Revenue Recognition - Revenues by Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Lease income	$ 487,306
Total revenues	534,668	$ 536,437
New York
Disaggregation of Revenue [Line Items]
Total revenues	443,285	448,484
Other
Disaggregation of Revenue [Line Items]
Total revenues	91,383	87,953
Rental revenues
Disaggregation of Revenue [Line Items]
Total revenues	499,877	500,420
Rental revenues | New York
Disaggregation of Revenue [Line Items]
Total revenues	407,637	413,836
Rental revenues | Other
Disaggregation of Revenue [Line Items]
Total revenues	92,240	86,584
Property rentals
Disaggregation of Revenue [Line Items]
Lease income	457,741	454,403
Property rentals | New York
Disaggregation of Revenue [Line Items]
Lease income	385,803	389,385
Property rentals | Other
Disaggregation of Revenue [Line Items]
Lease income	71,938	65,018
Hotel Pennsylvania
Disaggregation of Revenue [Line Items]
Lease income	12,609	14,680
Hotel Pennsylvania | New York
Disaggregation of Revenue [Line Items]
Lease income	12,609	14,680
Hotel Pennsylvania | Other
Disaggregation of Revenue [Line Items]
Lease income	0	0
Trade shows
Disaggregation of Revenue [Line Items]
Lease income	16,956	18,873
Trade shows | New York
Disaggregation of Revenue [Line Items]
Lease income	0	0
Trade shows | Other
Disaggregation of Revenue [Line Items]
Lease income	16,956	18,873
Lease revenues
Disaggregation of Revenue [Line Items]
Lease income	487,306	487,956
Lease revenues | New York
Disaggregation of Revenue [Line Items]
Lease income	398,412	404,065
Lease revenues | Other
Disaggregation of Revenue [Line Items]
Lease income	88,894	83,891
Tenant services
Disaggregation of Revenue [Line Items]
Revenue	12,571	12,464
Tenant services | New York
Disaggregation of Revenue [Line Items]
Revenue	9,225	9,771
Tenant services | Other
Disaggregation of Revenue [Line Items]
Revenue	3,346	2,693
Fee and other income
Disaggregation of Revenue [Line Items]
Revenue	34,791	36,017
Total revenues	34,791	36,017
Fee and other income | New York
Disaggregation of Revenue [Line Items]
Revenue	35,648	34,648
Fee and other income | Other
Disaggregation of Revenue [Line Items]
Revenue	(857)	1,369
BMS cleaning fees
Disaggregation of Revenue [Line Items]
Revenue	29,785	28,355
BMS cleaning fees | New York
Disaggregation of Revenue [Line Items]
Revenue	31,757	30,153
BMS cleaning fees | Other
Disaggregation of Revenue [Line Items]
Revenue	(1,972)	(1,798)
Management and leasing fees
Disaggregation of Revenue [Line Items]
Revenue	2,237	2,764
Management and leasing fees | New York
Disaggregation of Revenue [Line Items]
Revenue	2,251	2,481
Management and leasing fees | Other
Disaggregation of Revenue [Line Items]
Revenue	(14)	283
Other income
Disaggregation of Revenue [Line Items]
Revenue	2,769	4,898
Other income | New York
Disaggregation of Revenue [Line Items]
Revenue	1,640	2,014
Other income | Other
Disaggregation of Revenue [Line Items]
Revenue	$ 1,129	$ 2,884