Note 6 - Stockholders' Equity and Stock-based Compensation Expense - Stock-based Compensation Expense 2 (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Stock-based compensation expense | $ 4,071 | $ 4,582 | $ 8,140 | $ 9,806 |
| Location, Statement of Income, Balance [Axis]: us-gaap:GeneralAndAdministrativeExpense | ||||
| Stock-based compensation expense | 2,723 | 3,420 | 5,459 | 6,272 |
| Location, Statement of Income, Balance [Axis]: us-gaap:ResearchAndDevelopmentExpense | ||||
| Stock-based compensation expense | $ 1,348 | $ 1,162 | $ 2,681 | $ 3,534 |