XML 134 R113.htm IDEA: XBRL DOCUMENT
v3.25.3

Acquisitions - R.J. O’Brien - Schedule of Unaudited Pro Forma Financial Information (Details) - RJO - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2025 | Sep. 30, 2024
Business Combination, Pro Forma Information [Line Items] |  |
Total revenues | $ 133,102.0 | $ 100,784.7
Operating revenues | 4,850.7 | 4,333.1
Net income | $ 329.2 | $ 345.6
Basic earnings per share (in dollars per share) | $ 6.37 | $ 6.84
Diluted earnings per share (in dollars per share) | $ 6.05 | $ 6.62

X
- Definition Business Combination, Pro Forma Information, Operating Revenues + References No definition available. + Details
Name: | intl_BusinessCombinationProFormaInformationOperatingRevenues
Namespace Prefix: | intl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Per basic share amount, after tax, of pro forma income (loss) of combined entity as if acquisition date of business combination occurred as of beginning of period. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-3 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(2) -SubTopic 10 -Topic 805 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(3) -SubTopic 10 -Topic 805 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 + Details
Name: | us-gaap_BusinessAcquisitionProFormaEarningsPerShareBasic
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Per diluted share amount, after tax, of pro forma income (loss) of combined entity as if acquisition date of business combination occurred as of beginning of period. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-3 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(2) -SubTopic 10 -Topic 805 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(3) -SubTopic 10 -Topic 805 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 + Details
Name: | us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

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 Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-8 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 50 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479303/805-10-55-50 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-3 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(4) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 + Details
Name: | us-gaap_BusinessAcquisitionProFormaInformationNonrecurringAdjustmentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after tax, of pro forma income (loss) of combined entity as if acquisition date of business combination occurred as of beginning of period. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-8 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 49 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479303/805-10-55-49 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 50 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479303/805-10-55-50 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-3 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of pro forma revenue of combined entity as if acquisition date of business combination occurred as of beginning of period. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-8 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 49 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479303/805-10-55-49 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-2 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 805 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479328/805-10-50-3 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=intl_R.J.OBrienMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |