Revenues - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) community	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) community	Jun. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Disaggregation of Revenue [Line Items]
Rental and other property	$ 348,757	$ 368,149	$ 701,633	$ 757,899
Management and other fees from affiliates	2,221	2,348	4,470	4,965
Total revenues	$ 350,978	370,497	$ 706,103	762,864
Occupancy threshold for classification as stabilized	90.00%		90.00%
Apartment communities owned (in communities) | community	246		246
Deferred revenue	$ 2,800		$ 2,800		$ 3,100
Deferred revenue, revenue recognized			300
Deferred revenue balance from contracts with remaining performance obligations	2,800		2,800
Rental income
Disaggregation of Revenue [Line Items]
Rental and other property	343,322	363,087	690,627	746,585
Other property
Disaggregation of Revenue [Line Items]
Rental and other property	5,435	5,062	11,006	11,314
Rental and other property revenues
Disaggregation of Revenue [Line Items]
Rental and other property	348,757	368,149	701,633	757,899
Rental and other property revenues | Same-property
Disaggregation of Revenue [Line Items]
Rental and other property	314,949	324,654	632,755	670,306
Rental and other property revenues | Acquisitions
Disaggregation of Revenue [Line Items]
Rental and other property	13,948	13,696	27,621	26,254
Rental and other property revenues | Development
Disaggregation of Revenue [Line Items]
Rental and other property	7,500	4,420	14,430	8,495
Rental and other property revenues | Redevelopment
Disaggregation of Revenue [Line Items]
Rental and other property	4,149	5,096	8,739	10,497
Rental and other property revenues | Non-residential/other, net
Disaggregation of Revenue [Line Items]
Rental and other property	$ 11,156	17,308	$ 24,402	39,372
Apartment communities owned (in communities) | community	3		3
Rental and other property revenues | Straight line rent concession
Disaggregation of Revenue [Line Items]
Rental and other property	$ (2,945)	2,975	$ (6,314)	2,975
Rental and other property revenues | Operating Segments | Southern California
Disaggregation of Revenue [Line Items]
Rental and other property	143,230	140,510	286,242	292,405
Rental and other property revenues | Operating Segments | Northern California
Disaggregation of Revenue [Line Items]
Rental and other property	143,386	152,118	290,076	310,574
Rental and other property revenues | Operating Segments | Seattle Metro
Disaggregation of Revenue [Line Items]
Rental and other property	59,267	60,649	117,900	123,693
Rental and other property revenues | Other real estate assets
Disaggregation of Revenue [Line Items]
Rental and other property	$ 2,874	$ 14,872	$ 7,415	$ 31,227