Commitments and Contingencies (Notes)	9 Months Ended
Jun. 30, 2015
Commitments and Contingencies [Abstract]
Commitments and Contingencies Disclosure [Text Block]	Commitments and Contingencies Legal and Regulatory Proceedings Certain conditions may exist as of the date that the financial statements are issued, which may result in a loss to the Company but which will only be resolved when one or more future events occur or fail to occur. The Company assesses such contingent liabilities, and such assessment inherently involves an exercise of judgment. In assessing loss contingencies related to legal and regulatory proceedings that are pending against the Company or unasserted claims that may result in such proceedings, the Company’s legal counsel evaluates the perceived merits of any legal proceedings or unasserted claims as well as the perceived merits of the amount of relief sought or expected to be sought therein. If the assessment of a contingency indicates that it is probable that a material loss had been incurred at the date of the financial statements and the amount of the liability can be estimated, then the estimated liability would be accrued in the Company’s financial statements. If the assessment indicates that a potentially material loss contingency is not probable, but is reasonably possible, or is probable but cannot be estimated, then the nature of the contingent liability, together with an estimate of the range of possible loss if determinable and material, would be disclosed. Neither accrual nor disclosure is required for loss contingencies that are deemed remote. The Company accrues legal fees related to contingent liabilities as they are incurred. Our assessments are based on estimates and assumptions that have been deemed reasonable by management, but that may later prove to be incomplete or inaccurate, and unanticipated events and circumstances may occur that might cause us to change those estimates and assumptions. In addition to the matters discussed below, from time to time and in the ordinary course of business, the Company is involved in various legal actions and proceedings, including tort claims, contractual disputes, employment matters, workers’ compensation claims and collections. The Company carries insurance that provides protection against certain types of claims, up to the policy limits of the insurance. As of June 30, 2015 and September 30, 2014, the condensed consolidated balance sheets include loss contingency accruals recorded prior to these periods then ended, which are not material, individually or in the aggregate, to the Company’s financial position or liquidity. In the opinion of management, possible exposure from loss contingencies in excess of the amounts accrued, and in addition to the possible losses discussed below, is not likely to be material to the Company’s earnings, financial position or liquidity. The following is a summary of significant legal matters involving the Company. Securities Litigation and Regulatory Proceedings In January 2014, a purported class action was filed in the United States District Court for the Southern District of New York against the Company and certain of its officers and directors. The complaint alleged violations of federal securities laws, and claimed that the Company issued false and misleading information concerning the Company’s business and prospects. The action sought unspecified damages on behalf of persons who purchased the Company’s shares between February 17, 2010 and December 16, 2013. The lead plaintiff’s amended complaint was filed in June 2014. The Company’s motion to dismiss the complaint was filed in July 2014. At the court hearing on February 4, 2015, the Company’s motion was granted and the amended complaint was dismissed, however the lead plaintiff was given leave to amend its complaint. The lead plaintiff’s second amended complaint was filed on March 6, 2015, and it narrowed the purported class to persons who purchased Company’s shares between December 15, 2010 and December 16, 2013. On March 27, 2015, the Company filed a motion to dismiss the second amended complaint. The lead plaintiff’s memorandum in opposition was filed on April 13, 2015 and the Company’s reply in support of its motion to dismiss the second amended complaint was filed on April 27, 2015. The matter was heard on July 9, 2015 and on July 13, 2015 the second amended complaint was dismissed in its entirety, with prejudice and without leave to replead. Sentinel Litigation The Company’s subsidiary, FCStone, LLC, had a portion of its excess segregated funds invested with Sentinel Management Group Inc. (“Sentinel”), a registered FCM and an Illinois-based money manager that provided cash management services to other FCMs. In August 2007, Sentinel halted redemptions to customers and sold certain of the assets it managed to an unaffiliated third party at a significant discount. On August 17, 2007, subsequent to Sentinel’s sale of certain assets, Sentinel filed for bankruptcy protection. In aggregate, $15.5 million of FCStone, LLC’s $21.9 million in invested funds were returned to it before and after Sentinel’s bankruptcy petition. In August 2008, the bankruptcy trustee of Sentinel filed adversary proceedings against FCStone, LLC, and a number of other FCMs in the Bankruptcy Court for the Northern District of Illinois. The case was subsequently reassigned to the United States District Court, for the Northern District of Illinois. In the complaint, the trustee sought avoidance of alleged transfers or withdrawals of funds received by FCStone, LLC and other FCMs within 90 days prior to the filing of the Sentinel bankruptcy petition, as well as avoidance of post-petition distributions and disallowance of the proof of claim filed by FCStone, LLC. The trustee sought recovery of pre- and post-petition transfers totaling approximately $15.5 million. The trial of this matter took place, as a test case, during October 2012. The trial court entered a judgment against FCStone, LLC on January 4, 2013. On January 17, 2013, the trial court entered an agreed order, staying execution and enforcement, pending an appeal of the judgment. On March 19, 2014, the appeal court ruled in favor of FCStone, LLC. In April 2014, the trustee filed a petition for rehearing of the appeal. In May 2014, the U.S. Court of Appeals for the Seventh Circuit denied the petition. The trustee did not file a writ for certiorari with the U.S. Supreme Court during the time allowed to do so. The Company continues to be involved in litigation against the trustee to recover its share of the cash held in reserve accounts under Sentinel’s Fourth Amended Chapter 11 Plan of Liquidation. On February 10, 2015, based on a new theory, the trustee filed a motion for judgment against FCStone in the United States District Court, for the Northern District of Illinois, seeking to claw back the post-petition transfer of $14.5 million and to recover the funds held in reserve in the name of FCStone. FCStone filed its opposition brief and an associated motion for judgment on March 17, 2015. The trustee filed its reply briefs on April 7, 2015 and the Company filed its reply briefs on April 22, 2015. The Company has determined that losses related to this matter are neither probable nor reasonably possible. The Company believes the case is without merit and intends to defend itself vigorously. Contractual Commitments Contingent Liabilities - Acquisitions Under the terms of the purchase agreements related to the acquisitions listed below, the Company has obligations to pay additional consideration if specific conditions and earnings targets are met. In accordance with the Business Combinations Topic of the ASC, the fair value of the additional consideration is recognized as a contingent liability as of the acquisition date. The contingent liability for these estimated additional purchase price considerations of $3.3 million and $5.5 million are included in ‘accounts payable and other accrued liabilities’ in the condensed consolidated balance sheets as of June 30, 2015 and September 30, 2014. The acquisition date fair value of additional consideration is remeasured to its fair value each reporting period, with changes in fair value recorded in current earnings. The change in fair value during the nine months ended June 30, 2015 and 2014 were increases of $0.4 million and $0.1 million, respectively, and are included in ‘other’ in the condensed consolidated income statements. The Company has a contingent liability relating to the December 2012 acquisition of the accounts of Tradewire Securities, LLC, which may result in the payment of additional purchase price consideration. The contingent liability recorded represents the fair value of the expected consideration to be paid, based on the forecasted adjusted pre-tax net earnings during three annual periods and a six month period, after the third annual period, following the closing of the acquisition, for a total of four payments, with a discount rate being applied to those future payments. The present value of the estimated total purchase price, including contingent consideration, is $3.9 million as of June 30, 2015, of which $1.8 million remains outstanding and is included in ‘accounts payable and other accrued liabilities’ in the condensed consolidated balance sheet. The Company has a contingent liability relating to the January 2015 acquisition of G.X. Clarke, which may result in the payment of additional purchase price consideration. The contingent consideration, which in no event shall exceed $1.5 million, is expected to be paid in two payments. See additional discussion of the acquisition and contingent consideration in Note 17 - Acquisitions. The estimated total purchase price, including contingent consideration, is $28.9 million as of June 30, 2015, of which $1.5 million remains outstanding and is included in ‘accounts payable and other accrued liabilities’ in the condensed consolidated balance sheet. Exchange Member Guarantees The Company is a member of various exchanges that trade and clear futures and option contracts. Associated with its memberships, the Company may be required to pay a proportionate share of the financial obligations of another member who may default on its obligations to the exchanges. While the rules governing different exchange memberships vary, in general the Company’s guarantee obligations would arise only if the exchange had previously exhausted its resources. In addition, any such guarantee obligation would be apportioned among the other non-defaulting members of the exchange. Any potential contingent liability under these membership agreements cannot be estimated. The Company has not recorded any contingent liability in the condensed consolidated financial statements for these agreements and believes that any potential requirement to make payments under these agreements is remote. Self-Insurance On January 1, 2014, the Company entered into a program to self-insure its costs related to medical and dental claims. The Company is self-insured, up to a stop loss amount, for eligible participating employees and retirees, and for qualified dependent medical and dental claims, subject to deductibles and limitations. Liabilities are recognized based on claims filed and an estimate of claims incurred but not reported. The Company has purchased stop-loss coverage to limit its exposure on a per claim basis and in aggregate in the event that aggregated actual claims would exceed 120% of actuarially estimated claims. The Company is insured for covered costs in excess of these limits. Although the ultimate outcome of these matters may exceed the amounts recorded and additional losses may be incurred, the Company does not believe that any additional potential exposure for such liabilities will have a material adverse effect on the Company’s condensed consolidated financial position or results of operations. As of June 30, 2015, the Company had $1.0 million accrued for self-insured medical and dental claims included in ‘accounts payable and other liabilities’ in the condensed consolidated balance sheet.

Commitments and Contingencies

Legal and Regulatory Proceedings

Certain conditions may exist as of the date that the financial statements are issued, which may result in a loss to the Company but which will only be resolved when one or more future events occur or fail to occur. The Company assesses such contingent liabilities, and such assessment inherently involves an exercise of judgment. In assessing loss contingencies related to legal and regulatory proceedings that are pending against the Company or unasserted claims that may result in such proceedings, the Company’s legal counsel evaluates the perceived merits of any legal proceedings or unasserted claims as well as the perceived merits of the amount of relief sought or expected to be sought therein.

If the assessment of a contingency indicates that it is probable that a material loss had been incurred at the date of the financial statements and the amount of the liability can be estimated, then the estimated liability would be accrued in the Company’s financial statements. If the assessment indicates that a potentially material loss contingency is not probable, but is reasonably possible, or is probable but cannot be estimated, then the nature of the contingent liability, together with an estimate of the range of possible loss if determinable and material, would be disclosed. Neither accrual nor disclosure is required for loss contingencies that are deemed remote. The Company accrues legal fees related to contingent liabilities as they are incurred. Our assessments are based on estimates and assumptions that have been deemed reasonable by management, but that may later prove to be incomplete or inaccurate, and unanticipated events and circumstances may occur that might cause us to change those estimates and assumptions.

In addition to the matters discussed below, from time to time and in the ordinary course of business, the Company is involved in various legal actions and proceedings, including tort claims, contractual disputes, employment matters, workers’ compensation claims and collections. The Company carries insurance that provides protection against certain types of claims, up to the policy limits of the insurance.

As of June 30, 2015 and September 30, 2014, the condensed consolidated balance sheets include loss contingency accruals recorded prior to these periods then ended, which are not material, individually or in the aggregate, to the Company’s financial position or liquidity. In the opinion of management, possible exposure from loss contingencies in excess of the amounts accrued, and in addition to the possible losses discussed below, is not likely to be material to the Company’s earnings, financial position or liquidity.

The following is a summary of significant legal matters involving the Company.

Securities Litigation and Regulatory Proceedings

In January 2014, a purported class action was filed in the United States District Court for the Southern District of New York against the Company and certain of its officers and directors. The complaint alleged violations of federal securities laws, and claimed that the Company issued false and misleading information concerning the Company’s business and prospects. The action sought unspecified damages on behalf of persons who purchased the Company’s shares between February 17, 2010 and December 16, 2013. The lead plaintiff’s amended complaint was filed in June 2014. The Company’s motion to dismiss the complaint was filed in July 2014. At the court hearing on February 4, 2015, the Company’s motion was granted and the amended complaint was dismissed, however the lead plaintiff was given leave to amend its complaint. The lead plaintiff’s second amended complaint was filed on March 6, 2015, and it narrowed the purported class to persons who purchased Company’s shares between December 15, 2010 and December 16, 2013. On March 27, 2015, the Company filed a motion to dismiss the second amended complaint. The lead plaintiff’s memorandum in opposition was filed on April 13, 2015 and the Company’s reply in support of its motion to dismiss the second amended complaint was filed on April 27, 2015. The matter was heard on July 9, 2015 and on July 13, 2015 the second amended complaint was dismissed in its entirety, with prejudice and without leave to replead.

Sentinel Litigation

The Company’s subsidiary, FCStone, LLC, had a portion of its excess segregated funds invested with Sentinel Management Group Inc. (“Sentinel”), a registered FCM and an Illinois-based money manager that provided cash management services to other FCMs. In August 2007, Sentinel halted redemptions to customers and sold certain of the assets it managed to an unaffiliated third party at a significant discount. On August 17, 2007, subsequent to Sentinel’s sale of certain assets, Sentinel filed for bankruptcy protection. In aggregate, $15.5 million of FCStone, LLC’s $21.9 million in invested funds were returned to it before and after Sentinel’s bankruptcy petition.

In August 2008, the bankruptcy trustee of Sentinel filed adversary proceedings against FCStone, LLC, and a number of other FCMs in the Bankruptcy Court for the Northern District of Illinois. The case was subsequently reassigned to the United States District Court, for the Northern District of Illinois. In the complaint, the trustee sought avoidance of alleged transfers or withdrawals of funds received by FCStone, LLC and other FCMs within 90 days prior to the filing of the Sentinel bankruptcy petition, as well as avoidance of post-petition distributions and disallowance of the proof of claim filed by FCStone, LLC. The trustee sought recovery of pre- and post-petition transfers totaling approximately $15.5 million.

The trial of this matter took place, as a test case, during October 2012. The trial court entered a judgment against FCStone, LLC on January 4, 2013. On January 17, 2013, the trial court entered an agreed order, staying execution and enforcement, pending an appeal of the judgment. On March 19, 2014, the appeal court ruled in favor of FCStone, LLC. In April 2014, the trustee filed a petition for rehearing of the appeal. In May 2014, the U.S. Court of Appeals for the Seventh Circuit denied the petition. The trustee did not file a writ for certiorari with the U.S. Supreme Court during the time allowed to do so. The Company continues to be involved in litigation against the trustee to recover its share of the cash held in reserve accounts under Sentinel’s Fourth Amended Chapter 11 Plan of Liquidation.

On February 10, 2015, based on a new theory, the trustee filed a motion for judgment against FCStone in the United States District Court, for the Northern District of Illinois, seeking to claw back the post-petition transfer of $14.5 million and to recover the funds held in reserve in the name of FCStone. FCStone filed its opposition brief and an associated motion for judgment on March 17, 2015. The trustee filed its reply briefs on April 7, 2015 and the Company filed its reply briefs on April 22, 2015. The Company has determined that losses related to this matter are neither probable nor reasonably possible. The Company believes the case is without merit and intends to defend itself vigorously.

Contractual Commitments

Contingent Liabilities - Acquisitions

Under the terms of the purchase agreements related to the acquisitions listed below, the Company has obligations to pay additional consideration if specific conditions and earnings targets are met. In accordance with the Business Combinations Topic of the ASC, the fair value of the additional consideration is recognized as a contingent liability as of the acquisition date. The contingent liability for these estimated additional purchase price considerations of $3.3 million and $5.5 million are included in ‘accounts payable and other accrued liabilities’ in the condensed consolidated balance sheets as of June 30, 2015 and September 30, 2014. The acquisition date fair value of additional consideration is remeasured to its fair value each reporting period, with changes in fair value recorded in current earnings. The change in fair value during the nine months ended June 30, 2015 and 2014 were increases of $0.4 million and $0.1 million, respectively, and are included in ‘other’ in the condensed consolidated income statements.

The Company has a contingent liability relating to the December 2012 acquisition of the accounts of Tradewire Securities, LLC, which may result in the payment of additional purchase price consideration. The contingent liability recorded represents the fair value of the expected consideration to be paid, based on the forecasted adjusted pre-tax net earnings during three annual periods and a six month period, after the third annual period, following the closing of the acquisition, for a total of four payments, with a discount rate being applied to those future payments. The present value of the estimated total purchase price, including contingent consideration, is $3.9 million as of June 30, 2015, of which $1.8 million remains outstanding and is included in ‘accounts payable and other accrued liabilities’ in the condensed consolidated balance sheet.

The Company has a contingent liability relating to the January 2015 acquisition of G.X. Clarke, which may result in the payment of additional purchase price consideration. The contingent consideration, which in no event shall exceed $1.5 million, is expected to be paid in two payments. See additional discussion of the acquisition and contingent consideration in Note 17 - Acquisitions. The estimated total purchase price, including contingent consideration, is $28.9 million as of June 30, 2015, of which $1.5 million remains outstanding and is included in ‘accounts payable and other accrued liabilities’ in the condensed consolidated balance sheet.

Exchange Member Guarantees

The Company is a member of various exchanges that trade and clear futures and option contracts. Associated with its memberships, the Company may be required to pay a proportionate share of the financial obligations of another member who may default on its obligations to the exchanges. While the rules governing different exchange memberships vary, in general the Company’s guarantee obligations would arise only if the exchange had previously exhausted its resources. In addition, any such guarantee obligation would be apportioned among the other non-defaulting members of the exchange. Any potential contingent liability under these membership agreements cannot be estimated. The Company has not recorded any contingent liability in the condensed consolidated financial statements for these agreements and believes that any potential requirement to make payments under these agreements is remote.

Self-Insurance

On January 1, 2014, the Company entered into a program to self-insure its costs related to medical and dental claims. The Company is self-insured, up to a stop loss amount, for eligible participating employees and retirees, and for qualified dependent medical and dental claims, subject to deductibles and limitations. Liabilities are recognized based on claims filed and an estimate of claims incurred but not reported. The Company has purchased stop-loss coverage to limit its exposure on a per claim basis and in aggregate in the event that aggregated actual claims would exceed 120% of actuarially estimated claims. The Company is insured for covered costs in excess of these limits. Although the ultimate outcome of these matters may exceed the amounts recorded and additional losses may be incurred, the Company does not believe that any additional potential exposure for such liabilities will have a material adverse effect on the Company’s condensed consolidated financial position or results of operations. As of June 30, 2015, the Company had $1.0 million accrued for self-insured medical and dental claims included in ‘accounts payable and other liabilities’ in the condensed consolidated balance sheet.