| Schedule of Debt [Table Text Block] |
| | | June 30, 2026 | | | December 31, 2025 | |
| | | Total | | | Balance | | | Unused | | | Total | | | Balance | | | Unused | |
| | | Commitment | | | Outstanding | | | Commitment | | | Commitment | | | Outstanding | | | Commitment | |
| | | (In thousands) | |
| Key Facility | | $ | 150,000 | | | $ | — | | | $ | 150,000 | | | $ | 150,000 | | | $ | — | | | $ | 150,000 | |
| NYL Facility | | | 250,000 | | | | 181,000 | | | | 69,000 | | | | 250,000 | | | | 181,000 | | | | 69,000 | |
| Nuveen Facility | | | 200,000 | | | | 90,000 | | | | 110,000 | | | | 200,000 | | | | 90,000 | | | | 110,000 | |
| 2028 Notes | | | 57,500 | | | | 57,500 | | | | — | | | | 57,500 | | | | 57,500 | | | | — | |
| 2027 Notes | | | 57,500 | | | | 57,500 | | | | — | | | | 57,500 | | | | 57,500 | | | | — | |
| 2026 Notes | | | — | | | | — | | | | — | | | | 57,500 | | | | 57,500 | | | | — | |
| 2030 Convertible Notes | | | 16,450 | | | | 16,450 | | | | — | | | | 31,500 | | | | 31,500 | | | | — | |
| 2031 Convertible Notes | | | 2,750 | | | | 2,750 | | | | — | | | | 2,750 | | | | 2,750 | | | | — | |
| Total before debt issuance costs | | | 734,200 | | | | 405,200 | | | | 329,000 | | | | 806,750 | | | | 477,750 | | | | 329,000 | |
| Unamortized debt issuance costs attributable to term borrowings | | | — | | | | (2,757 | ) | | | — | | | | — | | | | (4,723 | ) | | | — | |
| Total borrowings outstanding, net | | $ | 734,200 | | | $ | 402,443 | | | $ | 329,000 | | | $ | 806,750 | | | $ | 473,027 | | | $ | 329,000 | |
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