Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Payables and Accruals [Abstract] | ||
| Accrued payroll and related expenses | $ 2,008 | $ 1,802 |
| Accrued research and development expenses | 892 | 3,727 |
| Accrued restructuring | 376 | |
| Accrued professional fees | 347 | 422 |
| Accrued other | 110 | 161 |
| Accrued expenses | $ 3,733 | $ 6,112 |