Retirement Plans - Schedule of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Retirement Benefits [Abstract]
Service cost	$ 2	$ 2	$ 4	$ 4
Interest cost	3	2	6	4
Expected return on plan assets	(4)	(4)	(8)	(8)
Net periodic benefit cost	$ 1	$ 0	$ 2	$ 0