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Share-Based Payments - PEP, RSU (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Information concerning outstanding and exercisable options
Compensation expense related to share-based payments	$ 45.9	$ 38.5	$ 44.7
Unrecognized compensation expense	$ 48.3	$ 45.9
Recognition period of unrecognized compensation expense	3 years	3 years
PEP Units
Information concerning outstanding and exercisable options
Weighted average grant-date fair value of awards granted (in dollars per share)	$ 94.64	$ 85.46	$ 52.76
Restricted Stock Units (RSUs) [Member]
Information concerning outstanding and exercisable options
Weighted average grant-date fair value of awards granted (in dollars per share)	$ 83.64	$ 74.30	$ 49.21
Performance Earnings Program | PEP Units
Information concerning outstanding and exercisable options
Vesting period	3 years

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
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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

+ References

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-Topic 718
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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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