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The aggregate expected value at the end of their useful life of a major finite-lived intangible asset class acquired during the period either individually or as part of a group of assets (in either an asset acquisition or business combination). A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

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The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Amount classified as assets attributable to disposal group held for sale or disposed of.

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Amount, before recovery, of expense for known and estimated future costs arising from requirement to perform environmental remediation.

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Indicates line item in statement of income or comprehensive income that includes environmental remediation expense before recovery.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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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.

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Amount classified as liabilities attributable to disposal group held for sale or disposed of.

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The loss relating to components of the gain (loss) on the cash flow hedging instrument excluded from the assessment of cash flow hedge effectiveness. Recognized in earnings.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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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.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Basis of Presentation and Major Accounting Policies (Narrative) (Details)	12 Months Ended
	Sep. 30, 2023 USD ($) segment	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Accounting Policies [Abstract]
Number of reportable segments \| segment	5
Assets of discontinued operations	$ 0	$ 0
Liabilities of discontinued operations	0	0
Environmental expenditures	24,900,000	22,300,000	$ 18,600,000
Asset retirement obligations	297,300,000	$ 274,700,000	$ 269,600,000
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, residual value	$ 0
Environmental Remediation Expense, Statement of Income or Comprehensive Income [Extensible Enumeration]	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest
Other Non-Operating Income (Expense), Net
Accounting Policies [Abstract]
Excluded components recognized within earnings	$ 25,100,000	$ 23,200,000	$ 31,000,000.0
Finite-Lived Intangible Assets [Line Items]
Excluded components recognized within earnings	$ 25,100,000	$ 23,200,000	$ 31,000,000.0
Computer software costs \| Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Computer software costs \| Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	5 years
Customer relationships \| Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	5 years
Customer relationships \| Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	25 years
Patents and technology \| Minimum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	5 years
Patents and technology \| Maximum
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	15 years
Land Use Rights
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, useful life	50 years