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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Apr. 04, 2024 | Sep. 30, 2024 USD ($) loan investment | Sep. 30, 2023 USD ($) loan investment | Sep. 30, 2022 USD ($)
Summary of Investment Holdings [Line Items] |  |  |  |  |  |
Reverse stock split, conversion ratio | 0.5 |  |  |  |  |
Cost |  | $ 771,011 | [1] | $ 722,269 | [2] |
Fair Value |  | 796,260 | [1] | 704,815 | [2] |
Total interest income (excluding PIK interest income) |  | 87,618 |  | 79,480 |  | $ 49,759
PIK interest income |  | $ 5,676 |  | 3,550 |  | 4,229
Investment company, target percentage of taxable income to distribute to shareholders (up to) |  | 100.00% |  |  |  |
OID |  |  |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |  |  |
Fair Value |  | $ 600 |  | $ 700 |  |
Number of loans | loan |  | 2 |  | 4 |  |
Total interest income (excluding PIK interest income) |  | $ 400 |  | $ 200 |  | 500
PIK |  |  |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |  |  |
Number of investments | investment |  | 8 |  | 8 |  |
Proceeds from interest received |  | $ 200 |  | $ 1,100 |  | $ 2,400
B+T Group Acquisition, Inc., Edge Adhesives Holdings, Inc,. And WB Xcel Holdings, LLC |  |  |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |  |  |
Cost |  | $ 28,300 |  |  |  |
Cost percentage |  | 4.10% |  |  |  |
Fair Value |  | $ 12,800 |  |  |  |
Fair value percentage |  | 1.90% |  |  |  |
Edge Adhesives Holdings, Inc. |  |  |  |  |  |
Summary of Investment Holdings [Line Items] |  |  |  |  |  |
Cost |  |  |  | $ 6,100 |  |
Cost percentage |  |  |  | 0.90% |  |
Fair Value |  |  |  | $ 2,900 |  |
Fair value percentage |  |  |  | 0.50% |  |
[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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