Segment Reporting - Sales from Products (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Sales	$ 15,901	$ 10,627
Revenue related to the sale of the marketing rights	114	56
U.S.
Segment Reporting Information [Line Items]
Sales	7,339	4,790
Int’l
Segment Reporting Information [Line Items]
Sales	8,563	5,837
Operating Segments
Segment Reporting Information [Line Items]
Sales	15,589	10,656
Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	7,246	4,731
Operating Segments \| Int’l
Segment Reporting Information [Line Items]
Sales	8,343	5,925
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Sales	312	(29)
Corporate, Non-Segment \| U.S.
Segment Reporting Information [Line Items]
Sales	93	59
Corporate, Non-Segment \| Int’l
Segment Reporting Information [Line Items]
Sales	220	(88)
Pharmaceutical \| Operating Segments
Segment Reporting Information [Line Items]
Sales	14,107	9,238
Pharmaceutical \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	6,773	4,294
Pharmaceutical \| Operating Segments \| Int’l
Segment Reporting Information [Line Items]
Sales	7,334	4,944
Pharmaceutical \| Operating Segments \| Keytruda
Segment Reporting Information [Line Items]
Sales	4,809	3,899
Pharmaceutical \| Operating Segments \| Keytruda \| U.S.
Segment Reporting Information [Line Items]
Sales	2,779	2,181
Pharmaceutical \| Operating Segments \| Keytruda \| Int’l
Segment Reporting Information [Line Items]
Sales	2,030	1,718
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza
Segment Reporting Information [Line Items]
Sales	266	228
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| U.S.
Segment Reporting Information [Line Items]
Sales	141	118
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| Int’l
Segment Reporting Information [Line Items]
Sales	125	110
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima
Segment Reporting Information [Line Items]
Sales	227	130
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| U.S.
Segment Reporting Information [Line Items]
Sales	156	85
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| Int’l
Segment Reporting Information [Line Items]
Sales	71	44
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl
Segment Reporting Information [Line Items]
Sales	52	0
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| U.S.
Segment Reporting Information [Line Items]
Sales	27	0
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| Int’l
Segment Reporting Information [Line Items]
Sales	25	0
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	1,460	917
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| U.S.
Segment Reporting Information [Line Items]
Sales	418	313
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| Int’l
Segment Reporting Information [Line Items]
Sales	1,042	604
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	470	449
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| U.S.
Segment Reporting Information [Line Items]
Sales	371	333
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| Int’l
Segment Reporting Information [Line Items]
Sales	99	117
Pharmaceutical \| Operating Segments \| RotaTeq
Segment Reporting Information [Line Items]
Sales	216	158
Pharmaceutical \| Operating Segments \| RotaTeq \| U.S.
Segment Reporting Information [Line Items]
Sales	175	118
Pharmaceutical \| Operating Segments \| RotaTeq \| Int’l
Segment Reporting Information [Line Items]
Sales	41	41
Pharmaceutical \| Operating Segments \| Pneumovax 23
Segment Reporting Information [Line Items]
Sales	173	171
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| U.S.
Segment Reporting Information [Line Items]
Sales	118	73
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| Int’l
Segment Reporting Information [Line Items]
Sales	55	99
Pharmaceutical \| Operating Segments \| Vaqta
Segment Reporting Information [Line Items]
Sales	36	34
Pharmaceutical \| Operating Segments \| Vaqta \| U.S.
Segment Reporting Information [Line Items]
Sales	29	25
Pharmaceutical \| Operating Segments \| Vaqta \| Int’l
Segment Reporting Information [Line Items]
Sales	7	9
Pharmaceutical \| Operating Segments \| Bridion
Segment Reporting Information [Line Items]
Sales	395	340
Pharmaceutical \| Operating Segments \| Bridion \| U.S.
Segment Reporting Information [Line Items]
Sales	195	167
Pharmaceutical \| Operating Segments \| Bridion \| Int’l
Segment Reporting Information [Line Items]
Sales	199	173
Pharmaceutical \| Operating Segments \| Prevymis
Segment Reporting Information [Line Items]
Sales	94	82
Pharmaceutical \| Operating Segments \| Prevymis \| U.S.
Segment Reporting Information [Line Items]
Sales	40	35
Pharmaceutical \| Operating Segments \| Prevymis \| Int’l
Segment Reporting Information [Line Items]
Sales	54	47
Pharmaceutical \| Operating Segments \| Primaxin
Segment Reporting Information [Line Items]
Sales	58	65
Pharmaceutical \| Operating Segments \| Primaxin \| U.S.
Segment Reporting Information [Line Items]
Sales	1	0
Pharmaceutical \| Operating Segments \| Primaxin \| Int’l
Segment Reporting Information [Line Items]
Sales	58	65
Pharmaceutical \| Operating Segments \| Noxafil
Segment Reporting Information [Line Items]
Sales	57	67
Pharmaceutical \| Operating Segments \| Noxafil \| U.S.
Segment Reporting Information [Line Items]
Sales	10	15
Pharmaceutical \| Operating Segments \| Noxafil \| Int’l
Segment Reporting Information [Line Items]
Sales	48	52
Pharmaceutical \| Operating Segments \| Cancidas
Segment Reporting Information [Line Items]
Sales	53	57
Pharmaceutical \| Operating Segments \| Cancidas \| U.S.
Segment Reporting Information [Line Items]
Sales	1	3
Pharmaceutical \| Operating Segments \| Cancidas \| Int’l
Segment Reporting Information [Line Items]
Sales	52	55
Pharmaceutical \| Operating Segments \| Dificid
Segment Reporting Information [Line Items]
Sales	52	27
Pharmaceutical \| Operating Segments \| Dificid \| U.S.
Segment Reporting Information [Line Items]
Sales	49	25
Pharmaceutical \| Operating Segments \| Dificid \| Int’l
Segment Reporting Information [Line Items]
Sales	3	2
Pharmaceutical \| Operating Segments \| Invanz
Segment Reporting Information [Line Items]
Sales	52	57
Pharmaceutical \| Operating Segments \| Invanz \| U.S.
Segment Reporting Information [Line Items]
Sales	1	4
Pharmaceutical \| Operating Segments \| Invanz \| Int’l
Segment Reporting Information [Line Items]
Sales	52	52
Pharmaceutical \| Operating Segments \| Zerbaxa
Segment Reporting Information [Line Items]
Sales	30	(8)
Pharmaceutical \| Operating Segments \| Zerbaxa \| U.S.
Segment Reporting Information [Line Items]
Sales	18	(2)
Pharmaceutical \| Operating Segments \| Zerbaxa \| Int’l
Segment Reporting Information [Line Items]
Sales	12	(6)
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo
Segment Reporting Information [Line Items]
Sales	72	74
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| U.S.
Segment Reporting Information [Line Items]
Sales	71	68
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| Int’l
Segment Reporting Information [Line Items]
Sales	1	6
Pharmaceutical \| Operating Segments \| Adempas
Segment Reporting Information [Line Items]
Sales	61	55
Pharmaceutical \| Operating Segments \| Adempas \| U.S.
Segment Reporting Information [Line Items]
Sales	0	0
Pharmaceutical \| Operating Segments \| Adempas \| Int’l
Segment Reporting Information [Line Items]
Sales	61	55
Pharmaceutical \| Operating Segments \| Lagevrio
Segment Reporting Information [Line Items]
Sales	3,247	0
Pharmaceutical \| Operating Segments \| Lagevrio \| U.S.
Segment Reporting Information [Line Items]
Sales	1,523	0
Pharmaceutical \| Operating Segments \| Lagevrio \| Int’l
Segment Reporting Information [Line Items]
Sales	1,723	0
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	158	209
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| U.S.
Segment Reporting Information [Line Items]
Sales	61	71
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| Int’l
Segment Reporting Information [Line Items]
Sales	97	138
Pharmaceutical \| Operating Segments \| Belsomra
Segment Reporting Information [Line Items]
Sales	69	79
Pharmaceutical \| Operating Segments \| Belsomra \| U.S.
Segment Reporting Information [Line Items]
Sales	20	18
Pharmaceutical \| Operating Segments \| Belsomra \| Int’l
Segment Reporting Information [Line Items]
Sales	48	61
Pharmaceutical \| Operating Segments \| Simponi
Segment Reporting Information [Line Items]
Sales	186	214
Pharmaceutical \| Operating Segments \| Simponi \| U.S.
Segment Reporting Information [Line Items]
Sales	0	0
Pharmaceutical \| Operating Segments \| Simponi \| Int’l
Segment Reporting Information [Line Items]
Sales	186	214
Pharmaceutical \| Operating Segments \| Remicade
Segment Reporting Information [Line Items]
Sales	61	85
Pharmaceutical \| Operating Segments \| Remicade \| U.S.
Segment Reporting Information [Line Items]
Sales	0	0
Pharmaceutical \| Operating Segments \| Remicade \| Int’l
Segment Reporting Information [Line Items]
Sales	61	85
Pharmaceutical \| Operating Segments \| Januvia
Segment Reporting Information [Line Items]
Sales	779	809
Pharmaceutical \| Operating Segments \| Januvia \| U.S.
Segment Reporting Information [Line Items]
Sales	325	348
Pharmaceutical \| Operating Segments \| Januvia \| Int’l
Segment Reporting Information [Line Items]
Sales	454	461
Pharmaceutical \| Operating Segments \| Janumet
Segment Reporting Information [Line Items]
Sales	454	486
Pharmaceutical \| Operating Segments \| Janumet \| U.S.
Segment Reporting Information [Line Items]
Sales	63	84
Pharmaceutical \| Operating Segments \| Janumet \| Int’l
Segment Reporting Information [Line Items]
Sales	391	401
Pharmaceutical \| Operating Segments \| Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	520	554
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| U.S.
Segment Reporting Information [Line Items]
Sales	181	212
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| Int’l
Segment Reporting Information [Line Items]
Sales	339	341
Animal Health \| Operating Segments
Segment Reporting Information [Line Items]
Sales	1,482	1,418
Animal Health \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	473	437
Animal Health \| Operating Segments \| Int’l
Segment Reporting Information [Line Items]
Sales	1,009	981
Animal Health \| Operating Segments \| Livestock
Segment Reporting Information [Line Items]
Sales	832	819
Animal Health \| Operating Segments \| Livestock \| U.S.
Segment Reporting Information [Line Items]
Sales	171	157
Animal Health \| Operating Segments \| Livestock \| Int’l
Segment Reporting Information [Line Items]
Sales	661	662
Animal Health \| Operating Segments \| Companion Animals
Segment Reporting Information [Line Items]
Sales	650	599
Animal Health \| Operating Segments \| Companion Animals \| U.S.
Segment Reporting Information [Line Items]
Sales	302	280
Animal Health \| Operating Segments \| Companion Animals \| Int’l
Segment Reporting Information [Line Items]
Sales	$ 348	$ 319