Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Narrative) (Details)

v3.21.2
Stockholders' Equity (Narrative) (Details) - USD ($)
3 Months Ended 9 Months Ended
Aug. 29, 2020
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Aug. 27, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock-based compensation expense   $ 4,326,000 $ 3,171,000 $ 12,449,000 $ 10,319,000  
Stock options, unrecognized compensation expense   0   0    
Oaktree Note [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Class of Warrant or Right, Number of Securities Called by Warrants or Rights           1,749,450
Exercise price of warrants $ 3.20          
Percentage of market price of common stock for additional warrants 95.00%          
Warrants expiration date Aug. 27, 2030          
Fair value assumptions, expected term 10 years          
Fair value assumptions, expected volatility rate 0.868%          
Fair value assumptions, risk free interest rate 0.74%          
Fair value assumptions, expected return $ 4,800,000          
Warrants, fair value   4,400,000   4,400,000   $ 4,400,000
Maximum [Member] | Oaktree Note [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Class of Warrant or Right, Number of Securities Called by Warrants or Rights 1,749,450          
Research and Development Expense [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock-based compensation expense   1,100,000 700,000 3,100,000 2,500,000  
General and Administrative Expense [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock-based compensation expense   3,200,000 2,500,000 9,400,000 7,800,000  
Employee Stock Option [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock-based compensation expense   $ 31,000 38,000 $ 100,000 100,000  
Predetermined fair value percentage during offering period   85.00%   85.00%    
Shares purchased in connection with the ESPP offering       636,408    
Number of shares available for future issuance   363,592   363,592    
Restricted Stock Awards and Restricted Stock Units [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Unrecognized compensation expense for awards other than options   $ 21,100,000 17,500,000 $ 21,100,000 $ 17,500,000  
Share-based compensation, period for recognition of expense       3 years 1 month 6 days 3 years 10 months 24 days  
Warrants [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock-based compensation expense   $ 0 $ 32,000 $ 0 $ 97,000