Income Taxes - Components of Deferred Income Taxes (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Components Of Deferred Tax Assets [Abstract]
Deferred expenses	$ 17	$ 22
Intangible assets	23	43
Inventory	4	1
Other	4	14
Pension and other benefits	45	59
Net operating loss carry-forwards	146	149
Foreign tax credit carry-forwards	12	132
R&D credit carry-forwards	41	38
Other business credit carry-forwards	39	37
Subtotal	331	495
Valuation allowance	(169)	(168)
Total deferred tax assets	162	327
Property, plant and equipment	(56)	(116)
Unremitted earnings of non-U.S. subsidiaries	(14)	(12)
Total deferred tax liabilities	$ (70)	$ (128)