Note 2 - Basis of Presentation and Recent Accounting Pronouncements - Fair Value of Items Measured on a Recurring Basis (Details) - USD ($) $ in Thousands |
Sep. 30, 2026 |
Dec. 31, 2025 |
Sep. 30, 2025 |
|---|---|---|---|
| Investments in debt securities (short-term) | $ 5,457 | $ 4,917 | $ 5,563 |
| Investments in debt securities (long-term) | 3,929 | 7,606 | $ 7,053 |
| Fair Value, Recurring [Member] | |||
| Investments in debt securities (short-term) | 5,457 | 4,917 | |
| Investments in debt securities (long-term) | 3,929 | 7,606 | |
| Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | |||
| Investments in debt securities (short-term) | 4,786 | 4,817 | |
| Investments in debt securities (long-term) | 2,656 | 5,481 | |
| Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | |||
| Investments in debt securities (short-term) | 671 | 100 | |
| Investments in debt securities (long-term) | 1,273 | 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 |