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DERIVATIVES AND HEDGING ACTIVITIES - Impact of Derivative Instruments on AOCI (Details) - Cash flow hedging - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2025 | Sep. 30, 2024
Derivative [Line Items] |  |
Total pre-tax gain/(loss) recognized in AOCI | $ (18,040) | $ (67,102)
Pay fixed/receive floating swaps on cash flow hedges of borrowings |  |
Derivative [Line Items] |  |
Pay fixed/receive floating swaps on cash flow hedges of borrowings | $ (18,040) | $ (67,102)

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