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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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