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Derivatives and Hedging Activities - Impact of Derivative Instruments on AOCI (Details) - Cash flow hedging - USD ($) $ in Thousands | 3 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021
Derivative [Line Items] |  |
Total pre-tax gain/(loss) recognized in AOCI | $ (6,806) | $ 6,446
Pay fixed/receive floating swaps on borrowings cash flow hedges |  |
Derivative [Line Items] |  |
Pay fixed/receive floating swaps on borrowings cash flow hedges | $ (6,806) | $ 6,446

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