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Commitments and Contingencies - Contingencies and Litigation (Details) $ in Millions | Sep. 30, 2019 USD ($)
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Commitments and Contingencies [Abstract] |
Loss Contingency, Range of Possible Loss, Portion Not Accrued | $ 29.2

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- Definition Commitments and Contingencies [Abstract] + References No definition available. + Details
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Namespace Prefix: | intl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition The difference between the maximum amount of estimated loss and the amount recorded as of the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 05 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=99385795&loc=d3e12631-108344 + Details
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Balance Type: | debit
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