Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Rental properties:
Land and land improvements	$ 2,566,586	$ 2,424,930
Buildings and improvements	9,753,982	8,819,751
Total rental properties	12,320,568	11,244,681
Less accumulated depreciation	(1,858,134)	(1,564,806)
Net real estate	10,462,434	9,679,875
Real estate under development	226,690	429,096
Co-investments	1,036,043	1,042,423
Real estate held for sale, net	8,742	56,300
Total real estate	11,733,909	11,207,694
Cash and cash equivalents-unrestricted	35,668	25,610
Cash and cash equivalents-restricted	36,638	70,139
Marketable securities and other investments	133,058	117,240
Notes and other receivables	22,668	24,923
Acquired in place lease value, net	12,675	47,748
Prepaid expenses and other assets	38,101	33,378
Total assets	12,012,717	11,526,732
Liabilities [Abstract]
Unsecured debt, net	3,090,896	2,603,548
Mortgage notes payable, net	2,224,513	2,234,317
Lines of credit, net	2,011	242,824
Accounts payable and accrued liabilities	177,807	135,162
Construction payable	26,411	30,892
Dividends payable	99,945	88,221
Other liabilities	34,722	32,444
Total liabilities	$ 5,656,305	$ 5,367,408
Commitments and contingencies
Redeemable noncontrolling interest	$ 24,589	$ 23,256
Equity:
Common stock; $0.0001 par value, 656,020,000 shares authorized; 65,234,597 and 63,682,646 shares issued and outstanding, respectively	6	6
Cumulative redeemable 7.125% Series H preferred stock at liquidation value	73,750	73,750
Additional paid-in capital	6,980,443	6,651,165
Distributions in excess of accumulated earnings	(782,801)	(650,797)
Accumulated other comprehensive loss, net	(50,357)	(51,452)
Total stockholders' equity	6,221,041	6,022,672
Noncontrolling interest	110,782	113,396
Total equity	6,331,823	6,136,068
Total liabilities and equity	12,012,717	11,526,732
Essex Portfolio, L.P. [Member]
Rental properties:
Land and land improvements	2,566,586	2,424,930
Buildings and improvements	9,753,982	8,819,751
Total rental properties	12,320,568	11,244,681
Less accumulated depreciation	(1,858,134)	(1,564,806)
Net real estate	10,462,434	9,679,875
Real estate under development	226,690	429,096
Co-investments	1,036,043	1,042,423
Real estate held for sale, net	8,742	56,300
Total real estate	11,733,909	11,207,694
Cash and cash equivalents-unrestricted	35,668	25,610
Cash and cash equivalents-restricted	36,638	70,139
Marketable securities and other investments	133,058	117,240
Notes and other receivables	22,668	24,923
Acquired in place lease value, net	12,675	47,748
Prepaid expenses and other assets	38,101	33,378
Total assets	12,012,717	11,526,732
Liabilities [Abstract]
Unsecured debt, net	2,224,513	2,234,317
Mortgage notes payable, net	3,090,896	2,603,548
Lines of credit, net	2,011	242,824
Accounts payable and accrued liabilities	177,807	135,162
Construction payable	26,411	30,892
Dividends payable	99,945	88,221
Other liabilities	34,722	32,444
Total liabilities	$ 5,656,305	$ 5,367,408
Commitments and contingencies
Redeemable noncontrolling interest	$ 24,589	$ 23,256
Equity:
General Partner	6,271,398	6,074,124
Common equity (2,176,563 and 2,168,158 units issued and outstanding, respectively)	46,793	48,665
Accumulated other comprehensive loss, net	(48,224)	(49,356)
Total partners' capital	6,269,967	6,073,433
Noncontrolling interest	61,856	62,635
Total capital	6,331,823	6,136,068
Total liabilities and equity	12,012,717	11,526,732
Essex Portfolio, L.P. [Member] | General Partner [Member] | Common Capital [Member]
Equity:
General Partner	6,200,189	6,002,915
Total capital	6,200,189	6,002,915
Essex Portfolio, L.P. [Member] | General Partner [Member] | Preferred Capital [Member]
Equity:
General Partner	71,209	71,209
Total capital	$ 71,209	$ 71,209