Organization and Basis of Presentation - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) community building project partnership apartment investment shares	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) shares
Real Estate Properties [Line Items]
Apartment communities owned (in communities) | community	253
Apartment units owned (in apartments) | apartment	62,290
Ownership interest, number of commercial buildings (in commercial buildings) | building	3
Ownership interest, number of consolidated projects (in projects) | project	1
Ownership interest, number of unconsolidated joint venture projects (in projects) | project	1
Equity securities	$ 800		$ 800
Sales and maturities of marketable securities	27,900	$ 14,800
Marketable securities, realized gain (loss)	12,200	2,600
Unrealized gain (loss) on equity securities recognized through income	$ (24,585)	6,276
DownREIT limited partnerships consolidated by company (in partnerships) | partnership	18
Communities within DownREIT partnerships (in communities) | community	9
Number of previously consolidated co-investments considered VIE (in investments) | investment	6
Assets related to variable interest entities net of intercompany eliminations	$ 900,600		909,300
Liabilities related to variable interest entities net of intercompany eliminations	323,700		320,100
Noncontrolling interest in variable interest entity	122,500		122,400
Fixed rate debt carrying amount	5,700,000		5,700,000
Fixed rate debt fair value	5,600,000		6,000,000
Variable rate debt, carrying amount	321,400		564,900
Variable rate debt fair value	319,400		561,700
Capitalized internal costs related to development and redevelopment projects	5,400	6,400
Redeemable noncontrolling interest	$ 39,738		$ 34,666
Minimum
Real Estate Properties [Line Items]
Apartment lease term	9 months
Maximum
Real Estate Properties [Line Items]
Apartment lease term	12 months
Interest And Other Income (Expense)
Real Estate Properties [Line Items]
Unrealized gain (loss) on equity securities recognized through income	$ (24,600)	6,300
Essex Portfolio, L.P.
Real Estate Properties [Line Items]
Operating Partnership units outstanding (in shares) | shares	2,282,464		2,282,464
Redemption value of operating partnership units outstanding	$ 788,500		$ 804,000
Unrealized gain (loss) on equity securities recognized through income	(24,585)	$ 6,276
Redeemable noncontrolling interest	$ 39,738		$ 34,666
Partnership Interest
Real Estate Properties [Line Items]
Ownership interest in partnership	96.60%		96.60%