Property, Plant and Equipment - Components of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Property Plant And Equipment [Abstract]
Land and land improvements	$ 151	$ 150
Buildings	531	512
Machinery and equipment	2,527	2,446
Other	243	237
Construction in progress	150	88
Total property, plant and equipment	3,602	3,433
Less: accumulated depreciation	(2,297)	(2,143)
Net property, plant and equipment	$ 1,305	$ 1,290	$ 1,383