XML 26 R14.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Goodwill (Notes) | 6 Months Ended
--- | ---
Mar. 31, 2017
Goodwill [Abstract] |
Goodwill Disclosure [Text Block] | Goodwill The carrying value of goodwill is allocated to the Company’s operating segments as follows:
(in millions) | March 31, 2017 |  | September 30, 2016
Commercial Hedging | $ | 30.7 |  |  | $ | 30.7 |
Global Payments | 6.3 |  |  | 6.3 |
Physical Commodities | 2.4 |  |  | 2.4 |
Securities | 8.1 |  |  | 8.1 |
Goodwill | $ | 47.5 |  |  | $ | 47.5 |

X
- Definition Goodwill [Abstract] + References No definition available. + Details
Name: | intl_GoodwillAbstract
Namespace Prefix: | intl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for goodwill. + References No definition available. + Details
Name: | us-gaap_GoodwillDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration