Annual report pursuant to Section 13 and 15(d)

Common Stock - Stock Warrants - Additional Information (Detail)

v3.20.1
Common Stock - Stock Warrants - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Jun. 30, 2019
May 30, 2019
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Jun. 19, 2018
Class Of Warrant Or Right [Line Items]            
Exercise price per unit of warrant           $ 4.00
Proceeds from aggregate warrant exercise     $ 4,199 $ 1,324    
Expected volatility     94.25% 88.23%    
Risk-free interest rate     2.52% 2.93%    
Expected term     5 years 11 months 19 days 5 years 8 months 4 days    
Number of warrants exercised         0  
Common stock, shares issued     29,485,178 6,721,117    
New Warrant [Member]            
Class Of Warrant Or Right [Line Items]            
Fair value of warrants recognized into accumulated deficit $ (3,900)          
Stock price $ 4.23          
Expected volatility 97.16%          
Risk-free interest rate 2.06%          
Expected term 6 years          
Warrants Issued In June 2018 [Member]            
Class Of Warrant Or Right [Line Items]            
Exercise price per unit of warrant     $ 4.0000 $ 4.00    
Proceeds from aggregate warrant exercise     $ 3,400 $ 1,300    
Number of warrants exercised     837,500 330,500    
Warrants Issued in October 2018 [Member]            
Class Of Warrant Or Right [Line Items]            
Exercise price per unit of warrant     $ 3.1445      
Proceeds from aggregate warrant exercise     $ 800      
Number of warrants exercised     270,313      
Armistice [Member]            
Class Of Warrant Or Right [Line Items]            
Proceeds from aggregate warrant exercise   $ 4,200        
Armistice [Member] | October 2018 Financing [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants to purchase common stock   270,313        
Exercise price per unit of warrant   $ 3.1445        
Armistice [Member] | June 2018 Financing [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants to purchase common stock   837,500        
Exercise price per unit of warrant   $ 4.00        
Armistice [Member] | New Warrant [Member]            
Class Of Warrant Or Right [Line Items]            
Warrants to purchase common stock   1,200,000        
Exercise price per unit of warrant   $ 4.50        
Warrants, exercise period   6 years