Subsequent Events - Additional Information (Details) $ in Thousands		3 Months Ended
	May. 03, 2016 USD ($) ft²	Mar. 31, 2016 USD ($) ft²	Dec. 31, 2015 USD ($)
Subsequent Event [Line Items]
Area of office properties | ft²		10,400,000
Mezzanine Loans, Interest Rate		4.68%
Mortgages and notes payable		$ 2,942,026	$ 2,941,524
31 West 52nd Street [Member]
Subsequent Event [Line Items]
Mezzanine Loans, Interest Rate		4.23%
Mortgages and notes payable		$ 413,490	413,490
Maturity date of debt		2017-12
31 West 52nd Street [Member] | Mortgages and Notes Payable with Fixed Rate [Member]
Subsequent Event [Line Items]
Mezzanine Loans, Interest Rate		6.04%
Mortgages and notes payable		$ 237,600	$ 237,600
Maturity date of debt		2017-12
Subsequent Event [Member] | 31 West 52nd Street [Member]
Subsequent Event [Line Items]
Mortgage refinancing extended amount	$ 500,000
Area of office properties | ft²	786,647
Debt instrument term of notes	10 years
Proceeds after repayment of existing loan	$ 65,000
Subsequent Event [Member] | 31 West 52nd Street [Member] | Mortgages and Notes Payable with Fixed Rate [Member]
Subsequent Event [Line Items]
Mezzanine Loans, Interest Rate	3.80%