Goodwill and Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Sep. 30, 2024
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	$ 100	$ 96
Accumulated Amortization	(43)	(43)
Net Intangible Assets, finite lives	57	53
Developed Technologies [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	40	34
Accumulated Amortization	(12)	(12)
Net Intangible Assets, finite lives	28	22
Trademarks [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	2	2
Accumulated Amortization	(1)	(1)
Net Intangible Assets, finite lives	1	1
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Value, finite lives	58	60
Accumulated Amortization	(30)	(30)
Net Intangible Assets, finite lives	$ 28	$ 30