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INVESTMENTS - Fair Value Measurement Inputs and Valuation Techniques (Details) $ in Thousands | Sep. 30, 2024 USD ($) | Sep. 30, 2023 USD ($)
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Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | $ 796,260 | [1] | $ 704,815 | [2]
Leeds Acquisition Holdings, LLC |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 38 |  | 200 |
Funko Acquisition Holdings, LLC |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value |  |  | 22 |
Significant Unobservable Inputs (Level 3) |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 796,222 |  | 704,562 |
Significant Unobservable Inputs (Level 3) | Yield Analysis | Secured first lien debt |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 464,090 |  | 461,638 |
Significant Unobservable Inputs (Level 3) | Yield Analysis | Secured second lien debt |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | $ 101,928 |  | $ 110,820 |
Significant Unobservable Inputs (Level 3) | Yield Analysis | Discount Rate | Secured first lien debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.108 |  | 0.118 |
Significant Unobservable Inputs (Level 3) | Yield Analysis | Discount Rate | Secured first lien debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.173 |  | 0.299 |
Significant Unobservable Inputs (Level 3) | Yield Analysis | Discount Rate | Secured first lien debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.126 |  | 0.148 |
Significant Unobservable Inputs (Level 3) | Yield Analysis | Discount Rate | Secured second lien debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.122 |  | 0.125 |
Significant Unobservable Inputs (Level 3) | Yield Analysis | Discount Rate | Secured second lien debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.160 |  | 0.156 |
Significant Unobservable Inputs (Level 3) | Yield Analysis | Discount Rate | Secured second lien debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.141 |  | 0.145 |
Significant Unobservable Inputs (Level 3) | TEV | Secured first lien debt |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | $ 90,847 |  | $ 49,063 |
Significant Unobservable Inputs (Level 3) | TEV | Secured second lien debt |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 8,547 |  | 7,425 |
Significant Unobservable Inputs (Level 3) | TEV | Unsecured debt |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 32 |  | 24 |
Significant Unobservable Inputs (Level 3) | TEV | Preferred and common equity / equivalents |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | $ 127,537 |  | $ 65,983 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA multiple | Secured first lien debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 4.1 |  | 4.7 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA multiple | Secured first lien debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 13.9 |  | 6.8 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA multiple | Secured first lien debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 10.0 |  | 6.7 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA multiple | Secured second lien debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 5.4 |  | 5.6 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA multiple | Secured second lien debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 5.4 |  | 5.6 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA multiple | Secured second lien debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 5.4 |  | 5.6 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA multiple | Preferred and common equity / equivalents | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 4.1 |  | 4.7 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA multiple | Preferred and common equity / equivalents | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 13.9 |  | 13.0 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA multiple | Preferred and common equity / equivalents | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 8.0 |  | 6.9 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA | Secured first lien debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | $ 3,020 |  | $ 995 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA | Secured first lien debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 16,211 |  | 14,002 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA | Secured first lien debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 10,309 |  | 13,624 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA | Secured second lien debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 3,343 |  | 3,690 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA | Secured second lien debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 3,343 |  | 3,690 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA | Secured second lien debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 3,343 |  | 3,690 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA | Preferred and common equity / equivalents | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 1,182 |  | 995 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA | Preferred and common equity / equivalents | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 144,458 |  | 112,841 |
Significant Unobservable Inputs (Level 3) | TEV | EBITDA | Preferred and common equity / equivalents | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | $ 10,847 |  | $ 10,570 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue multiple | Secured first lien debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.2 |  | 0.3 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue multiple | Secured first lien debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 4.6 |  | 0.8 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue multiple | Secured first lien debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 2.1 |  | 0.6 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue multiple | Unsecured debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 1.0 |  | 1.0 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue multiple | Unsecured debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 1.0 |  | 1.0 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue multiple | Unsecured debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 1.0 |  | 1.0 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue multiple | Preferred and common equity / equivalents | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.2 |  | 0.3 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue multiple | Preferred and common equity / equivalents | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 4.6 |  | 3.0 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue multiple | Preferred and common equity / equivalents | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 2.0 |  | 1.2 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue | Secured first lien debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | $ 6,336 |  | $ 14,934 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue | Secured first lien debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 21,118 |  | 16,283 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue | Secured first lien debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 13,981 |  | 15,361 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue | Unsecured debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 7,834 |  | 5,044 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue | Unsecured debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 7,834 |  | 5,044 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue | Unsecured debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 7,834 |  | 5,044 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue | Preferred and common equity / equivalents | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 4,672 |  | 4,213 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue | Preferred and common equity / equivalents | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 21,118 |  | 16,283 |
Significant Unobservable Inputs (Level 3) | TEV | Revenue | Preferred and common equity / equivalents | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | 12,587 |  | 14,959 |
Significant Unobservable Inputs (Level 3) | Market Quote | Secured second lien debt |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investments owned, fair value | $ 3,241 |  | $ 9,609 |
Significant Unobservable Inputs (Level 3) | Market Quote | IBP | Secured second lien debt | Minimum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.880 |  | 0.678 |
Significant Unobservable Inputs (Level 3) | Market Quote | IBP | Secured second lien debt | Maximum |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.880 |  | 0.940 |
Significant Unobservable Inputs (Level 3) | Market Quote | IBP | Secured second lien debt | Weighted Average |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |
Investment owned, measurement input | 0.880 |  | 0.822 |
[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.
[2] | Cumulative gross unrealized depreciation for federal income tax purposes is $56.9 million; cumulative gross unrealized appreciation for federal income tax purposes is $33.7 million. Cumulative net unrealized depreciation is $23.2 million, based on a tax cost of $728.0 million.

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