XML 143 R122.htm IDEA: XBRL DOCUMENT v3.25.3

Regulatory Requirements and Subsidiary Dividend Restrictions - Customer Reserve Requirements - Narrative (Details) - USD ($) $ in Millions	Oct. 02, 2025	Sep. 30, 2025
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		$ 149.0
Customer SRBA
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		147.5
Customer SRBA | Subsequent Event
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit made	$ 17.2
PAB
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		8.9
PAB Reserve Requirement
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		8.9
PAB SRBA
Capital and Other Regulatory Requirements [Line Items]
Cash reserve deposit required		$ 14.5
PAB SRBA | Subsequent Event
Capital and Other Regulatory Requirements [Line Items]
Cash reserve withdrawal	$ 0.6

X

- Definition

Capital and Other Regulatory Requirements [Line Items]

+ References

No definition available.

+ Details

Name:	intl_CapitalAndOtherRegulatoryRequirementsLineItems
Namespace Prefix:	intl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

cashreservedepositrequired

+ References

No definition available.

+ Details

Name:	intl_CashReserveDepositRequired
Namespace Prefix:	intl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Cash Reserve Withdrawal

+ References

No definition available.

+ Details

Name:	intl_CashReserveWithdrawal
Namespace Prefix:	intl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Cash deposited in a special reserve account for the exclusive benefit of customers pursuant to SEC Regulations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-SubTopic 210
-Topic 942
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478482/942-210-50-1

+ Details

Name:	us-gaap_CashReserveDepositRequiredAndMade
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	intl_ReserveRequirementAxis=intl_CustomerSRBAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	intl_ReserveRequirementAxis=intl_PABMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	intl_ReserveRequirementAxis=intl_PABReserveRequirementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	intl_ReserveRequirementAxis=intl_PABSRBAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: