Maximum Borrowing Capacity Under Credit Facilities

No definition available.

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

- Definition

Number of credit facilities available to the company.

+ References

No definition available.

+ Details

Name:	intl_NumberOfCreditFacilities
Namespace Prefix:	intl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationPeriod
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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Including the current and noncurrent portions, the carrying value as of the balance sheet date of notes payable to banks, excluding mortgage notes, initially due beyond one year or beyond the operating cycle if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_CreditFacilityAxis=intl_StoneXIncBankOfAmericaSyndicatedCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=intl_FCSMarginLineOfCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=intl_FMSSubNoteCommodityLineOfCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=intl_StoneXLtdMember
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Credit Facilities - Number of Credit Facilities (Details)	6 Months Ended
	Mar. 31, 2023 USD ($) facility	Dec. 30, 2022 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2020 USD ($)
Line of Credit Facility [Line Items]
Number of credit facilities \| facility	4
Maximum borrowing capacity under credit facilities	$ 1,130,000,000
Notes payable to bank	$ 7,800,000		$ 8,100,000	$ 9,000,000
Debt, weighted average interest rate				2.35%
Senior StoneX Group Inc. Committed Credit Facility - Revolving Line of Credit
Line of Credit Facility [Line Items]
Term of syndicated loan facility	3 years
Line of credit facility borrowing	$ 475,000,000.0
Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility borrowing	475,000,000
StoneX Financial Inc.
Line of Credit Facility [Line Items]
Line of credit facility borrowing	180,000,000.0	$ 75,000,000
StoneX Commodity Solutions LLC
Line of Credit Facility [Line Items]
Line of credit facility borrowing	400,000,000
StoneX Financial Ltd.
Line of Credit Facility [Line Items]
Line of credit facility borrowing	$ 75,000,000.0