Quarterly report pursuant to Section 13 or 15(d)

Oxford Finance Loan Agreement - Additional Information (Details)

v3.20.2
Oxford Finance Loan Agreement - Additional Information (Details)
3 Months Ended 9 Months Ended
Feb. 12, 2020
USD ($)
TermLoanAdvance
$ / shares
shares
Sep. 30, 2020
USD ($)
shares
Sep. 30, 2020
USD ($)
shares
Sep. 30, 2019
shares
Debt Instrument [Line Items]        
Warrants to purchase common stock | shares   2,118,094 2,118,094 2,118,344
Loan Agreement        
Debt Instrument [Line Items]        
Term loan, aggregate principal amount $ 60,000,000.0      
Term loan $ 20,000,000.0      
Additional term loan advances, description A $20.0 million term loan was funded on February 12, 2020, and two additional term loan advances of $20.0 million each remain available under the Loan Agreement, subject to certain terms and conditions, including the achievement of certain milestones      
Each of additional term loan advances | TermLoanAdvance 2      
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, facilities fee $ 100,000      
Term loan, final payment fee percentage 5.00%      
Warrants to purchase common stock | shares 27,548      
Warrant exercise price of common stock per share | $ / shares $ 7.26      
Warrant exercisable period from date of issuance 5 years      
Change fair value of warrants $ 100,000      
Interest expense   $ 500,000 $ 1,200,000  
Loan Agreement | Weighted Average Volatility | Weighted Average        
Debt Instrument [Line Items]        
Fair value of weighted average volatility 75.43%      
Loan Agreement | Weighted Average Expected Term | Weighted Average        
Debt Instrument [Line Items]        
Fair value of weighted expected term 5 years      
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 | Second Loan Tranche        
Debt Instrument [Line Items]        
Term loan, facilities fee $ 75,000      
Loan Agreement | Third Loan Tranche        
Debt Instrument [Line Items]        
Term loan, facilities fee $ 50,000