Annual report pursuant to Section 13 and 15(d)

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

v3.19.1
Stockholders' Equity - Reconciliation of Warrant Liability Measured at Fair Value (Detail) - USD ($)
$ in Thousands
5 Months Ended 12 Months Ended
Aug. 01, 2017
Dec. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]        
Change in common stock warrant fair value     $ 951 $ 128
Basis of Fair Value Measurements, Level 3        
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]        
Beginning Balance     954 49
Change in common stock warrant fair value $ 37 $ (165) (951)  
Conversion of 2014 warrants to common stock       (87)
Fair value of common stock warrants       1,120
Ending Balance   $ 954 $ 3 $ 954