Quarterly report pursuant to Section 13 or 15(d)

Organization and Description of Business - Additional Information (Detail)

v3.20.2
Organization and Description of Business - Additional Information (Detail)
$ / shares in Units, $ in Millions
Aug. 31, 2020
USD ($)
May 27, 2020
USD ($)
$ / shares
shares
Dec. 18, 2019
USD ($)
shares
Dec. 12, 2019
USD ($)
shares
Sep. 30, 2020
shares
Organization And Description Of Business [Line Items]          
Number of shares issued   11,797,752 2,565,000 3,715,000  
Net proceeds received | $   $ 48.9 $ 10.0    
Net proceed | $   $ 3.0   $ 13.0  
Pfizer Warrants [Member]          
Organization And Description Of Business [Line Items]          
Warrants to purchase shares of common stock   505,617      
Warrant exercise price per share | $ / shares   $ 4.90      
Follow-on Offering [Member]          
Organization And Description Of Business [Line Items]          
Number of shares issued   11,797,752      
Warrants to purchase shares of common stock   8,848,314      
Warrant exercise price per share | $ / shares   $ 4.90      
Public offering price, per unit | $ / shares   $ 4.45      
Conversion ratio of common stock   0.75      
Net proceeds received | $ $ 150.0 $ 48.9      
Private Placement [Member]          
Organization And Description Of Business [Line Items]          
Warrants to purchase shares of common stock         18,915
Public offering price, per unit | $ / shares   $ 4.45      
Issuance of securities in private placement, Shares   674,156   1,111,111  
IPO [Member]          
Organization And Description Of Business [Line Items]          
Conversion ratio of common stock   0.75