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Income Taxes (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended
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Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019
Effective Income Tax Rate Reconciliation, Federal Transition Tax, Amount | $ 0.0 | $ 0.0 | $ (0.6)
Unrecognized Tax Benefits, Interest on Income Taxes Accrued | 0.6 | 0.4 |
Income tax expense (benefit) | 24.5 | 22.1 | 18.3
Deferred Tax Assets, Tax Credit Carryforwards, Foreign |  | 4.5 |
Unrecognized Tax Benefits | 4.8 | 4.5 | $ 3.3
transition tax liability | $ 4.7 | $ 5.2 |

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- Definition transition tax liability + References No definition available. + Details
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign tax credit carryforwards. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32632-109319 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32621-109319 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32559-109319 + Details
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- Definition Amount of interest expense accrued for an underpayment of income taxes. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32718-109319 + Details
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