Segment, Geographic and Other Revenue Information - Narrative (Detail) treatmentCourse in Millions, $ in Millions	2 Months Ended	3 Months Ended		9 Months Ended
	Feb. 29, 2024 treatmentCourse	Sep. 29, 2024 USD ($) treatmentCourse	Mar. 31, 2024 USD ($)	Sep. 29, 2024 USD ($) operatingSegment treatmentCourse	Oct. 01, 2023	Dec. 31, 2023 USD ($) treatmentCourse
Segment Reporting Information [Line Items]
Number of segments | operatingSegment				3
Total assets		$ 219,476		$ 219,476		$ 226,501
Deferred revenues, current		2,020		2,020		2,700
Comirnaty [Member]
Segment Reporting Information [Line Items]
Remaining performance obligation		$ 6,000		6,000
Paxlovid [Member]
Segment Reporting Information [Line Items]
Reversal of revenue						$ 3,500
Estimated government emergency use authorization inventory to be returned to company, number of treatment courses | treatmentCourse						6.5
Favorable adjustment for government emergency use authorization inventory returned to the company during the period			$ 771	$ 771
Government emergency use authorization inventory returned to the company during the period, number of treatment courses | treatmentCourse	5.1
Paxlovid, NDA-Labeled, U.S. Strategic National Stockpile [Member]
Segment Reporting Information [Line Items]
Supply commitment, minimum amount committed, number of treatment courses | treatmentCourse		1.0		1.0
Revenues		$ 442		$ 442
Paxlovid, NDA-Labeled [Member]
Segment Reporting Information [Line Items]
Supply commitment, minimum amount committed, number of treatment courses | treatmentCourse		6.1		6.1
Paxlovid [Member]
Segment Reporting Information [Line Items]
Remaining performance obligation		$ 1,000		$ 1,000
Government and Government Sponsored [Member] | Paxlovid and Comirnaty [Member]
Segment Reporting Information [Line Items]
Deferred revenues		3,500		3,500		$ 5,100
Deferred revenues, current		2,000		2,000		2,600
Deferred revenues, noncurrent		1,500		1,500		$ 2,500
Deferred revenue recognized		$ 1,100		$ 2,300
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | US Government [Member]
Segment Reporting Information [Line Items]
Concentration risk		9.00%		7.00%	7.00%