Financial Information by Segment & Geographic Area - Revenue from External Customers and Property, Plant and Equipment Information by Geographic Area (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues from external customers	$ 3,409	$ 2,614	$ 3,337
Net property, plant and equipment	1,376	1,314
United States [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues from external customers	668	581	702
Net property, plant and equipment	513	493
China [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues from external customers	858	598	738
Net property, plant and equipment	333	295
Other Countries [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues from external customers	1,883	1,435	$ 1,897
Net property, plant and equipment	$ 530	$ 526