Note 8 - Share-based Compensation - Key Assumptions (Details) - $ / shares |
Sep. 09, 2024 |
Mar. 01, 2021 |
Mar. 01, 2020 |
Dec. 20, 2019 |
Feb. 01, 2019 |
|---|---|---|---|---|---|
| Fair value lower range (in dollars per share) | $ 0 | $ 8.76 | $ 9.48 | $ 16.86 | |
| Fair value higher range (in dollars per share) | 15.59 | 8.94 | 9.66 | 17.16 | |
| Exercise price (in dollars per share) | $ 2.75 | $ 13.98 | $ 15.36 | $ 28.32 | |
| Expected volatility | 65.00% | 80.00% | 70.00% | 70.00% | 65.00% |
| Risk-free rate | 3.70% | 1.05% | 1.85% | 2.61% | |
| Maximum [Member] | |||||
| Fair value lower range (in dollars per share) | $ 26.04 | ||||
| Fair value higher range (in dollars per share) | 26.58 | ||||
| Exercise price (in dollars per share) | $ 37.98 | ||||
| Expected term (Year) | 4 years 3 months 18 days | 1 year 3 months 18 days | 1 year 6 months | 1 year 7 months 6 days | 1 year 3 months 18 days |
| Risk-free rate | 1.18% | ||||
| Minimum [Member] | |||||
| Expected term (Year) | 3 years | 1 year | 1 year | 1 year | 1 year |