Acquisitions	6 Months Ended
Mar. 31, 2012
Acquisitions [Abstract]
Business Combination Disclosure [Text Block]	Acquisitions Coffee Network In November 2011, the Company entered into an agreement to acquire 100% of the ownership interests in Coffee Network LLC ("Coffee Network"), an online news and analysis portal for the global coffee industry. Coffee Network provides up-to-the-minute news and in-depth analysis to subscribers around the globe from a network of correspondents and commodity analysts located in key coffee producing and consuming regions. These services provide a unique information solution to subscribers and a competitive advantage in today's information-driven marketplace. The purchase price for the Coffee Network acquisition consists of an initial payment of $0.2 million, three additional annual contingent payments and a final contingent payment. The value of certain assets and liabilities are preliminary in nature, and are subject to adjustment as additional information is obtained, including but not limited to the calculation of the contingent consideration and valuation of separately identifiable intangible assets. These areas are subject to change within the measurement period (up to one year from the acquisition date) as valuations are finalized. When the valuations are finalized, any changes to the preliminary valuation of assets acquired or liabilities assumed may result in adjustments to separately identifiable intangible assets and goodwill. The purchase provisional amounts recorded and the total purchase price for the acquisition of Coffee Network are not material. MF Metals Team On November 25, 2011, INTL FCStone (Europe) Ltd, the Company's wholly owned subsidiary in the United Kingdom, arranged with the administrator of MF Global's UK operations to acquire the Metals Division of MF Global UK Limited (in special administration). As part of the arrangement, the Company received an assignment of customer accounts and customer account documentation. Additionally, as part of the transaction, the Company hired more than 50 professional staff from MF Global's metals trading business based in London. The Company anticipates that a number of the customers of this metals trading operation will elect to become active trading customers of the Company. The Company expects to allocate equity capital to integrate these brokers and their customers into the Company's operations, through a combination of increased regulatory capital to support the accounts of these customers and increased compensation and related personnel costs for the brokers. The amount of the required capital will primarily depend upon the activity in and balances of the new accounts. The allocation of the purchase price to separately identifiable intangible assets is preliminary in nature, and is subject to adjustment as additional information is obtained. The provisional intangible asset amounts recorded and the total purchase price of this transaction are not material. TRX Futures Limited In December 2011, the Company's wholly-owned subsidiary in the United Kingdom ("UK"), INTL Holding (UK) Limited, entered into a memorandum of understanding with Neumann Gruppe GmbH to acquire its subsidiary TRX Futures Limited ("TRX"). TRX is a London-based niche clearing firm for commercial coffee and cocoa customers, as well as energy and financial products. The acquisition is contingent upon the approval by the UK Financial Services Authority of the proposed change of control of TRX, which was granted in April 2012. The transaction closed on April 30, 2012. The purchase price was equal to the tangible net asset value ("NAV") of TRX, which was approximately $12.9 million. The acquisition is not expected to have any immediate impact on the Company's earnings, and this transaction is not considered to be material. Aporte DTVM In February 2012, the Company's subsidiaries, INTL Participacoes LTDA and FCStone do Brasil, acquired 100% of the shares of Aporte DTVM (“DTVM”). DTVM is based in Brazil and its activities consist of stock trading, IPOs, trustee services, structured financial services, management of portfolios, as well as financial consulting. The purchase price for the acquisition of 100% of the shares of DTVM was approximately $1.5 million (or 2.5 million (BRL)). There are no additional payments remaining for this acquisition. The value of certain assets and liabilities are preliminary in nature, and are subject to adjustment as additional information is obtained, including but not limited to the valuation of separately identifiable intangible assets, if applicable. These areas are subject to change within the measurement period (up to one year from the acquisition date) as valuations are finalized. When the valuations are finalized, any changes to the preliminary valuation of assets acquired or liabilities assumed may result in adjustments to separately identifiable intangible assets and goodwill. The provisional asset and liability amounts recorded and the total purchase price for the acquisition of DTVM are not material.

Acquisitions

6 Months Ended

Mar. 31, 2012

Business Combination Disclosure [Text Block]

Acquisitions

Coffee Network

In November 2011, the Company entered into an agreement to acquire 100% of the ownership interests in Coffee Network LLC ("Coffee Network"), an online news and analysis portal for the global coffee industry. Coffee Network provides up-to-the-minute news and in-depth analysis to subscribers around the globe from a network of correspondents and commodity analysts located in key coffee producing and consuming regions. These services provide a unique information solution to subscribers and a competitive advantage in today's information-driven marketplace.

The purchase price for the Coffee Network acquisition consists of an initial payment of $0.2 million, three additional annual contingent payments and a final contingent payment. The value of certain assets and liabilities are preliminary in nature, and are subject to adjustment as additional information is obtained, including but not limited to the calculation of the contingent consideration and valuation of separately identifiable intangible assets. These areas are subject to change within the measurement period (up to one year from the acquisition date) as valuations are finalized. When the valuations are finalized, any changes to the preliminary valuation of assets acquired or liabilities assumed may result in adjustments to separately identifiable intangible assets and goodwill. The purchase provisional amounts recorded and the total purchase price for the acquisition of Coffee Network are not material.

MF Metals Team

On November 25, 2011, INTL FCStone (Europe) Ltd, the Company's wholly owned subsidiary in the United Kingdom, arranged with the administrator of MF Global's UK operations to acquire the Metals Division of MF Global UK Limited (in special administration). As part of the arrangement, the Company received an assignment of customer accounts and customer account documentation. Additionally, as part of the transaction, the Company hired more than 50 professional staff from MF Global's metals trading business based in London. The Company anticipates that a number of the customers of this metals trading operation will elect to become active trading customers of the Company. The Company expects to allocate equity capital to integrate these brokers and their customers into the Company's operations, through a combination of increased regulatory capital to support the accounts of these customers and increased compensation and related personnel costs for the brokers. The amount of the required capital will primarily depend upon the activity in and balances of the new accounts.

The allocation of the purchase price to separately identifiable intangible assets is preliminary in nature, and is subject to adjustment as additional information is obtained. The provisional intangible asset amounts recorded and the total purchase price of this transaction are not material.

TRX Futures Limited

In December 2011, the Company's wholly-owned subsidiary in the United Kingdom ("UK"), INTL Holding (UK) Limited, entered into a memorandum of understanding with Neumann Gruppe GmbH to acquire its subsidiary TRX Futures Limited ("TRX"). TRX is a London-based niche clearing firm for commercial coffee and cocoa customers, as well as energy and financial products. The acquisition is contingent upon the approval by the UK Financial Services Authority of the proposed change of control of TRX, which was granted in April 2012. The transaction closed on April 30, 2012. The purchase price was equal to the tangible net asset value ("NAV") of TRX, which was approximately $12.9 million. The acquisition is not expected to have any immediate impact on the Company's earnings, and this transaction is not considered to be material.

Aporte DTVM

In February 2012, the Company's subsidiaries, INTL Participacoes LTDA and FCStone do Brasil, acquired 100% of the shares of Aporte DTVM (“DTVM”). DTVM is based in Brazil and its activities consist of stock trading, IPOs, trustee services, structured financial services, management of portfolios, as well as financial consulting.

The purchase price for the acquisition of 100% of the shares of DTVM was approximately $1.5 million (or 2.5 million (BRL)). There are no additional payments remaining for this acquisition. The value of certain assets and liabilities are preliminary in nature, and are subject to adjustment as additional information is obtained, including but not limited to the valuation of separately identifiable intangible assets, if applicable. These areas are subject to change within the measurement period (up to one year from the acquisition date) as valuations are finalized. When the valuations are finalized, any changes to the preliminary valuation of assets acquired or liabilities assumed may result in adjustments to separately identifiable intangible assets and goodwill. The provisional asset and liability amounts recorded and the total purchase price for the acquisition of DTVM are not material.