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DISTRIBUTIONS TO COMMON STOCKHOLDERS - Schedule of 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, 2025 | Sep. 30, 2024
Equity [Abstract] |  |
Undistributed net investment income | $ (947) | $ (1,299)
Accumulated net realized gain (loss) | 1,053 | 1,310
Capital in excess of par value | $ (106) | $ (11)

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