Annual report pursuant to Section 13 and 15(d)

Share-based Compensation, Weighted Average Assumptions Used in Black-Scholes Option-pricing Model (Details)

v3.20.4
Share-based Compensation, Weighted Average Assumptions Used in Black-Scholes Option-pricing Model (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Abstract]    
Common stock available for future issuance (in shares) 446,843  
2018 Equity Incentive Plan [Member]    
Weighted-average Assumptions Used in Black-Scholes Option-pricing Model [Abstract]    
Expected stock price volatility 86.80% 92.10%
Expected life of options (years) 7 years 2 months 12 days 5 years 6 months
Expected dividend yield 0.00% 0.00%
Risk free interest rate 0.60% 1.70%
Share-based Compensation Arrangement by Share-based Payment Award [Abstract]    
Stock options vested (in shares) 379,576 423,747
Weighted average fair value per share of options vesting (in dollars per share) $ 2.77 $ 0.66
Stock options forfeited (in shares) 43,002 0
Common stock available for future issuance (in shares) 446,843  
Unrecognized share-based compensation cost $ 2.5  
Weighted average period to recognized share-based compensation 1 year 6 months