Organization and Basis of Presentation - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2024 USD ($) community investment building apartment partnership shares	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) community partnership investment shares
Real Estate Properties [Line Items]
Apartment communities owned (in communities) | community	253
Apartment units owned (in apartments) | apartment	62,271
Ownership interest, number of commercial buildings (in commercial buildings) | building	3
Marketable securities	$ 100		$ 100
DownREIT limited partnerships consolidated by company (in partnerships) | partnership	18		18
Communities within DownREIT partnerships (in communities) | community	9		9
Number of previously consolidated co-investments considered VIE (in investments) | investment	6		6
Assets related to variable interest entities net of intercompany eliminations	$ 963,500		$ 956,700
Liabilities related to variable interest entities net of intercompany eliminations	326,100		324,500
Noncontrolling interest in variable interest entity	121,000		121,100
Fixed rate debt carrying amount	6,000,000		5,700,000
Fixed rate debt fair value	5,600,000		5,300,000
Variable rate debt, carrying amount	520,000		520,000
Variable rate debt fair value	518,800		519,000
Capitalized internal costs related to development and redevelopment projects	5,300	$ 4,800
Redeemable noncontrolling interest	32,192		$ 32,205
Gain contingencies from legal settlements	$ 42,500	$ 7,700
Minimum
Real Estate Properties [Line Items]
Apartment lease term	9 months
Maximum
Real Estate Properties [Line Items]
Apartment lease term	12 months
Essex Portfolio, L.P.
Real Estate Properties [Line Items]
Operating partnership units outstanding (in shares) | shares	2,258,812		2,258,812
Redemption value of operating partnership units outstanding	$ 553,000		$ 560,000
Redeemable noncontrolling interest	$ 32,192		$ 32,205
Partnership Interest
Real Estate Properties [Line Items]
Ownership interest in partnership	96.60%		96.60%