Intangible Assets - Components of Intangible Assets (Detail) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 20,122	$ 19,748
Accumulated Amortization	(7,385)	(5,981)
Finite-Lived Intangible Assets, Net	12,737	13,767
Unamortized intangible assets	46	46
Acquired in-process research and development
Finite And Indefinite Lived Intangible Assets [Line Items]
Unamortized intangible assets	44	44
Trademarks
Finite And Indefinite Lived Intangible Assets [Line Items]
Unamortized intangible assets	2	2
Developed technology
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	14,399	14,105
Accumulated Amortization	(4,983)	(3,959)
Finite-Lived Intangible Assets, Net	9,417	10,146
Customer relationships
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,658	4,616
Accumulated Amortization	(1,839)	(1,509)
Finite-Lived Intangible Assets, Net	2,818	3,107
Product rights
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	123	119
Accumulated Amortization	(83)	(73)
Finite-Lived Intangible Assets, Net	40	46
Trademarks
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	409	408
Accumulated Amortization	(137)	(120)
Finite-Lived Intangible Assets, Net	271	288
Patents and other
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	533	500
Accumulated Amortization	(342)	(320)
Finite-Lived Intangible Assets, Net	$ 191	$ 180