Goodwill and Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	$ 115	$ 111
Accumulated Amortization	(19)	(13)
Net Intangible Assets, finite lives	96	98
Developed Technologies [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	50	52
Accumulated Amortization	(5)	(2)
Net Intangible Assets, finite lives	45	50
Trademarks [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	8	8
Net Intangible Assets, finite lives	8	8
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	57	51
Accumulated Amortization	(14)	(11)
Net Intangible Assets, finite lives	$ 43	$ 40