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Business Acquisitions and Divestitures - Narrative (Details) $ in Thousands |  | 1 Months Ended | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | ---
Jun. 30, 2025 USD ($) | Dec. 31, 2024 | Nov. 30, 2023 | Dec. 31, 2025 | Sep. 30, 2025 USD ($) | Jun. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Jun. 30, 2026 USD ($) | Jul. 17, 2025 option stage
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Measurement period adjustments |  |  |  |  |  |  |  | $ (1,109) |  |  |
Contingent consideration, adjustment |  |  |  |  |  |  |  | 4,054 | $ 1,547 |  |
Proceeds from business divestiture |  |  |  |  |  |  |  | 116,020 | 0 |  |
Gain on sale of business |  |  |  |  | $ 0 |  | $ 0 | 94,412 | $ 0 |  |
Aquiline Capital Partners LP |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proceeds from business divestiture | $ 116,020 |  |  |  |  |  |  |  |  |  |
Gain on sale of business | $ 94,412 |  |  |  |  |  |  |  |  |  |
Stratos Wealth Holdings |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of call options | option |  |  |  |  |  |  |  |  |  |  | 3
Number of stages in business combination transaction | stage |  |  |  |  |  |  |  |  |  |  | 2
Stratos Wealth Holdings | Call Option One |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Call option, term (in months) |  |  |  |  |  |  |  |  |  |  | 36 months
Stratos Wealth Holdings | Call Option Two |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Call option, term (in months) |  |  |  |  |  |  |  |  |  |  | 54 months
Stratos Wealth Holdings | Call Option Three |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Call option, term (in months) |  |  |  |  |  |  |  |  |  |  | 72 months
Stratos Wealth Holdings | Subsequent Event |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Subsidiary, ownership percentage, parent, if options fully exercised |  |  |  |  |  |  |  |  |  | 100.00% |
Stratos Wealth Holdings | Subsequent Event | United States |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Total business combination in stage one (as a percent) |  |  |  | 0.800 |  |  |  |  |  |  |
LifeYield, LLC |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, earning period |  | 4 years |  |  |  |  |  |  |  |  |
Measurement period adjustments |  |  |  |  |  |  |  | 1,109 |  |  |
Contingent consideration, adjustment |  |  |  |  |  |  |  | 1,467 |  |  |
Contingent consideration |  |  |  |  | $ 9,252 |  |  | $ 9,252 |  |  |
XPS Pensions (Nexus) Limited |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Contingent consideration, earning period |  |  | 2 years |  |  |  |  |  |  |  |
Contingent consideration, adjustment |  |  |  |  |  | $ 2,587 |  |  |  |  |
Forecast | Stratos Wealth Holdings |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Business combination, consideration transferred |  |  |  |  |  |  |  |  |  | $ 527,000 |
Percentage ownership |  |  |  |  |  |  |  |  |  | 57.50% |
Forecast | Stratos Wealth Holdings | Certain Legacy Stratos Equity Holders |  |  |  |  |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |  |  |  |  |
Percentage ownership |  |  |  |  |  |  |  |  |  | 42.50% |

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