Schedule III - Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				$ 3,819,434
Initial cost to company, Land				1,966,237
Initial cost to company, Building and Improvements				5,430,368
Costs capitalized subsequent to acquisition, Building and Improvements				566,710
Gross amount at which carried at close of period, Land				1,966,237
Gross amount at which carried at close of period, Buildings and Improvements				5,997,078
Gross amount at which carried at close of period, Total	$ 7,889,885	$ 7,793,784	$ 7,653,276	7,963,315
Accumulated depreciation and amortization	(790,216)	(617,974)	(445,328)	(966,697)
Costs capitalized subsequent to acquisition, Building and Improvements, other				9,625
Gross amount at which carried at close of period, Buildings and Improvements, other				9,625
Gross amount at which carried at close of period, other				9,625
Accumulated depreciation and amortization, other	$ (4,199)
Date acquired, other	Nov. 24, 2014
Real Estate:
Beginning balance	$ 7,889,885	7,793,784	7,653,276
Buildings and improvements	82,571	104,408	144,666
Assets sold and written-off	(9,141)	(8,307)	(4,158)
Ending balance	7,963,315	7,889,885	7,793,784
Accumulated Depreciation:
Beginning balance	790,216	617,974	445,328
Additions charged to expense	185,622	180,549	176,804
Accumulated depreciation related to assets sold and written-off	(9,141)	(8,307)	(4,158)
Ending balance	$ 966,697	$ 790,216	$ 617,974
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				151,358
Gross amount at which carried at close of period, Land				502,846
Gross amount at which carried at close of period, Buildings and Improvements				1,549,699
Gross amount at which carried at close of period, Total	$ 2,052,545			2,052,545
Accumulated depreciation and amortization	$ (258,683)			(258,683)
Date of construction	Dec. 31, 1971
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 2,052,545
Accumulated Depreciation:
Ending balance	$ 258,683
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				101,642
Gross amount at which carried at close of period, Land				406,039
Gross amount at which carried at close of period, Buildings and Improvements				1,153,339
Gross amount at which carried at close of period, Total	$ 1,559,378			1,559,378
Accumulated depreciation and amortization	$ (199,657)			(199,657)
Date of construction	Dec. 31, 1963
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 1,559,378
Accumulated Depreciation:
Ending balance	$ 199,657
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				62,997
Gross amount at which carried at close of period, Land				221,318
Gross amount at which carried at close of period, Buildings and Improvements				667,991
Gross amount at which carried at close of period, Total	$ 889,309			889,309
Accumulated depreciation and amortization	$ (107,164)			(107,164)
Date of construction	Dec. 31, 1987
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 889,309
Accumulated Depreciation:
Ending balance	$ 107,164
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				61,785
Gross amount at which carried at close of period, Land				174,688
Gross amount at which carried at close of period, Buildings and Improvements				432,338
Gross amount at which carried at close of period, Total	$ 607,026			607,026
Accumulated depreciation and amortization	$ (68,822)			(68,822)
Date of construction	Dec. 31, 1989
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 607,026
Accumulated Depreciation:
Ending balance	$ 68,822
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				28,335
Gross amount at which carried at close of period, Land				103,741
Gross amount at which carried at close of period, Buildings and Improvements				324,366
Gross amount at which carried at close of period, Total	$ 428,107			428,107
Accumulated depreciation and amortization	$ (56,831)			(56,831)
Date of construction	Dec. 31, 1983
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 428,107
Accumulated Depreciation:
Ending balance	$ 56,831
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				406,117
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				4,127,733
Gross amount at which carried at close of period, Total	$ 5,536,365			5,536,365
Accumulated depreciation and amortization	(691,157)			(691,157)
Real Estate:
Ending balance	5,536,365
Accumulated Depreciation:
Ending balance	691,157
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				95,035
Gross amount at which carried at close of period, Land				288,743
Gross amount at which carried at close of period, Buildings and Improvements				1,083,049
Gross amount at which carried at close of period, Total	1,371,792			1,371,792
Accumulated depreciation and amortization	$ (187,570)			(187,570)
Date of construction	Dec. 31, 1976
Date acquired	Nov. 24, 2014
Real Estate:
Ending balance	$ 1,371,792
Accumulated Depreciation:
Ending balance	$ 187,570
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
300 Mission Street [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				244,434
Initial cost to company, Land				141,097
Initial cost to company, Building and Improvements				343,819
Costs capitalized subsequent to acquisition, Building and Improvements				40,887
Gross amount at which carried at close of period, Land				141,097
Gross amount at which carried at close of period, Buildings and Improvements				384,706
Gross amount at which carried at close of period, Total	$ 525,803			525,803
Accumulated depreciation and amortization	$ (36,360)			(36,360)
Date of construction	Dec. 31, 1968
Date acquired	Dec. 31, 2017
Real Estate:
Ending balance	$ 525,803
Accumulated Depreciation:
Ending balance	$ 36,360
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
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				15,046
Gross amount at which carried at close of period, Land				127,765
Gross amount at which carried at close of period, Buildings and Improvements				391,965
Gross amount at which carried at close of period, Total	$ 519,730			519,730
Accumulated depreciation and amortization	$ (47,411)			(47,411)
Date of construction	Dec. 31, 1979
Date acquired	Dec. 31, 2016
Real Estate:
Ending balance	$ 519,730
Accumulated Depreciation:
Ending balance	$ 47,411
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				1,219,434
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				150,968
Gross amount at which carried at close of period, Land				557,605
Gross amount at which carried at close of period, Buildings and Improvements				1,859,720
Gross amount at which carried at close of period, Total	$ 2,417,325			2,417,325
Accumulated depreciation and amortization	(271,341)			$ (271,341)
Real Estate:
Ending balance	2,417,325
Accumulated Depreciation:
Ending balance	$ 271,341