Note 12 - Share-based Compensation - Stock Options Outstanding (Details) | 6 Months Ended |
Jun. 30, 2022 $ / shares shares |
Outstanding, shares (in shares) | shares | 2,623,998 |
Outstanding, weighted average remaining contractual life (Year) | 7 years 9 months 18 days |
Outstanding, weighted average exercise price (in dollars per share) | $ 4.37 |
Exercisable, shares (in shares) | shares | 1,358,459 |
Exercisable, weighted average remaining contractual life (Year) | 6 years 3 months 18 days |
Exercise Price Range 1 [Member] | |
Per share exercise price, lower range (in dollars per share) | $ 2 |
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share) | $ 2.99 |
Outstanding, shares (in shares) | shares | 800,398 |
Outstanding, weighted average remaining contractual life (Year) | 8 years 7 months 6 days |
Outstanding, weighted average exercise price (in dollars per share) | $ 2.53 |
Exercisable, shares (in shares) | shares | 133,000 |
Exercisable, weighted average remaining contractual life (Year) | 4 years |
Exercise Price Range 2 [Member] | |
Per share exercise price, lower range (in dollars per share) | $ 3 |
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share) | $ 3.99 |
Outstanding, shares (in shares) | shares | 328,008 |
Outstanding, weighted average remaining contractual life (Year) | 8 years 7 months 6 days |
Outstanding, weighted average exercise price (in dollars per share) | $ 3.82 |
Exercisable, shares (in shares) | shares | 85,472 |
Exercisable, weighted average remaining contractual life (Year) | 6 years 10 months 24 days |
Exercise Price Range 3 [Member] | |
Per share exercise price, lower range (in dollars per share) | $ 4 |
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share) | $ 4.99 |
Outstanding, shares (in shares) | shares | 943,567 |
Outstanding, weighted average remaining contractual life (Year) | 6 years 9 months 18 days |
Outstanding, weighted average exercise price (in dollars per share) | $ 4.55 |
Exercisable, shares (in shares) | shares | 871,399 |
Exercisable, weighted average remaining contractual life (Year) | 6 years 8 months 12 days |
Exercise Price Range 4 [Member] | |
Per share exercise price, lower range (in dollars per share) | $ 5 |
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share) | $ 9.99 |
Outstanding, shares (in shares) | shares | 512,025 |
Outstanding, weighted average remaining contractual life (Year) | 8 years |
Outstanding, weighted average exercise price (in dollars per share) | $ 7.96 |
Exercisable, shares (in shares) | shares | 237,338 |
Exercisable, weighted average remaining contractual life (Year) | 6 years 8 months 12 days |
Exercise Price Range 5 [Member] | |
Per share exercise price, lower range (in dollars per share) | $ 10 |
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share) | $ 27.06 |
Outstanding, shares (in shares) | shares | 40,000 |
Outstanding, weighted average remaining contractual life (Year) | 4 years |
Outstanding, weighted average exercise price (in dollars per share) | $ 13.42 |
Exercisable, shares (in shares) | shares | 31,250 |
Exercisable, weighted average remaining contractual life (Year) | 2 years 8 months 12 days |