Employee Retirement Plans - Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
ABO	$ 21,000,000	$ 22,000,000
Fair value of plan assets	18,000,000	16,000,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Contribution made to Pension Plan	19,000,000	15,000,000
Projected benefit obligations of unfunded and non qualified supplemental executive retirement plans	623,000,000	633,000,000	$ 870,000,000
Costs associated with the plans	(4,000,000)	(1,000,000)	8,000,000
Payments for defined benefit retirement plan	36,000,000	34,000,000
Supplemental Employee Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations of unfunded and non qualified supplemental executive retirement plans	34,000,000	44,000,000
Costs associated with the plans	0	0
Payments for defined benefit retirement plan	0	0	12,000,000
Fair value of pension and other postretirement benefit contributions	26,000,000	31,000,000
U.S. | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Contribution made to Pension Plan	18,000,000	$ 14,000,000	$ 13,000,000
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 22,000,000