XML 52 R41.htm IDEA: XBRL DOCUMENT v3.21.2
Stock-based Compensation - Schedule of Estimating Fair Value of the Stock Options and Common stock Warrants Granted (Details)
6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Employee Service Share Based Compensation Aggregate Disclosures [Abstract]    
Volatility 88.78% 83.30%
Expected life (years) 6 years 29 days 6 years 29 days
Risk-free interest rate 0.67%  
Risk-free interest rate minimum   0.45%
Risk-free interest rate maximum   1.40%
Dividend rate 0.00% 0.00%