Credit Facilities - Number of Credit Facilities (Details) $ in Millions	Dec. 31, 2019 USD ($)
Number of credit facilities	4
Main line of credit facilities [Member]
Borrowing Capacity Under Credit Facilities	$ 769.0
HCO Syndicated line of credit facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	196.5
Borrowing Capacity Under Credit Facilities	384.0
FCS Margin line of credit facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	75.0
FMS Sub-note commodity line of credit facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity	260.0
INTL FCStone Ltd [Member]
Line of Credit Facility, Maximum Borrowing Capacity	100.0
INTL FCStone Ltd [Member]
Line of Credit Facility, Maximum Borrowing Capacity	$ 50.0