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Risks and Uncertainties (Details) - USD ($)
$ in Thousands
6 Months Ended 19 Months Ended
Jun. 30, 2022
Jun. 30, 2021
Jun. 30, 2022
Dec. 31, 2021
Jul. 15, 2019
Concentration Risk [Line Items]          
Cash and cash equivalents $ 17,695   $ 17,695 $ 28,024  
Accumulated deficit $ 286,318   $ 286,318 $ 256,796  
At-the-market offering          
Concentration Risk [Line Items]          
Number of shares issued in transaction (in shares) 1,404,878   8,886,297    
Consideration received on sale of stock $ 2,473   $ 38,306    
Payments for stock issuance costs 139 $ 933 1,903    
Remaining amount available for offering $ 34,791   $ 34,791    
Senior secured notes due 2025          
Concentration Risk [Line Items]          
Interest rate 12.50%   12.50%    
Senior secured notes due 2025 | Senior notes          
Concentration Risk [Line Items]          
Interest rate 12.50%   12.50%   12.50%