Note 6 - Marketable Securities - Short-term and Long-term Available for Sale Securities (Details) - USD ($) $ in Thousands |
Mar. 31, 2023 |
Dec. 31, 2022 |
|---|---|---|
| Amortized Cost | $ 43,720 | $ 51,366 |
| Unrealized Gains | 0 | 0 |
| Unrealized Losses | (1,045) | (1,379) |
| Fair Value | 42,675 | 49,987 |
| US States and Political Subdivisions Debt Securities [Member] | ||
| Amortized Cost | 14,377 | 15,574 |
| Unrealized Gains | 0 | 0 |
| Unrealized Losses | (330) | (417) |
| Fair Value | 14,047 | 15,157 |
| Corporate Debt Securities [Member] | ||
| Amortized Cost | 6,567 | 9,578 |
| Unrealized Gains | 0 | 0 |
| Unrealized Losses | (153) | (205) |
| Fair Value | 6,414 | 9,373 |
| US Government Agencies Debt Securities [Member] | ||
| Amortized Cost | 22,282 | 25,275 |
| Unrealized Gains | 0 | 0 |
| Unrealized Losses | (558) | (750) |
| Fair Value | 21,724 | 24,525 |
| Bank Time Deposits [Member] | ||
| Amortized Cost | 494 | 939 |
| Unrealized Gains | 0 | 0 |
| Unrealized Losses | (4) | (7) |
| Fair Value | $ 490 | $ 932 |