Share-Based Compensation - Weighted Average Grant Date Fair Value of Restricted Stock Units (Details) - $ / shares	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Performance-Based
Schedule Of Share Based Compensation, Restricted Stock Units Award, Grant Date Fair Value of Units Granted [Line Items]
Granted, stock units weighted average grant date fair value (in USD per share)	$ 214.38	$ 223.60	$ 227.11
Time-Vested
Schedule Of Share Based Compensation, Restricted Stock Units Award, Grant Date Fair Value of Units Granted [Line Items]
Granted, stock units weighted average grant date fair value (in USD per share)	$ 211.46	$ 231.32	$ 231.58

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).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(01)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration