Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Cash flows from operating activities:
Net income	$ 69,615	$ 90,076	$ 246,564	$ 418,841
Adjustments to reconcile net income to net cash provided by operating activities:
Straight-lined rents			5,825	(2,803)
Depreciation and amortization			257,323	265,168
Amortization of discount on marketable securities			0	(4,862)
Amortization of discount and debt financing costs, net			6,311	3,973
Loss on sale of marketable securities			(2,499)	(33)
Income form early redemption of notes receivable			(4,747)	0
Provision for credit losses			(107)	97
Unrealized (gains) losses on equity securities recognized through income			(16,681)	1,073
Earnings from co-investments			(35,259)	(38,554)
Operating distributions from co-investments			57,364	29,613
Accrued interest from notes and other receivables			(8,530)	(835)
Gain on the sale of real estate and land			(100,096)	(16,597)
Equity-based compensation			3,776	4,043
Loss on early retirement of debt, net	16,465	5,027	18,982	4,706
Gain on remeasurement of co-investment	(2,260)	0	(2,260)	(234,694)
Changes in operating assets and liabilities:
Prepaid expenses, receivables, operating lease right-of-use assets, and other assets			(5,348)	(6,421)
Accounts payable, accrued liabilities, and operating lease liabilities			3,209	2,565
Other liabilities			4,244	830
Net cash provided by operating activities			428,071	426,110
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures, net of cash acquired			(18,418)	(458,857)
Redevelopment			(19,981)	(32,211)
Development acquisitions of and additions to real estate under development			(34,640)	(54,994)
Capital expenditures on rental properties			(49,044)	(40,013)
Investments in notes receivable			(71,613)	(6,669)
Collections of notes and other receivables			36,244	98,711
Proceeds from insurance for property losses			117	568
Proceeds from dispositions of real estate			243,365	230,935
Contributions to co-investments			(160,719)	(43,817)
Changes in refundable deposits			(968)	96
Purchases of marketable securities			(23,509)	(10,989)
Sales and maturities of marketable securities			14,931	4,301
Non-operating distributions from co-investments			78,600	25,136
Net cash used in investing activities			(5,635)	(287,803)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes			745,505	856,630
Payments on unsecured debt and mortgage notes			(951,727)	(286,074)
Proceeds from lines of credit			453,359	1,038,426
Repayments of lines of credit			(368,359)	(1,093,426)
Retirement of common stock			(9,172)	(196,404)
Additions to deferred charges			(6,361)	(7,297)
Payments related to debt prepayment penalties			(18,342)	(1,696)
Net proceeds from issuance of common stock			(84)	(133)
Net proceeds from stock options exercised			2,275	14,865
Payments related to tax withholding for share-based compensation			(5,445)	(5,664)
Contributions from noncontrolling interest			1,900	0
Distributions to noncontrolling interest			(14,787)	(15,613)
Redemption of noncontrolling interest			(2,318)	(1,703)
Redemption of redeemable noncontrolling interest			(3,808)	0
Common stock dividends paid			(270,937)	(264,837)
Net cash (used in) provided by financing activities			(448,301)	37,074
Net (decrease) increase in unrestricted and restricted cash and cash equivalents			(25,865)	175,381
Unrestricted and restricted cash and cash equivalents at beginning of period			84,041	81,094	$ 81,094
Unrestricted and restricted cash and cash equivalents at end of period	58,176	256,475	58,176	256,475	84,041
Supplemental disclosure of cash flow information:
Cash paid for interest (net of $3.8 million and $9.0 million capitalized in 2021 and 2020, respectively)			96,541	98,358
Operating cash flows from operating leases			5,316	3,430
Supplemental disclosure of noncash investing and financing activities:
Transfers between real estate under development and rental properties, net			218,835	131,960
Transfer from real estate under development to co-investments			1,337	1,473
Reclassifications to (from) redeemable noncontrolling interest to/from additional paid in capital and noncontrolling interest			6,593	(4,169)
Essex Portfolio, L.P.
Cash flows from operating activities:
Net income	69,615	90,076	246,564	418,841
Adjustments to reconcile net income to net cash provided by operating activities:
Straight-lined rents			5,825	(2,803)
Depreciation and amortization			257,323	265,168
Amortization of discount on marketable securities			0	(4,862)
Amortization of discount and debt financing costs, net			6,311	3,973
Loss on sale of marketable securities			(2,499)	(33)
Income form early redemption of notes receivable			(4,747)	0
Provision for credit losses			(107)	97
Unrealized (gains) losses on equity securities recognized through income			(16,681)	1,073
Earnings from co-investments			(35,259)	(38,554)
Operating distributions from co-investments			57,364	29,613
Accrued interest from notes and other receivables			(8,530)	(835)
Gain on the sale of real estate and land			(100,096)	(16,597)
Equity-based compensation			3,776	4,043
Loss on early retirement of debt, net	16,465	5,027	18,982	4,706
Gain on remeasurement of co-investment	(2,260)	0	(2,260)	(234,694)
Changes in operating assets and liabilities:
Prepaid expenses, receivables, operating lease right-of-use assets, and other assets			(5,348)	(6,421)
Accounts payable, accrued liabilities, and operating lease liabilities			3,209	2,565
Other liabilities			4,244	830
Net cash provided by operating activities			428,071	426,110
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures, net of cash acquired			(18,418)	(458,857)
Redevelopment			(19,981)	(32,211)
Development acquisitions of and additions to real estate under development			(34,640)	(54,994)
Capital expenditures on rental properties			(49,044)	(40,013)
Investments in notes receivable			(71,613)	(6,669)
Collections of notes and other receivables			36,244	98,711
Proceeds from insurance for property losses			117	568
Proceeds from dispositions of real estate			243,365	230,935
Contributions to co-investments			(160,719)	(43,817)
Changes in refundable deposits			(968)	96
Purchases of marketable securities			(23,509)	(10,989)
Sales and maturities of marketable securities			14,931	4,301
Non-operating distributions from co-investments			78,600	25,136
Net cash used in investing activities			(5,635)	(287,803)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes			745,505	856,630
Payments on unsecured debt and mortgage notes			(951,727)	(286,074)
Proceeds from lines of credit			453,359	1,038,426
Repayments of lines of credit			(368,359)	(1,093,426)
Retirement of common stock			(9,172)	(196,404)
Additions to deferred charges			(6,361)	(7,297)
Payments related to debt prepayment penalties			(18,342)	(1,696)
Net proceeds from issuance of common stock			(84)	(133)
Net proceeds from stock options exercised			2,275	14,865
Payments related to tax withholding for share-based compensation			(5,445)	(5,664)
Contributions from noncontrolling interest			1,900	0
Distributions to noncontrolling interest			(4,238)	(4,152)
Redemption of noncontrolling interest			(2,318)	(1,703)
Common stock dividends paid			(281,486)	(276,298)
Net cash (used in) provided by financing activities			(448,301)	37,074
Net (decrease) increase in unrestricted and restricted cash and cash equivalents			(25,865)	175,381
Unrestricted and restricted cash and cash equivalents at beginning of period			84,041	81,094	81,094
Unrestricted and restricted cash and cash equivalents at end of period	$ 58,176	$ 256,475	58,176	256,475	$ 84,041
Supplemental disclosure of cash flow information:
Cash paid for interest (net of $3.8 million and $9.0 million capitalized in 2021 and 2020, respectively)			96,541	98,358
Operating cash flows from operating leases			5,316	3,430
Supplemental disclosure of noncash investing and financing activities:
Transfers between real estate under development and rental properties, net			218,835	131,960
Transfer from real estate under development to co-investments			1,337	1,473
Reclassifications to (from) redeemable noncontrolling interest to/from additional paid in capital and noncontrolling interest			$ 6,593	$ (4,169)