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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 | 9 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Document Period End Date |  |  | Jun. 30, 2020 |
Bad debts | $ 1.8 | $ 0.5 | $ 6.2 | $ 1.5
Payments for Legal Settlements |  |  |  | 8.4
Recovery of bad debt on physical coal | 0.0 | $ 0.0 | 0.0 | $ 2.4
Commodity and Risk Management [Member] |  |  |  |
Bad debts | 1.1 |  | 3.3 |
Accounts Receivable, Allowance for Credit Loss, Recovery | 0.6 |  |  |
Clearing and Execution Services Segment |  |  |  |
Bad debts | $ 2.4 |  | 2.7 |
Physical Commodities |  |  |  |
Bad debts |  |  | $ 0.2 |

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- Definition The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD. + References No definition available. + Details
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- Definition Amount of increase in allowance for credit loss on accounts receivable, from recovery. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 20 -Section 50 -Paragraph 13 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919249-210447 + Details
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