Basis of Presentation and Consolidation and Accounting Standards Adopted (Policies)	6 Months Ended
Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying unaudited Condensed Consolidated Balance Sheet as of September 30, 2023, which has been derived from the audited consolidated balance sheet of September 30, 2023, and the unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and disclosures normally included in annual consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to those rules and regulations. The Company believes that the included disclosures clearly and fairly present the information within. In management’s opinion, all adjustments, generally consisting of normal accruals, considered necessary to fairly present the condensed consolidated financial statements for the interim periods presented have been reflected as required by Rule 10-01 of Regulation S-X. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes contained in the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2023, as filed with the SEC.
Consolidation	These condensed consolidated financial statements include the accounts of StoneX Group Inc. and all entities in which the Company has a controlling financial interest. All material intercompany transactions and balances have been eliminated in consolidation.
Fiscal Period	The Company’s fiscal year end is September 30, and its fiscal quarters end on December 31, March 31, June 30 and September 30. Unless otherwise stated, all dates refer to fiscal years and fiscal interim periods.
Use of Estimates	Preparing condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities as of the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant of these estimates and assumptions relate to fair value measurement for financial instruments, revenue recognition, valuation of inventories, and income taxes. These estimates are based on management’s best knowledge of current events and actions the Company may undertake in the future. The Company reviews all significant estimates affecting the financial statements on a recurring basis and records the effect of any necessary adjustments prior to financial statement issuance. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from these estimates. Estimates and assumptions were considered and made in context with the information reasonably available to the Company as of March 31, 2024 and through the date of this Form 10-Q.
Restricted Cash	Restricted Cash During the three months ended March 31, 2024, the Company established an escrow account designated to hold immediately available funds deposited by the Company and distribute the same amount on June 15, 2024, the intended redemption date, for the settlement of its 8.625% Senior Secured Notes due 2025. The Company has classified these funds as restricted because the funding is irrevocable, and the Company does not have the ability to withdraw the funds. See Note 9.
Gain on Acquisition	Gain on Acquisition In October 2022, the Company’s wholly owned subsidiary, StoneX Netherlands B.V., acquired CDI-Societe Cotonniere De Distribution S.A. The fair value of identifiable net assets acquired was approximately $66.2 million and the purchase price was approximately $42.7 million. The value that the Company acquired in excess of consideration paid resulted in a gain on acquisition of $23.5 million for the six months ended March 31, 2023.
Accounting Standards	Accounting Standards The Company did not adopt any new accounting standards during the three and six months ended March 31, 2024.
Earnings per Share	The Company presents basic and diluted earnings per share (“EPS”) using the two-class method, which requires all outstanding unvested share-based payment awards that contain rights to non-forfeitable dividends and therefore participate in undistributed earnings with common stockholders be included in computing earnings per share. Under the two-class method, net income is reduced by the amount of dividends declared in the period for each class of common stock and participating security. The remaining undistributed earnings are then allocated to common stock and participating securities, based on their respective rights to receive dividends. Restricted stock awards granted to certain employees and directors contain non-forfeitable rights to dividends at the same rate as common stock and are considered participating securities. Basic EPS has been computed by dividing net income by the weighted-average number of common shares outstanding.
Income Taxes	The income tax provision for interim periods comprises income tax on ordinary income (loss) at the most recent estimated annual effective income tax rate, adjusted for the income tax effect of discrete items. Management uses an estimated annual effective income tax rate based on the forecasted pretax income/(loss) and statutory tax rates in the various jurisdictions in which the Company operates. The Company’s effective income tax rate differs from the U.S. statutory income tax rate primarily due to state and local taxes, global intangible low taxed income (“GILTI”), and differing statutory tax rates applied to the income of non-U.S. subsidiaries. The Company records the tax effect of certain discrete items, including the effects of changes in tax laws, tax rates and adjustments with respect to valuation allowances or other unusual or nonrecurring tax adjustments, in the interim period in which they occur, as an addition to, or reduction from, the income tax provision, rather than being included in the estimated effective annual income tax rate. In addition, jurisdictions with a projected loss for the year or a year-to-date loss where no income tax benefit can be recognized are excluded from the estimated annual effective income tax rate.

Basis of Presentation and Consolidation and Accounting Standards Adopted (Policies)

6 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

The accompanying unaudited Condensed Consolidated Balance Sheet as of September 30, 2023, which has been derived from the audited consolidated balance sheet of September 30, 2023, and the unaudited interim condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and disclosures normally included in annual consolidated financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to those rules and regulations. The Company believes that the included disclosures clearly and fairly present the information within. In management’s opinion, all adjustments, generally consisting of normal accruals, considered necessary to fairly present the condensed consolidated financial statements for the interim periods presented have been reflected as required by Rule 10-01 of Regulation S-X.

Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and related notes contained in the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2023, as filed with the SEC.

Consolidation

These condensed consolidated financial statements include the accounts of StoneX Group Inc. and all entities in which the Company has a controlling financial interest. All material intercompany transactions and balances have been eliminated in consolidation.

Fiscal Period

The Company’s fiscal year end is September 30, and its fiscal quarters end on December 31, March 31, June 30 and September 30. Unless otherwise stated, all dates refer to fiscal years and fiscal interim periods.

Use of Estimates

Preparing condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities as of the date of the condensed consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. The most significant of these estimates and assumptions relate to fair value measurement for financial instruments, revenue recognition, valuation of inventories, and income taxes. These estimates are based on management’s best knowledge of current events and actions the Company may undertake in the future. The Company reviews all significant estimates affecting the financial statements on a recurring basis and records the effect of any necessary adjustments prior to financial statement issuance. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from these estimates. Estimates and assumptions were considered and made in context with the information reasonably available to the Company as of March 31, 2024 and through the date of this Form 10-Q.

Restricted Cash

During the three months ended March 31, 2024, the Company established an escrow account designated to hold immediately available funds deposited by the Company and distribute the same amount on June 15, 2024, the intended redemption date, for the settlement of its 8.625% Senior Secured Notes due 2025. The Company has classified these funds as restricted because the funding is irrevocable, and the Company does not have the ability to withdraw the funds. See Note 9.

Gain on Acquisition

In October 2022, the Company’s wholly owned subsidiary, StoneX Netherlands B.V., acquired CDI-Societe Cotonniere De Distribution S.A. The fair value of identifiable net assets acquired was approximately $66.2 million and the purchase price was approximately $42.7 million. The value that the Company acquired in excess of consideration paid resulted in a gain on acquisition of $23.5 million for the six months ended March 31, 2023.

Accounting Standards

The Company did not adopt any new accounting standards during the three and six months ended March 31, 2024.

Earnings per Share

The Company presents basic and diluted earnings per share (“EPS”) using the two-class method, which requires all outstanding unvested share-based payment awards that contain rights to non-forfeitable dividends and therefore participate in undistributed earnings with common stockholders be included in computing earnings per share. Under the two-class method, net income is reduced by the amount of dividends declared in the period for each class of common stock and participating security. The remaining undistributed earnings are then allocated to common stock and participating securities, based on their respective rights to receive dividends. Restricted stock awards granted to certain employees and directors contain non-forfeitable rights to dividends at the same rate as common stock and are considered participating securities. Basic EPS has been computed by dividing net income by the weighted-average number of common shares outstanding.

Income Taxes

The income tax provision for interim periods comprises income tax on ordinary income (loss) at the most recent estimated annual effective income tax rate, adjusted for the income tax effect of discrete items. Management uses an estimated annual effective income tax rate based on the forecasted pretax income/(loss) and statutory tax rates in the various jurisdictions in which the Company operates. The Company’s effective income tax rate differs from the U.S. statutory income tax rate primarily due to state and local taxes, global intangible low taxed income (“GILTI”), and differing statutory tax rates applied to the income of non-U.S. subsidiaries. The Company records the tax effect of certain discrete items, including the effects of changes in tax laws, tax rates and adjustments with respect to valuation allowances or other unusual or nonrecurring tax adjustments, in the interim period in which they occur, as an addition to, or reduction from, the income tax provision, rather than being included in the estimated effective annual income tax rate. In addition, jurisdictions with a projected loss for the year or a year-to-date loss where no income tax benefit can be recognized are excluded from the estimated annual effective income tax rate.