Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Payroll and employee-related costs	$ 5,181	$ 5,011
Professional services	2,062	1,123
Property and equipment purchases	2,058	471
Other	1,451	809
Accrued expenses	$ 10,752	$ 7,414