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Goodwill - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2025 | Sep. 30, 2024
Goodwill [Line Items] |  |  |
Goodwill, foreign exchange translation, decline |  | $ 0.7 | $ 0.3
Additional goodwill from acquisition |  | $ 238.0 |
Commercial |  |  |
Goodwill [Line Items] |  |  |
Goodwill transfers | $ 2.2 |  |
Trust Advisory Group, Ltd |  |  |
Goodwill [Line Items] |  |  |
Additional goodwill from acquisition |  |  | $ 2.0

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