Quarterly report pursuant to Section 13 or 15(d)

Common Stock - Common Stock Warrants - Additional Information (Detail)

v3.20.2
Common Stock - Common Stock Warrants - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 6 Months Ended
May 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Dec. 31, 2019
Class of Warrant or Right [Line Items]        
Common stock, par value   $ 0.001   $ 0.001
Proceeds from exercise of warrants, net of issuance costs $ 4,200 $ 589 $ 4,199  
Expected volatility   104.64% 94.25%  
Risk-free interest rate   1.43% 2.52%  
Expected term   5 years 11 months 23 days 5 years 11 months 19 days  
October 2018 Financing [Member]        
Class of Warrant or Right [Line Items]        
Warrants to purchase common stock 13,515      
Common stock, par value $ 0.001      
Exercise price per unit of warrant $ 62.89      
June 2018 Financing [Member]        
Class of Warrant or Right [Line Items]        
Warrants to purchase common stock 41,875      
Exercise price per unit of warrant $ 80.00      
New Warrant [Member]        
Class of Warrant or Right [Line Items]        
Warrants to purchase common stock 60,000      
Exercise price per unit of warrant $ 90.00      
Warrants, exercise period 6 years      
Fair value of warrants recognized into accumulated deficit   $ (3,900)    
Stock price   $ 84.60    
Expected volatility   97.16%    
Risk-free interest rate   2.06%    
Expected term   6 years    
Warrants Issued in December 2019 [Member]        
Class of Warrant or Right [Line Items]        
Warrants to purchase common stock   89,281    
Exercise price per unit of warrant   $ 6.6000    
Proceeds from exercise of warrants, net of issuance costs   $ 600    
Warrants Issued in June 2018 [Member]        
Class of Warrant or Right [Line Items]        
Warrants to purchase common stock     41,875  
Exercise price per unit of warrant   $ 80.0000 $ 80.00  
Proceeds from exercise of warrants, net of issuance costs     $ 3,400  
Warrants Issued in October 2018 [Member]        
Class of Warrant or Right [Line Items]        
Warrants to purchase common stock     13,515  
Exercise price per unit of warrant   $ 62.8900 $ 62.89  
Proceeds from exercise of warrants, net of issuance costs     $ 800