Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 203,049	$ 263,346
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	238,435	233,442
Amortization of discount on marketable securities	(8,469)	(7,270)
Amortization of (premium) discount and debt financing costs, net	(1,352)	(4,317)
Gain on sale of marketable securities and other investments	(549)	(1,618)
Unrealized loss on equity securities recognized through income	754	0
Earnings from co-investments	(47,823)	(21,207)
Operating distributions from co-investments	61,107	27,451
Accrued interest from notes and other receivables	(2,633)	(1,575)
Gain on the sale of real estate and land	(22,244)	(26,174)
Equity-based compensation	5,906	3,361
Gain on remeasurement of co-investment	0	(88,641)
Changes in operating assets and liabilities:
Prepaid expenses, receivables and other assets	(6,078)	(1,751)
Accounts payable and accrued liabilities	2,839	(3,169)
Other liabilities	579	646
Net cash provided by operating activities	423,521	372,524
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures	(5,476)	(193,527)
Redevelopment	(36,466)	(30,509)
Development acquisitions of and additions to real estate under development	(75,303)	(51,563)
Capital expenditures on rental properties	(30,975)	(25,648)
Investments in notes receivable	0	(12,750)
Collections of notes receivable	29,500	0
Proceeds from insurance for property losses	917	435
Proceeds from dispositions of real estate	130,730	131,230
Contributions to co-investments	(97,826)	(144,599)
Changes in refundable deposits	(3,785)	467
Purchases of marketable securities	(27,995)	(33,615)
Sales and maturities of marketable securities	18,975	28,766
Non-operating distributions from co-investments	38,696	67,674
Net cash used in investing activities	(59,008)	(263,639)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes	298,773	597,981
Payments on unsecured debt and mortgage notes	(110,829)	(412,653)
Proceeds from lines of credit	438,528	467,313
Repayments of lines of credit	(614,858)	(592,313)
Retirement of common stock	(3,774)	0
Additions to deferred charges	(3,771)	(3,890)
Net proceeds from issuance of common stock	(353)	80,565
Net proceeds from stock options exercised	1,864	22,041
Payments related to tax withholding for share-based compensation	(23)	(118)
Distributions to noncontrolling interest	(15,066)	(14,371)
Redemption of noncontrolling interest	(57)	(3,528)
Redemption of redeemable noncontrolling interest	(43)	(720)
Common and preferred stock dividends paid	(238,454)	(219,618)
Net cash used in financing activities	(248,063)	(79,311)
Net increase (decrease) in unrestricted and restricted cash and cash equivalents	116,450	29,574
Unrestricted and restricted cash and cash equivalents at beginning of period	61,126	170,302
Unrestricted and restricted cash and cash equivalents at end of period	177,576	199,876
Supplemental disclosure of cash flow information:
Cash paid for interest, net of $8.4 million and $6.6 million capitalized in 2018 and 2017, respectively	100,496	106,448
Supplemental disclosure of noncash investing and financing activities:
Issuance of DownREIT units in connection with acquisition of real estate	0	22,506
Transfers between real estate under development to rental properties, net	98,318	1,540
Transfer from real estate under development to co-investments	640	3,340
Reclassifications to redeemable noncontrolling interest from additional paid in capital and noncontrolling interest	1,845	1,117
Redemption of redeemable noncontrolling interest via reduction of note receivable	4,751	0
Debt assumed in connection with acquisition	0	51,882
Essex Portfolio, L.P. [Member]
Cash flows from operating activities:
Net income	203,049	263,346
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	238,435	233,442
Amortization of discount on marketable securities	(8,469)	(7,270)
Amortization of (premium) discount and debt financing costs, net	(1,352)	(4,317)
Gain on sale of marketable securities and other investments	(549)	(1,618)
Unrealized loss on equity securities recognized through income	754	0
Earnings from co-investments	(47,823)	(21,207)
Operating distributions from co-investments	61,107	27,451
Accrued interest from notes and other receivables	(2,633)	(1,575)
Gain on the sale of real estate and land	(22,244)	(26,174)
Equity-based compensation	5,906	3,361
Gain on remeasurement of co-investment	0	(88,641)
Changes in operating assets and liabilities:
Prepaid expenses, receivables and other assets	(6,078)	(1,751)
Accounts payable and accrued liabilities	2,839	(3,169)
Other liabilities	579	646
Net cash provided by operating activities	423,521	372,524
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures	(5,476)	(193,527)
Redevelopment	(36,466)	(30,509)
Development acquisitions of and additions to real estate under development	(75,303)	(51,563)
Capital expenditures on rental properties	(30,975)	(25,648)
Investments in notes receivable	0	(12,750)
Collections of notes receivable	29,500	0
Proceeds from insurance for property losses	917	435
Proceeds from dispositions of real estate	130,730	131,230
Contributions to co-investments	(97,826)	(144,599)
Changes in refundable deposits	(3,785)	467
Purchases of marketable securities	(27,995)	(33,615)
Sales and maturities of marketable securities	18,975	28,766
Non-operating distributions from co-investments	38,696	67,674
Net cash used in investing activities	(59,008)	(263,639)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes	298,773	597,981
Payments on unsecured debt and mortgage notes	(110,829)	(412,653)
Proceeds from lines of credit	438,528	467,313
Repayments of lines of credit	(614,858)	(592,313)
Retirement of common stock	(3,774)	0
Additions to deferred charges	(3,771)	(3,890)
Net proceeds from issuance of common stock	(353)	80,565
Net proceeds from stock options exercised	1,864	22,041
Payments related to tax withholding for share-based compensation	(23)	(118)
Distributions to noncontrolling interest	(4,460)	(3,600)
Redemption of noncontrolling interest	(57)	(3,528)
Redemption of redeemable noncontrolling interest	(43)	(720)
Common and preferred stock dividends paid	(249,060)	(230,389)
Net cash used in financing activities	(248,063)	(79,311)
Net increase (decrease) in unrestricted and restricted cash and cash equivalents	116,450	29,574
Unrestricted and restricted cash and cash equivalents at beginning of period	61,126	170,302
Unrestricted and restricted cash and cash equivalents at end of period	177,576	199,876
Supplemental disclosure of cash flow information:
Cash paid for interest, net of $8.4 million and $6.6 million capitalized in 2018 and 2017, respectively	100,496	106,448
Supplemental disclosure of noncash investing and financing activities:
Issuance of DownREIT units in connection with acquisition of real estate	0	22,506
Transfers between real estate under development to rental properties, net	98,318	1,540
Transfer from real estate under development to co-investments	640	3,340
Reclassifications to redeemable noncontrolling interest from additional paid in capital and noncontrolling interest	1,845	1,117
Redemption of redeemable noncontrolling interest via reduction of note receivable	4,571	0
Debt assumed in connection with acquisition	$ 0	$ 51,882