Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 348,381	$ 233,893
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	350,893	329,847
Amortization of discount on marketable securities and other investments	(11,128)	(10,771)
Amortization of (premium) discount and debt financing costs, net	(5,132)	(11,432)
Gain on sale of marketable securities and other investments	(1,650)	(2,876)
Company's share of gain on the sales of co-investment	(10,058)	(13,046)
Earnings from co-investments	(30,876)	(25,886)
Operating distributions from co-investments	47,702	45,342
Gain on the sale of real estate and land	(26,423)	(20,258)
Equity-based compensation	4,894	4,436
Loss on early retirement of debt, net	0	211
Gain on remeasurement of co-investment	(88,641)	0
Changes in operating assets and liabilities:
Prepaid expenses, receivables and other assets	(7,862)	656
Accounts payable and accrued liabilities	50,788	49,961
Other liabilities	399	420
Net cash provided by operating activities	621,287	580,497
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures	(200,028)	(124,054)
Redevelopment	(50,642)	(62,983)
Development acquisitions of and additions to real estate under development	(92,936)	(58,575)
Capital expenditures on rental properties	(46,455)	(40,503)
Investments in notes receivable	(76,961)	(4,375)
Proceeds from insurance for property losses	648	3,288
Proceeds from dispositions of real estate	132,039	48,008
Contributions to co-investments	(231,552)	(121,972)
Changes in restricted cash and refundable deposits	91,209	65,858
Purchases of marketable securities	(65,668)	(18,779)
Sales and maturities of marketable securities and other investments	33,377	14,708
Non-operating distributions from co-investments	112,572	34,564
Net cash used in investing activities	(394,397)	(264,815)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes	597,981	499,724
Payments on unsecured debt and mortgage notes	(460,040)	(244,583)
Proceeds from lines of credit	564,833	321,373
Repayments of lines of credit	(687,224)	(336,373)
Repayment of cumulative redeemable preferred stock	0	(73,750)
Additions to deferred charges	(4,108)	(5,300)
Net proceeds from issuance of common stock	80,377	(382)
Net proceeds from stock options exercised	24,079	17,878
Payments related to tax withholding for share-based compensation	(118)	(222)
Distributions to noncontrolling interest	(20,405)	(19,844)
Redemption of noncontrolling interest	(4,849)	(2,435)
Redemption of redeemable noncontrolling interest	(720)	0
Common and preferred stock dividends paid	(335,110)	(306,284)
Net cash used in financing activities	(245,304)	(150,198)
Net (decrease) increase in cash and cash equivalents	(18,414)	165,484
Cash and cash equivalents at beginning of period	64,921	29,683
Cash and cash equivalents at end of period	46,507	195,167
Supplemental disclosure of cash flow information:
Cash paid for interest, net of $10.0 million and $9.4 million capitalized in 2017 and 2016, respectively	148,742	140,183
Supplemental disclosure of noncash investing and financing activities:
Issuance of DownREIT units in connection with acquisition of real estate	22,506	0
Transfers between real estate under development to rental properties, net	2,195	106,255
Transfer from real estate under development to co-investments	4,122	8,332
Reclassifications to (from) redeemable noncontrolling interest to or from additional paid in capital and noncontrolling interest	903	(1,343)
Debt assumed in connection with acquisition	51,882	48,832
Essex Portfolio, L.P. [Member]
Cash flows from operating activities:
Net income	348,381	233,893
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	350,893	329,847
Amortization of discount on marketable securities and other investments	(11,128)	(10,771)
Amortization of (premium) discount and debt financing costs, net	(5,132)	(11,432)
Gain on sale of marketable securities and other investments	(1,650)	(2,876)
Company's share of gain on the sales of co-investment	(10,058)	(13,046)
Earnings from co-investments	(30,876)	(25,886)
Operating distributions from co-investments	47,702	45,342
Gain on the sale of real estate and land	(26,423)	(20,258)
Equity-based compensation	4,894	4,436
Loss on early retirement of debt, net	0	211
Gain on remeasurement of co-investment	(88,641)	0
Changes in operating assets and liabilities:
Prepaid expenses, receivables and other assets	(7,862)	656
Accounts payable and accrued liabilities	50,788	49,961
Other liabilities	399	420
Net cash provided by operating activities	621,287	580,497
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures	(200,028)	(124,054)
Redevelopment	(50,642)	(62,983)
Development acquisitions of and additions to real estate under development	(92,936)	(58,575)
Capital expenditures on rental properties	(46,455)	(40,503)
Investments in notes receivable	(76,961)	(4,375)
Proceeds from insurance for property losses	648	3,288
Proceeds from dispositions of real estate	132,039	48,008
Contributions to co-investments	(231,552)	(121,972)
Changes in restricted cash and refundable deposits	91,209	65,858
Purchases of marketable securities	(65,668)	(18,779)
Sales and maturities of marketable securities and other investments	33,377	14,708
Non-operating distributions from co-investments	112,572	34,564
Net cash used in investing activities	(394,397)	(264,815)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes	597,981	499,724
Payments on unsecured debt and mortgage notes	(460,040)	(244,583)
Proceeds from lines of credit	564,833	321,373
Repayments of lines of credit	(687,224)	(336,373)
Repayment of cumulative redeemable preferred stock	0	(73,750)
Additions to deferred charges	(4,108)	(5,300)
Net proceeds from issuance of common stock	80,377	(382)
Net proceeds from stock options exercised	24,079	17,878
Payments related to tax withholding for share-based compensation	(118)	(222)
Distributions to noncontrolling interest	(5,568)	(5,171)
Redemption of noncontrolling interest	(4,849)	(2,435)
Redemption of redeemable noncontrolling interest	(720)	0
Common and preferred stock dividends paid	(349,947)	(320,957)
Net cash used in financing activities	(245,304)	(150,198)
Net (decrease) increase in cash and cash equivalents	(18,414)	165,484
Cash and cash equivalents at beginning of period	64,921	29,683
Cash and cash equivalents at end of period	46,507	195,167
Supplemental disclosure of cash flow information:
Cash paid for interest, net of $10.0 million and $9.4 million capitalized in 2017 and 2016, respectively	148,742	140,183
Supplemental disclosure of noncash investing and financing activities:
Issuance of DownREIT units in connection with acquisition of real estate	22,506	0
Transfers between real estate under development to rental properties, net	2,195	106,255
Transfer from real estate under development to co-investments	4,122	8,332
Reclassifications to (from) redeemable noncontrolling interest to or from additional paid in capital and noncontrolling interest	903	(1,343)
Debt assumed in connection with acquisition	$ 51,882	$ 48,832