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Stock-based Compensation Plans (Schedule of Share-based Compensation, Effect on Statement of Operations) (Details) - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended
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Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2020
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] |  |  |
Decrease in operating income | $ 9.9 | $ 11.0 | $ 7.2
Effect on net income or loss | $ (7.6) | $ (8.2) | $ (5.5)
Effect on earnings or loss per basic share | $ (0.05) | $ (0.05) | $ (0.03)
Effect on earnings or loss per diluted share | $ (0.05) | $ (0.05) | $ (0.03)

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- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901 + Details
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- Definition Amount, after tax, of expense for award under share-based payment arrangement. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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