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Litigation, Claims and Contingencies - Summary of Components of Environmental Remediation Expense Included within Selling, General and Administrative Expense (Parenthetical) (Details) - USD ($) $ in Millions | 12 Months Ended
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Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2017
Environmental Expense And Liabilities [Abstract] |  |  |
Net expense relates to divested businesses | $ 7 | $ 5 | $ 3

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- Definition Net expense related to divested businesses. + References No definition available. + Details
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- References No definition available. + Details
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