XML 61 R38.htm IDEA: XBRL DOCUMENT v3.20.4
Summary of Significant Accounting Policies - Schedule of Weighted-Average Assumptions (Details)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate, minimum 0.22% 1.38% 2.39%
Risk-free interest rate, maximum 1.34% 2.54% 2.95%
Expected dividend yield 0.00%    
Stock options      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected common stock price volatility 118.00% 110.00% 85.00%
Expected term of options (years) 4 years 7 months 6 days 4 years 9 months 18 days 6 years
Expected dividend yield 0.00% 0.00% 0.00%