Regulatory Requirements and Subsidiary Dividend Restrictions (Tables)

12 Months Ended

Sep. 30, 2016

Capital and Other Regulatory Requirements [Abstract]

Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block]

All subsidiaries of the Company are in compliance with all of their regulatory requirements as of September 30, 2017, as follows:

(in millions)			As of September 30, 2017
Subsidiary	Regulatory Authority	Requirement Type	Actual		Minimum Requirement
INTL FCStone Financial Inc.	SEC and CFTC	Net capital	$	157.1	$	74.0
INTL FCStone Financial Inc.	CFTC	Segregated funds	$	2,248.0	$	2,195.7
INTL FCStone Financial Inc.	CFTC	Secured funds	$	165.1	$	148.7
INTL FCStone Financial Inc.	SEC	Customer reserve	$	7.2	$	—
INTL FCStone Financial Inc.	SEC	PAB reserve	$	13.5	$	0.2
INTL Custody & Clearing Solutions Inc.	SEC	Net capital	$	1.5	$	0.1
SA Stone Wealth Management Inc.	SEC	Net capital	$	4.9	$	0.3
INTL FCStone Ltd	FCA (United Kingdom)	Net capital	$	158.7	$	88.3
INTL FCStone Ltd	FCA (United Kingdom)	Segregated funds	$	107.1	$	106.6
INTL Netherlands BV	FCA (United Kingdom)	Net capital	$	158.0	$	88.3
INTL FCStone DTVM Ltda.	Brazilian Central Bank and Securities and Exchange Commission of Brazil	Capital adequacy	$	13.0	$	0.5
INTL Gainvest S.A.	National Securities Commission ("CNV")	Capital adequacy	$	5.1	$	0.2
INTL Gainvest S.A.	CNV	Net capital	$	0.4	$	0.1
INTL CIBSA S.A.	CNV	Capital adequacy	$	7.6	$	0.9
INTL CIBSA S.A.	CNV	Net capital	$	1.4	$	0.5

Schedule of Regulatory Assets [Table Text Block]

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