Note 9 - Income Taxes (Details Textual) $ in Thousands |
12 Months Ended |
|---|---|
|
Dec. 31, 2021
USD ($)
| |
| Income Taxes Paid | $ 0 |
| Research Tax Credit Carryforward [Member] | |
| Tax Credit Carryforward, Amount | 1,600 |
| Domestic Tax Authority [Member] | |
| Operating Loss Carryforwards, Total | 75,200 |
| Operating Loss Carryforwards, Subject to Expiration | $ 48,900 |