Quarterly report [Sections 13 or 15(d)]

INVESTMENTS - Schedule of Investment Holdings (Details)

v3.25.4
INVESTMENTS - Schedule of Investment Holdings (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2025
Sep. 30, 2025
Summary of Investment Holdings [Line Items]    
Cost $ 926,040 $ 876,614 [1]
Fair Value 902,912 859,124 [1]
South    
Summary of Investment Holdings [Line Items]    
Fair Value 320,014 287,371
Midwest    
Summary of Investment Holdings [Line Items]    
Fair Value 266,400 237,417
West    
Summary of Investment Holdings [Line Items]    
Fair Value 213,878 233,564
Northeast    
Summary of Investment Holdings [Line Items]    
Fair Value 102,620 100,772
Healthcare, Education, and Childcare    
Summary of Investment Holdings [Line Items]    
Fair Value 288,403 273,262
Diversified/Conglomerate Manufacturing    
Summary of Investment Holdings [Line Items]    
Fair Value 203,153 202,466
Diversified/Conglomerate Service    
Summary of Investment Holdings [Line Items]    
Fair Value 146,845 152,042
Beverage, Food, and Tobacco    
Summary of Investment Holdings [Line Items]    
Fair Value 77,921 54,605
Cargo Transportation    
Summary of Investment Holdings [Line Items]    
Fair Value 50,000 20,000
Home and Office Furnishings, Housewares and Durable Consumer Products    
Summary of Investment Holdings [Line Items]    
Fair Value 29,928 30,000
Machinery    
Summary of Investment Holdings [Line Items]    
Fair Value 26,467 26,381
Personal, Food, and Miscellaneous Supplies    
Summary of Investment Holdings [Line Items]    
Fair Value 22,751 23,700
Oil and Gas    
Summary of Investment Holdings [Line Items]    
Fair Value 16,746 17,512
Personal and Non-Durable Consumer Products    
Summary of Investment Holdings [Line Items]    
Fair Value 13,576 13,866
Automobile    
Summary of Investment Holdings [Line Items]    
Fair Value 9,264 27,361
Printing and Publishing    
Summary of Investment Holdings [Line Items]    
Fair Value 5,365 5,809
Other    
Summary of Investment Holdings [Line Items]    
Fair Value $ 12,493 $ 12,120
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 31.90% 31.80%
Investment Owned, At Fair Value | Industry Concentration Risk | Diversified/Conglomerate Manufacturing    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 22.50% 23.60%
Investment Owned, At Fair Value | Industry Concentration Risk | Diversified/Conglomerate Service    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 16.30% 17.70%
Investment Owned, At Fair Value | Industry Concentration Risk | Beverage, Food, and Tobacco    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 8.60% 6.40%
Investment Owned, At Fair Value | Industry Concentration Risk | Cargo Transportation    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 5.50% 2.30%
Investment Owned, At Fair Value | Industry Concentration Risk | Home and Office Furnishings, Housewares and Durable Consumer Products    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 3.30% 3.50%
Investment Owned, At Fair Value | Industry Concentration Risk | Machinery    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 3.00% 3.10%
Investment Owned, At Fair Value | Industry Concentration Risk | Personal, Food, and Miscellaneous Supplies    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 2.50% 2.70%
Investment Owned, At Fair Value | Industry Concentration Risk | Oil and Gas    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 1.90% 2.00%
Investment Owned, At Fair Value | Industry Concentration Risk | Personal and Non-Durable Consumer Products    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 1.50% 1.60%
Investment Owned, At Fair Value | Industry Concentration Risk | Automobile    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 1.00% 3.20%
Investment Owned, At Fair Value | Industry Concentration Risk | Printing and Publishing    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 0.60% 0.70%
Investment Owned, At Fair Value | Industry Concentration Risk | Other    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 1.40% 1.40%
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 35.40% 33.50%
Investment Owned, At Fair Value | Geographic Regions Risk | Midwest    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 29.50% 27.60%
Investment Owned, At Fair Value | Geographic Regions Risk | West    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 23.70% 27.20%
Investment Owned, At Fair Value | Geographic Regions Risk | Northeast    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 11.40% 11.70%
Debt Securities    
Summary of Investment Holdings [Line Items]    
Cost $ 841,559 $ 796,623
Fair Value $ 818,584 $ 773,246
Debt Securities | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 90.90% 90.90%
Debt Securities | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 90.60% 90.00%
Secured first lien debt    
Summary of Investment Holdings [Line Items]    
Cost $ 671,528 $ 646,131
Fair Value $ 647,576 $ 622,371
Secured first lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 72.50% 73.70%
Secured first lien debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 71.70% 72.40%
Secured second lien debt    
Summary of Investment Holdings [Line Items]    
Cost $ 169,463 $ 149,937
Fair Value $ 170,662 $ 150,542
Secured second lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 18.30% 17.10%
Secured second lien debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 18.90% 17.50%
Unsecured debt    
Summary of Investment Holdings [Line Items]    
Cost $ 568 $ 555
Fair Value $ 346 $ 333
Unsecured debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 0.10% 0.10%
Unsecured debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 0.00% 0.10%
Equity Securities    
Summary of Investment Holdings [Line Items]    
Cost $ 84,481 $ 79,991
Fair Value $ 84,328 $ 85,878
Equity Securities | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 9.10% 9.10%
Equity Securities | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 9.40% 10.00%
Preferred Equity    
Summary of Investment Holdings [Line Items]    
Cost $ 42,369 $ 37,429
Fair Value $ 36,761 $ 31,214
Preferred Equity | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 4.60% 4.30%
Preferred Equity | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 4.10% 3.60%
Common Equity/ Equivalents    
Summary of Investment Holdings [Line Items]    
Cost $ 42,112 $ 42,562
Fair Value $ 47,567 $ 54,664
Common Equity/ Equivalents | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 4.50% 4.80%
Common Equity/ Equivalents | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration Risk, Percentage 5.30% 6.40%
[1] Cumulative gross unrealized depreciation for federal income tax purposes is $59.7 million; cumulative gross unrealized appreciation for federal income tax purposes is $34.1 million. Cumulative net unrealized depreciation is $25.5 million, based on a tax cost of $884.7 million.