XML 78 R66.htm IDEA: XBRL DOCUMENT
v3.19.1

Intangible Assets Intangible Assets Acquired (Details) $ in Millions | 6 Months Ended
--- | ---
Mar. 31, 2019 USD ($)
Intangible Assets Acquired [Abstract] |
Indefinite-lived Intangible Assets Acquired | $ 2.7

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

X
- Definition Amount of increase in assets, excluding financial assets and goodwill, lacking physical substance with an indefinite life, from an acquisition. + References No definition available. + Details
Name: | us-gaap_IndefinitelivedIntangibleAssetsAcquired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration