Commodity and Other Repurchase Agreements Commodity and Other Repurchase Agreements (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014
Commodity and Other Repurchase Agreements [Abstract]
Financing Receivables, net - Sales/Repurchase Agreements	$ 31.0intl_SalesRepurchaseAgreements	$ 20.6intl_SalesRepurchaseAgreements
Obligations outstanding related to commodities sold under repurchase agreements	$ 18.1	$ 7.5

Amount to be repaid to the counterparty to the repurchase agreement when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under the repurchase agreement exceeds 10 percent of total assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph m

-Subparagraph 1

-Article 4

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(m)(1)(i)(A)(ii))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Name:	us-gaap_AssetsSoldUnderAgreementsToRepurchaseRepurchaseLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant