Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	656,020,000	656,020,000
Common stock, shares issued (in shares)	65,426,726	65,379,359
Common stock, shares outstanding (in shares)	65,426,726	65,379,359
Series H Preferred Interest [Member]
Preferred stock, stated interest percentage	7.125%	7.125%
Essex Portfolio, L.P. [Member] | Series H Preferred Interest [Member]
Preferred interest, liquidation value	$ 73,750	$ 73,750
Preferred stock, stated interest percentage	7.125%	7.125%
Essex Portfolio, L.P. [Member] | General Partner [Member]
Common stock, shares issued (in shares)	65,426,726	65,379,359
Common stock, shares outstanding (in shares)	65,426,726	65,379,359
Essex Portfolio, L.P. [Member] | Limited Partners [Member]
Common stock, shares issued (in shares)	2,224,968	2,214,545
Common stock, shares outstanding (in shares)	2,224,968	2,214,545