Note 6 - Stock-based Compensation - Non-cash Stock Compensation Expense (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2022 |
Sep. 30, 2021 |
Sep. 30, 2022 |
Sep. 30, 2021 |
|
| Share-based payment expense | $ 179 | $ 142 | $ 552 | $ 512 |
| Share-Based Payment Arrangement, Option [Member] | ||||
| Share-based payment expense | 176 | 131 | 538 | 468 |
| Restricted Stock [Member] | ||||
| Share-based payment expense | $ 3 | $ 11 | $ 14 | $ 44 |