Summary of Critical and Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) property community partnership shares	Dec. 31, 2015 USD ($) community shares	Dec. 31, 2014 USD ($)	Jan. 01, 2016 investment	Dec. 31, 2013 USD ($)
Principles of Consolidation [Abstract]
Noncontrolling interest in Operating Partnership (in hundredths)	3.30%	3.30%
Property, Plant and Equipment [Line Items]
Lines of credit	$ 125,000,000	$ 15,000,000
Prepaid expenses and other assets	$ 48,450,000	41,730,000
Real Estate Rental Properties [Abstract]
Threshold useful life of assets for capitalization	1 year
Depreciable life of various categories of fixed assets [Abstract]
Acquired in-place lease value, net	$ 1,400,000	$ 2,900,000
Number of communities held-for-sale | community	1	2
Revenues and Gains on Sale of Real Estate [Abstract]
Lease terms, minimum	6 months
Lease terms, maximum	12 months
Cash Equivalents and Restricted Cash [Abstract]
Original maturities of highly liquid investments to be classified as cash equivalents, maximum	3 months
Marketable Securities [Abstract]
Maturity date of investments in mortgage backed securities, first	November 2019	November 2019
Maturity date of investments in mortgage backed securities, final	September 2020	September 2020
Available-for-sale Securities [Abstract]
Available for sale - Carrying Value	$ 139,189,000	$ 137,485,000
Held-to-maturity Securities [Abstract]
Total marketable securities and other investments, amortized cost	137,715,000	130,335,000
Total marketable securities and other investments, gross unrealized gain	1,474,000	7,150,000
Total marketable securities and other investments, carrying value	139,189,000	137,485,000
Proceeds from sale of available-for-sale securities	30,500,000	3,300,000	$ 8,800,000
Gain on sale of available-for-sale securities	4,800,000	0	900,000
Sale of other investments	0	5,600,000	0
Gain on sale of other investments	600,000
Capitalization Policy [Abstract]
Capitalized internal costs related to development and redevelopment projects	18,500,000	17,600,000	17,600,000
Fair Value of Financial Instruments [Abstract]
Fixed rate debt carrying amount	5,100,000,000	4,800,000,000
Fixed rate debt fair value	5,100,000,000	4,800,000,000
Variable rate debt, carrying amount	499,700,000	525,300,000
Variable rate debt fair value	502,800,000	527,600,000
Mortgage backed securities fair value	$ 108,800,000	110,200,000
Investments, Owned, Federal Income Tax Note [Line Items]
Number of properties disposed | property	2
Deferred tax expense on gain on sale of real estate and land	$ (4,410,000)	0	0
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	6,237,733,000
Stockholders' equity, ending balance	$ 6,192,178,000	6,237,733,000
Number of consolidated co-investments that now meet the definition of a VIE | investment				9
Number of DownREIT limited partnerships the company consolidates | partnership	19
Number of communities within the DownREIT partnership | community	11
Assets related to variable interest entities, net intercompany eliminations	$ 989,300,000	893,100,000
Liabilities related to variable interest entities, net of intercompany eliminations	288,100,000	231,800,000
Noncontrolling interests in VIEs	$ 52,900,000	$ 54,600,000
Common Stock, Redemption Of Limited Partnership Interest, Shares Issuable Per Unit | shares	1
Total DownREIT units outstanding (in shares) | shares	952,140	963,172
Redemption value of the variable interest entities	$ 221,400,000	$ 230,600,000
Redeemable noncontrolling interest	44,684,000	45,452,000	23,256,000		$ 0
Noncontrolling interest in limited partnerships	18,600,000	18,400,000
Essex Portfolio, L.P. [Member]
Property, Plant and Equipment [Line Items]
Lines of credit	125,000,000	15,000,000
Prepaid expenses and other assets	48,450,000	41,730,000
Investments, Owned, Federal Income Tax Note [Line Items]
Deferred tax expense on gain on sale of real estate and land	(4,410,000)	0	$ 0
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Redeemable noncontrolling interest	$ 44,684,000	45,452,000
Computer software and equipment [Member] | Minimum [Member]
Depreciable life of various categories of fixed assets [Abstract]
Depreciable life, average	3 years
Computer software and equipment [Member] | Maximum [Member]
Depreciable life of various categories of fixed assets [Abstract]
Depreciable life, average	5 years
Interior apartment home improvements [Member]
Depreciable life of various categories of fixed assets [Abstract]
Depreciable life, average	5 years
Furniture, fixtures and equipment [Member] | Minimum [Member]
Depreciable life of various categories of fixed assets [Abstract]
Depreciable life, average	5 years
Furniture, fixtures and equipment [Member] | Maximum [Member]
Depreciable life of various categories of fixed assets [Abstract]
Depreciable life, average	10 years
Land improvements and certain exterior components of real property [Member]
Depreciable life of various categories of fixed assets [Abstract]
Depreciable life, average	10 years
Real estate structures [Member]
Depreciable life of various categories of fixed assets [Abstract]
Depreciable life, average	30 years
Investment-grade unsecured bonds [Member]
Available-for-sale Securities [Abstract]
Available for sale - Amortized Cost	$ 19,604,000	11,618,000
Available for sale - Gross Unrealized Gain (Loss)	(73,000)	68,000
Available for sale - Carrying Value	19,531,000	11,686,000
Investment funds - U.S. treasuries [Member]
Available-for-sale Securities [Abstract]
Available for sale - Amortized Cost	10,022,000	3,675,000
Available for sale - Gross Unrealized Gain (Loss)	(22,000)	(9,000)
Available for sale - Carrying Value	10,000,000	3,666,000
Common stock and stock funds [Member]
Available-for-sale Securities [Abstract]
Available for sale - Amortized Cost	13,696,000	34,655,000
Available for sale - Gross Unrealized Gain (Loss)	1,569,000	7,091,000
Available for sale - Carrying Value	15,265,000	41,746,000
Mortgage backed securities [Member]
Held-to-maturity Securities [Abstract]
Held to maturity - Amortized Cost	94,393,000	80,387,000
Held to maturity - Gross Unrealized Gain (Loss)	0	0
Held to maturity - Securities	$ 94,393,000	$ 80,387,000
Common stock and stock funds [Member]
Status of cash dividends distributed [Abstract]
Ordinary income (in hundredths)	86.68%	99.28%	70.03%
Capital gains (in hundredths)	7.11%	0.72%	21.95%
Unrecaptured section 1250 capital gain (in hundredths)	6.21%	0.00%	8.02%
Total cash dividends distributed (in hundredths)	100.00%	100.00%	100.00%
Series G and H Preferred Stock [Member]
Status of cash dividends distributed [Abstract]
Ordinary income (in hundredths)	86.68%	99.28%	70.03%
Capital gains (in hundredths)	7.11%	0.72%	21.95%
Unrecaptured section 1250 capital gain (in hundredths)	6.21%	0.00%	8.02%
Total cash dividends distributed (in hundredths)	100.00%	100.00%	100.00%
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	$ (42,011,000)
Other comprehensive income before reclassification	24,570,000
Amounts reclassified from accumulated other comprehensive loss	(14,657,000)
Other comprehensive income	9,913,000
Stockholders' equity, ending balance	(32,098,000)	$ (42,011,000)
Accumulated Other Comprehensive Income (Loss) [Member] | Essex Portfolio, L.P. [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(39,598,000)
Other comprehensive income before reclassification	25,406,000
Amounts reclassified from accumulated other comprehensive loss	(15,156,000)
Other comprehensive income	10,250,000
Stockholders' equity, ending balance	(29,348,000)	(39,598,000)
Change in fair value and amortization of swap settlements [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(48,366,000)
Other comprehensive income before reclassification	25,371,000
Amounts reclassified from accumulated other comprehensive loss	(9,968,000)
Other comprehensive income	15,403,000
Stockholders' equity, ending balance	(32,963,000)	(48,366,000)
Change in fair value and amortization of swap settlements [Member] | Essex Portfolio, L.P. [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	(46,087,000)
Other comprehensive income before reclassification	26,234,000
Amounts reclassified from accumulated other comprehensive loss	(10,308,000)
Other comprehensive income	15,926,000
Stockholders' equity, ending balance	(30,161,000)	(46,087,000)
Unrealized gains on available for sale securities [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	6,355,000
Other comprehensive income before reclassification	(801,000)
Amounts reclassified from accumulated other comprehensive loss	(4,689,000)
Other comprehensive income	(5,490,000)
Stockholders' equity, ending balance	865,000	6,355,000
Unrealized gains on available for sale securities [Member] | Essex Portfolio, L.P. [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Stockholders' equity, beginning balance	6,489,000
Other comprehensive income before reclassification	(828,000)
Amounts reclassified from accumulated other comprehensive loss	(4,848,000)
Other comprehensive income	(5,676,000)
Stockholders' equity, ending balance	$ 813,000	6,489,000
Accounting Standards Update 2015-03
Property, Plant and Equipment [Line Items]
Lines of credit		3,300,000
Prepaid expenses and other assets		$ (3,300,000)