Debt - Additional Information (Details)		9 Months Ended
	May 03, 2016 USD ($) ft²	Sep. 30, 2016 USD ($) ft²	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Area of office properties | ft²		10,400,000
Notes and mortgages payable, interest rate		4.60%
Notes and mortgages payable		$ 3,039,149,000	$ 2,941,524,000
Payment of swap breakage costs	$ 21,972,000
31 West 52nd Street [Member]
Debt Instrument [Line Items]
Mortgage refinancing extended amount	$ 500,000,000
Area of office properties | ft²	786,647
Debt instrument term of notes	10 years
Notes and mortgages payable, interest rate		3.80%
Proceeds after repayment of existing loan	$ 64,538,000
Notes and mortgages payable		$ 500,000,000	413,490,000
31 West 52nd Street [Member] | Existing Loan [Member]
Debt Instrument [Line Items]
Notes and mortgages payable, interest rate		4.23%
Notes and mortgages payable		$ 413,490,000
Maturity date of debt		2017-12
31 West 52nd Street [Member] | Mortgages and Notes Payable with Fixed Rate [Member]
Debt Instrument [Line Items]
Notes and mortgages payable, interest rate	3.80%	3.80%
Notes and mortgages payable		$ 500,000,000	$ 237,600,000
Maturity date of debt		2026-05