Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Sep. 30, 2025
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Certain conditions may exist as of the date the financial statements are issued, which may result in a loss to the Company but which will only be resolved when one or more future events occur or fail to occur. The Company assesses such contingent liabilities, and such assessment inherently involves an exercise of judgment. In assessing loss contingencies related to legal and regulatory proceedings that are pending against the Company or unasserted claims that may result in such proceedings, the Company’s legal counsel evaluates the perceived merits of any legal or regulatory proceedings or unasserted claims as well as the perceived merits of the amount of relief sought or expected to be sought therein. If the assessment of a contingency indicates that it is probable that a material loss has been incurred at the date of the financial statements and the amount of the liability can be estimated, then the estimated liability would be accrued in the Company’s financial statements. If the assessment indicates that a potentially material loss contingency is not probable, but is reasonably possible, or is probable but cannot be estimated, then the nature of the contingent liability, together with an estimate of the range of possible loss if determinable and material, would be disclosed. Neither accrual nor disclosure is required for loss contingencies that are deemed remote. The Company accrues legal fees related to contingent liabilities as they are incurred. 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 and workers’ compensation claims. The Company carries insurance that provides protection against certain types of claims, up to the limits of the respective policy. Additionally, the Company is subject to extensive regulation and supervision by U.S. federal and international governmental agencies and various self-regulatory organizations. The Company and its advisors periodically engage with such regulatory agencies and organizations, in the context of examinations or otherwise, to respond to inquiries, informational requests, and investigations. From time to time, such engagements result in regulatory complaints or other matters, the resolution of which can include fines and other remediation. In November 2023, BTIG filed a civil complaint (the “BTIG complaint”) against the Company and StoneX Financial Inc. in San Francisco Superior Court (CGC-23-610525) seeking monetary damages and injunctive relief for, among other things, alleged theft of purported trade secrets by former BTIG employees later employed at StoneX. The proceedings have moved to FINRA Arbitration and the court action is stayed. The Company intends to vigorously defend itself. The Company received from the U.S. Department of Justice (the “DOJ”) and the SEC subpoenas that the Company believes are related to conduct alleged in the BTIG complaint, and the Company is cooperating with these agencies. The ultimate outcomes of the BTIG complaint and the DOJ and SEC subpoenas cannot presently be determined. As of September 30, 2025 and 2024, the Consolidated Balance Sheets include loss contingency accruals, recorded during and prior to these years then ended, which are not material, individually or in the aggregate, to the Company’s financial position or liquidity. Management does not currently believe exposure from loss contingencies in excess of the amounts accrued, and in addition to the possible losses discussed below, to be material to the Company’s earnings, financial position or liquidity. Contingencies The Company had receivables, net of collections and other allowable deductions, of $9.2 million as of September 30, 2025, due from account holders in connection with the liquidation of their accounts in accordance with StoneX Financial Inc.’s client agreements and obligations under market regulation standards after the balances in the accounts fell below required maintenance margin levels and into deficit balances. The allowance against these uncollected balances was $3.3 million as of September 30, 2025. The Company is pursuing collection of the outstanding 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. relating to the trading losses in their accounts. During the fiscal year ended September 30, 2025, the Company favorably resolved several of these arbitration claims through arbitration decisions and privately negotiated settlements. All of the arbitration panels that issued decisions during the year awarded StoneX Financial Inc. the full amount of the uncollected balances. As noted, several of the arbitrations were resolved through privately negotiated settlement, pursuant to which the account holders agreed to pay some or all of their outstanding deficit balances. 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. Contractual Commitments Purchase Commitments The Company determines an estimate of contractual purchase commitments in the ordinary course of business primarily for the purchase of precious metals and agricultural and energy commodities. Unpriced contract commitments have been estimated using September 30, 2025 fair values. Purchase commitments and other obligations as of September 30, 2025 for less than one year, one to three years, three to five years, and after five years were $150,309.5 million, $651.0 million, $102.3 million, and $1,280.9 million respectively. The purchase commitments for less than one year will be offset by corresponding sales commitments of $147,941.2 million. Acquisition Consideration As part of certain of its acquisitions, the Company has contingent liabilities or amounts already determined to be paid at a future date. These are discussed in detail in Note 20. Exchange Member Guaranties The Company is a member of various exchanges that trade and clear futures and option contracts. The Company is also a member of and provides guaranties to securities clearinghouses and exchanges in connection with client trading activities. Associated with its memberships, the Company may be required to pay a proportionate share of the financial obligations of another member who may default on its obligations to the exchanges. While the rules governing different exchange memberships vary, in general the Company’s guaranty obligations would arise only if the exchange had previously exhausted its resources. In addition, any such guaranty obligation would be apportioned among the other non-defaulting members of the exchange. Any potential contingent liability under these arrangements is not quantifiable and could exceed the cash and securities posted to the clearinghouse as collateral. The Company has not recorded any contingent liability in the consolidated financial statements for these agreements and believes that any potential requirement to make payments under these agreements is remote. Self-Insurance The Company self-insures its medical and dental claims costs up to a stop loss amount, for eligible participating employees and retirees, and for qualified dependents, subject to deductibles and limitations. Liabilities are recognized based on claims filed and an estimate of claims incurred but not reported. The Company has purchased stop-loss coverage to limit its exposure on a per claim basis and in aggregate in the event that aggregated actual claims would exceed 120% of the actuarial estimate. The Company is insured for covered costs in excess of these limits. Although the ultimate outcome of these matters may exceed the amounts recorded and additional losses may be incurred, the Company does not believe that any additional potential exposure for such liabilities will have a material adverse effect on the Company’s consolidated financial position or results of operations. As of September 30, 2025 and 2024, the Company had $2.0 million and $2.2 million, respectively, accrued for self-insured medical and dental claims included in Accounts payable and other liabilities in the Consolidated Balance Sheets.