Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Option pricing model (Details)

v3.20.4
Stockholders' Equity - Option pricing model (Details)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Stockholders' Equity    
Risk-free interest rate, Minimum 0.65% 1.77%
Risk-free interest rate, Maximum 1.02% 2.72%
Expected dividend yield 0.00% 0.00%
Expected term in years 10 years 10 years
Expected volatility, Minimum 101.27% 99.84%
Expected volatility, Maximum 104.60% 103.79%