Defined Benefit Pension and Other Postretirement Plans - Components of Net Periodic Pension Cost (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure
Service cost	$ 4	$ 3	$ 12	$ 9
Interest cost	6	5	19	16
Expected return on assets	(12)	(10)	(37)	(30)
Amortization of:
Actuarial loss	2	4	6	11
Net cost	$ 0	$ 2	$ 0	$ 6