Note 4 - Prepaid Expenses - Prepaid Expenses and Other Assets (Details) - USD ($) $ in Thousands  | 
Sep. 30, 2024  | 
Dec. 31, 2023  | 
|---|---|---|
| Prepaid Expense and Other Assets [Abstract] | ||
| Prepaid research and development expenses | $ 662 | $ 720 | 
| Prepaid insurance | 71 | 882 | 
| Other prepaid Operating expenses | 179 | 440 | 
| Total | $ 912 | $ 2,042 | 
| X | ||||||||||
- Definition Amount of consideration paid in advance for research and development that provides economic benefits within a future period of one year or the normal operating cycle, if longer. No definition available. 
  | 
| X | ||||||||||
- Definition Amount of asset related to consideration paid in advance for other costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef 
  | 
| X | ||||||||||
- References No definition available. 
  | 
| X | ||||||||||
- Definition Amount of asset related to consideration paid in advance for costs that provide economic benefits within a future period of one year or the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/exampleRef 
  | 
| X | ||||||||||
- Definition Amount of asset related to consideration paid in advance for insurance that provides economic benefits within a future period of one year or the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/exampleRef 
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