Fair Value of Financial Instruments - Schedule of Fair Value of Financial Liabilities (Detail) $ in Thousands	Dec. 31, 2016 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
2016 Placement Warrants Liability	$ 2,723
2016 Placement Warrants Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
2016 Placement Warrants Liability	2,723
Level 3 | 2016 Placement Warrants Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
2016 Placement Warrants Liability	$ 2,723