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DISTRIBUTIONS TO COMMON STOCKHOLDERS - Adjustments for Book-tax Differences to Reflect Tax Character (Details) - USD ($) $ in Thousands | 6 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2023 | Sep. 30, 2022
Retained Earnings |  |
Investment Company, Changes in Net Assets [Line Items] |  |
Tax reclassification, increase (decrease) | $ 271 | $ (5,606)
Accumulated Long-term Capital Gains |  |
Investment Company, Changes in Net Assets [Line Items] |  |
Tax reclassification, increase (decrease) | (271) | 7,013
Additional Paid-in Capital |  |
Investment Company, Changes in Net Assets [Line Items] |  |
Tax reclassification, increase (decrease) | $ 0 | $ (1,407)

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