XML 93 R71.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Receivables from customers, net and notes receivable, net - Allowance for Notes Receivable (Details) - USD ($) $ in Millions | Sep. 30, 2017 | Sep. 30, 2016
--- | --- | ---
Receivables from customers and notes receivable, net [Abstract] |  |
Allowance Notes Receivable | $ 0.0 | $ 0.2

X
- Definition A valuation allowance relating to a written agreement to receive money (at a specified future date(s), consisting of principal as well as any accrued interest) for the portion that is expected to be uncollectible. + References No definition available. + Details
Name: | intl_AllowanceNotesReceivable
Namespace Prefix: | intl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Receivables from customers and notes receivable, net [Abstract] + References No definition available. + Details
Name: | intl_ReceivablesFromCustomersAndNotesReceivableNetAbstract
Namespace Prefix: | intl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration