Quarterly report pursuant to Section 13 or 15(d)

Capital Structure - Additional Information (Detail)

v3.20.2
Capital Structure - Additional Information (Detail)
1 Months Ended 6 Months Ended
May 27, 2020
USD ($)
$ / shares
shares
Dec. 18, 2019
USD ($)
shares
Dec. 12, 2019
USD ($)
shares
Jul. 25, 2017
USD ($)
Jul. 27, 2016
USD ($)
Feb. 29, 2020
shares
Jun. 30, 2020
USD ($)
shares
Jun. 12, 2015
$ / shares
Class of Stock [Line Items]                
Common stock, shares authorized | shares           200,000,000 125,000,000  
Number of shares issued | shares 11,797,752 2,565,000 3,715,000          
Net proceeds received $ 48,900,000 $ 10,000,000            
Gross Proceed $ 3,000,000   $ 13,000,000          
Dividends declared or paid             $ 0  
Combined Net Proceeds     $ 21,300,000          
Issuance costs allocated to warrants             $ 2,174,653  
Common stock, voting rights             The holders of shares of common stock are entitled to one vote for each share of common stock held at all meetings of stockholders and written actions in lieu of meetings.  
Stockholders' Equity, Reverse Stock Split           1-for-10 reverse stock-split    
Private Placement [Member]                
Class of Stock [Line Items]                
Public offering price, per unit | $ / shares $ 4.45              
Issuance of securities in private placement, Shares | shares 674,156   1,111,111          
Warrants to purchase shares of common stock | shares             18,915  
Private placement, securities description             Each investor received one share of common stock and a warrant to purchase one-half share of common stock at a price of $42.30 per common share purchased.  
Exercise price per common share | $ / shares               $ 42.30
Class of warrant purchase percentage             4.00%  
Warrant expiration date             Jun. 11, 2020  
Follow-on Offering [Member]                
Class of Stock [Line Items]                
Number of shares issued | shares 11,797,752              
Public offering price, per unit | $ / shares $ 4.45              
Net proceeds received $ 48,900,000              
Warrants to purchase shares of common stock | shares 8,848,314              
Warrant exercise price per share | $ / shares $ 4.90              
Conversion ratio of common stock             0.75  
Follow-on Offering [Member] | 2016 Warrants [Member]                
Class of Stock [Line Items]                
Fair value of warrants         $ 18,600,000      
Issuance costs allocated to warrants         $ 1,600,000      
Follow-on Offering [Member] | 2017 Warrants [Member]                
Class of Stock [Line Items]                
Fair value of warrants       $ 12,400,000        
Issuance costs allocated to warrants       $ 900,000        
Follow-on Offering [Member] | 2020 Warrants [Member]                
Class of Stock [Line Items]                
Fair value of warrants $ 31,400,000              
Issuance costs allocated to warrants $ 2,200,000              
Pfizer Warrants [Member]                
Class of Stock [Line Items]                
Warrants to purchase shares of common stock | shares 505,617              
Warrant exercise price per share | $ / shares $ 4.90