Related Party Transactions - Summary of Fees to Vornado (Detail) - Vornado - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Related Party Transaction [Line Items]
Fees to related party	$ 3,361	$ 1,742	$ 9,980	$ 5,116
Company management fees
Related Party Transaction [Line Items]
Fees to related party	700	700	2,100	2,100
Development fees
Related Party Transaction [Line Items]
Fees to related party	0	17	29	26
Leasing fees
Related Party Transaction [Line Items]
Fees to related party	1,422	13	4,168	13
Property management, cleaning, engineering and security fees
Related Party Transaction [Line Items]
Fees to related party	$ 1,239	$ 1,012	$ 3,683	$ 2,977