Note 12 - Stock Option and Equity Incentive Plans - Future Share-based Compensation Expense (Details) $ in Thousands	Dec. 31, 2020 USD ($)
2021	$ 1,076
2022	588
2023	262
2024	23
Total	1,949
Employee and Nonemployee Stock Option [Member]
2021	93
2022	0
2023	0
2024	0
Total	93
Restricted Stock Units (RSUs) [Member]
2021	983
2022	588
2023	262
2024	23
Total	$ 1,856