Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Payroll and employee-related costs	$ 13,044	$ 8,375
Professional services	2,221	2,038
Property and equipment purchases	115	1,194
Other	5,198	1,215
Accrued expenses	$ 20,578	$ 12,822