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INVESTMENTS - Schedule of Investment Concentrations (Details) - USD ($) $ in Thousands | 6 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2025 | Mar. 31, 2025 | Jun. 30, 2025
Summary of Investment Holdings [Line Items] |  |  |  |
Investments, cost | $ 1,037,200 | $ 939,066 | [1] |
Investments at fair value | 1,130,859 | 979,320 | [1] |
PSI Molded |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments, cost |  |  |  | $ 10,600
South |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 485,593 | 317,294 |  |
West |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 223,709 | 222,062 |  |
Midwest |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 211,483 | 227,415 |  |
Northeast |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 183,216 | 182,669 |  |
Canada |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 26,858 | 29,880 |  |
Diversified/Conglomerate Services |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 189,018 | 170,360 |  |
Aerospace and Defense |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 172,193 | 107,869 |  |
Home and Office Furnishings, Housewares, and Durable Consumer Products |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 152,666 | 159,236 |  |
Machinery (Non-Agriculture, Non-Construction, and Non-Electronic) |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 130,538 | 105,432 |  |
Leisure, Amusement, Motion Pictures, and Entertainment |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 84,102 | 78,460 |  |
Oil and Gas |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 83,054 | 69,589 |  |
Buildings and Real Estate |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 73,492 | 69,320 |  |
Electronics |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 71,875 | 71,573 |  |
Chemicals, Plastics, and Rubber |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 51,182 | 11,612 |  |
Healthcare, Education, and Childcare |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 45,767 | 51,501 |  |
Mining, Steel, Iron and Non-Precious Metals |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 38,304 | 41,010 |  |
Printing and Publishing |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 11,325 | 11,681 |  |
Cargo Transport |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | 10,293 | 12,624 |  |
Other less than 2.0% |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments at fair value | $ 17,050 | $ 19,053 |  |
Investment Owned, at Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 100.00% | 100.00% |  |
Investment Owned, at Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 100.00% | 100.00% |  |
Investment Owned, at Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 100.00% | 100.00% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Diversified/Conglomerate Services |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 16.70% | 17.40% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Aerospace and Defense |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 15.20% | 10.90% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Home and Office Furnishings, Housewares, and Durable Consumer Products |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 13.60% | 16.30% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Machinery (Non-Agriculture, Non-Construction, and Non-Electronic) |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 11.60% | 10.80% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Leisure, Amusement, Motion Pictures, and Entertainment |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 7.40% | 8.00% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Oil and Gas |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 7.30% | 7.10% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Buildings and Real Estate |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 6.50% | 7.10% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Electronics |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 6.40% | 7.20% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Chemicals, Plastics, and Rubber |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 4.50% | 1.20% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Healthcare, Education, and Childcare |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 4.00% | 5.30% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Mining, Steel, Iron and Non-Precious Metals |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 3.40% | 4.20% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Printing and Publishing |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 1.00% | 1.20% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Cargo Transport |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 0.90% | 1.30% |  |
Investment Owned, at Fair Value | Industry Concentration Risk | Other less than 2.0% |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 1.50% | 2.00% |  |
Investment Owned, at Fair Value | Geographic Regions Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 100.00% | 100.00% |  |
Investment Owned, at Fair Value | Geographic Regions Risk | South |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 42.90% | 32.40% |  |
Investment Owned, at Fair Value | Geographic Regions Risk | West |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 19.80% | 22.70% |  |
Investment Owned, at Fair Value | Geographic Regions Risk | Midwest |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 18.70% | 23.20% |  |
Investment Owned, at Fair Value | Geographic Regions Risk | Northeast |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 16.20% | 18.70% |  |
Investment Owned, at Fair Value | Geographic Regions Risk | Canada |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 2.40% | 3.00% |  |
Total debt |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments, cost | $ 737,498 | $ 687,982 |  |
Investments at fair value | $ 684,612 | $ 617,914 |  |
Total debt | Investment Owned, at Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 71.10% | 73.30% |  |
Total debt | Investment Owned, at Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 60.50% | 63.10% |  |
Secured First Lien Debt |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments, cost | $ 644,158 | $ 584,026 |  |
Investments at fair value | $ 593,979 | $ 514,334 |  |
Secured First Lien Debt | Investment Owned, at Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 62.10% | 62.20% |  |
Secured First Lien Debt | Investment Owned, at Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 52.50% | 52.50% |  |
Secured Second Lien Debt |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments, cost | $ 93,340 | $ 103,956 |  |
Investments at fair value | $ 90,633 | $ 103,580 |  |
Secured Second Lien Debt | Investment Owned, at Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 9.00% | 11.10% |  |
Secured Second Lien Debt | Investment Owned, at Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 8.00% | 10.60% |  |
Total equity/equivalents |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments, cost | $ 299,702 | $ 251,084 |  |
Investments at fair value | $ 446,247 | $ 361,406 |  |
Total equity/equivalents | Investment Owned, at Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 28.90% | 26.70% |  |
Total equity/equivalents | Investment Owned, at Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 39.50% | 36.90% |  |
Preferred Equity |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments, cost | $ 250,105 | $ 201,487 |  |
Investments at fair value | $ 365,278 | $ 302,163 |  |
Preferred Equity | Investment Owned, at Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 24.10% | 21.50% |  |
Preferred Equity | Investment Owned, at Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 32.30% | 30.90% |  |
Common Equity/ Equivalents |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Investments, cost | $ 49,597 | $ 49,597 |  |
Investments at fair value | $ 80,969 | $ 59,243 |  |
Common Equity/ Equivalents | Investment Owned, at Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 4.80% | 5.20% |  |
Common Equity/ Equivalents | Investment Owned, at Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 7.20% | 6.00% |  |
[1] | Cumulative gross unrealized appreciation for federal income tax purposes is $183.3 million; cumulative gross unrealized depreciation for federal income tax purposes is $144.9 million. Cumulative net unrealized appreciation is $38.5 million, based on a tax cost of $940.9 million.

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