Quarterly report pursuant to Section 13 or 15(d)

Oxford Finance Loan Agreement - Additional Information (Details)

v3.21.1
Oxford Finance Loan Agreement - Additional Information (Details)
3 Months Ended
Dec. 23, 2020
USD ($)
$ / shares
shares
Feb. 12, 2020
USD ($)
$ / shares
shares
Mar. 31, 2021
USD ($)
shares
Mar. 31, 2020
shares
Debt Instrument [Line Items]        
Warrants to purchase common stock | shares     2,117,094 2,118,094
Loan Agreement        
Debt Instrument [Line Items]        
Term loan, aggregate principal amount   $ 60,000,000.0    
Additional term loan advances, description   A first tranche term loan for $20.0 million was funded on February 12, 2020, and a second tranche term loan for $20.0 million was funded on December 23, 2020. The remaining $20.0 million is still available under the Loan Agreement, at the sole discretion of the Lender.    
Each of available additional term loan advances   $ 20,000,000.0    
Term loan, interest rate terms   The term loan bears interest at an annual rate equal to the greater of (i) 7.75% and (ii) the sum of 5.98% and the greater of (A) one-month LIBOR or (B) 1.77%.    
Term loan, interest rate   7.75%    
Term loan, effective interest rate   5.98%    
Term loan, variable interest rate basis   one-month LIBOR    
Term loan, variable interest rate basis spread   1.77%    
Term loan, maturity date   Feb. 01, 2025    
Term loan, final payment fee percentage   5.00%    
Warrants to purchase common stock | shares     27,548 27,548
Warrant exercisable period from date of issuance     5 years  
Interest expense     $ 900,000  
Loan Agreement | Advance Prepaid in First 12 Months        
Debt Instrument [Line Items]        
Term loan, prepayment fee, equal to percentage of the principal amount being prepaid   2.00%    
Loan Agreement | Advance Prepaid After 12 Months But Prior to 24 Months        
Debt Instrument [Line Items]        
Term loan, prepayment fee, equal to percentage of the principal amount being prepaid   1.00%    
Loan Agreement | Advance Prepaid After 24 Months But Prior to Maturity Date        
Debt Instrument [Line Items]        
Term loan, prepayment fee, equal to percentage of the principal amount being prepaid   0.50%    
Loan Agreement | First Loan Tranche        
Debt Instrument [Line Items]        
Term loan   $ 20,000,000.0    
Term Loan, facilities fee   $ 100,000    
Warrants to purchase common stock | shares   27,548    
Warrant exercise price of common stock per share | $ / shares   $ 7.26    
Fair value of warrants   $ 100,000    
Loan Agreement | First Loan Tranche | Expected volatility | Weighted Average        
Debt Instrument [Line Items]        
Fair value of weighted average volatility   75.43    
Loan Agreement | First Loan Tranche | Expected life (in years) | Weighted Average        
Debt Instrument [Line Items]        
Fair value of weighted expected term   5 years    
Loan Agreement | Second Loan Tranche        
Debt Instrument [Line Items]        
Term loan $ 20,000,000.0      
Term Loan, facilities fee $ 75,000      
Warrants to purchase common stock | shares 17,389      
Warrant exercise price of common stock per share | $ / shares $ 11.50      
Fair value of warrants $ 200,000      
Loan Agreement | Second Loan Tranche | Expected volatility | Weighted Average        
Debt Instrument [Line Items]        
Fair value of weighted average volatility 82.41      
Loan Agreement | Second Loan Tranche | Expected life (in years) | Weighted Average        
Debt Instrument [Line Items]        
Fair value of weighted expected term 5 years      
Loan Agreement | Third Loan Tranche        
Debt Instrument [Line Items]        
Term loan, facilities fee   $ 50,000