Basis of Presentation and Consolidation and Recently Issued Accounting Standards (Policies)	3 Months Ended
	Dec. 31, 2015
Basis of Presentation and Consolidation [Abstract]
Basis of Accounting, Policy [Policy Text Block]	The accompanying condensed consolidated balance sheet as of September 30, 2015, which has been derived from audited financial statements, 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 note disclosures normally included in annual 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 disclosures made are adequate to make the information presented not misleading. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation of 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. It is suggested that these interim 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 Form 10-K for the fiscal year ended September 30, 2015 filed with the SEC.
Consolidation, Policy [Policy Text Block]	These condensed consolidated financial statements include the accounts of INTL FCStone Inc. and all other entities in which the Company has a controlling financial interest. All material intercompany transactions and balances have been eliminated in consolidation.
Fiscal Period, Policy [Policy Text Block]	The Company’s fiscal year end is September 30, and the 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, Policy [Policy Text Block]	The preparation of 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 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 measurements for financial instruments and investments, revenue recognition, the provision for potential losses from bad debts, valuation of inventories, valuation of goodwill and intangible assets, self-insurance liabilities, incomes taxes and contingencies. Although these and other estimates and assumptions are based on the best available information, actual results could be materially different from these estimates.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements In January 2016, the Financial Accounting Standards Board (“FASB”) issued authoritative guidance addressing the recognition, measurement, presentation and disclosure of financial assets and liabilities. The guidance primarily affects the accounting for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. In addition, the guidance clarifies the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. This guidance is effective for the Company in the first quarter of fiscal 2019, and early adoption is not permitted, with certain exceptions. The amendments are required to be applied by means of a cumulative-effect adjustment on the balance sheet as of the beginning of the fiscal year of adoption. The Company is currently assessing the impact, if any, the guidance may have upon adoption.