Investment in Unconsolidated Joint Venture - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended
	Oct. 18, 2017	Jun. 01, 2017	Mar. 31, 2018	Dec. 31, 2017	Oct. 30, 2013
Worldwide Plaza [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage			50.10%		48.90%
Debt refinance amount	$ 1,200,000
Cash received from sale and excess proceeds from financing	446,500
Defeasance and prepayment costs	108,300
Reserved amount	$ 90,700
Debt blended rate	3.98%
Maturity date			2027-11
Property selling percentage			100.00%
Option to purchase percentage of property			100.00%
Property purchase option period			45 days
Re-offer property selling percentage			92.50%
Worldwide Plaza [Member] | SL Green Realty Corp. and RXR Realty LLC [Member]
Schedule of Equity Method Investments [Line Items]
Ownership percentage	48.70%
Liquidation value of property	$ 1,725,000
Liquidation Value [Member]
Schedule of Equity Method Investments [Line Items]
Mortgage notes payable			$ 57,112	$ 215,494
Liquidation Value [Member] | Worldwide Plaza [Member]
Schedule of Equity Method Investments [Line Items]
Additional acquire percentage		49.90%
Ownership percentage			98.80%
Aggregate cost		$ 276,700
Purchase obligation		1,400,000
Mortgage notes payable		$ 875,000
Joint venture partner's right to maintain minimum ownership percentage		1.20%
Liquidation value of property			$ 1,725,000