Goodwill and Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	$ 159	$ 154
Accumulated Amortization	(22)	(14)
Net Intangible Assets, finite lives	137	140
Developed Technologies [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	49	48
Accumulated Amortization	(7)	(4)
Net Intangible Assets, finite lives	42	44
Trademarks [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	16	16
Accumulated Amortization	(1)	(1)
Net Intangible Assets, finite lives	15	15
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	94	90
Accumulated Amortization	(14)	(9)
Net Intangible Assets, finite lives	$ 80	$ 81