Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Reconciliation of Warrant Liability Measured at Fair Value (Detail)

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Stockholders' Equity - Reconciliation of Warrant Liability Measured at Fair Value (Detail) - USD ($)
$ in Thousands
2 Months Ended 7 Months Ended 9 Months Ended
Sep. 30, 2017
Jul. 31, 2017
Sep. 30, 2017
Sep. 30, 2016
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]        
Change in common stock warrant fair value     $ 269 $ (2)
Basis of Fair Value Measurements, Level 3        
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]        
Beginning Balance   $ 49 49  
Change in common stock warrant fair value   $ (3) 272  
Warrant liability related to Merger on August 1, 2017     1,120  
Ending Balance $ 1,392   $ 1,392  
Basis of Fair Value Measurements, Level 3 | 2014 Warrants        
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]        
Exercise of warrant put related to 2014 warrants $ (46)