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INVESTMENTS - Summary Investment Holdings (Details) - USD ($) $ in Thousands | 12 Months Ended
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Mar. 31, 2025 | Mar. 31, 2024
Summary of Investment Holdings [Line Items] |  |  |  |
Cost | $ 939,066 | [1] | $ 854,290 | [2]
Fair Value | $ 979,320 | [1] | $ 920,504 | [2]
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 | Geographic Regions Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 100.00% |  | 100.00% |
South |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 317,294 |  | $ 346,838 |
South | Investment Owned, At Fair Value | Geographic Regions Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 32.40% |  | 37.70% |
Midwest |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 227,415 |  | $ 141,925 |
Midwest | Investment Owned, At Fair Value | Geographic Regions Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 23.20% |  | 15.40% |
West |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 222,062 |  | $ 223,871 |
West | Investment Owned, At Fair Value | Geographic Regions Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 22.70% |  | 24.30% |
Northeast |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 182,669 |  | $ 207,870 |
Northeast | Investment Owned, At Fair Value | Geographic Regions Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 18.70% |  | 22.60% |
Canada |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 29,880 |  | $ 0 |
Canada | Investment Owned, At Fair Value | Geographic Regions Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 3.00% |  | 0.00% |
Diversified/Conglomerate Services |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 170,360 |  | $ 264,535 |
Diversified/Conglomerate Services | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 17.40% |  | 28.70% |
Home and Office Furnishings, Housewares, and Durable Consumer Products |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 159,236 |  | $ 160,038 |
Home and Office Furnishings, Housewares, and Durable Consumer Products | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 16.30% |  | 17.30% |
Aerospace and Defense |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 107,869 |  | $ 29,064 |
Aerospace and Defense | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 10.90% |  | 3.20% |
Machinery (Non-Agriculture, Non-Construction, and Non-Electronic) |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 105,432 |  | $ 92,781 |
Machinery (Non-Agriculture, Non-Construction, and Non-Electronic) | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 10.80% |  | 10.10% |
Leisure, Amusement, Motion Pictures, and Entertainment |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 78,460 |  | $ 39,350 |
Leisure, Amusement, Motion Pictures, and Entertainment | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 8.00% |  | 4.30% |
Electronics |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 71,573 |  | $ 0 |
Electronics | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 7.20% |  | 0.00% |
Oil and Gas |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 69,589 |  | $ 51,171 |
Oil and Gas | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 7.10% |  | 5.60% |
Buildings and Real Estate |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 69,320 |  | $ 60,431 |
Buildings and Real Estate | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 7.10% |  | 6.60% |
Healthcare, Education, and Childcare |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 51,501 |  | $ 49,638 |
Healthcare, Education, and Childcare | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 5.30% |  | 5.40% |
Mining, Steel, Iron and Non-Precious Metals |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 41,010 |  | $ 30,537 |
Mining, Steel, Iron and Non-Precious Metals | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 4.20% |  | 3.30% |
Cargo Transport |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 12,624 |  | $ 13,500 |
Cargo Transport | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 1.30% |  | 1.50% |
Printing and Publishing |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 11,681 |  | $ 14,238 |
Printing and Publishing | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 1.20% |  | 1.50% |
Chemicals, Plastics, and Rubber |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 11,612 |  | $ 20,363 |
Chemicals, Plastics, and Rubber | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 1.20% |  | 2.20% |
Hotels, Motels, Inns, and Gaming |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 0 |  | $ 77,366 |
Hotels, Motels, Inns, and Gaming | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 0.00% |  | 8.40% |
Other less than 2.0% |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Fair Value | $ 19,053 |  | $ 17,492 |
Other less than 2.0% | Investment Owned, At Fair Value | Industry Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 2.00% |  | 1.90% |
Total debt |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Cost | $ 687,982 |  | $ 658,383 |
Fair Value | $ 617,914 |  | $ 613,559 |
Total debt | Investment Owned, At Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 73.30% |  | 77.00% |
Total debt | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 63.10% |  | 66.60% |
Secured First Lien Debt |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Cost | $ 584,026 |  | $ 513,425 |
Fair Value | $ 514,334 |  | $ 474,856 |
Secured First Lien Debt | Investment Owned, At Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 62.20% |  | 60.10% |
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% |  | 51.60% |
Secured Second Lien Debt |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Cost | $ 103,956 |  | $ 144,958 |
Fair Value | $ 103,580 |  | $ 138,703 |
Secured Second Lien Debt | Investment Owned, At Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 11.10% |  | 16.90% |
Secured Second Lien Debt | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 10.60% |  | 15.00% |
Total equity/equivalents |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Cost | $ 251,084 |  | $ 195,907 |
Fair Value | $ 361,406 |  | $ 306,945 |
Total equity/equivalents | Investment Owned, At Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 26.70% |  | 23.00% |
Total equity/equivalents | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 36.90% |  | 33.40% |
Preferred Equity |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Cost | $ 201,487 |  | $ 145,070 |
Fair Value | $ 302,163 |  | $ 213,480 |
Preferred Equity | Investment Owned, At Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 21.50% |  | 17.00% |
Preferred Equity | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 30.90% |  | 23.20% |
Common Equity/ Equivalents |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Cost | $ 49,597 |  | $ 50,837 |
Fair Value | $ 59,243 |  | $ 93,465 |
Common Equity/ Equivalents | Investment Owned, At Cost | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 5.20% |  | 6.00% |
Common Equity/ Equivalents | Investment Owned, At Fair Value | Investment Type Concentration Risk |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |
Percentage of Total Investments | 6.00% |  | 10.20% |
[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.
[2] | Cumulative gross unrealized appreciation for federal income tax purposes is $180.5 million; cumulative gross unrealized depreciation for federal income tax purposes is $115.8 million. Cumulative net unrealized appreciation is $64.7 million, based on a tax cost of $855.8 million.

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