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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
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Decrease in operating income	$ 11.1	$ 9.9	$ 11.0
Effect on net income or loss	$ (8.7)	$ (7.6)	$ (8.2)
Effect on earnings or loss per basic share	$ (0.06)	$ (0.05)	$ (0.05)
Effect on earnings or loss per diluted share	$ (0.06)	$ (0.05)	$ (0.05)

X

- Definition

Share-based Compensation, Increase (Decrease) in Earnings Per Share, Basic

+ References

No definition available.

+ Details

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- Definition

Share-based Compensation, Increase (Decrease) in Earnings Per Share, Diluted

+ References

No definition available.

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X

- Definition

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479830/718-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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- Definition

Amount, after tax, of expense for award under share-based payment arrangement.

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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.

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