Note 4 - Investments - Available-for-sale Investments (Details) - USD ($) $ in Thousands |
Dec. 31, 2025 |
Sep. 30, 2025 |
|---|---|---|
| Fair value | $ 142,847 | $ 144,306 |
| Short-term US Treasury Securities [Member] | ||
| Amortized cost | 82,151 | 84,192 |
| Unrealized gains | 190 | 119 |
| Unrealized losses | (30) | (70) |
| Fair value | 82,311 | 84,241 |
| Short-term Certificates of Deposit [Member] | ||
| Amortized cost | 248 | 248 |
| Unrealized gains | 0 | 0 |
| Unrealized losses | (3) | (5) |
| Fair value | 245 | 243 |
| Short-term Investment [Member] | ||
| Amortized cost | 82,399 | 84,440 |
| Unrealized gains | 190 | 119 |
| Unrealized losses | (33) | (75) |
| Fair value | 82,556 | 84,484 |
| US Treasury Securities [Member] | ||
| Amortized cost | 59,794 | |
| Unrealized gains | 62 | |
| Unrealized losses | (34) | |
| Fair value | 59,822 | |
| Long-term Investment [Member] | ||
| Amortized cost | 60,244 | 59,794 |
| Unrealized gains | 47 | 62 |
| Unrealized losses | 0 | (34) |
| Fair value | 60,291 | $ 59,822 |
| Long-term US Treasury Securities [Member] | ||
| Amortized cost | 60,244 | |
| Unrealized gains | 47 | |
| Unrealized losses | 0 | |
| Fair value | $ 60,291 |
| X | ||||||||||
- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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