Quarterly report pursuant to Section 13 or 15(d)

Stockholder's Equity - Additional Information (Detail)

v3.19.2
Stockholder's Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 6 Months Ended
Sep. 30, 2016
Apr. 30, 2019
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Jun. 18, 2019
Jun. 17, 2019
Dec. 31, 2018
Sep. 14, 2018
Schedule Of Capitalization Equity [Line Items]                    
Common stock, par value (in dollars per share)     $ 0.001   $ 0.001       $ 0.001  
Common stock, shares authorized (in shares)     250,000,000   250,000,000   250,000,000 125,000,000 125,000,000  
Common stock, shares issued (in shares)     54,520,131   54,520,131       47,971,989  
Common stock, shares outstanding (in shares)     54,520,131   54,520,131       47,971,989  
Derivative liability fair value adjustment     $ 1,324 $ 0 $ (2,101) $ 0        
Warrant liabilities fair value adjustment     (2,049) $ 2,874 4,473 $ (680)        
Warrant liabilities     5,500   5,500          
Number of warrants issued to purchase common stock (in shares)                   13,198,075
Warrants to purchase common stock associated with Loan Agreement                    
Schedule Of Capitalization Equity [Line Items]                    
Number of warrants issued to purchase common stock (in shares) 122,435                  
Exercise price of warrants (in dollars per share) $ 3.6754                  
Warrant expiration period 5 years                  
Senior Convertible Note Purchase Agreement                    
Schedule Of Capitalization Equity [Line Items]                    
Conversion of convertible note, amount   $ 2,000                
Conversion of convertible note exchanged for shares   1,626,000                
Senior Convertible Note Purchase Agreement | Other (Income) Expense                    
Schedule Of Capitalization Equity [Line Items]                    
Derivative liability fair value adjustment     $ 1,300   $ (2,100)