Fair Value - Schedule of Fair Value of Investments for which Level 3 Inputs (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Schedule of Fair Value of Investments for which Level 3 Inputs [Line Items] | ||||
| Fair value, beginning of period | $ 2,266,618,000 | $ 1,995,928,000 | $ 2,151,743,000 | $ 1,741,919,000 |
| Purchases of investments | 87,642,000 | 266,531,000 | 315,082,000 | 678,915,000 |
| Investment restructuring | 0 | 0 | ||
| Proceeds from sales of investments and principal repayments | (114,914,000) | (73,489,000) | (218,197,000) | (232,638,000) |
| Net change in unrealized gain (loss) | (8,472,000) | (5,438,000) | (22,698,000) | (14,570,000) |
| Net realized gain (loss) | (14,901,000) | 10,000 | (27,200,000) | 606,000 |
| Net accretion of discount on investments | 3,739,000 | 3,820,000 | 10,017,000 | 10,637,000 |
| PIK interest and dividends | 2,956,000 | 2,149,000 | 13,921,000 | 4,642,000 |
| Transfers into (out of) Level 3 | 0 | 0 | 0 | 0 |
| Fair value, end of period | 2,222,668,000 | 2,189,511,000 | 2,222,668,000 | 2,189,511,000 |
| First-lien senior secured debt investments [Member] | ||||
| Schedule of Fair Value of Investments for which Level 3 Inputs [Line Items] | ||||
| Fair value, beginning of period | 2,222,793,000 | 1,970,489,000 | 2,110,721,000 | 1,719,182,000 |
| Purchases of investments | 86,937,000 | 254,531,000 | 313,771,000 | 666,250,000 |
| Investment restructuring | (7,045,000) | (7,045,000) | ||
| Proceeds from sales of investments and principal repayments | (114,914,000) | (73,479,000) | (218,197,000) | (231,782,000) |
| Net change in unrealized gain (loss) | (3,115,000) | (7,001,000) | (19,538,000) | (18,420,000) |
| Net realized gain (loss) | (14,901,000) | 0 | (27,200,000) | 0 |
| Net accretion of discount on investments | 3,739,000 | 3,820,000 | 10,017,000 | 10,637,000 |
| PIK interest and dividends | 2,956,000 | 2,149,000 | 13,921,000 | 4,642,000 |
| Transfers into (out of) Level 3 | 0 | 0 | 0 | 0 |
| Fair value, end of period | 2,176,450,000 | 2,150,509,000 | 2,176,450,000 | 2,150,509,000 |
| Private equity investments [Member] | ||||
| Schedule of Fair Value of Investments for which Level 3 Inputs [Line Items] | ||||
| Fair value, beginning of period | 43,825,000 | 25,439,000 | 41,022,000 | 22,737,000 |
| Purchases of investments | 705,000 | 12,000,000 | 1,311,000 | 12,665,000 |
| Investment restructuring | 7,045,000 | 7,045,000 | ||
| Proceeds from sales of investments and principal repayments | 0 | (10,000) | 0 | (856,000) |
| Net change in unrealized gain (loss) | (5,357,000) | 1,563,000 | (3,160,000) | 3,850,000 |
| Net realized gain (loss) | 0 | 10,000 | 0 | 606,000 |
| Net accretion of discount on investments | 0 | 0 | 0 | 0 |
| PIK interest and dividends | 0 | 0 | 0 | 0 |
| Transfers into (out of) Level 3 | 0 | 0 | 0 | 0 |
| Fair value, end of period | $ 46,218,000 | $ 39,002,000 | $ 46,218,000 | $ 39,002,000 |