Note 6 - Stockholders' Equity and Stock-based Compensation Expense - Stock-based Compensation Expense 2 (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Stock-based compensation expense | $ 3,476 | $ 4,402 | $ 11,616 | $ 14,208 |
| Location, Statement of Income, Balance [Axis]: us-gaap:GeneralAndAdministrativeExpense | ||||
| Stock-based compensation expense | 2,421 | 3,108 | 7,880 | 9,380 |
| Location, Statement of Income, Balance [Axis]: us-gaap:ResearchAndDevelopmentExpense | ||||
| Stock-based compensation expense | $ 1,055 | $ 1,294 | $ 3,736 | $ 4,828 |