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Credit Facilities - Narrative (Details) - USD ($) |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Jun. 17, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2023 | Jul. 08, 2025 | Mar. 01, 2024
Line of Credit Facility [Line Items] |  |  |  |  |  |
Loss on extinguishment of debt |  | $ 0 | $ 3,700,000 | $ 0 |  |
Senior Notes |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Loss on extinguishment of debt |  | 3,700,000 |  |  |  |
Deferred debt issuance cost, writeoff |  | 2,400,000 |  |  |  |
Deferred financing costs |  | 1,300,000 |  |  |  |
Subordinated Credit Facility | Line of Credit | RJO |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Line of credit facility borrowing |  | $ 180,000,000 |  |  |  |
Senior Secured Notes due 2031 | Senior Notes |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  | $ 550,000,000
Stated interest rate (as a percent) |  | 7.875% |  |  |  | 7.875%
Discount rate at issuance of face value (as a percent) |  |  |  |  |  | 100.00%
Debt issuance costs, gross |  |  |  |  |  | $ 7,600,000
Senior Notes Due 2025 | Senior Notes |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Stated interest rate (as a percent) | 8.625% |  |  |  |  |
Repayments of long-term debt | $ 363,000,000 |  |  |  |  |
Senior Secured Notes due 2032 | Senior Notes |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  | $ 625,000,000 |
Stated interest rate (as a percent) |  | 6.875% |  |  |  |
Debt issuance costs, gross |  |  |  |  | $ 10,500,000 |
Senior Secured Notes due 2032 | Senior Notes | RJO |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Stated interest rate (as a percent) |  |  |  |  | 100.00% |
Revolving Credit Facility |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Line of credit facility borrowing |  | $ 1,705,000,000 |  |  |  |

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