Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 223,566	$ 203,049
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	240,033	238,435
Amortization of discount on marketable securities	(10,869)	(8,469)
Amortization of discount (premium) and debt financing costs, net	1,726	(1,352)
Gain on sale of marketable securities	(498)	(549)
Unrealized (gain) loss on equity securities recognized through income	(4,454)	754
Company's share of gain on the sales of co-investments	(870)	0
Earnings from co-investments	(32,365)	(47,823)
Operating distributions from co-investments	38,699	61,107
Accrued interest from notes and other receivables	(2,896)	(2,633)
Gain on the sale of real estate and land	0	(22,244)
Equity-based compensation	5,321	5,906
Gain on early retirement of debt, net	(1,668)	0
Gain on remeasurement of co-investment	(31,535)	0
Changes in operating assets and liabilities:
Prepaid expenses, receivables, operating lease right-of-use assets, and other assets	(7,925)	(6,078)
Accounts payable, accrued liabilities, and operating lease liabilities	12,486	2,839
Other liabilities	1,082	579
Net cash provided by operating activities	429,833	423,521
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures	(47,585)	(5,476)
Redevelopment	(30,804)	(36,466)
Development acquisitions of and additions to real estate under development	(86,108)	(75,303)
Capital expenditures on rental properties	(41,927)	(30,975)
Collections of notes and other receivables	2,500	29,500
Proceeds from insurance for property losses	2,698	917
Proceeds from dispositions of real estate	0	130,730
Contributions to co-investments	(167,278)	(97,826)
Changes in refundable deposits	252	(3,785)
Purchases of marketable securities	(40,098)	(27,995)
Sales and maturities of marketable securities	50,226	18,975
Non-operating distributions from co-investments	26,657	38,696
Net cash used in investing activities	(331,467)	(59,008)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes	498,234	298,773
Payments on unsecured debt and mortgage notes	(473,528)	(110,829)
Proceeds from lines of credit	975,832	438,528
Repayments of lines of credit	(858,832)	(614,858)
Retirement of common stock	(56,989)	(3,774)
Additions to deferred charges	(5,873)	(3,771)
Net proceeds from issuance of common stock	(82)	(353)
Net proceeds from stock options exercised	8,743	1,864
Payments related to tax withholding for share-based compensation	(3,515)	(23)
Distributions to noncontrolling interest	(13,842)	(15,066)
Redemption of noncontrolling interest	(14,179)	(57)
Redemption of redeemable noncontrolling interest	(73)	(43)
Common and preferred stock dividends paid	(250,686)	(238,454)
Net cash used in financing activities	(194,790)	(248,063)
Net (decrease) increase in unrestricted and restricted cash and cash equivalents	(96,424)	116,450
Unrestricted and restricted cash and cash equivalents at beginning of period	151,395	61,126
Unrestricted and restricted cash and cash equivalents at end of period	54,971	177,576
Supplemental disclosure of cash flow information:
Cash paid for interest (net of $12.3 million and $8.4 million capitalized in 2019 and 2018, respectively)	94,925	100,496
Operating cash flows from operating leases	3,392	0
Supplemental disclosure of noncash investing and financing activities:
Issuance of DownREIT limited partnership units in connection with acquisition of real estate	65,472	0
Transfers between real estate under development to rental properties, net	138	98,318
Transfer from real estate under development to co-investments	240	640
Reclassifications to redeemable noncontrolling interest from additional paid in capital and noncontrolling interest	1,428	1,845
Redemption of redeemable noncontrolling interest via reduction of note receivable	0	4,751
Initial recognition of operating lease right-of-use assets	77,645	0
Initial recognition of operating lease liabilities	79,693	0
Debt assumed in connection with acquisition	98,681	0
Essex Portfolio, L.P. [Member]
Cash flows from operating activities:
Net income	223,566	203,049
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	240,033	238,435
Amortization of discount on marketable securities	(10,869)	(8,469)
Amortization of discount (premium) and debt financing costs, net	1,726	(1,352)
Gain on sale of marketable securities	(498)	(549)
Unrealized (gain) loss on equity securities recognized through income	(4,454)	754
Company's share of gain on the sales of co-investments	(870)	0
Earnings from co-investments	(32,365)	(47,823)
Operating distributions from co-investments	38,699	61,107
Accrued interest from notes and other receivables	(2,896)	(2,633)
Gain on the sale of real estate and land	0	(22,244)
Equity-based compensation	5,321	5,906
Gain on early retirement of debt, net	(1,668)	0
Gain on remeasurement of co-investment	(31,535)	0
Changes in operating assets and liabilities:
Prepaid expenses, receivables, operating lease right-of-use assets, and other assets	(7,925)	(6,078)
Accounts payable, accrued liabilities, and operating lease liabilities	12,486	2,839
Other liabilities	1,082	579
Net cash provided by operating activities	429,833	423,521
Additions to real estate:
Acquisitions of real estate and acquisition related capital expenditures	(47,585)	(5,476)
Redevelopment	(30,804)	(36,466)
Development acquisitions of and additions to real estate under development	(86,108)	(75,303)
Capital expenditures on rental properties	(41,927)	(30,975)
Collections of notes and other receivables	2,500	29,500
Proceeds from insurance for property losses	2,698	917
Proceeds from dispositions of real estate	0	130,730
Contributions to co-investments	(167,278)	(97,826)
Changes in refundable deposits	252	(3,785)
Purchases of marketable securities	(40,098)	(27,995)
Sales and maturities of marketable securities	50,226	18,975
Non-operating distributions from co-investments	26,657	38,696
Net cash used in investing activities	(331,467)	(59,008)
Cash flows from financing activities:
Proceeds from unsecured debt and mortgage notes	498,234	298,773
Payments on unsecured debt and mortgage notes	(473,528)	(110,829)
Proceeds from lines of credit	975,832	438,528
Repayments of lines of credit	(858,832)	(614,858)
Retirement of common stock	(56,989)	(3,774)
Additions to deferred charges	(5,873)	(3,771)
Net proceeds from issuance of common stock	(82)	(353)
Net proceeds from stock options exercised	8,743	1,864
Payments related to tax withholding for share-based compensation	(3,515)	(23)
Distributions to noncontrolling interest	(3,925)	(4,460)
Redemption of noncontrolling interest	(14,179)	(57)
Redemption of redeemable noncontrolling interest	(73)	(43)
Common and preferred stock dividends paid	(260,603)	(249,060)
Net cash used in financing activities	(194,790)	(248,063)
Net (decrease) increase in unrestricted and restricted cash and cash equivalents	(96,424)	116,450
Unrestricted and restricted cash and cash equivalents at beginning of period	151,395	61,126
Unrestricted and restricted cash and cash equivalents at end of period	54,971	177,576
Supplemental disclosure of cash flow information:
Cash paid for interest (net of $12.3 million and $8.4 million capitalized in 2019 and 2018, respectively)	94,925	100,496
Operating cash flows from operating leases	3,392	0
Supplemental disclosure of noncash investing and financing activities:
Issuance of DownREIT limited partnership units in connection with acquisition of real estate	65,472	0
Transfers between real estate under development to rental properties, net	138	98,318
Transfer from real estate under development to co-investments	240	640
Reclassifications to redeemable noncontrolling interest from additional paid in capital and noncontrolling interest	1,428	1,845
Redemption of redeemable noncontrolling interest via reduction of note receivable	0	4,571
Initial recognition of operating lease right-of-use assets	77,645	0
Initial recognition of operating lease liabilities	$ 79,693	$ 0