Income Taxes - Deferred Taxes (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Components of Deferred Tax Assets [Abstract]
Valuation allowance	$ (43.7)	$ (36.4)	$ (35.5)	$ (41.6)
Assets \| Noncurrent
Components of Deferred Tax Assets [Abstract]
Lease liabilities	61.9	49.1
Disallowed interest carryforwards	56.0	53.9
Derivative, equity securities and investment adjustments	40.6	41.0
Net operating loss and credit carryforwards	27.6	20.9
Inventory	26.8	16.0
Accrued vacation, incentive and severance	24.6	10.3
Stock-based and deferred compensation	23.7	20.6
Capitalized research and development	18.3	11.2
Accrued liabilities	10.9	10.8
Basis difference attributable to equity method investment	4.7	4.7
Other items	6.5	6.9
Deferred Tax Assets, Gross, Total	301.6	245.4
Valuation allowance	(43.7)	(36.4)
Total deferred income taxes	257.9	209.0
Liability \| Noncurrent
Components of Deferred Tax Liabilities [Abstract]
Intangible assets	(585.5)	(592.2)
Property	(239.9)	(226.1)
ROU assets	(58.9)	(46.2)
Pension and other postretirement benefits	(23.8)	(16.2)
Other items	(2.8)	(2.7)
Deferred Tax Liabilities, Gross	(910.9)	(883.4)
Net Assets \| Noncurrent
Components of Deferred Tax Assets [Abstract]
Lease liabilities	61.9	49.1
Disallowed interest carryforwards	56.0	53.9
Derivative, equity securities and investment adjustments	40.6	41.0
Net operating loss and credit carryforwards	27.6	20.9
Inventory	26.8	16.0
Accrued vacation, incentive and severance	24.6	10.3
Stock-based and deferred compensation	23.7	20.6
Capitalized research and development	18.3	11.2
Accrued liabilities	10.9	10.8
Basis difference attributable to equity method investment	4.7	4.7
Other items	3.7	4.2
Valuation allowance	(43.7)	(36.4)
Components of Deferred Tax Liabilities [Abstract]
Intangible assets	(585.5)	(592.2)
Property	(239.9)	(226.1)
ROU assets	(58.9)	(46.2)
Pension and other postretirement benefits	(23.8)	(16.2)
Deferred Tax Liabilities, Gross	(609.3)	(638.0)
Total deferred tax liabilities, gross	$ (653.0)	$ (674.4)

Deferred Tax Assets, Leasing Arrangements

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Deferred Tax Assets, Tax Deferred Expense, Disallowed Interest Carryforwards

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Deferred Tax Liabilities, Basis Difference of Equity Method Investment

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Deferred Tax Liabilities, Tax Deferred Expense, Compensation and Benefits, Pension and Other Postreitrement Benefits

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary difference from in-process research and development cost acquired in business combination or from joint venture formation or both.

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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