Quarterly report [Sections 13 or 15(d)]

INVESTMENTS - Schedule of Investment Concentrations (Details)

v3.25.3
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.