Debt (U.S. Committed Credit Facilities) (Details) - Revolving credit agreement	6 Months Ended
	Mar. 31, 2026 USD ($)
364-Day Agreement | Line of Credit
Debt Instrument [Line Items]
Debt instrument term	364 days
Maximum borrowing capacity	$ 500,000,000
Credit facility, amount borrowed and outstanding	$ 0
Credit Agreement 2024 | Line of Credit
Debt Instrument [Line Items]
Debt instrument term	5 years
Maximum borrowing capacity	$ 3,000,000,000.0
Credit facility, amount borrowed and outstanding	$ 0