Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 413,599	$ 458,043	$ 438,410
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	479,884	468,881	441,682
Amortization of discount on marketable securities	(17,637)	(15,119)	(14,211)
Amortization of (premium) discount and financing costs, net	(2,587)	(5,948)	(15,234)
Gain on sale of marketable securities	(737)	(1,909)	(5,719)
Unrealized gain on equity securities recognized through income	5,159	0	0
Company's share of gain on the sales of co-investments	(10,569)	(44,837)	(13,046)
Earnings from co-investments	(78,563)	(41,608)	(35,652)
Operating distributions from co-investments	99,593	76,764	60,472
Accrued interest from notes and other receivables	(5,436)	(4,030)	(302)
Gain on the sale of real estate and land	(61,861)	(26,423)	(154,561)
Equity-based compensation	7,135	9,286	9,811
Loss on early retirement of debt, net	0	1,796	606
Gain on remeasurement of co-investment	(1,253)	(88,641)	0
Changes in operating assets and liabilities:
Prepaid expenses, receivables and other assets	(1,203)	(3,004)	2,730
Accounts payable and accrued liabilities	(145)	(13,474)	2,302
Other liabilities	1,175	(170)	(496)
Net cash provided by operating activities	826,554	769,607	716,792
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures	(15,311)	(206,194)	(315,632)
Redevelopment	(73,000)	(69,928)	(83,927)
Development acquisitions of and additions to real estate under development	(182,772)	(137,733)	(75,367)
Capital expenditures on rental properties	(81,684)	(72,812)	(64,769)
Acquisition of membership interest in co-investments	0	0	0
Investments in notes receivable	0	(106,461)	(24,070)
Collections of notes and other receivables	29,500	55,000	4,070
Proceeds from insurance for property losses	1,408	648	5,543
Proceeds from dispositions of real estate	347,587	132,039	239,289
Contributions to co-investments	(162,437)	(293,363)	(183,989)
Changes in refundable deposits	(414)	837	(2,129)
Purchases of marketable securities	(37,952)	(67,893)	(18,779)
Sales and maturities of marketable securities	31,521	35,481	30,458
Non-operating distributions from co-investments	83,661	162,439	76,231
Net cash used in investing activities	(59,893)	(567,940)	(413,071)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes	298,773	597,981	669,282
Payments on unsecured debt and mortgage notes	(230,398)	(561,160)	(532,020)
Proceeds from lines of credit	742,961	982,246	596,106
Repayments of lines of credit	(921,961)	(928,246)	(486,106)
Repayment of cumulative redeemable preferred stock	0	0	(73,750)
Retirement of common stock	(51,233)	0	(1,045)
Additions to deferred charges	(4,250)	(4,108)	(7,926)
Payments related to debt prepayment penalties	0	(1,630)	(215)
Net proceeds from issuance of common stock	(919)	89,055	(384)
Net proceeds from stock options exercised	6,213	26,635	18,949
Payments related to tax withholding for share-based compensation	(869)	(316)	(386)
Distributions to noncontrolling interest	(29,050)	(26,552)	(25,334)
Redemption of noncontrolling interest	(1,333)	(28,580)	(2,511)
Redemption of redeemable noncontrolling interest	(144)	(5,543)	0
Common and preferred stock/units dividends paid and preferred interest distributions paid	(484,182)	(450,625)	(411,134)
Net cash used in financing activities	(676,392)	(310,843)	(256,474)
Net increase (decrease) in unrestricted and restricted cash and cash equivalents	90,269	(109,176)	47,247
Unrestricted and restricted cash and cash equivalents at beginning of period	61,126	170,302	123,055
Unrestricted and restricted cash and cash equivalents at end of period	151,395	61,126	170,302
Supplemental disclosure of cash flow information:
Cash paid for interest, net of capitalized interest	203,803	212,163	203,743
Interest capitalized	18,708	13,860	12,486
Supplemental disclosure of noncash investing and financing activities:
Issuance of Operating Partnership units for contributed properties	7,919	0	0
Issuance of DownREIT limited partnership units in connection with acquisition of real estate	0	22,506	0
Transfers between real estate under development to rental properties, net	100,415	2,413	104,159
Transfer from real estate under development to co-investments	853	5,075	9,919
Reclassifications to (from) redeemable noncontrolling interest to or from additional paid in capital and noncontrolling interest	1,165	65	(768)
Redemption of redeemable noncontrolling interest via reduction of note receivable	4,751	0	0
Debt assumed in connection with acquisition	45,804	51,882	48,832
Debt deconsolidated in connection with BEX II transaction	0	0	20,195
Repayment of mortgage note from new financing proceeds	52,000	0	0
Essex Portfolio, L.P. [Member]
Cash flows from operating activities:
Net income	413,599	458,043	438,410
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	479,884	468,881	441,682
Amortization of discount on marketable securities	(17,637)	(15,119)	(14,211)
Amortization of (premium) discount and financing costs, net	(2,587)	(5,948)	(15,234)
Gain on sale of marketable securities	(737)	(1,909)	(5,719)
Unrealized gain on equity securities recognized through income	5,159	0	0
Company's share of gain on the sales of co-investments	(10,569)	(44,837)	(13,046)
Earnings from co-investments	(78,563)	(41,608)	(35,652)
Operating distributions from co-investments	99,593	76,764	60,472
Accrued interest from notes and other receivables	(5,436)	(4,030)	(302)
Gain on the sale of real estate and land	(61,861)	(26,423)	(154,561)
Equity-based compensation	7,135	9,286	9,811
Loss on early retirement of debt, net	0	1,796	606
Gain on remeasurement of co-investment	(1,253)	(88,641)	0
Changes in operating assets and liabilities:
Prepaid expenses, receivables and other assets	(1,203)	(3,004)	2,730
Accounts payable and accrued liabilities	(145)	(13,474)	2,302
Other liabilities	1,175	(170)	(496)
Net cash provided by operating activities	826,554	769,607	716,792
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures	(15,311)	(206,194)	(315,632)
Redevelopment	(73,000)	(69,928)	(83,927)
Development acquisitions of and additions to real estate under development	(182,772)	(137,733)	(75,367)
Capital expenditures on rental properties	(81,684)	(72,812)	(64,769)
Investments in notes receivable	0	(106,461)	(24,070)
Collections of notes and other receivables	29,500	55,000	4,070
Proceeds from insurance for property losses	1,408	648	5,543
Proceeds from dispositions of real estate	347,587	132,039	239,289
Contributions to co-investments	(162,437)	(293,363)	(183,989)
Changes in refundable deposits	(414)	837	(2,129)
Purchases of marketable securities	(37,952)	(67,893)	(18,779)
Sales and maturities of marketable securities	31,521	35,481	30,458
Non-operating distributions from co-investments	83,661	162,439	76,231
Net cash used in investing activities	(59,893)	(567,940)	(413,071)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes	298,773	597,981	669,282
Payments on unsecured debt and mortgage notes	(230,398)	(561,160)	(532,020)
Proceeds from lines of credit	742,961	982,246	596,106
Repayments of lines of credit	(921,961)	(928,246)	(486,106)
Repayment of cumulative redeemable preferred stock	0	0	(73,750)
Retirement of common stock	(51,233)	0	(1,045)
Additions to deferred charges	(4,250)	(4,108)	(7,926)
Payments related to debt prepayment penalties	0	(1,630)	(215)
Net proceeds from issuance of common stock	(919)	89,055	(384)
Net proceeds from stock options exercised	6,213	26,635	18,949
Payments related to tax withholding for share-based compensation	(869)	(316)	(386)
Distributions to noncontrolling interest	(8,518)	(7,752)	(6,960)
Redemption of noncontrolling interest	(1,333)	(28,580)	(2,511)
Redemption of redeemable noncontrolling interest	(144)	(5,543)	0
Common and preferred stock/units dividends paid and preferred interest distributions paid	(504,714)	(469,425)	(429,508)
Net cash used in financing activities	(676,392)	(310,843)	(256,474)
Net increase (decrease) in unrestricted and restricted cash and cash equivalents	90,269	(109,176)	47,247
Unrestricted and restricted cash and cash equivalents at beginning of period	61,126	170,302	123,055
Unrestricted and restricted cash and cash equivalents at end of period	151,395	61,126	170,302
Supplemental disclosure of cash flow information:
Cash paid for interest, net of capitalized interest	203,803	212,163	203,743
Interest capitalized	18,708	13,860	12,486
Supplemental disclosure of noncash investing and financing activities:
Issuance of Operating Partnership units for contributed properties	7,919	0	0
Issuance of DownREIT limited partnership units in connection with acquisition of real estate	0	22,506	0
Transfers between real estate under development to rental properties, net	100,415	2,413	104,159
Transfer from real estate under development to co-investments	853	5,075	9,919
Reclassifications to (from) redeemable noncontrolling interest to or from additional paid in capital and noncontrolling interest	1,165	65	(768)
Redemption of redeemable noncontrolling interest via reduction of note receivable	4,751	0	0
Debt assumed in connection with acquisition	45,804	51,882	48,832
Debt deconsolidated in connection with BEX II transaction	0	0	20,195
Repayment of mortgage note from new financing proceeds	$ 52,000	$ 0	$ 0