Intangible Assets - Components of Intangible Assets (Detail) - USD ($) $ in Millions	Jun. 30, 2021	Sep. 30, 2020
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 19,998	$ 19,748
Accumulated Amortization	(7,047)	(5,981)
Unamortized intangible assets	46	46
Trademarks
Finite And Indefinite Lived Intangible Assets [Line Items]
Unamortized intangible assets	2	2
Acquired in-process research and development
Finite And Indefinite Lived Intangible Assets [Line Items]
Unamortized intangible assets	44	44
Developed technology
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	14,273	14,105
Accumulated Amortization	(4,732)	(3,959)
Customer relationships
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	4,656	4,616
Accumulated Amortization	(1,757)	(1,509)
Product rights
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	126	119
Accumulated Amortization	(83)	(73)
Trademarks
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	408	408
Accumulated Amortization	(134)	(120)
Patents and other
Finite And Indefinite Lived Intangible Assets [Line Items]
Gross Carrying Amount	535	500
Accumulated Amortization	$ (341)	$ (320)