Goodwill - Schedule of Goodwill Reconciliation (Details) $ in Millions	9 Months Ended
Jun. 30, 2026 USD ($)
Business Combination [Line Items]
Total Goodwill Recorded	$ 3.5
Intercam Advisors, Inc. and Intercam Securities, Inc. \| Self-Directed/Retail
Business Combination [Line Items]
Total Goodwill Recorded	0.4
Plantureux et Associés \| Commercial
Business Combination [Line Items]
Total Goodwill Recorded	2.9
WCS International Limited \| Payments
Business Combination [Line Items]
Total Goodwill Recorded	8.0
R.J. O’Brien & Associates, LLC \| Commercial
Business Combination [Line Items]
Total Goodwill Recorded	(3.4)
R.J. O’Brien & Associates, LLC \| Institutional
Business Combination [Line Items]
Total Goodwill Recorded	$ (4.4)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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