Annual report pursuant to Section 13 and 15(d)

Convertible Notes Payable - Additional Information (Detail)

v3.20.2
Convertible Notes Payable - Additional Information (Detail)
$ in Millions
12 Months Ended
Dec. 18, 2019
shares
Mar. 31, 2020
USD ($)
shares
Sep. 26, 2019
USD ($)
Promissory_Notes
Aug. 01, 2019
USD ($)
Promissory_Notes
Accrued Interest [Member]        
Convertible Notes Payable [Line Items]        
Accrued interest waived   $ 0.6    
Common stock [Member]        
Convertible Notes Payable [Line Items]        
Exchange of Common Stock | shares 42,080,376 3,499,995    
RTW Convertible Promissory Notes [Member]        
Convertible Notes Payable [Line Items]        
Number of promissory notes issued | Promissory_Notes       2
Debt face amount     $ 22.5 $ 25.0
Debt instrument, interest rate       5.00%
Prepayment     $ 2.5  
BVF Convertible Promissory Notes [Member]        
Convertible Notes Payable [Line Items]        
Number of promissory notes issued | Promissory_Notes     4  
Debt face amount     $ 10.0  
Convertible Promissory Notes [Member]        
Convertible Notes Payable [Line Items]        
Conversion of convertible notes into common stock | shares   7,156,495