XML 97 R77.htm IDEA: XBRL DOCUMENT
v3.20.4

Intangible Assets - Intangible Assets Acquired During the Period (Details) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2020 USD ($)
UOB Bullion and Futures Limited [Member] | Customer Base [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Finite-lived intangible assets acquired | $ 3.1
IFCM Commodities Acquisition [Member] | Customer Base [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Finite-lived intangible assets acquired | 1.0
Quest Capital Strategies Inc [Member] | Customer Base [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Finite-lived intangible assets acquired | 1.7
Gain Capital Holdings Inc [Member] | Customer Base [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Finite-lived intangible assets acquired | 9.8
Gain Capital Holdings Inc [Member] | Software Programs/Platforms [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Finite-lived intangible assets acquired | 22.2
Gain Capital Holdings Inc [Member] | Trade/Domain Names [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Finite-lived intangible assets acquired | 3.7
GIROXX [Member] | Software Programs/Platforms [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Finite-lived intangible assets acquired | 1.5
GIROXX [Member] | Business Licenses [Member] |
Acquired Finite-Lived Intangible Assets [Line Items] |
Finite-lived intangible assets acquired | $ 0.4

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_AcquiredFiniteLivedIntangibleAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of increase in assets, excluding financial assets, lacking physical substance with a definite life, from an acquisition. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275 + Details
Name: | us-gaap_FinitelivedIntangibleAssetsAcquired1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=intl_UOBBullionAndFuturesLimitedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=intl_IFCMCommoditiesAcquisitionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=intl_QuestCapitalStrategiesIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=intl_GainCapitalHoldingsIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_ComputerSoftwareIntangibleAssetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_TradeNamesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=intl_GIROXXAcquisitionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_LicensingAgreementsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |