Quarterly report pursuant to Section 13 or 15(d)

INVESTMENTS - Summary Investment Holdings (Details)

v3.23.2
INVESTMENTS - Summary Investment Holdings (Details) - USD ($)
$ in Thousands
 9 Months Ended 12 Months Ended
Jun. 30, 2023
Sep. 30, 2022
Summary of Investment Holdings [Line Items]    
Cost $ 735,182 $ 656,053
Fair Value $ 715,324 $ 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 $ 290,432 $ 326,524
South | Investment Owned, At Fair Value | Geographic Regions Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 40.60% 50.30%
West    
Summary of Investment Holdings [Line Items]    
Fair Value $ 220,602 $ 169,415
West | Investment Owned, At Fair Value | Geographic Regions Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 30.80% 26.10%
Midwest    
Summary of Investment Holdings [Line Items]    
Fair Value $ 146,324 $ 118,191
Midwest | Investment Owned, At Fair Value | Geographic Regions Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 20.50% 18.20%
Northeast    
Summary of Investment Holdings [Line Items]    
Fair Value $ 57,966 $ 35,485
Northeast | Investment Owned, At Fair Value | Geographic Regions Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 8.10% 5.40%
Diversified/Conglomerate Service    
Summary of Investment Holdings [Line Items]    
Fair Value $ 164,261 $ 148,907
Diversified/Conglomerate Service | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 23.00% 22.90%
Diversified/Conglomerate Manufacturing    
Summary of Investment Holdings [Line Items]    
Fair Value $ 160,904 $ 114,105
Diversified/Conglomerate Manufacturing | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 22.50% 17.60%
Healthcare, Education, and Childcare    
Summary of Investment Holdings [Line Items]    
Fair Value $ 145,011 $ 136,401
Healthcare, Education, and Childcare | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 20.30% 21.00%
Aerospace and Defense    
Summary of Investment Holdings [Line Items]    
Fair Value $ 87,932 $ 88,649
Aerospace and Defense | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 12.30% 13.60%
Beverage, Food, and Tobacco    
Summary of Investment Holdings [Line Items]    
Fair Value $ 74,641 $ 64,283
Beverage, Food, and Tobacco | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 10.40% 9.90%
Oil and Gas    
Summary of Investment Holdings [Line Items]    
Fair Value $ 26,887 $ 25,373
Oil and Gas | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 3.80% 3.90%
Automobile    
Summary of Investment Holdings [Line Items]    
Fair Value $ 22,191 $ 20,144
Automobile | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 3.10% 3.10%
Personal and Non-Durable Consumer Products    
Summary of Investment Holdings [Line Items]    
Fair Value $ 14,742 $ 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 2.10% 2.90%
Machinery    
Summary of Investment Holdings [Line Items]    
Fair Value $ 6,676 $ 9,562
Machinery | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 0.90% 1.50%
Telecommunications    
Summary of Investment Holdings [Line Items]    
Fair Value $ 5,976 $ 10,088
Telecommunications | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 0.80% 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 $ 6,103 $ 5,542
Other | Investment Owned, At Fair Value | Industry Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 0.80% 0.80%
Debt Securities    
Summary of Investment Holdings [Line Items]    
Cost $ 672,739 $ 595,048
Fair Value $ 653,305 $ 579,841
Debt Securities | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 91.50% 90.70%
Debt Securities | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 91.30% 89.20%
Secured first lien debt    
Summary of Investment Holdings [Line Items]    
Cost $ 549,860 $ 475,806
Fair Value $ 533,237 $ 463,858
Secured first lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 74.80% 72.50%
Secured first lien debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 74.50% 71.40%
Secured second lien debt    
Summary of Investment Holdings [Line Items]    
Cost $ 122,681 $ 118,949
Fair Value $ 120,036 $ 115,928
Secured second lien debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 16.70% 18.20%
Secured second lien debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 16.80% 17.80%
Unsecured debt    
Summary of Investment Holdings [Line Items]    
Cost $ 198 $ 293
Fair Value $ 32 $ 55
Unsecured debt | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 0.00% 0.00%
Unsecured debt | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 0.00% 0.00%
Equity Securities    
Summary of Investment Holdings [Line Items]    
Cost $ 62,443 $ 61,005
Fair Value $ 62,019 $ 69,774
Equity Securities | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 8.50% 9.30%
Equity Securities | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 8.70% 10.80%
Preferred Equity    
Summary of Investment Holdings [Line Items]    
Cost $ 35,617 $ 34,505
Fair Value $ 27,991 $ 27,046
Preferred Equity | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 4.80% 5.30%
Preferred Equity | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 3.90% 4.20%
Common Equity/ Equivalents    
Summary of Investment Holdings [Line Items]    
Cost $ 26,826 $ 26,500
Fair Value $ 34,028 $ 42,728
Common Equity/ Equivalents | Investment Owned, At Cost | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 3.70% 4.00%
Common Equity/ Equivalents | Investment Owned, At Fair Value | Investment Type Concentration Risk    
Summary of Investment Holdings [Line Items]    
Concentration risk, percentage 4.80% 6.60%