Organization and Basis of Presentation - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2026 USD ($) building investment project community apartment partnership shares	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($) community partnership investment shares
Real Estate Properties [Line Items]
Apartment communities owned (in communities) | community	259
Apartment units owned (in apartments) | apartment	63,099
Ownership interest, number of commercial buildings (in commercial buildings) | building	2
Development pipeline consisting of consolidated project | project	1
Marketable securities (less than)	$ 100		$ 100
DownREIT limited partnerships consolidated by company (in partnerships) | partnership	18		18
Communities within DownREIT partnerships (in communities) | community	10		10
Number of previously consolidated co-investments considered VIE (in investments) | investment	4		4
Assets related to variable interest entities net of intercompany eliminations	$ 979,600		$ 970,600
Liabilities related to variable interest entities net of intercompany eliminations	243,800		242,500
Noncontrolling interest in variable interest entity	101,200		101,200
Fixed rate debt carrying amount	5,900,000		5,900,000
Fixed rate debt fair value	5,700,000		5,800,000
Variable rate debt, carrying amount	859,200		854,400
Variable rate debt fair value	857,600		853,200
Capitalized internal costs related to development and redevelopment projects	6,700	$ 6,200
Redeemable noncontrolling interest	$ 25,788		$ 28,263
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	2,184,025		2,250,339
Redemption value of operating partnership units outstanding	$ 528,500		$ 588,900
Redeemable noncontrolling interest	$ 25,788		$ 28,263
Partnership Interest
Real Estate Properties [Line Items]
Ownership interest in partnership	96.70%		96.60%