketPricePerShareHigh	$ 171.11ess_CommonStockMarketPricePerShareHigh	$ 156.36ess_CommonStockMarketPricePerShareHigh
Low (in dollars per share)	$ 206.35ess_CommonStockMarketPricePerShareLow	$ 178.27ess_CommonStockMarketPricePerShareLow	$ 183.36ess_CommonStockMarketPricePerShareLow	$ 166.95ess_CommonStockMarketPricePerShareLow	$ 137.53ess_CommonStockMarketPricePerShareLow	$ 139.64ess_CommonStockMarketPricePerShareLow	$ 147.56ess_CommonStockMarketPricePerShareLow	$ 147.06ess_CommonStockMarketPricePerShareLow
Close (in dollars per share)	$ 206.60ess_Close	$ 178.75ess_Close	$ 184.91ess_Close	$ 170.05ess_Close	$ 143.51ess_Close	$ 147.70ess_Close	$ 158.92ess_Close	$ 150.58ess_Close
Dividends declared (in dollars per share)	$ 1.30	$ 1.30	$ 1.30	$ 1.21	$ 1.21	$ 1.21	$ 1.21	$ 1.21
Essex Portfolio, L.P. [Member]
Total property revenues	276,209	268,118	256,614	159,017	155,986	152,177	148,783	145,057	959,958	602,003	526,696
Income before discontinued operations	44,805	58,582	4,645	26,406	20,020	62,718	28,983	29,161	134,438	140,882	127,653
Net income	44,805	58,582	4,645	26,406	36,903	75,875	29,575	29,702	134,438	172,055	139,590
Net income available to common stockholders	$ 41,599	$ 55,382	$ 1,416	$ 23,329	$ 33,776	$ 72,777	$ 26,493	$ 26,703	$ 121,726	$ 159,749	$ 127,771
Net income:
Basic (in dollars per share)	$ 0.63	$ 0.85	$ 0.02	$ 0.58	$ 0.87	$ 1.84	$ 0.67	$ 0.68	$ 2.07	$ 4.06	$ 3.43
Diluted (in dollars per share)	$ 0.63	$ 0.85	$ 0.02	$ 0.58	$ 0.86	$ 1.84	$ 0.67	$ 0.68	$ 2.07	$ 4.05	$ 3.42
Market price:
Dividends declared (in dollars per share)	$ 1.30	$ 1.30	$ 1.30	$ 1.21	$ 1.21	$ 1.21	$ 1.21	$ 1.21

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