Regulatory Capital Requirements (Details) $ in Millions	Mar. 31, 2024 USD ($)
Capital and Other Regulatory Requirements [Abstract]
Adjusted net capital	$ 10.0
StoneX Financial Inc.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	351.2
Minimum Requirement	257.2
StoneX Financial Ltd.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	455.5
Minimum Requirement	358.0
Gain Capital Group, LLC
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	50.6
Minimum Requirement	29.9
StoneX Financial Pte. Ltd.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	91.3
Minimum Requirement	25.8
StoneX Markets LLC
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Actual	219.2
Minimum Requirement	$ 125.9

Capital and Other Regulatory Requirements [Abstract]

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- Definition

Minimum amount of net capital required to be maintained by broker-dealer subsidiary to engage in security transaction, calculated under Aggregate Indebtedness Standard.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Rule 15c3-1
-Number 240
-Section 15c3-1
-Publisher SEC

+ Details

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- Definition

Amount of adjusted net capital of futures commission merchant (FCM) per Commodity Futures Trading Commission's (CFTC) requirement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Rule 17
-Number 1
-Section 17
-Paragraph (c)
-Subparagraph (5)
-Publisher CFTC

+ Details

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Amount of net capital required to be maintained by futures commission merchant (FCM) per Commodity Futures Trading Commission's (CFTC) requirement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Rule 17
-Number 1
-Section 17
-Paragraph (a)
-Subparagraph (1)(i)
-Publisher CFTC

+ Details

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- 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/2009/role/commonPracticeRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1

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