Debt and Financing Arrangements - Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Dec. 11, 2023
Debt Instrument [Line Items]
Interest paid	$ 298,000,000	$ 226,000,000	$ 242,000,000
$2.5 Billion Facility Expiring Dec 2024
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	2,500,000,000
$500 million facility expiring Nov 2023
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	500,000,000
$2.5 billion facility expiring Dec 2028 | Subsequent Event
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 2,500,000,000
$500 million facility expiring Dec 2024 | Subsequent Event
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 500,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Long-term debt	$ 0