Derivatives and Hedging Activities - Schedule of Impact of Client Swap Program that are Not Designated in Accounting Hedges (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Interest rate contracts | ||||
| Derivative [Line Items] | ||||
| Derivative instruments not designated as hedging instruments, gain (loss), net | $ (12) | $ 56 | $ 392 | $ 126 |
| Pay fixed/receive floating swap | ||||
| Derivative [Line Items] | ||||
| Derivative instruments not designated as hedging instruments, gain (loss), net | 5,105 | (7,677) | 4,389 | 1,013 |
| Receive fixed/pay floating swap | ||||
| Derivative [Line Items] | ||||
| Derivative instruments not designated as hedging instruments, gain (loss), net | $ (5,117) | $ 7,733 | $ (3,997) | $ (887) |