Credit Facilities - Credit Facilities (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Mar. 31, 2014	Sep. 30, 2013
Line of Credit Facility [Line Items]
Line of Credit Facility, Amount Outstanding	$ 40.5	$ 61.0
Senior unsecured notes	45.5	45.5
Debt and Capital Lease Obligations	86.0	106.5
Debt Instrument, Interest Rate, Stated Percentage	8.50%
Debt Instrument, Call Feature, Redemption Price Percentage of Principal	100.00%
Debt Issuance Cost	1.7
Main line of credit facilities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	270.0
Line of Credit Facility, Current Borrowing Capacity	25
HCO Syndicated line of credit facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	140.0
Line of Credit Facility, Amount Outstanding	24.0	55.0
FCS Margin line of credit facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	75.0
Line of Credit Facility, Amount Outstanding	0	0
FMS Sub-note commodity line of credit facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	30.0
Line of Credit Facility, Amount Outstanding	16.5	6.0
INTL FCStone Ltd [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	25.0
Line of Credit Facility, Amount Outstanding	$ 0	$ 0