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Receivables From Customers, Net and Notes Receivable, Net Receivables from Customers, Net and Notes Receivables, Net - Bad Debt Expense and Recoveries (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Mar. 31, 2017 | Mar. 31, 2016 | Mar. 31, 2017
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease) |  | $ 1.3 |
Provision for Doubtful Accounts |  | 2.6 |
Commercial Hedging [Member] |  |  |
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease) |  | 1.1 | $ 2.7
Provision for Doubtful Accounts | $ 1.3 |  | 3.8
Securities [Member] |  |  |
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease) |  | $ 0.2 | $ 0.3

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- Definition Amount of expense related to write-down of receivables to the amount expected to be collected. Includes, but is not limited to, accounts receivable and notes receivable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.5) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 + Details
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