Revenue Recognition - Revenues by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Lease income	$ 391,218	$ 487,306
Total revenues	444,532	534,668
New York
Disaggregation of Revenue [Line Items]
Total revenues	355,615	443,285
Other
Disaggregation of Revenue [Line Items]
Total revenues	88,917	91,383
Rental revenues
Disaggregation of Revenue [Line Items]
Total revenues	401,274	499,877
Rental revenues | New York
Disaggregation of Revenue [Line Items]
Total revenues	314,733	407,637
Rental revenues | Other
Disaggregation of Revenue [Line Items]
Total revenues	86,541	92,240
Property rentals
Disaggregation of Revenue [Line Items]
Lease income	371,174	457,741
Property rentals | New York
Disaggregation of Revenue [Line Items]
Lease income	298,612	385,803
Property rentals | Other
Disaggregation of Revenue [Line Items]
Lease income	72,562	71,938
Hotel Pennsylvania
Disaggregation of Revenue [Line Items]
Lease income	8,741	12,609
Hotel Pennsylvania | New York
Disaggregation of Revenue [Line Items]
Lease income	8,741	12,609
Hotel Pennsylvania | Other
Disaggregation of Revenue [Line Items]
Lease income	0	0
Trade shows
Disaggregation of Revenue [Line Items]
Lease income	11,303	16,956
Trade shows | New York
Disaggregation of Revenue [Line Items]
Lease income	0	0
Trade shows | Other
Disaggregation of Revenue [Line Items]
Lease income	11,303	16,956
Lease revenues
Disaggregation of Revenue [Line Items]
Lease income	391,218	487,306
Lease revenues | New York
Disaggregation of Revenue [Line Items]
Lease income	307,353	398,412
Lease revenues | Other
Disaggregation of Revenue [Line Items]
Lease income	83,865	88,894
Tenant services
Disaggregation of Revenue [Line Items]
Revenue	10,056	12,571
Tenant services | New York
Disaggregation of Revenue [Line Items]
Revenue	7,380	9,225
Tenant services | Other
Disaggregation of Revenue [Line Items]
Revenue	2,676	3,346
Fee and other income
Disaggregation of Revenue [Line Items]
Revenue	43,258	34,791
Total revenues	43,258	34,791
Fee and other income | New York
Disaggregation of Revenue [Line Items]
Revenue	40,882	35,648
Fee and other income | Other
Disaggregation of Revenue [Line Items]
Revenue	2,376	(857)
BMS cleaning fees
Disaggregation of Revenue [Line Items]
Revenue	32,466	29,785
BMS cleaning fees | New York
Disaggregation of Revenue [Line Items]
Revenue	34,429	31,757
BMS cleaning fees | Other
Disaggregation of Revenue [Line Items]
Revenue	(1,963)	(1,972)
Management and leasing fees
Disaggregation of Revenue [Line Items]
Revenue	2,867	2,237
Management and leasing fees | New York
Disaggregation of Revenue [Line Items]
Revenue	2,874	2,251
Management and leasing fees | Other
Disaggregation of Revenue [Line Items]
Revenue	(7)	(14)
Other income
Disaggregation of Revenue [Line Items]
Revenue	7,925	2,769
Other income | New York
Disaggregation of Revenue [Line Items]
Revenue	3,579	1,640
Other income | Other
Disaggregation of Revenue [Line Items]
Revenue	$ 4,346	$ 1,129