| Investments in and Advances to Affiliates [Table Text Block] |
| | | | | | | | | | | Year ended December 31, 2025 | | | | | | | | | | | | | |
| | | Fair value at | | | | | | | | | | | | | | | Transfers | | | | | | | Net | | | | | | | Fair value at | | | | | |
| Portfolio | | December 31, | | | | | | | Principal | | | | | | | in/(out) at | | | Discount | | | unrealized | | | Net realized | | | December 31, | | | Interest | |
| Company | | 2024 | | | Purchases | | | payments | | | PIK | | | fair value | | | accretion | | | gain/(loss) | | | gain/(loss) | | | 2025 | | | income | |
| | | (In thousands) | |
| Aulea Medical, Inc. | | $ | — | | | $ | — | | | $ | — | | | $ | — | | | $ | — | | | $ | — | | | $ | — | | | | | | | $ | — | | | $ | — | |
| Evelo Biosciences, Inc. | | | 8,307 | | | | 2 | | | | (2,275 | ) | | | — | | | | — | | | | — | | | | (4,548 | ) | | | — | | | | 1,486 | | | | — | |
| Hound Labs II LLC | | | — | | | | — | | | | — | | | | 204 | | | | 11,350 | | | | — | | | | (185 | ) | | | — | | | | 11,369 | | | | 204 | |
| Nexii, Inc. | | | — | | | | 14 | | | | — | | | | — | | | | 1,116 | | | | — | | | | (1,130 | ) | | | — | | | | — | | | | 28 | |
| NextCar Holding Company, Inc. | | | — | | | | — | | | | (3,701 | ) | | | — | | | | 5,967 | | | | — | | | | (1,187 | ) | | | — | | | | 1,079 | | | | 46 | |
| Shengrow Inc. | | | — | | | | 10,000 | | | | — | | | | 985 | | | | 32,941 | | | | 138 | | | | 5,146 | | | | — | | | | 49,210 | | | | 1,433 | |
| Total non-controlled affiliates | | $ | 8,307 | | | $ | 10,016 | | | $ | (5,976 | ) | | $ | 1,189 | | | $ | 51,374 | | | $ | 138 | | | $ | (1,904 | ) | | $ | — | | | $ | 63,144 | | | $ | 1,711 | |
| | | | | | | | | | | Year ended December 31, 2024 | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | | Fair value at | | | | | | | | | | | | | | | Transfers | | | | | | | Net | | | | | | | Fair value at | | | | | |
| Portfolio | | December 31, | | | | | | | Principal | | | | | | | in/(out) at | | | Discount | | | unrealized | | | Net realized | | | December 31, | | | Interest | |
| Company | | 2023 | | | Purchases | | | payments | | | PIK | | | fair value | | | accretion | | | gain/(loss) | | | gain/(loss) | | | 2024 | | | income | |
| | | (In thousands) | |
| Aulea Medical, Inc. | | $ | — | | | $ | 3 | | | $ | (40 | ) | | $ | — | | | $ | — | | | $ | — | | | $ | — | | | $ | 37 | | | $ | — | | | $ | — | |
| Evelo Biosciences, Inc. | | | 1,132 | | | | 244 | | | | (1,430 | ) | | | — | | | | — | | | | — | | | | 8,361 | | | | — | | | | 8,307 | | | | — | |
| Total non-controlled affiliates | | $ | 1,132 | | | $ | 247 | | | $ | (1,470 | ) | | $ | — | | | $ | — | | | $ | — | | | $ | 8,361 | | | $ | 37 | | | $ | 8,307 | | | $ | — | |
| | | | | | | | | | | Year ended December 31, 2025 | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | | Fair value at | | | | | | | | | | | | | | | Transfers | | | | | | | Net | | | | | | | Fair value at | | | | | |
| Portfolio | | December 31, | | | | | | | Principal | | | | | | | in/(out) at | | | Discount | | | unrealized | | | Net realized | | | December 31, | | | Interest | |
| Company | | 2024 | | | Purchases | | | payments | | | PIK | | | fair value | | | accretion | | | gain/(loss) | | | gain/(loss) | | | 2025 | | | income (reversal) | |
| | | (In thousands) | |
| Better Place Forests Co. | | $ | — | | | $ | 2,354 | | | | | | | $ | — | | | $ | — | | | $ | — | | | $ | 2,207 | | | $ | (4,561 | ) | | $ | — | | | $ | — | |
| HIMV LLC | | | 6,230 | | | | 370 | | | | — | | | | — | | | | (1,178 | ) | | | — | | | | (5,422 | ) | | | — | | | | — | | | | — | |
| Nexii, Inc. | | | 8,547 | | | | 3,229 | | | | — | | | | — | | | | (1,116 | ) | | | — | | | | (10,660 | ) | | | — | | | | — | | | | 65 | |
| Swift Health Systems, Inc. | | | 17,042 | | | | 2,162 | | | | — | | | | 208 | | | | — | | | | 9 | | | | 1,135 | | | | (20,556 | ) | | | — | | | | (81 | ) |
| Total controlled affiliates | | $ | 31,819 | | | $ | 8,115 | | | $ | — | | | $ | 208 | | | $ | (2,294 | ) | | $ | 9 | | | $ | (12,740 | ) | | $ | (25,117 | ) | | $ | — | | | $ | (16 | ) |
| | | | | | | | | | | Year ended December 31, 2024 | | | | | | | | | | | | | |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| | | Fair value at | | | | | | | | | | | | | | | Transfers | | | | | | | Net | | | | | | | Fair value at | | | | | |
| Portfolio | | December 31, | | | | | | | Principal | | | | | | | in/(out) at | | | Discount | | | unrealized | | | Net realized | | | December 31, | | | Interest | |
| Company | | 2023 | | | Purchases | | | payments | | | PIK | | | fair value | | | accretion | | | gain/(loss) | | | gain/(loss) | | | 2024 | | | income | |
| | | (In thousands) | |
| Better Place Forests Co. | | $ | 7,993 | | | $ | 3,750 | | | $ | — | | | $ | 805 | | | $ | — | | | $ | 14 | | | $ | (12,562 | ) | | $ | — | | | $ | — | | | $ | 846 | |
| HIMV LLC | | | 6,230 | | | | 227 | | | | (592 | ) | | | — | | | | 463 | | | | — | | | | (98 | ) | | | — | | | | 6,230 | | | | — | |
| Nexii, Inc. | | | — | | | | 790 | | | | — | | | | — | | | | 6,716 | | | | — | | | | 1,041 | | | | — | | | | 8,547 | | | | 35 | |
| Swift Health Systems, Inc. | | | — | | | | 1,887 | | | | — | | | | 826 | | | | 15,462 | | | | 2 | | | | (1,135 | ) | | | — | | | | 17,042 | | | | 868 | |
| Total controlled affiliates | | $ | 14,223 | | | $ | 6,654 | | | $ | (592 | ) | | $ | 1,631 | | | $ | 22,641 | | | $ | 16 | | | $ | (12,754 | ) | | $ | — | | | $ | 31,819 | | | $ | 1,749 | |
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