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 |
|---|---|---|
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) |