Reportable Segments - NOI from Our Rental Real Estate for Each Segment Specific to Continuing Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Rental income	$ 724,067	$ 695,099	$ 2,146,464	$ 2,035,477
Operating expenses	231,945	224,409	704,044	668,176
NOI	492,122	470,690	1,442,420	1,367,301
Total Assets	20,108,975		20,108,975		$ 20,218,262
Capital Expenditures			229,763
Same Store
Segment Reporting Information [Line Items]
Rental income	704,090	676,387	2,069,856	1,949,748
Operating expenses	223,474	216,735	664,607	631,281
NOI	480,616	459,652	1,405,249	1,318,467
Total Assets	17,921,347		17,921,347
Capital Expenditures			202,207
Non-same store/other
Segment Reporting Information [Line Items]
Rental income	19,977	18,712	76,608	85,729
Operating expenses	8,471	7,674	39,437	36,895
NOI	11,506	11,038	37,171	48,834
Total Assets	2,187,628		2,187,628
Capital Expenditures			27,556
Los Angeles | Same Store
Segment Reporting Information [Line Items]
Rental income	121,098	116,770	355,341	344,579
Operating expenses	36,839	34,198	110,436	101,441
NOI	84,259	82,572	244,905	243,138
Total Assets	2,509,235		2,509,235
Capital Expenditures			38,810
Orange County | Same Store
Segment Reporting Information [Line Items]
Rental income	33,019	31,252	96,923	91,270
Operating expenses	7,316	6,792	21,689	19,804
NOI	25,703	24,460	75,234	71,466
Total Assets	345,945		345,945
Capital Expenditures			6,611
San Diego | Same Store
Segment Reporting Information [Line Items]
Rental income	25,258	23,860	68,904	64,540
Operating expenses	5,803	5,634	15,586	14,646
NOI	19,455	18,226	53,318	49,894
Total Assets	230,902		230,902
Capital Expenditures			12,921
Subtotal - Southern California | Same Store
Segment Reporting Information [Line Items]
Rental income	179,375	171,882	521,168	500,389
Operating expenses	49,958	46,624	147,711	135,891
NOI	129,417	125,258	373,457	364,498
Total Assets	3,086,082		3,086,082
Capital Expenditures			58,342
San Francisco | Same Store
Segment Reporting Information [Line Items]
Rental income	109,215	106,382	325,335	312,401
Operating expenses	32,782	32,025	98,848	93,778
NOI	76,433	74,357	226,487	218,623
Total Assets	3,006,656		3,006,656
Capital Expenditures			36,261
Washington D.C. | Same Store
Segment Reporting Information [Line Items]
Rental income	114,748	108,667	329,196	310,071
Operating expenses	36,521	37,073	106,687	104,515
NOI	78,227	71,594	222,509	205,556
Total Assets	3,023,064		3,023,064
Capital Expenditures			39,086
New York | Same Store
Segment Reporting Information [Line Items]
Rental income	118,326	112,595	356,157	318,757
Operating expenses	48,555	46,755	146,415	140,696
NOI	69,771	65,840	209,742	178,061
Total Assets	3,328,321		3,328,321
Capital Expenditures			16,248
Seattle | Same Store
Segment Reporting Information [Line Items]
Rental income	73,351	73,096	220,353	211,040
Operating expenses	21,575	20,258	62,621	59,858
NOI	51,776	52,838	157,732	151,182
Total Assets	2,092,677		2,092,677
Capital Expenditures			23,176
Boston | Same Store
Segment Reporting Information [Line Items]
Rental income	72,541	69,029	215,667	200,808
Operating expenses	20,773	20,860	64,156	61,934
NOI	51,768	48,169	151,511	138,874
Total Assets	1,762,350		1,762,350
Capital Expenditures			22,430
Denver | Same Store
Segment Reporting Information [Line Items]
Rental income	17,855	17,219	53,324	50,284
Operating expenses	5,384	5,132	15,883	14,463
NOI	12,471	12,087	37,441	35,821
Total Assets	832,017		832,017
Capital Expenditures			2,547
Other Expansion Markets | Same Store
Segment Reporting Information [Line Items]
Rental income	18,679	17,517	48,656	45,998
Operating expenses	7,926	8,008	22,286	20,146
NOI	10,753	9,509	26,370	25,852
Total Assets	790,180		790,180
Capital Expenditures			4,117
Non-same store | Non-same store/other
Segment Reporting Information [Line Items]
Rental income	19,035	13,343	70,736	53,449
Operating expenses	7,279	4,544	26,946	22,429
NOI	11,756	8,799	43,790	31,020
Total Assets	1,502,692		1,502,692
Capital Expenditures			27,291
Other | Non-same store/other
Segment Reporting Information [Line Items]
Rental income	942	5,369	5,872	32,280
Operating expenses	1,192	3,130	12,491	14,466
NOI	(250)	$ 2,239	(6,619)	$ 17,814
Total Assets	$ 684,936		684,936
Capital Expenditures			$ 265