Income Taxes - Temporary Differences and Carryforwards (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Deferred tax assets:
Accrued expenses and reserves	$ 135	$ 87
Employee and retiree benefits	25	38
Net operating loss and other credit carryforwards	1,293	1,226
Property, plant and equipment	113	113
Intangible assets	132	150
Operating lease liabilities	55	61
Research and development	66	27
Other	0	2
Deferred tax assets:	1,819	1,704
Valuation allowances	(1,655)	(1,662)
Deferred tax assets, net	164	42
Deferred tax liabilities:
Unremitted earnings of foreign subsidiaries	38	35
Indirect tax credits	10	25
Foreign currency adjustments	0	8
Operating lease right-of-use assets	55	61
Other	14	0
Deferred tax liabilities:	117	129
Net deferred tax asset/(liability)	$ 47
Net deferred tax asset/(liability)		$ (87)