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Physical Commodities Inventory - LCM Adjustments (Details) - USD ($) $ in Millions | Mar. 31, 2019 | Sep. 30, 2018 | Sep. 30, 2016
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Physical Commodities Inventory [Abstract] |  |  |
Inventory Adjustments | $ 0.1 | $ 0.4 | $ 0.6

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- Definition Physical Commodities Inventory [Abstract] + References No definition available. + Details
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- Definition Amount of inventory reserves for last-in first-out (LIFO) and other inventory valuation methods. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66092785&loc=d3e4492-108314 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.6(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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