Note 11 - Share-based Compensation - Share-based Compensation Expense (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2021 |
Sep. 30, 2020 |
Sep. 30, 2021 |
Sep. 30, 2020 |
|
| Total share-based compensation | $ 303 | $ 508 | $ 1,260 | $ 1,337 |
| Research and Development Expense [Member] | ||||
| Total share-based compensation | 100 | 141 | 371 | 379 |
| General and Administrative Expense [Member] | ||||
| Total share-based compensation | $ 203 | $ 367 | $ 889 | $ 958 |
| X | ||||||||||
- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
|
| X | ||||||||||
- Details
|
| X | ||||||||||
- Details
|