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Note 10 - Stock-based Compensation (Tables) | 9 Months Ended
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Sep. 30, 2022
Notes Tables |
Share-Based Payment Arrangement, Option, Activity [Table Text Block] |
|  |  |  |  |  | Weighted- |
|  |  |  |  |  | Average |
|  | Stock Options |  |  | Exercise Price |
Options outstanding at December 31, 2021 |  |  | 233,384 |  |  | $ | 97.78 |
Granted |  |  | 118,434 |  |  |  | 48.24 |
Exercised |  |  | (3,114 | ) |  |  | 30.58 |
Forfeited |  |  | (38,618 | ) |  |  | 91.27 |
Expired |  |  | (34,201 | ) |  |  | 89.71 |
Options outstanding at September 30, 2022 |  |  | 275,885 |  |  | $ | 79.19 |
Exercisable at September 30, 2022 |  |  | 108,659 |  |  | $ | 91.50 |
Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] |
|  | Nine Months Ended September 30, |
|  | 2022 |  |  | 2021 |
Risk-free interest rate |  |  | 1.94% - 3.40% |  |  |  | 0.80% - 1.12% |
Expected life (years) |  |  | 6.25 |  |  |  | 6.25 |
Expected volatility |  |  | 45.95% - 46.03% |  |  |  | 45.28 - 45.35% |
Expected dividend yield |  |  | 0% |  |  |  | 0% |
Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block] |
|  |  |  |  |  | Weighted- |
|  |  |  |  |  | Average |
|  |  |  |  |  | Grant Date |
|  | Restricted |  |  | Fair Value |
|  | Stock |  |  | Per Share |
Restricted stock at December 31, 2021 |  |  | 343,782 |  |  | $ | 111.79 |
Granted |  |  | 312,270 |  |  |  | 42.05 |
Restrictions lapsed |  |  | (120,606 | ) |  |  | 104.99 |
Forfeited |  |  | (39,480 | ) |  |  | 106.64 |
Restricted stock at September 30, 2022 |  |  | 495,966 |  |  | $ | 69.95 |
Schedule of Nonvested Performance-Based Units Activity [Table Text Block] |
|  |  |  |  |  | Weighted- |
|  |  |  |  |  | Average |
|  |  |  |  |  | Grant Date |
|  | Performance |  |  | Fair Value |
|  | Stock |  |  | Per Share |
Performance stock at December 31, 2021 |  |  | 16,839 |  |  | $ | 115.56 |
Granted |  |  | 35,697 |  |  |  | 96.71 |
Restrictions lapsed |  |  | - |  |  |  | - |
Performance change |  |  | - |  |  |  | - |
Forfeited |  |  | (3,578 | ) |  |  | 121.79 |
Performance stock at September 30, 2022 |  |  | 48,958 |  |  | $ | 109.80 |
Schedule of Share-based Payment Award, Awards Other Than Stock Options, Valuation Assumptions [Table Text Block] |
|  | Nine Months Ended September 30, |
|  | 2022 |  |  | 2021 |
Risk-free interest rate |  |  | 1.76% - 3.40% |  |  |  | 0.22% |
Expected life (years) |  |  | 2.34 - 2.87 |  |  |  | 2.87 |
Expected volatility |  |  | 53.5% - 53.6% |  |  |  | 51.40% |
Expected dividend yield |  |  | 0% |  |  |  | 0% |
Schedule of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block] |
|  | Nine Months Ended September 30, |
|  | 2022 |  |  | 2021 |
Risk-free interest rate |  |  | 0.17 - 2.06% |  |  |  | 0.06 - 0.12% |
Expected life (months) |  |  | 6.00 |  |  |  | 6.00 |
Expected volatility |  |  | 47.05 - 53.44% |  |  |  | 50.85 - 65.53% |
Expected dividend yield |  |  | 0% |  |  |  | 0% |

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