Reportable Segments - NOI from Our Rental Real Estate for Each Segment Specific to Continuing Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Rental income	$ 2,463,997	$ 2,571,705	$ 2,700,691
Operating income	1,675,841	1,317,990	1,356,160
Total Assets	21,169,241	20,286,891
Same Store
Segment Reporting Information [Line Items]
Rental income	2,342,257	2,425,025	2,519,235
Operating expenses	803,995	780,381	757,502
Operating income	1,538,262	1,644,644	1,761,733
Total Assets	17,810,840	18,433,017
Capital Expenditures	147,388	131,238
Non-same store/other
Segment Reporting Information [Line Items]
Rental income	121,740	146,680	181,456
Operating expenses	46,642	42,179	55,482
Operating income	75,098	104,501	125,974
Total Assets	3,358,401	1,853,874
Capital Expenditures	3,631	4,741
Same Store, Non-same Store and Other
Segment Reporting Information [Line Items]
Rental income	2,463,997	2,571,705	2,700,691
Operating expenses	850,637	822,560	812,984
Operating income	1,613,360	1,749,145	1,887,707
Total Assets	21,169,241	20,286,891
Capital Expenditures	151,019	135,979
Other markets | Same Store
Segment Reporting Information [Line Items]
Rental income	39,084	37,917	18,215
Operating expenses	11,209	11,040	4,713
Operating income	27,875	26,877	13,502
Los Angeles | Same Store
Segment Reporting Information [Line Items]
Rental income	447,094	444,129	485,084
Operating expenses	141,636	140,469	144,314
Operating income	305,458	303,660	340,770
Total Assets	2,792,948	2,905,404
Capital Expenditures	21,507	21,537
Subtotal - Southern California | Same Store
Segment Reporting Information [Line Items]
Rental income	635,230	624,102	663,869
Operating expenses	185,018	183,190	186,562
Operating income	450,212	440,912	477,307
Total Assets	3,396,356	3,536,840
Capital Expenditures	30,053	32,227
Orange County | Same Store
Segment Reporting Information [Line Items]
Rental income	109,427	105,236	105,087
Operating expenses	24,986	24,545	24,359
Operating income	84,441	80,691	80,728
Total Assets	371,063	389,007
Capital Expenditures	5,647	7,260
San Diego | Same Store
Segment Reporting Information [Line Items]
Rental income	78,709	74,737	73,698
Operating expenses	18,396	18,176	17,889
Operating income	60,313	56,561	55,809
Total Assets	232,345	242,429
Capital Expenditures	2,899	3,430
Washington D.C. | Same Store
Segment Reporting Information [Line Items]
Rental income	393,374	405,571	394,171
Operating expenses	130,445	125,353	119,419
Operating income	262,929	280,218	274,752
Total Assets	3,177,162	3,291,760
Capital Expenditures	27,148	23,637
New York | Same Store
Segment Reporting Information [Line Items]
Rental income	405,830	424,534	464,270
Operating expenses	202,954	197,740	191,514
Operating income	202,876	226,794	272,756
Total Assets	3,897,202	4,000,355
Capital Expenditures	29,623	25,716
San Francisco | Same Store
Segment Reporting Information [Line Items]
Rental income	391,022	435,371	473,102
Operating expenses	121,134	117,085	115,702
Operating income	269,888	318,286	357,400
Total Assets	3,195,089	3,310,083
Capital Expenditures	22,416	18,091
Boston | Same Store
Segment Reporting Information [Line Items]
Rental income	232,233	240,158	253,297
Operating expenses	75,698	71,611	70,875
Operating income	156,535	168,547	182,422
Total Assets	1,694,432	1,758,665
Capital Expenditures	21,095	18,367
Seattle | Same Store
Segment Reporting Information [Line Items]
Rental income	245,484	257,372	252,311
Operating expenses	77,537	74,362	68,717
Operating income	167,947	183,010	183,594
Total Assets	1,958,145	2,023,183
Capital Expenditures	15,038	11,621
Non-same store | Non-same store/other
Segment Reporting Information [Line Items]
Rental income	51,604	11,791	58,751
Operating expenses	21,296	2,706	17,702
Operating income	30,308	9,085	41,049
Total Assets	2,512,611	671,216
Capital Expenditures	1,704	73
Other [Member] | Non-same store/other
Segment Reporting Information [Line Items]
Rental income	70,136	134,889	122,705
Operating expenses	25,346	39,473	37,780
Operating income	44,790	95,416	$ 84,925
Total Assets	845,790	1,182,658
Capital Expenditures	1,927	4,668
Denver | Same Store
Segment Reporting Information [Line Items]
Total Assets	492,454	512,131
Capital Expenditures	$ 2,015	$ 1,579