Quarterly report pursuant to Section 13 or 15(d)

Warrants - Narrative (Details)

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Warrants - Narrative (Details) - USD ($)
3 Months Ended 6 Months Ended
Feb. 10, 2020
Jun. 30, 2020
Jun. 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Apr. 30, 2020
Feb. 29, 2020
Dec. 31, 2019
Warrants in Connection with February 2020 Stock Offering                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Shares purchased from issuance of warrants (in shares) 5,625,000           5,625,000  
Warrants, initial exercise period from time of issuance 6 months              
Exercise price for shares purchased from issuance of warrants (in dollars per share) $ 1.05              
Warrant term 5 years              
Oppenheimer & Co., Underwriter Warrant                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Shares purchased from issuance of warrants (in shares) 525,000              
Exercise price for shares purchased from issuance of warrants (in dollars per share) $ 1.05              
Equity Warrants Issued to Consultant, Contingent Vesting Conditions                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Shares purchased from issuance of warrants (in shares)           100,000    
Vesting contingency, research and development expenditures threshold           $ 10,000,000    
Warrants outstanding (in shares)   607,802   607,802       507,802
Warrants exercisable (in shares)   512,802   512,802       507,802
Equity Classified Warrants | Warrant                
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                
Stock compensation expense   $ 5,000 $ 0 $ 5,000 $ 2,000      
Unrecognized stock compensation expense related to equity-classified warrants   $ 91,000   $ 91,000