XML 146 R125.htm IDEA: XBRL DOCUMENT
v3.25.3

Segment and Geographic Information - Narrative (Details) market in Thousands | 12 Months Ended
--- | ---
Sep. 30, 2025 employee market currency country
Segment Reporting Information [Line Items] |
Number of employees (more than) | employee | 5,400
Number of countries in which entity operates (more than) | 180
Self-Directed/Retail |
Segment Reporting Information [Line Items] |
Number of countries in which entity operates (more than) | 180
Number of global financial markets (more than) | market | 18
Payments |
Segment Reporting Information [Line Items] |
Number of countries in which entity operates (more than) | 180
Number of different types of foreign currencies (more than) | currency | 140

X
- Definition Number of persons employed by the Entity + References No definition available. + Details
Name: | dei_EntityNumberOfEmployees
Namespace Prefix: | dei_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of different types of foreign currencies the company trades + References No definition available. + Details
Name: | intl_NumberOfDifferentTypesOfForeignCurrencies
Namespace Prefix: | intl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number Of Global Financial Markets + References No definition available. + Details
Name: | intl_NumberOfGlobalFinancialMarkets
Namespace Prefix: | intl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of countries in which the entity operates as of balance sheet date. + References No definition available. + Details
Name: | us-gaap_NumberOfCountriesInWhichEntityOperates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=intl_SelfDirectedRetailSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=intl_PaymentsSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |