Note 18 - Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands |
Dec. 31, 2021 |
Dec. 31, 2020 |
|---|---|---|
| Accruals and other | $ 3,989 | $ 4,136 |
| Research credits | 7,275 | 7,275 |
| Net operating loss carryforward | 75,452 | 65,274 |
| Section 59(e) R&D expenditures | 5,070 | 7,473 |
| Deferred revenue | 19,666 | 20,848 |
| Total deferred tax assets | 111,452 | 105,006 |
| Valuation allowance | (111,452) | (105,006) |
| Net deferred tax assets | $ 0 | $ 0 |