Annual report pursuant to Section 13 and 15(d)

Long-Term Debt and Other Financings - Silicon Valley Bank Loan Agreement (Details)

v3.20.4
Long-Term Debt and Other Financings - Silicon Valley Bank Loan Agreement (Details) - USD ($)
 1 Months Ended 12 Months Ended
May 07, 2018
Mar. 31, 2019
Sep. 30, 2018
May 31, 2018
Dec. 31, 2020
Dec. 31, 2019
Mar. 04, 2019
Long-term debt              
Proceeds from issuance of long-term debt           $ 9,500,000  
Debt amount         $ 20,852,000    
Current portion of long-term debt         8,088,000 5,184,000  
Long-term debt         $ 12,764,000 $ 27,093,000  
Common stock warrant, Exercise price $23.69 per share, Issued May 2018              
Long-term debt              
Exercise price of per share (in dollars per share)         $ 23.69 $ 23.69  
Common stock warrant, Exercise price $14.71 per share, Issued March 2019              
Long-term debt              
Exercise price of per share (in dollars per share)         $ 14.71 $ 14.71  
Silicon Valley Bank Loans              
Long-term debt              
Maximum borrowing capacity under loan agreement $ 20,000,000.0            
Period of monthly payments of principal and interest 24 months            
Maximum period following loan amortization date for which loan will mature 23 months            
Maximum period prior to loan maturity date of Novartis loan for which loan will mature 30 days            
Amount of loan that may be reborrowed after repayment $ 0            
Final payment fee (as a percent) 8.50%            
Additional interest rate in the event of default (as a percent) 4.00%            
Exercisable period of warrants         10 years    
Debt issuance costs $ 200,000            
Non-cash interest expense resulting from amortization of discount and accretion of final payment         $ 600,000 $ 500,000  
Debt amount         11,800,000 16,400,000  
Current portion of long-term debt         8,100,000 5,200,000  
Long-term debt         $ 3,700,000 11,200,000  
Silicon Valley Bank Loans | Minimum              
Long-term debt              
Interest rate (as a percent) 4.75%            
Silicon Valley Bank Loans | Common stock warrant, Exercise price $23.69 per share, Issued May 2018              
Long-term debt              
Aggregate number of shares of common stock called by warrants 6,332     6,332      
Exercise price of per share (in dollars per share) $ 23.69     $ 23.69      
Exercisable period of warrants 10 years     10 years      
Fair value of warrant $ 100,000     $ 100,000      
Silicon Valley Bank Loans | Common stock warrant, Exercise price $14.71 per share, Issued March 2019              
Long-term debt              
Aggregate number of shares of common stock called by warrants   4,845         4,845
Exercise price of per share (in dollars per share)   $ 14.71         $ 14.71
Exercisable period of warrants   10 years          
Fair value of warrant   $ 100,000         $ 100,000
Silicon Valley Bank Loans | Prime Rate              
Long-term debt              
Basis spread on variable rate 0.25%            
Silicon Valley Bank Loans | On or before first anniversary              
Long-term debt              
Prepayment fee (as a percent) 3.00%            
Silicon Valley Bank Loans | Following first anniversary              
Long-term debt              
Prepayment fee (as a percent) 2.00%            
Silicon Valley Bank Loans | Following second anniversary              
Long-term debt              
Prepayment fee (as a percent) 1.00%            
Silicon Valley Bank, First Term Loan              
Long-term debt              
Proceeds from issuance of long-term debt     $ 7,500,000        
Unamortized discount     $ 300,000        
Silicon Valley Bank, Second Term Loan              
Long-term debt              
Proceeds from issuance of long-term debt           9,500,000  
Unamortized discount           $ 45,000