Significant Transactions During The Nine Months Ended September 30, 2020 and Subsequent Events (Details)		1 Months Ended								3 Months Ended				9 Months Ended
	Sep. 30, 2020 USD ($) apartment	Oct. 31, 2020 USD ($) apartment investment	Sep. 30, 2020 USD ($)	Aug. 31, 2020 USD ($)	Jul. 31, 2020 USD ($) apartment	Jun. 30, 2020 USD ($) community	Apr. 30, 2020 USD ($) extension	Mar. 31, 2020 USD ($)	Jan. 31, 2020 USD ($) apartment community	Sep. 30, 2020 USD ($) shares	Jun. 30, 2020 USD ($) shares	Mar. 31, 2020 USD ($) investment shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 community	Sep. 30, 2020 apartment	May 31, 2020 USD ($)	Feb. 29, 2020 USD ($)
Other Commitments [Line Items]
Gain on remeasurement of co-investment										$ 0			$ 0	$ 234,694,000	$ 31,535,000
Revenue from disposition										2,347,000			2,428,000	7,312,000	7,023,000
Number of apartment units | apartment	115
Apartment communities owned (in communities)																247	1
Number of preferred equity method investments | investment												2
Commitments to acquire equity method investment										$ 10,500,000		$ 91,400,000
Preferred return rate										11.00%		11.30%
Funding amount to commitment of investment in mezzanine loan														20,431,000	140,663,000
Prepayment penalties														19,605,000	0
Senior Notes | 2032 Notes
Other Commitments [Line Items]
Debt issued						$ 150,000,000.0					$ 150,000,000.0
Debt offering price, percentage of par value						105.66%					105.66%
Reoffer yield percentage						2.093%
Senior Notes | 2031 Notes
Other Commitments [Line Items]
Debt offering price, percentage of par value				99.035%
Senior Notes | 2050 Notes
Other Commitments [Line Items]
Debt offering price, percentage of par value				99.691%
Senior Notes | 2022 Notes
Other Commitments [Line Items]
Debt issued				$ 300,000,000.0
Debt coupon rate				3.625%
Prepayment penalties				$ 19,100,000
Unsecured Term Loan
Other Commitments [Line Items]
Debt issued							$ 200,000,000.0
Number of extension options (in extensions) | extension							2
Extension period							12 months
Common Stock
Other Commitments [Line Items]
Shares repurchased during period (in shares) | shares										121,260	87,988	776,261
Shares repurchased during period, value										$ 26,600,000	$ 20,100,000	$ 176,300,000
Purchase authority remaining under stock repurchase plan	$ 203,300,000		$ 203,300,000							203,300,000				203,300,000
Stock repurchase plan amount	250,000,000.0		250,000,000.0							250,000,000.0				250,000,000.0				$ 250,000,000.0
CPPIB interest
Other Commitments [Line Items]
Investment interest acquired									45.00%
Value of property held by acquired investment									$ 1,000,000,000.0
Gain on remeasurement of co-investment									234,700,000
Promote income									6,500,000
Joint venture that holds property in Los Angeles, CA
Other Commitments [Line Items]
Proceeds from partial redemption of co-investment								$ 11,300,000
Early redemption fee								200,000
Preferred Equity Investment Property In Southern California
Other Commitments [Line Items]
Proceeds from partial redemption of co-investment			$ 10,600,000
Property Located in Anaheim, California
Other Commitments [Line Items]
Proceeds from redemption of notes receivable									$ 16,900,000
Multifamily Development Communities in Los Angeles, California
Other Commitments [Line Items]
Notes receivable, commitment to fund, amount								$ 15,000,000.0				$ 15,000,000.0
Notes receivable, interest rate								10.50%				10.50%
Notes receivable, term of extension option								2 years
Funding amount to commitment of investment in mezzanine loan	7,500,000
Multifamily Development Communities in Sacramento, California
Other Commitments [Line Items]
Notes receivable, commitment to fund, amount							$ 29,200,000
Notes receivable, interest rate							11.00%
Notes receivable, term of extension option							2 years
Funding amount to commitment of investment in mezzanine loan	$ 12,900,000
Apartment Building | CPPIB interest
Other Commitments [Line Items]
Number of communities held by acquired investment | community									6
Number of units held by acquired investment | apartment									2,020
Essex Portfolio, L.P.
Other Commitments [Line Items]
Gain on remeasurement of co-investment										0			0	234,694,000	31,535,000
Revenue from disposition										$ 2,347,000			$ 2,428,000	7,312,000	7,023,000
Funding amount to commitment of investment in mezzanine loan														20,431,000	140,663,000
Prepayment penalties														$ 19,605,000	$ 0
Essex Portfolio, L.P. | Senior Notes
Other Commitments [Line Items]
Debt issued				600,000,000.0
Essex Portfolio, L.P. | Senior Notes | 2032 Notes
Other Commitments [Line Items]
Debt issued																			$ 500,000,000.0
Debt coupon rate																			2.65%
Debt offering price, percentage of par value																			99.628%
Repayments of secured debt												$ 100,300,000
Essex Portfolio, L.P. | Senior Notes | 2031 Notes
Other Commitments [Line Items]
Debt issued				$ 300,000,000.0
Debt coupon rate				1.65%
Essex Portfolio, L.P. | Senior Notes | 2050 Notes
Other Commitments [Line Items]
Debt issued				$ 300,000,000.0
Debt coupon rate				2.65%
Affiliated Entity | Related party bridge loan - Wesco V
Other Commitments [Line Items]
Proceeds from redemption of notes receivable									$ 85,800,000
LIBOR | Unsecured Term Loan
Other Commitments [Line Items]
Basis spread on variable rate							1.20%
One South Market and Museum Park
Other Commitments [Line Items]
Revenue from disposition						$ 232,000,000.0
Gain (loss) on sale of properties						$ 16,600,000
One South Market and Museum Park | Apartment Building
Other Commitments [Line Items]
Number of units sold | community						2
Delano, Redmond, WA
Other Commitments [Line Items]
Revenue from disposition					$ 51,500,000
Gain (loss) on sale of properties					$ 22,700,000
Delano, Redmond, WA | Apartment Building
Other Commitments [Line Items]
Number of apartment units | apartment					126
Subsequent Event
Other Commitments [Line Items]
Number of preferred equity method investments | investment		2
Commitments to acquire equity method investment		$ 46,800,000
Preferred return rate		10.20%
Subsequent Event | Glendale, CA
Other Commitments [Line Items]
Revenue from disposition		$ 60,000,000.0
Subsequent Event | Glendale, CA | Apartment Building
Other Commitments [Line Items]
Number of apartment units | apartment		115