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DISTRIBUTIONS TO COMMON STOCKHOLDERS - Adjustments for Book-tax Differences to Reflect Tax Character (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
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Jun. 30, 2024 | Sep. 30, 2023
Equity [Abstract] |  |
Undistributed net investment income | $ (1,303) | $ (373)
Accumulated net realized gain | 1,305 | 373
Capital in excess of par value | $ (2) | $ 0

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