Quarterly report pursuant to Section 13 or 15(d)

Long-Term Debt - Silicon Valley Bank Loan Agreement - Additional Information (Details)

v3.19.3
Long-Term Debt - Silicon Valley Bank Loan Agreement - Additional Information (Details) - USD ($)
 3 Months Ended 9 Months Ended
Mar. 04, 2019
May 07, 2018
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Debt Instrument [Line Items]              
Current portion of long-term debt     $ 3,981,000   $ 3,981,000   $ 789,000 [1]
Long-term debt     28,698,000   $ 28,698,000   21,690,000 [1]
Loan and Security Agreement [Member] | Silicon Valley Bank [Member] | Warrants for Common Stock [Member]              
Debt Instrument [Line Items]              
Aggregate number of shares of common stock called by warrants 4,845 6,332          
Exercise price of per share $ 14.71 $ 23.69          
Fair value of warrant $ 100,000 $ 100,000          
Exercisable period of warrants         10 years    
Loan and Security Agreement [Member] | Term Loan [Member] | Silicon Valley Bank [Member]              
Debt Instrument [Line Items]              
Maximum borrowing capacity under loan agreement   20,000,000          
Increase borrowing capacity under loan agreement   $ 40,000,000          
End of the draw period of the term loan   Mar. 31, 2019          
Variable rate basis   The interest rate will be calculated at a rate equal to the greater of (i) 4.75%, and (ii) 0.25% plus the prime rate as reported from time to time in The Wall Street Journal.          
Debt instrument, frequency of periodic payment   The interest-only period will be followed by equal monthly payments of principal and interest over 24 months          
Debt instrument, maturity date   Each Term Loan Advance will mature at the earlier of (i) the 23 months following the applicable term loan amortization date for each such Term Loan Advance (ii) March 1, 2023, or (iii) 30 days prior to the earliest maturity of any portion of the Company’s loan with Novartis (the “Loan Maturity Date”). After repayment, no Term Loan Advance (or any portion thereof) may be reborrowed.          
Period of monthly payments of principal and interest   24 months          
Repayment of term loan   $ 0          
Loan borrowed   $ 0          
Percentage of final payment fee of Loan   8.50%          
Percentage of prepayment fee   3.00%          
Additional interest rate of outstanding payments due   4.00%          
Debt issuance costs   $ 200,000          
Extended end of the draw period of the term loan Mar. 31, 2020            
Loan and Security Agreement [Member] | Term Loan [Member] | Silicon Valley Bank [Member] | Agenus [Member]              
Debt Instrument [Line Items]              
Carrying value of debt     17,100,000   $ 17,100,000   7,300,000
Current portion of long-term debt     4,000,000   4,000,000   800,000
Long-term debt     13,100,000   13,100,000   $ 6,500,000
Loan and Security Agreement [Member] | Term Loan [Member] | Silicon Valley Bank [Member] | First Anniversary [Member]              
Debt Instrument [Line Items]              
Percentage of prepayment fee   2.00%          
Loan and Security Agreement [Member] | Term Loan [Member] | Silicon Valley Bank [Member] | Second Anniversary [Member]              
Debt Instrument [Line Items]              
Percentage of prepayment fee   1.00%          
Loan and Security Agreement [Member] | Term Loan [Member] | Silicon Valley Bank [Member] | Minimum [Member]              
Debt Instrument [Line Items]              
Minimum effective interest rate on debt   4.75%          
Loan and Security Agreement [Member] | Term Loan [Member] | Prime Rate [Member] | Silicon Valley Bank [Member]              
Debt Instrument [Line Items]              
Basis spread on variable rate   0.25%          
Loan and Security Agreement [Member] | Novartis [Member] | Silicon Valley Bank [Member]              
Debt Instrument [Line Items]              
Maturity date   Mar. 01, 2023          
Days of interest, period   30 days          
Earliest maturity of loan   30 days          
Loan and Security Agreement [Member] | First Term Loan [Member] | Silicon Valley Bank [Member] | Agenus [Member]              
Debt Instrument [Line Items]              
Loan borrowed       $ 7,500,000   $ 7,500,000  
Discount against debt       300,000   300,000  
Non-cash interest expense resulting from amortization of discount and accretion of final payment     200,000 $ 11,000 400,000 $ 11,000  
Loan and Security Agreement [Member] | Second Term Loan [Member] | Silicon Valley Bank [Member] | Aronora [Member]              
Debt Instrument [Line Items]              
Loan borrowed     9,500,000   9,500,000    
Discount against debt     $ 45,000   $ 45,000    
[1] The consolidated balance sheet as of December 31, 2018 has been derived from the audited consolidated financial statements as of that date included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018.