Summary of Significant Accounting Policies - Schedule of Reconciliation of Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
|
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Change in fair value of warrant liability | $ 269 | $ (539) | $ 673 | $ (539) |
Significant Unobservable Inputs (Level 3) [Member] | ||||
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||||
Beginning balance | 13,198 | |||
Change in fair value of warrant liability | 673 | |||
Ending balance | $ 13,871 | $ 13,871 |