Basis of Presentation and Consolidation and Recently Issued Accounting Standards (Policies)	6 Months Ended
	Mar. 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, 2014, 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, 2014 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 June 2014, the FASB issued ASU 2014-11, Transfers and Servicing: Repurchase-to-Maturity Transactions, Repurchase Financings, and Disclosures, which changes the accounting for repurchase-to-maturity transactions to secured borrowing accounting. Additionally, for repurchase financing arrangements, the amendments of this ASU require separate accounting for a transfer of a financial asset executed contemporaneously with a repurchase agreement with the same counterparty, which will result in secured borrowing accounting for the repurchase agreement. For public entities, the ASU is effective for the first interim or annual period beginning after December 15, 2014. Earlier application is not permitted. The Company adopted this guidance starting with the second quarter of fiscal year 2015. The adoption of this guidance did not have a material impact on the Company’s condensed consolidated financial statements. In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements - Going Concern: Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern, which requires management to evaluate whether there are conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued or are available to be issued. This ASU also requires management to disclose certain information depending on the results of the going concern evaluation. The provisions of this ASU are effective for annual periods ending after December 15, 2016, and for interim and annual periods thereafter. Early adoption is permitted. This amendment is applicable to the Company for the fiscal year ended September 30, 2017. The adoption of this standard is not expected to have a material impact on the condensed consolidated financial statements. In January 2015, the FASB issued ASU 2015-01, Income Statement - Extraordinary and Unusual Items: Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items, which eliminates from U.S. GAAP the concept of extraordinary items. The ASU retains and expands the existing presentation and disclosure guidance for items that are unusual in nature or occur infrequently to also include items that are both unusual in nature and infrequently occurring. The provisions of this ASU are effective for annual periods and interim periods within those annual periods beginning after December 15, 2015. Early adoption is permitted, provided that presentation applied to the beginning of the fiscal year of adoption. This amendment is applicable to the Company beginning October 1, 2016. The adoption of this standard is not expected to have a material impact on the condensed consolidated financial statements. In April 2015, the FASB issued ASU 2015-03, Interest- Imputation of Interest (Subtopic 835-03) - Simplifying the Presentation of Debt Issuance Costs which requires unamortized debt issuance costs to be presented as a reduction of the corresponding debt liability rather than a separate asset. Amortization of the costs is reported as interest expense. The provisions of this ASU are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is allowed for all entities for financial statements that have not been previously issued. Entities should apply the new guidance retrospectively to all prior periods. The guidance is applicable to the Company beginning October 1, 2016. The adoption of this standard is not expected to have a material impact on the condensed consolidated financial statements.

Disclosure of accounting policy regarding (1) the principles it follows in consolidating or combining the separate financial statements, including the principles followed in determining the inclusion or exclusion of subsidiaries or other entities in the consolidated or combined financial statements and (2) its treatment of interests (for example, common stock, a partnership interest or other means of exerting influence) in other entities, for example consolidation or use of the equity or cost methods of accounting. The accounting policy may also address the accounting treatment for intercompany accounts and transactions, noncontrolling interest, and the income statement treatment in consolidation for issuances of stock by a subsidiary.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02, 03

-Article 3A

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367646&loc=d3e18780-107790

Reference 3: http://www.xbrl.org/2003/role/presentationRef

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Topic 860

-SubTopic 40

-Section 45

-URI http://asc.fasb.org/section&trid=2197723

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-URI http://asc.fasb.org/subtopic&trid=2196966

Reference 6: http://www.xbrl.org/2003/role/presentationRef

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-URI http://asc.fasb.org/subtopic&trid=2197087

Reference 7: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.3A-02)

-URI http://asc.fasb.org/extlink&oid=27015204&loc=d3e355033-122828

Reference 8: http://www.xbrl.org/2003/role/presentationRef

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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-URI http://asc.fasb.org/extlink&oid=18733093&loc=d3e5614-111684

Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph k

-Article 1

+ Details

- Definition

Disclosure of accounting policy for determining an entity's fiscal year or other fiscal period. This disclosure may include identification of the fiscal period end-date, the length of the fiscal period, any reporting period lag between the entity and its subsidiaries, or equity investees. If a reporting lag exists, the closing date of the entity having a different period end is generally noted, along with an explanation of the necessity for using different closing dates. Any intervening events that materially affect the entity's financial position or results of operations are generally also disclosed.

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