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BORROWINGS - Fair Value Narrative (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Jun. 30, 2024 | Sep. 30, 2023
Debt Instrument [Line Items] |  |  |
Investments, at fair value | $ 757,745 | $ 704,815 | [1]
Collateral Pledged |  |  |
Debt Instrument [Line Items] |  |  |
Investments, at fair value | $ 674,400 | $ 628,300 |
Credit Facility | Line of Credit | Revolving Line of Credit |  |  |
Debt Instrument [Line Items] |  |  |
Unused fee percentage | 1.00% | 1.00% |
Credit Facility | Line of Credit | Revolving Line of Credit | SOFR |  |  |
Debt Instrument [Line Items] |  |  |
Debt instrument, basis spread on variable rate | 0.10% |  |
Credit Facility | Line of Credit | Revolving Line of Credit | One-Month Term Secured Overnight Financing Rate (SOFR) |  |  |
Debt Instrument [Line Items] |  |  |
Debt instrument, basis spread on variable rate | 3.10% | 3.10% |
[1] | 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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