Annual report pursuant to Section 13 and 15(d)

Fair Value Measurement - Summary of Changes in Fair Value of Level 3 Financial Liabilities on Recurring Basis (Details)

v3.20.4
Fair Value Measurement - Summary of Changes in Fair Value of Level 3 Financial Liabilities on Recurring Basis (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Loss on revaluation of warrants issued in June 2020, December 2019, May 2019 financing, and December 2015 equity financings $ 3,056 $ (6,376)
Warrant Liability    
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 4,307  
Initial fair value of warrants in connection with June 2020 financing 2,650  
Loss on revaluation of warrants issued in June 2020, December 2019, May 2019 financing, and December 2015 equity financings 3,056  
Reclassification of warrant liability to equity upon exercise of warrants (3,976)  
Gain on revaluation of contingent liability 0  
Ending balance 6,037 4,307
Contingent Success Fee Liability    
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 6  
Initial fair value of warrants in connection with June 2020 financing 0  
Loss on revaluation of warrants issued in June 2020, December 2019, May 2019 financing, and December 2015 equity financings 0  
Reclassification of warrant liability to equity upon exercise of warrants 0  
Gain on revaluation of contingent liability (6)  
Ending balance $ 0 $ 6