Revenues - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) community	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) community	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Disaggregation of Revenue [Line Items]
Rental and other property	$ 397,240	$ 348,757	$ 776,456	$ 701,633
Management and other fees from affiliates	2,738	2,221	5,427	4,470
Revenues	$ 399,978	350,978	$ 781,883	706,103
Occupancy threshold for classification as stabilized	90.00%		90.00%
Apartment communities owned (in communities) | community	253		253
Deferred revenue	$ 2,100		$ 2,100		$ 2,400
Deferred revenue, revenue recognized			300
Deferred revenue balance from contracts with remaining performance obligations	2,100		2,100
Rental income
Disaggregation of Revenue [Line Items]
Rental and other property	391,778	343,322	765,203	690,627
Other property
Disaggregation of Revenue [Line Items]
Rental and other property	5,462	5,435	11,253	11,006
Rental and other property revenues
Disaggregation of Revenue [Line Items]
Rental and other property	397,240	348,757	776,456	701,633
Rental and other property revenues | Same-property
Disaggregation of Revenue [Line Items]
Rental and other property	373,331	331,221	729,604	665,658
Rental and other property revenues | Acquisitions
Disaggregation of Revenue [Line Items]
Rental and other property	1,753	319	3,500	319
Rental and other property revenues | Development
Disaggregation of Revenue [Line Items]
Rental and other property	11,184	7,500	20,611	14,430
Rental and other property revenues | Redevelopment
Disaggregation of Revenue [Line Items]
Rental and other property	1,491	1,506	2,926	3,138
Rental and other property revenues | Non-residential/other, net
Disaggregation of Revenue [Line Items]
Rental and other property	$ 12,748	11,156	$ 25,666	24,402
Apartment communities owned (in communities) | community	2		2
Rental and other property revenues | Straight line rent concession
Disaggregation of Revenue [Line Items]
Rental and other property	$ (3,267)	(2,945)	$ (5,851)	(6,314)
Rental and other property revenues | Operating Segments | Southern California
Disaggregation of Revenue [Line Items]
Rental and other property	164,511	142,150	321,480	284,119
Rental and other property revenues | Operating Segments | Northern California
Disaggregation of Revenue [Line Items]
Rental and other property	160,498	143,386	313,088	290,076
Rental and other property revenues | Operating Segments | Seattle Metro
Disaggregation of Revenue [Line Items]
Rental and other property	67,707	59,267	131,910	117,900
Rental and other property revenues | Other real estate assets
Disaggregation of Revenue [Line Items]
Rental and other property	$ 4,524	$ 3,954	$ 9,978	$ 9,538