Employee Retirement Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
ABO	$ 22	$ 31
Fair value of plan assets	16	19
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Contribution made to Pension Plan	15	14
Projected benefit obligations of unfunded and non qualified supplemental executive retirement plans	633	870	$ 782
Costs associated with the plans	(1)	8	11
Net actuarial loss	(17)	13
Payments for defined benefit retirement plan	34	30
Supplemental Employee Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligations of unfunded and non qualified supplemental executive retirement plans	44	57
Costs associated with the plans	0	0
Net actuarial loss	1	10
Payments for defined benefit retirement plan	0	12	0
Fair value of pension and other postretirement benefit contributions	31	44
U.S. | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Contribution made to Pension Plan	$ 14	$ 13	$ 13