Note 1 - Organization and Significant Accounting Policies - Summary of Intangible Asset Activity (Details) - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Gross Carrying Amount | $ 1,310 | $ 1,897 |
| Accumulated Amortization | (757) | (991) |
| Net Carrying Amount | 553 | 906 |
| Patents [Member] | ||
| Gross Carrying Amount | 1,310 | 1,897 |
| Accumulated Amortization | (757) | (991) |
| Net Carrying Amount | $ 553 | $ 906 |
| Patents [Member] | Minimum [Member] | ||
| Amortization Period (Year) | 1 year | |
| Patents [Member] | Maximum [Member] | ||
| Amortization Period (Year) | 20 years |