Related Party Transactions - Summary of Fees to Vornado (Detail) - Vornado [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Related Party Transaction [Line Items]
Fees to related party	$ 1,709	$ 1,788	$ 5,097	$ 12,629
Company Management Fees [Member]
Related Party Transaction [Line Items]
Fees to related party	700	700	2,100	2,100
Development Fees [Member]
Related Party Transaction [Line Items]
Fees to related party	0	44	32	163
Leasing Fees [Member]
Related Party Transaction [Line Items]
Fees to related party	3	106	18	7,397
Property Management Fees and Payments for Cleaning and Security Services [Member]
Related Party Transaction [Line Items]
Fees to related party	$ 1,006	$ 938	$ 2,947	$ 2,969