Goodwill and Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Millions		Sep. 30, 2018	Sep. 30, 2017
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	[1]	$ 111	$ 159
Accumulated Amortization	[1]	(13)	(22)
Net Intangible Assets, finite lives	[1]	98	137
Developed Technologies [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	[1]	52	49
Accumulated Amortization	[1]	(2)	(7)
Net Intangible Assets, finite lives	[1]	50	42
Trademarks [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	[1]	8	16
Accumulated Amortization	[1]		(1)
Net Intangible Assets, finite lives	[1]	8	15
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	[1]	51	94
Accumulated Amortization	[1]	(11)	(14)
Net Intangible Assets, finite lives	[1]	$ 40	$ 80

[1] Refer to Note F for intangible assets impairment charges recorded in the second fiscal quarter of 2018