Revenues - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($) community	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) community	Sep. 30, 2022 USD ($)
Disaggregation of Revenue [Line Items]
Rental and other property	$ 416,398	$ 406,862	$ 1,239,319	$ 1,183,318
Management and other fees from affiliates	2,785	2,886	8,328	8,313
Revenues	$ 419,183	409,748	$ 1,247,647	1,191,631
Apartment communities owned (in communities) | community	252		252
Rental income
Disaggregation of Revenue [Line Items]
Rental and other property	$ 410,438	401,467	$ 1,222,859	1,166,670
Other property
Disaggregation of Revenue [Line Items]
Rental and other property	5,960	5,395	16,460	16,648
Rental and other property revenues
Disaggregation of Revenue [Line Items]
Rental and other property	416,398	406,862	1,239,319	1,183,318
Rental and other property revenues | Same-property
Disaggregation of Revenue [Line Items]
Rental and other property	$ 398,460	386,200	$ 1,181,559	1,126,489
Occupancy threshold for classification as stabilized	90.00%		90.00%
Rental and other property revenues | Acquisitions
Disaggregation of Revenue [Line Items]
Rental and other property	$ 1,528	675	$ 3,881	675
Rental and other property revenues | Development
Disaggregation of Revenue [Line Items]
Rental and other property	5,808	5,410	17,018	15,008
Rental and other property revenues | Redevelopment
Disaggregation of Revenue [Line Items]
Rental and other property	1,564	1,422	4,696	4,348
Rental and other property revenues | Non-residential/other, net
Disaggregation of Revenue [Line Items]
Rental and other property	$ 10,432	14,783	$ 33,658	44,403
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	$ (1,394)	(1,628)	$ (1,493)	(7,605)
Rental and other property revenues | Operating Segments | Southern California
Disaggregation of Revenue [Line Items]
Rental and other property	172,139	164,954	508,873	479,102
Rental and other property revenues | Operating Segments | Northern California
Disaggregation of Revenue [Line Items]
Rental and other property	168,224	163,157	498,263	476,415
Rental and other property revenues | Operating Segments | Seattle Metro
Disaggregation of Revenue [Line Items]
Rental and other property	70,631	69,054	210,885	200,964
Rental and other property revenues | Other real estate assets
Disaggregation of Revenue [Line Items]
Rental and other property	$ 5,404	$ 9,697	$ 21,298	$ 26,837