Quarterly report pursuant to Section 13 or 15(d)

INVESTMENTS - Summary Investment Holdings (Details)

v3.23.1
INVESTMENTS - Summary Investment Holdings (Details) - USD ($)
$ in Thousands
 6 Months Ended 12 Months Ended
Mar. 31, 2023
Sep. 30, 2022
Summary of Investment Holdings [Line Items]    
Cost $ 696,031 $ 656,053
Fair Value $ 678,759 $ 649,615
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 | Geographic Regions Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 100.00% 100.00%
South    
Summary of Investment Holdings [Line Items]    
Fair Value $ 303,139 $ 326,524
South | Investment Owned, At Fair Value | Geographic Regions Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 44.70% 50.30%
West    
Summary of Investment Holdings [Line Items]    
Fair Value $ 194,913 $ 169,415
West | Investment Owned, At Fair Value | Geographic Regions Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 28.70% 26.10%
Midwest    
Summary of Investment Holdings [Line Items]    
Fair Value $ 144,399 $ 118,191
Midwest | Investment Owned, At Fair Value | Geographic Regions Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 21.30% 18.20%
Northeast    
Summary of Investment Holdings [Line Items]    
Fair Value $ 36,308 $ 35,485
Northeast | Investment Owned, At Fair Value | Geographic Regions Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 5.30% 5.40%
Diversified/Conglomerate Service    
Summary of Investment Holdings [Line Items]    
Fair Value $ 158,695 $ 148,907
Diversified/Conglomerate Service | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 23.40% 22.90%
Diversified/Conglomerate Manufacturing    
Summary of Investment Holdings [Line Items]    
Fair Value $ 142,091 $ 114,105
Diversified/Conglomerate Manufacturing | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 20.90% 17.60%
Healthcare, Education, and Childcare    
Summary of Investment Holdings [Line Items]    
Fair Value $ 133,509 $ 136,401
Healthcare, Education, and Childcare | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 19.70% 21.00%
Aerospace and Defense    
Summary of Investment Holdings [Line Items]    
Fair Value $ 86,384 $ 88,649
Aerospace and Defense | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 12.70% 13.60%
Beverage, Food, and Tobacco    
Summary of Investment Holdings [Line Items]    
Fair Value $ 70,119 $ 64,283
Beverage, Food, and Tobacco | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 10.30% 9.90%
Oil and Gas    
Summary of Investment Holdings [Line Items]    
Fair Value $ 23,993 $ 25,373
Oil and Gas | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 3.50% 3.90%
Automobile    
Summary of Investment Holdings [Line Items]    
Fair Value $ 19,941 $ 20,144
Automobile | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 3.00% 3.10%
Personal and Non-Durable Consumer Products    
Summary of Investment Holdings [Line Items]    
Fair Value $ 17,123 $ 18,583
Personal and Non-Durable Consumer Products | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 2.50% 2.90%
Machinery    
Summary of Investment Holdings [Line Items]    
Fair Value $ 10,896 $ 9,562
Machinery | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 1.60% 1.50%
Telecommunications    
Summary of Investment Holdings [Line Items]    
Fair Value $ 7,464 $ 10,088
Telecommunications | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 1.10% 1.60%
Textiles and Leather    
Summary of Investment Holdings [Line Items]    
Fair Value $ 0 $ 7,978
Textiles and Leather | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 0.00% 1.20%
Other    
Summary of Investment Holdings [Line Items]    
Fair Value $ 8,544 $ 5,542
Other | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 1.30% 0.80%
Debt Securities    
Summary of Investment Holdings [Line Items]    
Cost $ 636,473 $ 595,048
Fair Value $ 618,757 $ 579,841
Debt Securities | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 91.40% 90.70%
Debt Securities | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 91.10% 89.20%
Secured first lien debt    
Summary of Investment Holdings [Line Items]    
Cost $ 513,175 $ 475,806
Fair Value $ 498,947 $ 463,858
Secured first lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 73.70% 72.50%
Secured first lien debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 73.50% 71.40%
Secured second lien debt    
Summary of Investment Holdings [Line Items]    
Cost $ 120,684 $ 118,949
Fair Value $ 117,438 $ 115,928
Secured second lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 17.30% 18.20%
Secured second lien debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 17.30% 17.80%
Unsecured debt    
Summary of Investment Holdings [Line Items]    
Cost $ 2,614 $ 293
Fair Value $ 2,372 $ 55
Unsecured debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 0.40% 0.00%
Unsecured debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 0.30% 0.00%
Equity Securities    
Summary of Investment Holdings [Line Items]    
Cost $ 59,558 $ 61,005
Fair Value $ 60,002 $ 69,774
Equity Securities | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 8.60% 9.30%
Equity Securities | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 8.90% 10.80%
Preferred Equity    
Summary of Investment Holdings [Line Items]    
Cost $ 34,732 $ 34,505
Fair Value $ 28,298 $ 27,046
Preferred Equity | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 5.00% 5.30%
Preferred Equity | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 4.20% 4.20%
Common Equity/ Equivalents    
Summary of Investment Holdings [Line Items]    
Cost $ 24,826 $ 26,500
Fair Value $ 31,704 $ 42,728
Common Equity/ Equivalents | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 3.60% 4.00%
Common Equity/ Equivalents | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 4.70% 6.60%