Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) extenstion_option
Other Commitments [Line Items]
Minimum initial term of noncancellable operating leases (in years)	1 year
Non-cancellable operating leases
2016	$ 20,440
2017	20,586
2018	20,586
2019	20,586
2020	20,586
Thereafter	328,088
Total minimum lease payments	$ 430,872
711 Third Avenue
Other Commitments [Line Items]
Percentage of the fee not owned by the entity	50.00%
711 Third Avenue | Through July 2016
Other Commitments [Line Items]
Required annual ground lease payments	$ 5,250
711 Third Avenue | After July 2016
Other Commitments [Line Items]
Required annual ground lease payments	5,500
461 Fifth Avenue
Other Commitments [Line Items]
Required annual ground lease payments	$ 2,100
Number of renewal options available | extenstion_option	3
Term of first renewal option (in years)	21 years
Term of second renewal option (in years)	21 years
Term of third renewal option (in years)	15 years
625 Madison Avenue
Other Commitments [Line Items]
Required annual ground lease payments	$ 4,600
Number of renewal options available | extenstion_option	2
Term of first renewal option (in years)	23 years
Term of second renewal option (in years)	23 years
1185 Avenue of the Americas
Other Commitments [Line Items]
Required annual ground lease payments	$ 6,900
Term of first renewal option (in years)	23 years