Exchange Memberships and Stock [Abstract] Exchange Memberships and Stock [Abstract] Exchange Memberships and Stock, [Text Block] Exchange Memberships and Stock [Text Block] The entire disclosure for reporting exchange memberships with rights of ownership, rights to conduct business and contributed exchange memberships. Segment Analysis [Abstract] Segment Analysis [Abstract] Segment Reporting Disclosure [Text Block] Segment Reporting Disclosure [Text Block] Income Taxes [Abstract] Income Taxes [Abstract] Income Tax Disclosure [Text Block] Income Tax Disclosure [Text Block] Credit Facilities [Abstract] Credit Facilities [Abstract] Debt Disclosure [Text Block] Debt Disclosure [Text Block] Condensed Consolidated Income Statements [Abstract] Condensed Consolidated Income Statements [Abstract] Statement [Table] Statement [Table] Statement, Scenario [Axis] Statement, Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Statement [Line Items] Statement [Line Items] Revenues: Revenues [Abstract] Sales of physical commodities Sales Revenue, Goods, Net Trading gains Trading Gains (Losses) Commission and clearing fees Fees and Commissions Consulting and management fees Asset Management Fees Interest income Interest Income, Operating Other income Other Income Total revenues Revenues Cost of sales of physical commodities Cost of Goods Sold Operating revenues Gross Profit Interest expense Interest Expense Net revenues Revenues, Net of Interest Expense Non-interest expenses: Noninterest Expense [Abstract] Compensation and benefits Labor and Related Expense Clearing and related expenses Floor Brokerage, Exchange and Clearance Fees Communication and data services Communications and Information Technology Introducing broker commissions Noninterest Expense Commission Expense Occupancy and equipment rental Occupancy, Net Professional fees Professional Fees Depreciation and amortization Depreciation, Depletion and Amortization Bad debts and impairments Provision for Doubtful Accounts Other Other Noninterest Expense Total non-interest expenses Noninterest Expense Income from continuing operations, before tax Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) Income from continuing operations Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest Income from discontinued operations, net of tax Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Income before extraordinary loss Income (Loss) from Operations before Extraordinary Items Extraordinary loss Extraordinary Item, Gain (Loss), Gross Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Add: Net loss attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to INTL FCStone Inc. common stockholders Net Income (Loss) Attributable to Parent Basic earnings per share: Earnings Per Share, Basic [Abstract] Income from continuing operations attributable to INTL FCStone Inc. common stockholders Income (Loss) from Continuing Operations, Per Basic Share Income from discontinued operations attributable to INTL FCStone Inc. common stockholders Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share Extraordinary loss attributable to INTL FCStone Inc. common stockholders Income (Loss) from Extraordinary Items, Net of Tax, Per Basic Share Net income attributable to INTL FCStone Inc. common stockholders Earnings Per Share, Basic Diluted earnings per share: Earnings Per Share, Diluted [Abstract] Income from continuing operations attributable to INTL FCStone Inc. common stockholders Income (Loss) from Continuing Operations, Per Diluted Share Income from discontinued operations attributable to INTL FCStone Inc. common stockholders Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share Extraordinary loss attributable to INTL FCStone Inc. common stockholders Income (Loss) from Extraordinary Items, Net of Tax, Per Diluted Share Net income attributable to INTL FCStone Inc. common stockholders Earnings Per Share, Diluted Weighted-average number of common shares outstanding: Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic Weighted Average Number of Shares Outstanding, Basic Diluted Weighted Average Number of Shares Outstanding, Diluted Amounts attributable to INTL FCStone Inc. common stockholders: Income Amounts Attributable to Parent, Disclosures [Abstract] Income from continuing operations, net of tax Income (Loss) from Continuing Operations Attributable to Parent Income from discontinued operations, net of tax Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent Extraordinary loss Extraordinary Item, Gain (Loss), Net of Tax, Attributable to Parent Net Income Stock-Based Compensation [Abstract] Stock-Based Compensation [Abstract] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Commitments and Contingencies [Abstract] Commitments and Contingencies [Abstract] Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Disclosure [Text Block] Receivables from customers and notes receivable, net [Abstract] Receivables from customers and notes receivable, net [Abstract] Financing Receivables [Text Block] Financing Receivables [Text Block] Basis of Presentation and Consolidation and Recently Issued Accounting Standards [Abstract] Basis of Presentation and Consolidation and Recently Issued Accounting Standards [Abstract] Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Note 3 – Earnings per Share [Abstract] Note 3 – Earnings per Share [Abstract] Earnings Per Share [Text Block] Earnings Per Share [Text Block] Discontinued Operations [Abstract] Discontinued Operations [Abstract] Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Convertible Subordinated Notes [Abstract] Convertible Subordinated Notes [Abstract] Subordinated Borrowings Disclosure [Text Block] Subordinated Borrowings Disclosure [Text Block] Condensed Consolidated Cash Flows Statements [Abstract] Condensed Consolidated Cash Flows Statements [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Cash paid for acquisitions, net Payments to Acquire Businesses, Net of Cash Acquired Purchase of exchange memberships and common stock Payments to Acquire Other Productive Assets Sale of exchange memberships and common stock Proceeds from Sale of Other Productive Assets Deconsolidation of affiliates Proceeds from Divestiture of Interest in Subsidiaries and Affiliates Purchase of property and equipment Payments to Acquire Property, Plant, and Equipment Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Net change in payable to lenders under loans and overdrafts Proceeds from (Repayments of) Debt Repayment of subordinated debt Repayments of Subordinated Debt Debt issuance costs Payments of Debt Issuance Costs Exercise of stock options Proceeds from Stock Options Exercised Income tax benefit on stock options and awards Tax Benefit from Stock Options Exercised Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rates on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents Net increase in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents at beginning of period Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents at end of period Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid for interest Interest Paid Income taxes paid, net of cash refunds Income Taxes Paid, Net Supplemental disclosure of non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Conversion of subordinated notes to common stock, net Stock Issued During Period, Value, Conversion of Convertible Securities Additional consideration payable related to acquisitions Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Asset Acquisitions [Abstract] Acquisitions [Abstract] Business Combination Disclosure [Text Block] Business Combination Disclosure [Text Block] Intangible Assets [Abstract] Intangible Assets [Abstract] Intangible Assets Disclosure [Text Block] Intangible Assets Disclosure [Text Block] Goodwill [Abstract] Goodwill [Abstract] Goodwill Disclosure [Text Block] Goodwill Disclosure [Text Block] Subsequent Events [Abstract] Subsequent Events [Text Block] Subsequent Events [Text Block] Capital and Other Regulatory Requirements [Abstract] Capital and Other Regulatory Requirements [Abstract] Regulatory Capital Requirements under Banking Regulations [Text Block] Regulatory Capital Requirements under Banking Regulations [Text Block] Physical Commodities Inventory [Abstract] Physical Commodities Inventory [Abstract] Inventory Disclosure [Text Block] Inventory Disclosure [Text Block] Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk [Abstract] Financial Instruments with Off-Balance Sheet Risk and Concentrations of Credit Risk [Abstract] Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Instruments and Hedging Activities Disclosure [Text Block] Extraordinary item [Abstract] Extraordinary Item [Abstract] Extraordinary Items Disclosure [Text Block] Extraordinary Items Disclosure [Text Block] Condensed Consolidated Balance Sheets [Abstract] Condensed Consolidated Balance Sheets [Abstract] ASSETS Assets [Abstract] Cash and cash equivalents Cash, securities and other assets segregated under federal and other regulations (including $25.2 and $0.8 at fair value at June 30, 2011 and September 30, 2010, respectively) Cash and Securities Segregated under Federal and Other Regulations Securities purchased under agreements to resell Securities Purchased under Agreements to Resell Deposits and receivables from: Receivables from Brokers-Dealers and Clearing Organizations [Abstract] Exchange-clearing organizations (including $1,120.5 and $906.4 at fair value at June 30, 2011 and September 30, 2010, respectively) Receivables from Clearing Organizations Broker-dealers, clearing organizations and counterparties (including $(2.5) and $56.1 at fair value at June 30, 2011 and September 30, 2010, respectively) Receivables from Brokers-Dealers and Clearing Organizations Receivables from customers, net Accounts Receivable, Net Notes receivable, net Notes, Loans and Financing Receivable, Net Income taxes receivable Income Taxes Receivable Financial instruments owned, at fair value Financial Instruments, Owned, at Fair Value Physical commodities inventory, at cost Inventory, Gross Deferred income taxes Deferred Tax Assets (Liabilities), Net Property and equipment, net Property, Plant and Equipment, Net Goodwill and intangible assets, net Goodwill and intangible assets, net Amount combines the carrying amounts for goodwill and finite- and indefinite-lived intangible assets. Goodwill represents the carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquire, adjusted for any amortization recognized prior to adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions. Indefinite-lived intangible assets represent the carrying amount of intangible assets, excluding goodwill, which have a projected indefinite period of benefit (hence are not amortized), allocated to the reportable segment. These assets, acquired either individually or as part of a group of assets, in either an asset acquisition or business combination, are assessed at least annually for impairment. Examples may include trade secrets, contractual rights, trade names, and licensing agreements. Finite-lived intangible assets are the aggregate sum of gross carrying value of a major finite-lived intangible asset class, less accumulated amortization and any impairment charges. A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company. Other assets Prepaid Expense and Other Assets Total assets Assets LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Liabilities: Liabilities [Abstract] Accounts payable and other accrued liabilities (including $27.7 and $32.3 at fair value at June 30, 2011 and September 30, 2010) Accounts Payable and Other Accrued Liabilities Payables to: Payables and Accruals [Abstract] Customers Payables to Customers Broker-dealers, clearing organizations and counterparties Payables to Broker-Dealers and Clearing Organizations Lenders under loans and overdrafts Long-term Line of Credit Income taxes payable Accrued Income Taxes Financial instruments sold, not yet purchased, at fair value Financial Instruments Sold, Not yet Purchased, at Fair Value Liabilities Subtotal Liabilities Subtotal Sum of the carrying amounts as of the balance sheet date of all liabilities (except for subordinated and convertible subordinated debt) that are recognized. Liabilities are probable future sacrifices of economic benefits arising from present obligations of an entity to transfer assets or provide services to other entities in the future. Subordinated debt Subordinated Debt Convertible subordinated notes payable Convertible Subordinated Debt Liabilities Liabilities Commitments and contingencies (see Notes 12 and 13) Commitments and Contingencies Equity: Equity [Abstract] INTL FCStone Inc. stockholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $.01 par value. Authorized 1,000,000 shares; no shares issued or outstanding Preferred Stock, Value, Outstanding Common stock, $.01 par value. Authorized 30,000,000 shares; 18,195,217 issued and 18,183,960 outstanding at June 30, 2011 and 17,612,792 issued and 17,601,535 outstanding at September 30, 2010 Common Stock, Value, Outstanding Common stock in treasury, at cost - 11,257 shares at June 30, 2011 and September 30, 2010 Treasury Stock, Value Additional paid-in capital Additional Paid in Capital Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total INTL FCStone Inc. stockholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and equity Liabilities and Equity Condensed Consolidated Statement of Shareholders’ Equity [Abstract] Condensed Consolidated Statement of Shareholders’ Equity [Abstract] Statement, Equity Components [Axis] Statement, Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common Stock [Member] Treasury Stock [Member] Treasury Stock [Member] Additional Paid-in Capital [Member] Additional Paid-in Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Accumulated Other Comprehensive Income (Loss) [Member] Accumulated Other Comprehensive Income (Loss) [Member] Noncontrolling Interest [Member] Noncontrolling Interest [Member] Comprehensive Income [Member] Comprehensive Income [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balances at beginning of period Components of comprehensive income Other Comprehensive Income (Loss), Net of Tax [Abstract] Net income (loss) Change in foreign currency translation Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Change in unrealized loss on derivative instruments Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Change in pension liabilities Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Change in unrealized gain or loss on available-for-sale securities Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax Total comprehensive income Other Comprehensive Income (Loss), Net of Tax Redemption of fund units Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Stock-based Compensation Share-based Compensation Debt Conversion, Converted Instrument, Amount Debt Conversion, Converted Instrument, Amount Balances at end of period Assets and Liabilities, at Fair Value [Abstract] Assets and Liabilities, at Fair Value [Abstract] Fair Value Disclosures [Text Block] Fair Value Disclosures [Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Document Information [Table] Document Information [Table] Document Information, Document [Axis] Document Information, Document [Axis] Document [Domain] Document [Domain] Document Information [Line Items] Document Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Balance Sheet Parenthetical [Abstract] Balance Sheet Parenthetical [Abstract] Assets Cash, securities - fair value Securities Segregated under Other Regulations Dep and rec -exch clear org - fair value Deposits, Fair Value Disclosure Dep and rec -b/d - fair value Receivables, Fair Value Disclosure Accounts pay and other accrued - fair value Accounts Payable, Fair Value Disclosure Preferred stock - par value Preferred Stock, Par or Stated Value Per Share Preferred stock - authorized Preferred Stock, Shares Authorized Preferred stock - issued Preferred Stock, Shares Issued Preferred stock - outstanding Preferred Stock, Shares Outstanding Common stock - par value Common Stock, Par or Stated Value Per Share Common stock - authorized Common Stock, Shares Authorized Common stock - issued Common Stock, Shares, Issued Common stock - outstanding Common Stock, Shares, Outstanding Treasury stock - shares Treasury Stock, Shares