Retirement Plans - Schedule of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Retirement Benefits [Abstract]
Defined Benefit Plan, Type [Extensible Enumeration]	Pension Plan [Member]
Service cost	$ 2	$ 2
Interest cost	3	2
Expected return on plan assets	(4)	(4)
Net periodic benefit cost	$ 1	$ 0