Credit Facilities - Credit Facilities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2012 Rate	Sep. 30, 2011
Line of Credit Facility [Line Items]
Line of Credit Facility, Amount Outstanding	$ 218.2	$ 77.4
Main line of credit facilities [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	385.0
INTL COM line of credit facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate at Period End	0.21%
Line of Credit Facility, Maximum Borrowing Capacity	140.0
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.75%
Line of Credit Facility, Amount Outstanding	107.0	60.0
HCO Syndicated line of credit facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate at Period End	3.22%
Line of Credit Facility, Maximum Borrowing Capacity	95.0
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.625%
Line of Credit Facility, Amount Outstanding	48.0	0
FCS Margin line of credit facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate at Period End	5.25%
Line of Credit Facility, Maximum Borrowing Capacity	75.0
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.50%
Line of Credit Facility, Amount Outstanding	20.0	0
FMS Sub-note commodity line of credit facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate at Period End	2.39%
Line of Credit Facility, Maximum Borrowing Capacity	75.0
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.50%
Line of Credit Facility, Amount Outstanding	43.2	0
FCF Sub-note commodity line of credit facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	0
Line of Credit Facility, Amount Outstanding	0	15.5
FMS line of credit for uncommited forward contracts [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	0
Line of Credit Facility, Amount Outstanding	$ 0	$ 1.9