Quarterly report [Sections 13 or 15(d)]

INVESTMENTS - Schedule of Investment Concentrations (Details)

v3.25.2
INVESTMENTS - Schedule of Investment Concentrations (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Jun. 30, 2025
Mar. 31, 2025
Summary of Investment Holdings [Line Items]    
Cost $ 997,538 $ 939,066 [1]
Fair Value 1,036,745 979,320 [1]
PSI Molded    
Summary of Investment Holdings [Line Items]    
Cost 10,600  
South    
Summary of Investment Holdings [Line Items]    
Fair Value 389,680 317,294
West    
Summary of Investment Holdings [Line Items]    
Fair Value 229,132 222,062
Midwest    
Summary of Investment Holdings [Line Items]    
Fair Value 212,997 227,415
Northeast    
Summary of Investment Holdings [Line Items]    
Fair Value 176,909 182,669
Canada    
Summary of Investment Holdings [Line Items]    
Fair Value 28,027 29,880
Diversified/Conglomerate Services    
Summary of Investment Holdings [Line Items]    
Fair Value 188,845 170,360
Home and Office Furnishings, Housewares, and Durable Consumer Products    
Summary of Investment Holdings [Line Items]    
Fair Value 150,749 159,236
Machinery (Non-Agriculture, Non-Construction, and Non-Electronic)    
Summary of Investment Holdings [Line Items]    
Fair Value 109,985 105,432
Aerospace and Defense    
Summary of Investment Holdings [Line Items]    
Fair Value 105,170 107,869
Leisure, Amusement, Motion Pictures, and Entertainment    
Summary of Investment Holdings [Line Items]    
Fair Value 79,588 78,460
Oil and Gas    
Summary of Investment Holdings [Line Items]    
Fair Value 72,286 69,589
Electronics    
Summary of Investment Holdings [Line Items]    
Fair Value 71,334 71,573
Buildings and Real Estate    
Summary of Investment Holdings [Line Items]    
Fair Value 69,075 69,320
Chemicals, Plastics, and Rubber    
Summary of Investment Holdings [Line Items]    
Fair Value 54,980 11,612
Healthcare, Education, and Childcare    
Summary of Investment Holdings [Line Items]    
Fair Value 48,197 51,501
Mining, Steel, Iron and Non-Precious Metals    
Summary of Investment Holdings [Line Items]    
Fair Value 43,505 41,010
Cargo Transport    
Summary of Investment Holdings [Line Items]    
Fair Value 13,000 12,624
Printing and Publishing    
Summary of Investment Holdings [Line Items]    
Fair Value 12,611 11,681
Other less than 2.0%    
Summary of Investment Holdings [Line Items]    
Fair Value $ 17,420 $ 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 18.20% 17.40%
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 14.50% 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 10.60% 10.80%
Investment Owned, at Fair Value | Industry Concentration Risk | Aerospace and Defense    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 10.10% 10.90%
Investment Owned, at Fair Value | Industry Concentration Risk | Leisure, Amusement, Motion Pictures, and Entertainment    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 7.70% 8.00%
Investment Owned, at Fair Value | Industry Concentration Risk | Oil and Gas    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 7.00% 7.10%
Investment Owned, at Fair Value | Industry Concentration Risk | Electronics    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 6.90% 7.20%
Investment Owned, at Fair Value | Industry Concentration Risk | Buildings and Real Estate    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 6.70% 7.10%
Investment Owned, at Fair Value | Industry Concentration Risk | Chemicals, Plastics, and Rubber    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 5.30% 1.20%
Investment Owned, at Fair Value | Industry Concentration Risk | Healthcare, Education, and Childcare    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 4.60% 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 4.20% 4.20%
Investment Owned, at Fair Value | Industry Concentration Risk | Cargo Transport    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 1.30% 1.30%
Investment Owned, at Fair Value | Industry Concentration Risk | Printing and Publishing    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 1.20% 1.20%
Investment Owned, at Fair Value | Industry Concentration Risk | Other less than 2.0%    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 1.70% 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 37.60% 32.40%
Investment Owned, at Fair Value | Geographic Regions Risk | West    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 22.10% 22.70%
Investment Owned, at Fair Value | Geographic Regions Risk | Midwest    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 20.50% 23.20%
Investment Owned, at Fair Value | Geographic Regions Risk | Northeast    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 17.10% 18.70%
Investment Owned, at Fair Value | Geographic Regions Risk | Canada    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 2.70% 3.00%
Total debt    
Summary of Investment Holdings [Line Items]    
Cost $ 718,936 $ 687,982
Fair Value $ 650,397 $ 617,914
Total debt | Investment Owned, at Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 72.10% 73.30%
Total debt | Investment Owned, at Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 62.70% 63.10%
Secured First Lien Debt    
Summary of Investment Holdings [Line Items]    
Cost $ 625,596 $ 584,026
Fair Value $ 557,057 $ 514,334
Secured First Lien Debt | Investment Owned, at Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 62.70% 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 53.70% 52.50%
Secured Second Lien Debt    
Summary of Investment Holdings [Line Items]    
Cost $ 93,340 $ 103,956
Fair Value $ 93,340 $ 103,580
Secured Second Lien Debt | Investment Owned, at Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 9.40% 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 9.00% 10.60%
Total equity/equivalents    
Summary of Investment Holdings [Line Items]    
Cost $ 278,602 $ 251,084
Fair Value $ 386,348 $ 361,406
Total equity/equivalents | Investment Owned, at Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 27.90% 26.70%
Total equity/equivalents | Investment Owned, at Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 37.30% 36.90%
Preferred Equity    
Summary of Investment Holdings [Line Items]    
Cost $ 229,005 $ 201,487
Fair Value $ 325,997 $ 302,163
Preferred Equity | Investment Owned, at Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 23.00% 21.50%
Preferred Equity | Investment Owned, at Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 31.50% 30.90%
Common Equity/ Equivalents    
Summary of Investment Holdings [Line Items]    
Cost $ 49,597 $ 49,597
Fair Value $ 60,351 $ 59,243
Common Equity/ Equivalents | Investment Owned, at Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 4.90% 5.20%
Common Equity/ Equivalents | Investment Owned, at Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Percentage of Total Investments 5.80% 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.