Income Taxes - Schedule of Current and Deferred Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Federal:
Current	$ 36	$ 23	$ 6
Deferred	(5)	44	31
Foreign:
Current	128	128	107
Deferred	(3)	(30)	(5)
U.S. State:
Current	19	21	9
Deferred	(5)	(1)	1
Income tax expense	170	185	149
Cash withholding taxes	$ 38	$ 27	$ 26