Income Taxes - Provisions for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Current expense (benefit):
Federal	$ (25)	$ (1)	$ 24
State	12	37	18
Foreign	32	49	50
Total current expense	19	85	92
Deferred expense (benefit):
Federal	82	34	45
State	34	(21)	(17)
Foreign	(64)	(433)	193
Total deferred expense (benefit)	52	(420)	221
Total income tax expense (benefit)	$ 71	$ (335)	$ 313