Schedule III - Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				$ 3,809,643
Initial cost to company, Land				2,018,805
Initial cost to company, Building and Improvements				5,525,242
Costs capitalized subsequent to acquisition, Land				(16,380)
Costs capitalized subsequent to acquisition, Building and Improvements				456,469
Gross amount at which carried at close of period, Land				2,002,425
Gross amount at which carried at close of period, Buildings and Improvements				5,981,711
Gross amount at which carried at close of period, Total	$ 8,101,651	$ 8,329,475	$ 7,849,093	7,984,136
Accumulated depreciation and amortization	(644,639)	(487,945)	(318,161)	(790,216)
Costs capitalized subsequent to acquisition, Building and Improvements, other				6,648
Gross amount at which carried at close of period, Buildings and Improvements, other				6,648
Gross amount at which carried at close of period, other				6,648
Accumulated depreciation and amortization, other	$ (2,110)
Date acquired, other	Nov. 24, 2014
Real Estate:
Beginning balance	$ 8,101,651	8,329,475	7,849,093
Acquisitions			484,916
Buildings and improvements	105,947	146,378	82,862
Real estate impairment loss	(42,000)	(46,000)
Assets sold and written-off	(181,462)	(328,202)	(87,396)
Ending balance	7,984,136	8,101,651	8,329,475
Accumulated Depreciation:
Beginning balance	644,639	487,945	318,161
Additions charged to expense	186,457	188,871	182,732
Accumulated depreciation related to assets sold and written-off	(40,880)	(32,177)	(12,948)
Ending balance	$ 790,216	$ 644,639	$ 487,945
Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed, other	5 years
Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed, other	40 years
1633 Broadway [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				1,250,000
Initial cost to company, Land				502,846
Initial cost to company, Building and Improvements				1,398,341
Costs capitalized subsequent to acquisition, Building and Improvements				141,496
Gross amount at which carried at close of period, Land				502,846
Gross amount at which carried at close of period, Buildings and Improvements				1,539,837
Gross amount at which carried at close of period, Total	$ 2,042,683			2,042,683
Accumulated depreciation and amortization	$ (214,523)			(214,523)
Date of construction	Dec. 31, 1971
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 2,042,683
Accumulated Depreciation:
Ending balance	$ 214,523
1633 Broadway [Member] | Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
1633 Broadway [Member] | Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
1301 Avenue of Americas [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				850,000
Initial cost to company, Land				406,039
Initial cost to company, Building and Improvements				1,051,697
Costs capitalized subsequent to acquisition, Building and Improvements				94,330
Gross amount at which carried at close of period, Land				406,039
Gross amount at which carried at close of period, Buildings and Improvements				1,146,027
Gross amount at which carried at close of period, Total	$ 1,552,066			1,552,066
Accumulated depreciation and amortization	$ (164,113)			(164,113)
Date of construction	Dec. 31, 1963
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 1,552,066
Accumulated Depreciation:
Ending balance	$ 164,113
1301 Avenue of Americas [Member] | Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
1301 Avenue of Americas [Member] | Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
31 West 52nd Street [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				500,000
Initial cost to company, Land				221,318
Initial cost to company, Building and Improvements				604,994
Costs capitalized subsequent to acquisition, Building and Improvements				60,269
Gross amount at which carried at close of period, Land				221,318
Gross amount at which carried at close of period, Buildings and Improvements				665,263
Gross amount at which carried at close of period, Total	$ 886,581			886,581
Accumulated depreciation and amortization	$ (87,516)			(87,516)
Date of construction	Dec. 31, 1987
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 886,581
Accumulated Depreciation:
Ending balance	$ 87,516
31 West 52nd Street [Member] | Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
31 West 52nd Street [Member] | Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
1325 Avenue of the Americas [Member]
Real Estate And Accumulated Depreciation [Line Items]
Initial cost to company, Land				174,688
Initial cost to company, Building and Improvements				370,553
Costs capitalized subsequent to acquisition, Building and Improvements				50,424
Gross amount at which carried at close of period, Land				174,688
Gross amount at which carried at close of period, Buildings and Improvements				420,977
Gross amount at which carried at close of period, Total	$ 595,665			595,665
Accumulated depreciation and amortization	$ (55,384)			(55,384)
Date of construction	Dec. 31, 1989
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 595,665
Accumulated Depreciation:
Ending balance	$ 55,384
1325 Avenue of the Americas [Member] | Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
1325 Avenue of the Americas [Member] | Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
900 Third Avenue [Member]
Real Estate And Accumulated Depreciation [Line Items]
Initial cost to company, Land				103,741
Initial cost to company, Building and Improvements				296,031
Costs capitalized subsequent to acquisition, Building and Improvements				19,983
Gross amount at which carried at close of period, Land				103,741
Gross amount at which carried at close of period, Buildings and Improvements				316,014
Gross amount at which carried at close of period, Total	$ 419,755			419,755
Accumulated depreciation and amortization	$ (46,675)			(46,675)
Date of construction	Dec. 31, 1983
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 419,755
Accumulated Depreciation:
Ending balance	$ 46,675
900 Third Avenue [Member] | Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
900 Third Avenue [Member] | Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
Total New York [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				2,600,000
Initial cost to company, Land				1,408,632
Initial cost to company, Building and Improvements				3,721,616
Costs capitalized subsequent to acquisition, Building and Improvements				366,502
Gross amount at which carried at close of period, Land				1,408,632
Gross amount at which carried at close of period, Buildings and Improvements				4,088,118
Gross amount at which carried at close of period, Total	$ 5,496,750			5,496,750
Accumulated depreciation and amortization	(568,211)			(568,211)
Real Estate:
Ending balance	5,496,750
Accumulated Depreciation:
Ending balance	568,211
1899 Pennsylvania Avenue [Member]
Real Estate And Accumulated Depreciation [Line Items]
Initial cost to company, Land				52,568
Initial cost to company, Building and Improvements				94,874
Costs capitalized subsequent to acquisition, Land				(16,380)
Costs capitalized subsequent to acquisition, Building and Improvements				(36,811)
Gross amount at which carried at close of period, Land				36,188
Gross amount at which carried at close of period, Buildings and Improvements				58,063
Gross amount at which carried at close of period, Total	$ 94,251			94,251
Date of construction	Dec. 31, 1915
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 94,251
1899 Pennsylvania Avenue [Member] | Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
1899 Pennsylvania Avenue [Member] | Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
300 Mission Street [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				234,643
Initial cost to company, Land				141,097
Initial cost to company, Building and Improvements				343,819
Costs capitalized subsequent to acquisition, Building and Improvements				25,390
Gross amount at which carried at close of period, Land				141,097
Gross amount at which carried at close of period, Buildings and Improvements				369,209
Gross amount at which carried at close of period, Total	$ 510,306			510,306
Accumulated depreciation and amortization	$ (28,523)			(28,523)
Date of construction	Dec. 31, 1968
Date acquired	Dec. 31, 2017
Real Estate:
Ending balance	$ 510,306
Accumulated Depreciation:
Ending balance	$ 28,523
300 Mission Street [Member] | Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
300 Mission Street [Member] | Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
Total Washington, D.C. [Member]
Real Estate And Accumulated Depreciation [Line Items]
Initial cost to company, Land				52,568
Initial cost to company, Building and Improvements				94,874
Costs capitalized subsequent to acquisition, Land				(16,380)
Costs capitalized subsequent to acquisition, Building and Improvements				(36,811)
Gross amount at which carried at close of period, Land				36,188
Gross amount at which carried at close of period, Buildings and Improvements				58,063
Gross amount at which carried at close of period, Total	$ 94,251			94,251
Real Estate:
Ending balance	94,251
One Market Plaza [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				975,000
Initial cost to company, Land				288,743
Initial cost to company, Building and Improvements				988,014
Costs capitalized subsequent to acquisition, Building and Improvements				79,718
Gross amount at which carried at close of period, Land				288,743
Gross amount at which carried at close of period, Buildings and Improvements				1,067,732
Gross amount at which carried at close of period, Total	1,356,475			1,356,475
Accumulated depreciation and amortization	$ (154,942)			(154,942)
Date of construction	Dec. 31, 1976
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 1,356,475
Accumulated Depreciation:
Ending balance	$ 154,942
One Market Plaza [Member] | Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
One Market Plaza [Member] | Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
One Front Street [Member]
Real Estate And Accumulated Depreciation [Line Items]
Initial cost to company, Land				127,765
Initial cost to company, Building and Improvements				376,919
Costs capitalized subsequent to acquisition, Building and Improvements				15,022
Gross amount at which carried at close of period, Land				127,765
Gross amount at which carried at close of period, Buildings and Improvements				391,941
Gross amount at which carried at close of period, Total	$ 519,706			519,706
Accumulated depreciation and amortization	$ (36,430)			(36,430)
Date of construction	Dec. 31, 1979
Date acquired	Dec. 31, 2016
Real Estate:
Ending balance	$ 519,706
Accumulated Depreciation:
Ending balance	$ 36,430
One Front Street [Member] | Minimum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
One Front Street [Member] | Maximum [Member]
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
Total San Francisco [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				1,209,643
Initial cost to company, Land				557,605
Initial cost to company, Building and Improvements				1,708,752
Costs capitalized subsequent to acquisition, Building and Improvements				120,130
Gross amount at which carried at close of period, Land				557,605
Gross amount at which carried at close of period, Buildings and Improvements				1,828,882
Gross amount at which carried at close of period, Total	$ 2,386,487			2,386,487
Accumulated depreciation and amortization	(219,895)			$ (219,895)
Real Estate:
Ending balance	2,386,487
Accumulated Depreciation:
Ending balance	$ 219,895