Quarterly report [Sections 13 or 15(d)]

INVESTMENTS - Schedule of Investment Holdings (Details)

v3.25.2
INVESTMENTS - Schedule of Investment Holdings (Details) - USD ($)
$ in Thousands
 9 Months Ended 12 Months Ended
Jun. 30, 2025
Sep. 30, 2024
Apr. 30, 2025
Summary of Investment Holdings [Line Items]      
Cost $ 777,851 $ 771,011 [1]  
Fair Value 751,260 796,260 [1]  
South      
Summary of Investment Holdings [Line Items]      
Fair Value 247,674 314,010  
Midwest      
Summary of Investment Holdings [Line Items]      
Fair Value 229,178 192,897  
West      
Summary of Investment Holdings [Line Items]      
Fair Value 218,612 249,082  
Northeast      
Summary of Investment Holdings [Line Items]      
Fair Value 55,796 40,271  
Healthcare, Education, and Childcare      
Summary of Investment Holdings [Line Items]      
Fair Value 272,883 101,707  
Diversified/Conglomerate Manufacturing      
Summary of Investment Holdings [Line Items]      
Fair Value 174,470 160,264  
Diversified/Conglomerate Service      
Summary of Investment Holdings [Line Items]      
Fair Value 110,727 179,032  
Beverage, Food, and Tobacco      
Summary of Investment Holdings [Line Items]      
Fair Value 56,001 88,327  
Automobile      
Summary of Investment Holdings [Line Items]      
Fair Value 27,147 28,286  
Machinery      
Summary of Investment Holdings [Line Items]      
Fair Value 25,831 21,816  
Cargo Transportation      
Summary of Investment Holdings [Line Items]      
Fair Value 20,000 20,200  
Oil and Gas      
Summary of Investment Holdings [Line Items]      
Fair Value 18,463 20,554  
Aerospace and Defense      
Summary of Investment Holdings [Line Items]      
Fair Value 16,975 153,096  
Personal and Non-Durable Consumer Products      
Summary of Investment Holdings [Line Items]      
Fair Value 12,743 13,586  
Printing and Publishing      
Summary of Investment Holdings [Line Items]      
Fair Value 5,445 4,312  
Other      
Summary of Investment Holdings [Line Items]      
Fair Value $ 10,575 $ 5,080  
Investment Owned, At Cost | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 100.00% 100.00%  
Investment Owned, At Fair Value | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 100.00% 100.00%  
Investment Owned, At Fair Value | Industry Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 100.00% 100.00%  
Investment Owned, At Fair Value | Industry Concentration Risk | Healthcare, Education, and Childcare      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 36.30% 12.80%  
Investment Owned, At Fair Value | Industry Concentration Risk | Diversified/Conglomerate Manufacturing      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 23.20% 20.10%  
Investment Owned, At Fair Value | Industry Concentration Risk | Diversified/Conglomerate Service      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 14.70% 22.50%  
Investment Owned, At Fair Value | Industry Concentration Risk | Beverage, Food, and Tobacco      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 7.50% 11.10%  
Investment Owned, At Fair Value | Industry Concentration Risk | Automobile      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 3.60% 3.60%  
Investment Owned, At Fair Value | Industry Concentration Risk | Machinery      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 3.40% 2.70%  
Investment Owned, At Fair Value | Industry Concentration Risk | Cargo Transportation      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 2.70% 2.50%  
Investment Owned, At Fair Value | Industry Concentration Risk | Oil and Gas      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 2.50% 2.60%  
Investment Owned, At Fair Value | Industry Concentration Risk | Aerospace and Defense      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 2.30% 19.20%  
Investment Owned, At Fair Value | Industry Concentration Risk | Personal and Non-Durable Consumer Products      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 1.70% 1.70%  
Investment Owned, At Fair Value | Industry Concentration Risk | Printing and Publishing      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 0.70% 0.50%  
Investment Owned, At Fair Value | Industry Concentration Risk | Other      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 1.40% 0.70%  
Investment Owned, At Fair Value | Geographic Regions Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 100.00% 100.00%  
Investment Owned, At Fair Value | Geographic Regions Risk | South      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 33.00% 39.40%  
Investment Owned, At Fair Value | Geographic Regions Risk | Midwest      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 30.50% 24.20%  
Investment Owned, At Fair Value | Geographic Regions Risk | West      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 29.10% 31.30%  
Investment Owned, At Fair Value | Geographic Regions Risk | Northeast      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 7.40% 5.10%  
Debt Securities      
Summary of Investment Holdings [Line Items]      
Cost $ 700,121 $ 694,625  
Fair Value $ 673,802 $ 668,685  
Debt Securities | Investment Owned, At Cost | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 90.00% 90.10%  
Debt Securities | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 89.70% 84.00%  
Secured first lien debt      
Summary of Investment Holdings [Line Items]      
Cost $ 555,347 $ 580,736  
Fair Value $ 529,149 $ 554,937  
Secured first lien debt | Eegee Acquisition Corporation      
Summary of Investment Holdings [Line Items]      
Cost     $ 12,800
Secured first lien debt | Investment Owned, At Cost | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 71.40% 75.30%  
Secured first lien debt | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 70.40% 69.70%  
Secured second lien debt      
Summary of Investment Holdings [Line Items]      
Cost $ 144,231 $ 113,691  
Fair Value $ 144,299 $ 113,716  
Secured second lien debt | Investment Owned, At Cost | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 18.50% 14.80%  
Secured second lien debt | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 19.20% 14.30%  
Unsecured debt      
Summary of Investment Holdings [Line Items]      
Cost $ 543 $ 198  
Fair Value $ 354 $ 32  
Unsecured debt | Investment Owned, At Cost | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 0.10% 0.00%  
Unsecured debt | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 0.10% 0.00%  
Equity Securities      
Summary of Investment Holdings [Line Items]      
Cost $ 77,730 $ 76,386  
Fair Value $ 77,458 $ 127,575  
Equity Securities | Investment Owned, At Cost | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 10.00% 9.90%  
Equity Securities | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 10.30% 16.00%  
Preferred Equity      
Summary of Investment Holdings [Line Items]      
Cost $ 37,279 $ 45,017  
Fair Value $ 25,717 $ 31,346  
Preferred Equity | Investment Owned, At Cost | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 4.80% 5.80%  
Preferred Equity | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 3.40% 3.90%  
Common Equity/ Equivalents      
Summary of Investment Holdings [Line Items]      
Cost $ 40,451 $ 31,369  
Fair Value $ 51,741 $ 96,229  
Common Equity/ Equivalents | Eegee Acquisition Corporation      
Summary of Investment Holdings [Line Items]      
Cost     $ 8,500
Common Equity/ Equivalents | Investment Owned, At Cost | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 5.20% 4.10%  
Common Equity/ Equivalents | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Summary of Investment Holdings [Line Items]      
Concentration Risk, Percentage 6.90% 12.10%  
[1] Cumulative gross unrealized depreciation for federal income tax purposes is $66.1 million; cumulative gross unrealized appreciation for federal income tax purposes is $85.8 million. Cumulative net unrealized appreciation is $19.7 million, based on a tax cost of $776.5 million.