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Stock Based Compensation - Assumptions used in the Black-Scholes option-pricing model (Details)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Volatility 100.34%  
Volatility, minimum   100.34%
Volatility, maximum   102.90%
Risk free interest rate, minimum 1.63% 2.56%
Risk free interest rate, maximum 2.60% 2.85%
Dividend yield 0.00% 0.00%
Minimum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected life (in years) 2 years 10 months 6 days 2 years 4 months 24 days
Maximum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected life (in years) 6 years 29 days 6 years 29 days