Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Research and Development	$ 402	$ 1,606
Payroll and other employee-related expenses	3,154	3,393
Professional services fees	1,957	926
Other	319	159
Interest expense	1,265	161
Total accrued expenses and other current liabilities	$ 7,097	$ 6,245