Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) segment	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of reportable segments | segment			3
Number of operating segments | segment			3
Net operating income	$ 292,502	$ 286,819	$ 875,787	$ 833,655
Management and other fees from affiliates	2,785	2,886	8,328	8,313
Corporate-level property management expenses	(11,504)	(10,184)	(34,387)	(30,532)
Depreciation and amortization	(137,357)	(135,511)	(410,422)	(403,561)
General and administrative	(14,611)	(15,172)	(43,735)	(40,541)
Expensed acquisition and investment related costs	(31)	(230)	(375)	(248)
Casualty loss	0	0	(433)	0
Gain on sale of real estate and land	0	0	59,238	0
Interest expense	(54,161)	(51,645)	(157,806)	(152,499)
Total return swap income	690	1,882	2,544	6,709
Interest and other income (loss)	4,406	(6,796)	29,055	(31,571)
Equity income from co-investments	10,694	10,985	33,802	23,756
Tax (expense) benefit on unconsolidated co-investments	(404)	(1,755)	(1,237)	7,863
Loss on early retirement of debt, net	0	(2)	0	(2)
Gain on remeasurement of co-investment	0	17,423	0	17,423
Net income	93,009	98,700	360,359	238,765
Net reportable operating segment - real estate assets	10,545,386		10,545,386		$ 10,814,094
Real estate under development	23,067		23,067		24,857
Co-investments	1,133,515		1,133,515		1,127,491
Cash and cash equivalents, including restricted cash	400,497	53,569	400,497	53,569	42,681	$ 58,638
Marketable securities	90,186		90,186		112,743
Notes and other receivables	164,603		164,603		103,045
Operating lease right-of-use assets	64,636		64,636		67,239
Prepaid expenses and other assets	75,757		75,757		80,755
Total assets	12,497,647		12,497,647		12,372,905
Rental and Other Property Revenues
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	416,398	406,862	1,239,319	1,183,318
Management and other fees from affiliates
Revenues from External Customers and Long-Lived Assets [Line Items]
Management and other fees from affiliates	2,785	2,886	8,328	8,313
Operating Segments | Southern California
Revenues from External Customers and Long-Lived Assets [Line Items]
Net operating income	121,110	117,014	359,975	339,992
Net reportable operating segment - real estate assets	3,824,670		3,824,670		3,892,003
Operating Segments | Southern California | Rental and Other Property Revenues
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	172,139	164,954	508,873	479,102
Operating Segments | Northern California
Revenues from External Customers and Long-Lived Assets [Line Items]
Net operating income	116,958	113,401	347,594	331,636
Net reportable operating segment - real estate assets	5,282,972		5,282,972		5,414,467
Operating Segments | Northern California | Rental and Other Property Revenues
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	168,224	163,157	498,263	476,415
Operating Segments | Seattle Metro
Revenues from External Customers and Long-Lived Assets [Line Items]
Net operating income	49,611	48,816	149,894	141,380
Net reportable operating segment - real estate assets	1,345,028		1,345,028		1,374,379
Operating Segments | Seattle Metro | Rental and Other Property Revenues
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	70,631	69,054	210,885	200,964
Other real estate assets
Revenues from External Customers and Long-Lived Assets [Line Items]
Net operating income	4,823	7,588	18,324	20,647
Net reportable operating segment - real estate assets	92,716		92,716		$ 133,245
Other real estate assets | Rental and Other Property Revenues
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 5,404	$ 9,697	$ 21,298	$ 26,837