Defined Benefit Pension and Other Postretirement Plans (Details) - Pension Benefits - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure
Service cost	$ 4	$ 3
Interest cost	6	5
Expected return on assets	(12)	(10)
Amortization of:
Actuarial loss	2	4
Net cost	$ 0	$ 2