Income Taxes - Schedule of Current and Deferred Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Federal:
Current	$ 33	$ 26	$ 36
Deferred	(28)	(45)	(5)
Foreign:
Current	163	137	128
Deferred	(62)	3	(3)
U.S. State:
Current	14	8	19
Deferred	0	(6)	(5)
Income tax expense	120	123	170
Cash withholding taxes	$ 46	$ 28	$ 38