Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Long-Term Debt - Silicon Valley Bank Loan Agreement - Additional Information (Details) - Loan and Security Agreement [Member] - Silicon Valley Bank [Member] - USD ($)
3 Months Ended
Mar. 04, 2019
May 07, 2018
Mar. 31, 2019
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  
Exercisable period of warrants 10 years 10 years  
Fair value of warrant $ 100,000 $ 100,000  
Term Loan [Member]      
Debt Instrument [Line Items]      
Maximum borrowing capacity under loan agreement   20,000,000  
Increase borrowing capacity under loan agreement   $ 40,000,000  
Earlier effecitve date of term loan   Mar. 31, 2019  
Effective date of term loan extended   Mar. 31, 2020  
Gross cash proceeds received from milestone and licensing payments   $ 20,000,000  
Basis spread on variable rate   4.75%  
Variable rate basis   The interest-only period will be followed by equal monthly payments of principal and interest over 24 months. 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  
Term Loan [Member] | Agenus [Member]      
Debt Instrument [Line Items]      
Loan borrowed     $ 7,500,000
Discount against debt     300,000
Non-cash interest expense resulting from amortization of discount and accretion of final payment     100,000
Carrying value of debt     $ 7,400,000
Term Loan [Member] | First Anniversary [Member]      
Debt Instrument [Line Items]      
Percentage of prepayment fee   2.00%  
Term Loan [Member] | Second Anniversary [Member]      
Debt Instrument [Line Items]      
Percentage of prepayment fee   1.00%  
Term Loan [Member] | Prime Rate [Member]      
Debt Instrument [Line Items]      
Basis spread on variable rate   0.25%  
Novartis [Member]      
Debt Instrument [Line Items]      
Maturity date   Mar. 01, 2023  
Days of interest, period   30 days  
Earliest maturity of loan   30 days