Note 11 - Stock-based Compensation - Share-based Payment Expense (Details) - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2019 |
Dec. 31, 2018 |
|
| Share-based payment expense | $ 2,296 | $ 4,276 |
| Research and Development Expense [Member] | ||
| Share-based payment expense | 474 | 1,026 |
| General and Administrative Expense [Member] | ||
| Share-based payment expense | $ 1,822 | $ 3,250 |
| 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
|