Schedule III - Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				$ 3,408,179
Initial cost to company, Land				2,091,535
Initial cost to company, Building and Improvements				5,521,449
Costs capitalized subsequent to acquisition, Building and Improvements				231,280
Gross amount at which carried at close of period, Land				2,091,535
Gross amount at which carried at close of period, Buildings and Improvements				5,757,558
Gross amount at which carried at close of period, Total	$ 7,849,093	$ 7,652,117	$ 7,530,239	7,849,093
Accumulated depreciation and amortization	(318,161)	(243,089)	(81,050)	(318,161)
Gross amount at which carried at close of period, Buildings and Improvements, other				(1,343)
Gross amount at which carried at close of period, other				(1,343)
Accumulated depreciation and amortization, other	$ (275)
Date acquired, other	Nov. 24, 2014
Rental Property:
Beginning balance	$ 7,652,117	7,530,239	414,998
Acquisitions	504,684		64,650
Acquisition of properties in connection with the Formation Transactions			7,043,650
Buildings and improvements	116,038	123,277	9,676
Assets held for sale	(412,315)
Assets sold and written-off	(11,431)	(1,399)	(2,735)
Ending balance	7,849,093	7,652,117	7,530,239
Accumulated Depreciation:
Beginning balance	243,089	81,050	57,689
Additions charged to expense	168,847	163,438	26,096
Assets held for sale	(82,344)
Accumulated depreciation related to assets sold and written-off	(11,431)	(1,399)	(2,735)
Ending balance	$ 318,161	$ 243,089	$ 81,050
Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed, other	5 years
Maximum
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				1,013,544
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				63,900
Gross amount at which carried at close of period, Land				502,846
Gross amount at which carried at close of period, Buildings and Improvements				1,462,241
Gross amount at which carried at close of period, Total	$ 1,965,087			1,965,087
Accumulated depreciation and amortization	$ (81,875)			(81,875)
Date of construction	Dec. 31, 1971
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 1,965,087
Accumulated Depreciation:
Ending balance	$ 81,875
1633 Broadway [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
1633 Broadway [Member] | Maximum
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				54,765
Gross amount at which carried at close of period, Land				406,039
Gross amount at which carried at close of period, Buildings and Improvements				1,106,462
Gross amount at which carried at close of period, Total	$ 1,512,501			1,512,501
Accumulated depreciation and amortization	$ (61,175)			(61,175)
Date of construction	Dec. 31, 1963
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 1,512,501
Accumulated Depreciation:
Ending balance	$ 61,175
1301 Avenue of Americas [Member] | Minimum
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
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				2,376
Gross amount at which carried at close of period, Land				221,318
Gross amount at which carried at close of period, Buildings and Improvements				607,370
Gross amount at which carried at close of period, Total	$ 828,688			828,688
Accumulated depreciation and amortization	$ (35,534)			(35,534)
Date of construction	Dec. 31, 1987
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 828,688
Accumulated Depreciation:
Ending balance	$ 35,534
31 West 52nd Street [Member] | Minimum
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
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				17,359
Gross amount at which carried at close of period, Land				174,688
Gross amount at which carried at close of period, Buildings and Improvements				387,912
Gross amount at which carried at close of period, Total	$ 562,600			562,600
Accumulated depreciation and amortization	$ (24,343)			(24,343)
Date of construction	Dec. 31, 1989
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 562,600
Accumulated Depreciation:
Ending balance	$ 24,343
1325 Avenue of the Americas [Member] | Minimum
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
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				6,835
Gross amount at which carried at close of period, Land				103,741
Gross amount at which carried at close of period, Buildings and Improvements				302,866
Gross amount at which carried at close of period, Total	$ 406,607			406,607
Accumulated depreciation and amortization	$ (20,881)			(20,881)
Date of construction	Dec. 31, 1983
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 406,607
Accumulated Depreciation:
Ending balance	$ 20,881
900 Third Avenue [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
900 Third Avenue [Member] | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
Total New York
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				2,363,544
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				145,235
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				3,866,851
Gross amount at which carried at close of period, Total	$ 5,275,483			5,275,483
Accumulated depreciation and amortization	(223,808)			(223,808)
Rental Property:
Ending balance	5,275,483
Accumulated Depreciation:
Ending balance	223,808
425 Eye Street [Member]
Real Estate And Accumulated Depreciation [Line Items]
Initial cost to company, Land				93,669
Initial cost to company, Building and Improvements				98,088
Costs capitalized subsequent to acquisition, Building and Improvements				4,866
Gross amount at which carried at close of period, Land				93,669
Gross amount at which carried at close of period, Buildings and Improvements				102,954
Gross amount at which carried at close of period, Total	196,623			196,623
Accumulated depreciation and amortization	$ (7,832)			(7,832)
Date of construction	Dec. 31, 1973
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 196,623
Accumulated Depreciation:
Ending balance	$ 7,832
425 Eye Street [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
425 Eye Street [Member] | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
Liberty Place [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				84,000
Initial cost to company, Land				46,401
Initial cost to company, Building and Improvements				96,422
Costs capitalized subsequent to acquisition, Building and Improvements				11,653
Gross amount at which carried at close of period, Land				46,401
Gross amount at which carried at close of period, Buildings and Improvements				108,075
Gross amount at which carried at close of period, Total	$ 154,476			154,476
Accumulated depreciation and amortization	$ (6,827)			(6,827)
Date of construction	Dec. 31, 1993
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 154,476
Accumulated Depreciation:
Ending balance	$ 6,827
Liberty Place [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
Liberty Place [Member] | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
1899 Pennsylvania Avenue [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				87,675
Initial cost to company, Land				52,568
Initial cost to company, Building and Improvements				94,874
Costs capitalized subsequent to acquisition, Building and Improvements				4,164
Gross amount at which carried at close of period, Land				52,568
Gross amount at which carried at close of period, Buildings and Improvements				99,038
Gross amount at which carried at close of period, Total	$ 151,606			151,606
Accumulated depreciation and amortization	$ (6,094)			(6,094)
Date of construction	Dec. 31, 1915
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 151,606
Accumulated Depreciation:
Ending balance	$ 6,094
1899 Pennsylvania Avenue [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
1899 Pennsylvania Avenue [Member] | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
2099 Pennsylvania Avenue [Member]
Real Estate And Accumulated Depreciation [Line Items]
Initial cost to company, Land				50,631
Initial cost to company, Building and Improvements				103,992
Costs capitalized subsequent to acquisition, Building and Improvements				10,926
Gross amount at which carried at close of period, Land				50,631
Gross amount at which carried at close of period, Buildings and Improvements				114,918
Gross amount at which carried at close of period, Total	$ 165,549			165,549
Accumulated depreciation and amortization	$ (6,990)			(6,990)
Date of construction	Dec. 31, 2001
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 165,549
Accumulated Depreciation:
Ending balance	$ 6,990
2099 Pennsylvania Avenue [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
2099 Pennsylvania Avenue [Member] | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
Waterview [Member]
Real Estate And Accumulated Depreciation [Line Items]
Initial cost to company, Land				78,300
Initial cost to company, Building and Improvements				297,669
Costs capitalized subsequent to acquisition, Building and Improvements				36,346
Gross amount at which carried at close of period, Land				78,300
Gross amount at which carried at close of period, Buildings and Improvements				334,015
Gross amount at which carried at close of period, Total	$ 412,315			412,315
Accumulated depreciation and amortization	$ (82,344)			(82,344)
Date of construction	Dec. 31, 2007
Date acquired	May 31, 2007
Rental Property:
Ending balance	$ 412,315
Accumulated Depreciation:
Ending balance	$ 82,344
Waterview [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
Waterview [Member] | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
Total Washington, D.C.
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				171,675
Initial cost to company, Land				243,269
Initial cost to company, Building and Improvements				393,376
Costs capitalized subsequent to acquisition, Building and Improvements				31,609
Gross amount at which carried at close of period, Land				243,269
Gross amount at which carried at close of period, Buildings and Improvements				424,985
Gross amount at which carried at close of period, Total	$ 668,254			668,254
Accumulated depreciation and amortization	(27,743)			(27,743)
Rental Property:
Ending balance	668,254
Accumulated Depreciation:
Ending balance	27,743
One Market Plaza [Member]
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				872,960
Initial cost to company, Land				288,743
Initial cost to company, Building and Improvements				988,014
Costs capitalized subsequent to acquisition, Building and Improvements				49,939
Gross amount at which carried at close of period, Land				288,743
Gross amount at which carried at close of period, Buildings and Improvements				1,037,953
Gross amount at which carried at close of period, Total	1,326,696			1,326,696
Accumulated depreciation and amortization	$ (62,309)			(62,309)
Date of construction	Dec. 31, 1976
Date acquired	Nov. 24, 2014
Rental Property:
Ending balance	$ 1,326,696
Accumulated Depreciation:
Ending balance	$ 62,309
One Market Plaza [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
One Market Plaza [Member] | Maximum
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
Gross amount at which carried at close of period, Land				127,765
Gross amount at which carried at close of period, Buildings and Improvements				376,919
Gross amount at which carried at close of period, Total	$ 504,684			504,684
Accumulated depreciation and amortization	$ (1,130)			(1,130)
Date of construction	Dec. 31, 1979
Date acquired	Dec. 31, 2016
Rental Property:
Ending balance	$ 504,684
Accumulated Depreciation:
Ending balance	$ 1,130
One Front Street [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
One Front Street [Member] | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years
Total San Francisco
Real Estate And Accumulated Depreciation [Line Items]
Encumbrances				872,960
Initial cost to company, Land				416,508
Initial cost to company, Building and Improvements				1,364,933
Costs capitalized subsequent to acquisition, Building and Improvements				49,939
Gross amount at which carried at close of period, Land				416,508
Gross amount at which carried at close of period, Buildings and Improvements				1,414,872
Gross amount at which carried at close of period, Total	$ 1,831,380			1,831,380
Accumulated depreciation and amortization	(63,439)			(63,439)
Rental Property:
Ending balance	1,831,380
Accumulated Depreciation:
Ending balance	63,439
Residential Development Fund ("75 Howard") [Member]
Real Estate And Accumulated Depreciation [Line Items]
Initial cost to company, Land				23,126
Initial cost to company, Building and Improvements				41,524
Costs capitalized subsequent to acquisition, Building and Improvements				4,497
Gross amount at which carried at close of period, Land				23,126
Gross amount at which carried at close of period, Buildings and Improvements				52,193
Gross amount at which carried at close of period, Total	75,319			75,319
Accumulated depreciation and amortization	$ (2,896)			$ (2,896)
Date acquired	Mar. 31, 2014
Rental Property:
Ending balance	$ 75,319
Accumulated Depreciation:
Ending balance	$ 2,896
Residential Development Fund ("75 Howard") [Member] | Minimum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	5 years
Residential Development Fund ("75 Howard") [Member] | Maximum
Real Estate And Accumulated Depreciation [Line Items]
Life on which depreciation in latest income statement is computed	40 years