Organization and Basis of Presentation - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023 USD ($) community partnership building apartment project investment shares	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) community partnership building apartment project investment shares	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($) investment partnership community shares
Real Estate Properties [Line Items]
Apartment communities owned (in communities) | community	252		252
Apartment units owned (in apartments) | apartment	61,997		61,997
Ownership interest, number of commercial buildings (in commercial buildings) | building	3		3
Ownership interest, number of unconsolidated joint venture projects (in projects) | project	1		1
Marketable securities	$ 100		$ 100		$ 200
DownREIT limited partnerships consolidated by company (in partnerships) | partnership	18		18		18
Communities within DownREIT partnerships (in communities) | community	9		9		9
Number of previously consolidated co-investments considered VIE (in investments) | investment	6		6		6
Assets related to variable interest entities net of intercompany eliminations	$ 954,400		$ 954,400		$ 939,400
Liabilities related to variable interest entities net of intercompany eliminations	327,600		327,600		324,300
Noncontrolling interest in variable interest entity	121,100		121,100		121,500
Fixed rate debt carrying amount	5,700,000		5,700,000		5,700,000
Fixed rate debt fair value	5,100,000		5,100,000		5,200,000
Variable rate debt, carrying amount	520,100		520,100		274,200
Variable rate debt fair value	519,200		519,200		273,200
Capitalized internal costs related to development and redevelopment projects	5,000	$ 4,500	14,400	$ 15,700
Redeemable noncontrolling interest	29,960		29,960		$ 27,150
Interest and Other Income (Expense)
Real Estate Properties [Line Items]
Unrealized gain (loss) on equity securities recognized through income	$ (4,600)	$ (7,800)	$ (700)	$ (30,600)
Minimum
Real Estate Properties [Line Items]
Apartment lease term	9 months		9 months
Maximum
Real Estate Properties [Line Items]
Apartment lease term	12 months		12 months
Essex Portfolio, L.P.
Real Estate Properties [Line Items]
Operating partnership units outstanding (in shares) | shares	2,258,812		2,258,812		2,272,496
Redemption value of operating partnership units outstanding	$ 479,100		$ 479,100		$ 481,600
Redeemable noncontrolling interest	$ 29,960		$ 29,960		$ 27,150
Partnership Interest
Real Estate Properties [Line Items]
Ownership interest in partnership			96.60%		96.60%