Retirement Plans - Schedule of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Retirement Benefits [Abstract]
Service cost	$ 2	$ 1	$ 3	$ 2
Interest cost	5	5	10	9
Expected return on plan assets	(3)	(3)	(6)	(6)
Net actuarial and settlement/curtailment (gain) loss	0	0	0	8
Net periodic benefit cost	$ 4	$ 3	$ 7	$ 13