Note 2 - Basis of Presentation and Recent Accounting Pronouncements - Fair Value of Items Measured on a Recurring Basis (Details) - USD ($) $ in Thousands |
Jun. 30, 2026 |
Dec. 31, 2025 |
Jun. 30, 2025 |
|---|---|---|---|
| Investments in debt securities (short-term) | $ 6,511 | $ 4,917 | $ 7,945 |
| Investments in debt securities (long-term) | 4,070 | 7,606 | $ 8,267 |
| Fair Value, Recurring [Member] | |||
| Investments in debt securities (short-term) | 6,511 | 4,917 | |
| Investments in debt securities (long-term) | 4,070 | 7,606 | |
| Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | |||
| Investments in debt securities (short-term) | 5,937 | 4,817 | |
| Investments in debt securities (long-term) | 2,682 | 5,481 | |
| Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | |||
| Investments in debt securities (short-term) | 574 | 100 | |
| Investments in debt securities (long-term) | 1,388 | 2,125 | |
| Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | |||
| Investments in debt securities (short-term) | 0 | 0 | |
| Investments in debt securities (long-term) | $ 0 | $ 0 |