Reportable Segments - NOI from Our Rental Real Estate for Each Segment Specific to Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Rental income	$ 2,873,964	$ 2,735,180	$ 2,463,997
Operating expenses	926,689	872,277	850,637
Operating income	1,947,275	1,862,903	1,613,360
Operating income	1,160,585	1,116,046	1,675,841
Total Assets	20,034,564	20,218,262
Capital Expenditures	319,342	221,086
Same Store
Segment Reporting Information [Line Items]
Rental income	2,754,711	2,609,766	2,291,604
Operating expenses	873,448	837,602	774,504
Operating income	1,881,263	1,772,164	1,517,100
Total Assets	17,790,858	18,314,739
Capital Expenditures	282,845	204,135
Non-same store/other
Segment Reporting Information [Line Items]
Rental income	119,253	125,414	172,393
Operating expenses	53,241	34,675	76,133
Operating income	66,012	90,739	96,260
Total Assets	2,243,706	1,903,523
Capital Expenditures	36,497	16,951
Los Angeles | Same Store
Segment Reporting Information [Line Items]
Rental income	466,980	450,635	431,954
Operating expenses	143,983	132,858	132,274
Operating income	322,997	317,777	299,680
Total Assets	2,489,180	2,549,606
Capital Expenditures	54,688	35,057
Orange County | Same Store
Segment Reporting Information [Line Items]
Rental income	130,343	122,660	109,427
Operating expenses	28,699	26,511	24,986
Operating income	101,644	96,149	84,441
Total Assets	343,219	356,396
Capital Expenditures	9,888	7,885
San Diego | Same Store
Segment Reporting Information [Line Items]
Rental income	92,691	86,728	78,709
Operating expenses	20,602	19,506	18,395
Operating income	72,089	67,222	60,314
Total Assets	231,549	228,471
Capital Expenditures	17,137	8,798
Subtotal - Southern California | Same Store
Segment Reporting Information [Line Items]
Rental income	690,014	660,023	620,090
Operating expenses	193,284	178,875	175,655
Operating income	496,730	481,148	444,435
Total Assets	3,063,948	3,134,473
Capital Expenditures	81,713	51,740
Washington D.C. | Same Store
Segment Reporting Information [Line Items]
Rental income	441,676	417,210	389,205
Operating expenses	140,696	138,570	129,065
Operating income	300,980	278,640	260,140
Total Assets	2,995,509	3,091,996
Capital Expenditures	50,504	34,640
San Francisco | Same Store
Segment Reporting Information [Line Items]
Rental income	430,390	415,173	383,817
Operating expenses	129,480	124,192	118,795
Operating income	300,910	290,981	265,022
Total Assets	2,972,476	3,049,771
Capital Expenditures	53,963	33,497
New York | Same Store
Segment Reporting Information [Line Items]
Rental income	476,319	434,820	367,370
Operating expenses	193,311	187,218	182,631
Operating income	283,008	247,602	184,739
Total Assets	3,326,831	3,421,373
Capital Expenditures	21,908	21,636
Seattle | Same Store
Segment Reporting Information [Line Items]
Rental income	290,894	281,959	256,988
Operating expenses	81,787	79,037	80,775
Operating income	209,107	202,922	176,213
Total Assets	2,075,966	2,141,346
Capital Expenditures	34,011	27,935
Boston | Same Store
Segment Reporting Information [Line Items]
Rental income	289,423	270,899	235,050
Operating expenses	85,579	82,523	76,374
Operating income	203,844	188,376
Operating income			158,676
Total Assets	1,748,887	1,807,629
Capital Expenditures	30,852	23,951
Denver | Same Store
Segment Reporting Information [Line Items]
Rental income	71,067	67,785	39,084
Operating expenses	21,328	19,569	11,209
Operating income	49,739	48,216	27,875
Total Assets	824,264	857,021
Capital Expenditures	4,220	8,561
Other Expansion Markets | Same Store
Segment Reporting Information [Line Items]
Rental income	64,928	61,897
Operating expenses	27,983	27,618
Operating income	36,945	34,279
Total Assets	782,977	811,130
Capital Expenditures	5,674	2,175
Non-same store | Non-same store/other
Segment Reporting Information [Line Items]
Rental income	100,970	74,379	59,629
Operating expenses	36,836	29,758	27,691
Operating income	64,134	44,621	31,938
Total Assets	1,493,139	1,134,000
Capital Expenditures	35,615	15,277
Other | Non-same store/other
Segment Reporting Information [Line Items]
Rental income	18,283	51,035	112,764
Operating expenses	(16,405)	4,917	48,442
Operating income	1,878	46,118	$ 64,322
Total Assets	750,567	769,523
Capital Expenditures	$ 882	$ 1,674