Pension and Postretirement Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	$ 8	$ (42)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1	0
Expected return on plan assets	(2)	(2)
Amortization of prior service credit	(1)	(1)
Net periodic benefit cost (credit)	(2)	(3)
United States | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Interest cost	21	10
Expected return on plan assets	(34)	(41)
Net actuarial loss (gain)	8	(42)
Settlement gain	0	(1)
Net periodic benefit cost (credit)	(5)	(74)
Foreign Plan | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	3	6
Interest cost	16	10
Expected return on plan assets	(18)	(21)
Net periodic benefit cost (credit)	$ 1	$ (5)