Annual report pursuant to Section 13 and 15(d)

Stock-based Compensation - Option Valuation Method (Details)

v3.21.1
Stock-based Compensation - Option Valuation Method (Details)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Weighted average expected volatility, employees 64.67% 66.47%
Weighted average expected volatility, non-employees directors 66.55% 65.36%
Weighted average risk-free interest rate, employees 1.18% 2.47%
Weighted average risk-free interest rate, non-employees directors 0.36% 2.11%
Weighted average expected term (in years), employees 5 years 11 months 19 days 6 years 10 days
Weighted average expected term (in years), non-employees directors 5 years 6 months 5 years 6 months 14 days