Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) extenstion_option	Dec. 31, 2015 USD ($)
Other Commitments [Line Items]
Employment agreements with certain executives, minimum cash-based compensation for next fiscal year	$ 5,200
Employment agreements with certain executives, grant date value of deferred compensation awards	1,600
Capital lease obligations	$ 42,132	$ 41,360
Number of renewal options available (extension option)	2
Cost basis	$ 47,445	47,445
Term of first renewal option (in years)	35 years
Initial term of non cancellable operating leases, minimum (in years)	1 year
Capital lease
2017	$ 2,387
2017	2,387
2018	2,411
2019	2,620
2020	2,794
Thereafter	822,688
Total minimum lease payments	835,287
Less amount representing interest	(793,155)
Capital lease obligations	42,132
Non-cancellable operating leases
2017	31,049
2017	31,049
2018	31,066
2019	31,436
2020	31,628
Thereafter	732,724
Total minimum lease payments	$ 888,952
30 East 40th Street
Other Commitments [Line Items]
Land as percentage of fair market value of property under lease	63.60%
Capital lease obligations	$ 20,000
420 Lexington Avenue
Other Commitments [Line Items]
Land as percentage of fair market value of property under lease	6.00%
Annual ground lease payments through December 2019	$ 10,900
Annual ground lease payments through December 2029	11,200
Annual ground lease payments due thereafter	$ 12,300
1080 Amsterdam Avenue
Other Commitments [Line Items]
Land as percentage of fair market value of property under lease	40.00%
Non-cancellable operating leases
Total minimum lease payments	$ 41,600
711 Third Avenue
Other Commitments [Line Items]
Percentage of the fee not owned by the entity (percent)	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]
Number of renewal options available (extension option) | extenstion_option	2
Required annual ground lease payments	$ 2,100
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]
Number of renewal options available (extension option) | extenstion_option	2
Required annual ground lease payments	$ 4,600
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
Belmont
Other Commitments [Line Items]
Loss reserves	$ 6,300	$ 6,400
TRIPRA 2015
Other Commitments [Line Items]
Program trigger	120,000
Per annum increase	$ 20,000
Coinsurance Percentage, TRIPRA	16.00%
Coinsurance Percentage, Annual Increase, TRIPRA	1.00%