Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Contingencies In November 2018, balances in approximately 300 client accounts of the FCM division of the Company’s wholly owned subsidiary, StoneX Financial Inc., declined below required maintenance margin levels and into deficit balances, primarily as a result of significant and unexpected price fluctuations in the natural gas markets. All positions in these accounts, which were managed by OptionSellers.com Inc. (“OptionSellers”), an independent Commodity Trading Advisor (“CTA”), were liquidated in accordance with StoneX Financial Inc.’s client agreements and obligations under market regulation standards. A CTA is registered with the U.S. Commodity Futures Trading Commission (“CFTC”) and a member of, and subject to audit by, the National Futures Association (“NFA”). OptionSellers was registered under a CFTC Rule 4.7 exemption for providing services only to “qualified eligible persons,” which requires the account holders authorizing OptionSellers to act as their CTA to meet or exceed certain minimum financial requirements. OptionSellers, in its role as a CTA, had been granted by each of its clients full discretionary authority to manage the trading in the clients’ accounts, while StoneX Financial Inc. acted solely as the clearing firm in its role as the FCM. StoneX Financial Inc.’s client agreements hold account holders liable for all losses in their accounts and obligate the account holders to reimburse StoneX Financial Inc. for any deficits in their accounts. As of March 31, 2023, the receivable from these client accounts, net of collections and other allowable deductions, was $22.0 million, with no individual account receivable exceeding $1.4 million. As of March 31, 2023, the allowance against these uncollected balances was $6.7 million. The Company is pursuing collection of the uncollected balances through arbitration proceedings against the account holders. The Company will consider developments in these proceedings, and any other relevant matters, in determining whether any changes in the allowance against the uncollected balances are required. In these and other arbitration proceedings, clients are seeking damages from StoneX Financial Inc. related to the trading losses in their accounts. During the six months ended March 31, 2023, the Company reached privately negotiated settlements of a number of arbitration proceedings, pursuant to which in most cases the account holders agreed to pay all or a substantial portion of their outstanding deficit balances and in some cases the Company agreed to make certain payments to the account holders that are not material to the Company, individually or in the aggregate. The Company intends to continue vigorously pursuing claims through arbitration and settling cases in what the Company determines to be appropriate circumstances. The ultimate outcome of remaining arbitrations cannot presently be determined. Depending on future collections and the outcomes of arbitration proceedings, any provisions for bad debts and actual losses may or may not be material to the Company’s financial results. However, the Company believes that the likelihood of a material adverse outcome is remote, and does not currently believe that any potential losses related to this matter would impact its ability to comply with its ongoing liquidity, capital, and regulatory requirements. Legal Proceedings From time to time and in the ordinary course of business, the Company is involved in various legal actions and proceedings, including tort claims, contractual disputes, employment matters, workers’ compensation claims and collections. The Company carries insurance that provides protection against certain types of claims, up to the relevant policy’s limits. As of March 31, 2023 and September 30, 2022, the Condensed Consolidated Balance Sheets include loss contingency accruals which are not material, individually or in the aggregate, to the Company’s financial position or liquidity. In the opinion of management, possible exposure from loss contingencies in excess of the amounts accrued, is not likely to be material to the Company’s earnings, financial position or liquidity. Other than the updates provided within Contingencies, above, there have been no material changes to the legal actions and proceedings compared to September 30, 2022. Contractual Commitments Self-Insurance The Company self-insures its costs related to medical and dental claims. The Company is self-insured, up to a stop loss amount, for eligible participating employees and retirees, and for qualified dependent medical and dental claims, subject to deductibles and limitations. As of March 31, 2023, the Company had $1.4 million accrued for self-insured medical and dental claims included in Accounts payable and other accrued liabilities in the Condensed Consolidated Balance Sheet.