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v3.10.0.1

Receivables from customers, net and notes receivable, net - Bad Debt Expense and Recoveries (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Provision for Doubtful Accounts |  | $ 3.1 | $ 4.3 | $ 4.4
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease) |  | 2.9 | 4.2 | 4.2
Provision for Other Losses |  | 0.3 | 0.1 |
Bad debt on physical coal | $ 1.0 | 1.0 | 47.0 | 0.0
Allowance for Doubtful Accounts Receivable, Charge-offs |  | 0.3 | 6.1 | 5.7
Allowance for Doubtful Accounts Receivable, Recoveries |  | 0.1 |  | 0.2
Commercial Hedging [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease) |  | 2.8 | 3.8 | 3.6
Allowance for Doubtful Accounts Receivable, Charge-offs |  |  |  | 0.4
Physical Commodities Segment [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease) |  |  | 0.2 | 0.4
Clearing and Execution Services Segment [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease) |  | $ 0.4 | $ 0.3 |
Securities Segment [Member] |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease) |  |  |  | $ 0.4

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- Definition Amount of direct write-downs of accounts receivable charged against the allowance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 954 -SubTopic 310 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=68075217&loc=SL9156395-115594 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.4) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.11) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 3: 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=98514028&loc=d3e3602-108585 + Details
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