Income Taxes	6 Months Ended
Mar. 31, 2012
Income Taxes [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes In determining the quarterly provision for income taxes, management uses an estimated annual effective tax rate which is based on the expected annual income and statutory tax rates in the various jurisdictions in which it operates. The Company’s effective tax rate differs from the U.S. statutory rate primarily due to state and local taxes, 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 tax benefit can be recognized are excluded from the estimated annual effective income tax rate. The Company is required to assess its deferred tax assets and the need for a valuation allowance at each reporting period. This assessment requires judgment on the part of management with respect to benefits that may be realized. The Company will record a valuation allowance against deferred tax assets when it is considered more likely than not that all or a portion of our deferred tax assets will not be realized. The income tax expense from continuing operations of $1.2 million and $8.0 million for the three months ended March 31, 2012 and 2011, respectively, and income tax expense from continuing operations of $1.0 million and $10.1 million for the six months ended March 31, 2012 and 2011, respectively, reflect estimated federal, foreign and state taxes. For the three months ended March 31, 2012, the Company’s effective tax rate was 33%, compared to 34% for the three months ended March 31, 2011. For the six months ended March 31, 2012, the Company's effective tax rate was 34%, compared to 35% for the six months ended March 31, 2011. The Company and its subsidiaries file income tax returns with the U.S. federal jurisdiction and various state and foreign jurisdictions. In January 2012, the Internal Revenue Service concluded its examination of the U.S. income tax return of FCStone for its fiscal year ended August 31, 2009, which was prior to acquisition, and there were no adjustments. FCStone is a wholly-owned subsidiary acquired on September 30, 2009. Both INTL FCStone Inc. and FCStone are under separate state examinations for various periods, ranging from August 31, 2006 through September 30, 2009.

Income Taxes

6 Months Ended

Mar. 31, 2012

Income Taxes

In determining the quarterly provision for income taxes, management uses an estimated annual effective tax rate which is based on the expected annual income and statutory tax rates in the various jurisdictions in which it operates. The Company’s effective tax rate differs from the U.S. statutory rate primarily due to state and local taxes, 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 tax benefit can be recognized are excluded from the estimated annual effective income tax rate.

The Company is required to assess its deferred tax assets and the need for a valuation allowance at each reporting period. This assessment requires judgment on the part of management with respect to benefits that may be realized. The Company will record a valuation allowance against deferred tax assets when it is considered more likely than not that all or a portion of our deferred tax assets will not be realized.

The income tax expense from continuing operations of $1.2 million and $8.0 million for the three months ended March 31, 2012 and 2011, respectively, and income tax expense from continuing operations of $1.0 million and $10.1 million for the six months ended March 31, 2012 and 2011, respectively, reflect estimated federal, foreign and state taxes. For the three months ended March 31, 2012, the Company’s effective tax rate was 33%, compared to 34% for the three months ended March 31, 2011. For the six months ended March 31, 2012, the Company's effective tax rate was 34%, compared to 35% for the six months ended March 31, 2011.

The Company and its subsidiaries file income tax returns with the U.S. federal jurisdiction and various state and foreign jurisdictions. In January 2012, the Internal Revenue Service concluded its examination of the U.S. income tax return of FCStone for its fiscal year ended August 31, 2009, which was prior to acquisition, and there were no adjustments. FCStone is a wholly-owned subsidiary acquired on September 30, 2009. Both INTL FCStone Inc. and FCStone are under separate state examinations for various periods, ranging from August 31, 2006 through September 30, 2009.