Income Taxes - Components of Deferred Income Taxes (Detail) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Components Of Deferred Tax Assets [Abstract]
Deferred expenses	$ 19	$ 15
Intangible assets	37	28
Inventory	13	9
Operating lease liability	20
Other	32	3
Pension and other benefits	35	41
Net operating loss carryforwards	109	124
Foreign tax credit carryforwards	58	20
R&D credit carryforwards	44	43
Other business credit carryforwards	23	29
Subtotal	390	312
Valuation allowance	(317)	(124)
Total deferred tax assets	73	188
Property, plant and equipment	(40)	(61)
Right of use asset	(20)
Unremitted earnings of non-U.S. subsidiaries	(18)	(5)
Total deferred tax liabilities	$ (78)	$ (66)