Income Taxes - Temporary Differences and Carryforwards (Details) - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023
Deferred tax assets:
Accrued expenses and reserves	$ 123	$ 135
Employee and retiree benefits	24	25
Net operating loss and other carryforwards	1,400	1,293
Property, plant and equipment	114	113
Intangible assets	112	132
Operating lease liabilities	57	55
Research and development	102	66
Deferred tax assets:	1,932	1,819
Valuation allowances	(1,769)	(1,655)
Deferred tax assets, net	163	164
Deferred tax liabilities:
Unremitted earnings of foreign subsidiaries	39	38
Indirect tax credits	0	10
Operating lease right-of-use assets	57	55
Other	13	14
Deferred tax liabilities:	109	117
Net deferred tax asset	$ 54	$ 47