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Income Taxes - Additional Information (Details) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2022
Income Tax Disclosure [Line Items] |  |  |  |
Tax cuts and jobs act, other tax effect, description | In 2019, acknowledging that taxpayers may require multiple tax accounting method changes associated with the implementation of the Tax Cuts and Jobs Act of 2017 (Tax Reform Act), the IRS waived the five-year “eligibility rule” for certain tax accounting method changes for the first three years ending on or after November 20, 2018. Citing a need to help companies impacted by the COVID-19 pandemic, the Coronavirus Aid, Relief, and Economic Security Act (CARES Act) allows a taxpayer to carryback net operating losses generated in years beginning after December 31, 2017 and before January 1, 2021 for five years. |  |  |
Discrete tax benefit related to tax plan | $ 75.3 |  |  |
Liability for unrecognized tax benefits uncertainty of tax position | 13.6 |  |  |
Liability for unrecognized tax benefits uncertainty of tax position, provision for income taxes | 3.7 |  |  |
Income tax expense (benefits), tax credit, discrete items | (96.0) | $ 8.0 | $ 1.9 |
Deferred tax assets, valuation allowance | 6.2 | 17.4 |  |
Undistributed earnings in non-U.S. subsidiaries | 380.4 |  |  |
Foreign and domestic income taxes and withholding taxes | 22.4 |  |  |
Potential tax liability | 18.4 |  |  |
Net unrecognized tax benefits, excluding interest and penalties that would affect the company's net income if recognized | 21.9 |  |  |
Interest and penalties | 0.7 | 1.3 | $ 0.1 |
Accruals for payment of interest and penalties | 6.4 | 5.7 |  |
Interest income related to federal income tax refunds | 1.6 |  |  |
Scenario Forecast |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |
Significant change in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit |  |  |  | $ 2.8
Foreign Tax Authority |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |
Valuation allowance on foreign net deferred tax assets benefits (expense) | 11.7 | $ (11.4) |  |
Operating loss carryforwards | $ 17.7 |  |  |
Tax credit carryforwards, foreign expiration period, minimum | 7 years |  |  |
Deferred tax assets, operating loss carryforwards | $ 4.5 |  |  |
Deferred tax assets, tax credit carryforwards | 6.4 |  |  |
Deferred tax assets, valuation allowance | 0.8 |  |  |
Deferred tax assets, foreign tax credit | 5.4 |  |  |
State and Local Jurisdiction |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |
Operating loss carryforwards | $ 40,400.0 |  |  |
Tax credit carryforwards, state expiration period, minimum | 5 years |  |  |
Tax credit carryforward, amount | $ 28.9 |  |  |
Tax credit carryforwards, expiration year start | 2027 |  |  |
Tax credit carryforwards, expiration year end | 2036 |  |  |
Deferred tax assets, operating loss carryforwards | $ 30.7 |  |  |
Deferred tax assets, tax credit carryforwards | 19.8 |  |  |
2021 Tax Accounting Method Changes Plan |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |
Net Operating loss | $ 800.0 |  |  |

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- Definition Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32537-109319 + Details
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