Segment Reporting - Sales from Products (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Segment Reporting Information [Line Items]
Sales	$ 14,487	$ 15,901
Revenue related to the sale of the marketing rights	51	114
Increase (Decrease) In Hedge Revenue	99	69
U.S.
Segment Reporting Information [Line Items]
Sales	6,659	7,339
Int’l
Segment Reporting Information [Line Items]
Sales	7,828	8,563
Operating Segments
Segment Reporting Information [Line Items]
Sales	14,212	15,589
Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	6,599	7,246
Operating Segments \| Int’l
Segment Reporting Information [Line Items]
Sales	7,614	8,343
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Sales	275	312
Corporate, Non-Segment \| U.S.
Segment Reporting Information [Line Items]
Sales	60	93
Corporate, Non-Segment \| Int’l
Segment Reporting Information [Line Items]
Sales	214	220
Pharmaceutical \| Operating Segments
Segment Reporting Information [Line Items]
Sales	12,721	14,107
Pharmaceutical \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	6,117	6,773
Pharmaceutical \| Operating Segments \| Int’l
Segment Reporting Information [Line Items]
Sales	6,604	7,334
Pharmaceutical \| Operating Segments \| Keytruda
Segment Reporting Information [Line Items]
Sales	5,795	4,809
Pharmaceutical \| Operating Segments \| Keytruda \| U.S.
Segment Reporting Information [Line Items]
Sales	3,485	2,779
Pharmaceutical \| Operating Segments \| Keytruda \| Int’l
Segment Reporting Information [Line Items]
Sales	2,310	2,030
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza
Segment Reporting Information [Line Items]
Sales	275	266
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| U.S.
Segment Reporting Information [Line Items]
Sales	142	141
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| Int’l
Segment Reporting Information [Line Items]
Sales	133	125
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima
Segment Reporting Information [Line Items]
Sales	232	227
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| U.S.
Segment Reporting Information [Line Items]
Sales	153	156
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| Int’l
Segment Reporting Information [Line Items]
Sales	79	71
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl
Segment Reporting Information [Line Items]
Sales	43	52
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| U.S.
Segment Reporting Information [Line Items]
Sales	30	27
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| Int’l
Segment Reporting Information [Line Items]
Sales	12	25
Pharmaceutical \| Operating Segments \| Welireg
Segment Reporting Information [Line Items]
Sales	42	18
Pharmaceutical \| Operating Segments \| Welireg \| U.S.
Segment Reporting Information [Line Items]
Sales	41	18
Pharmaceutical \| Operating Segments \| Welireg \| Int’l
Segment Reporting Information [Line Items]
Sales	1	0
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	1,972	1,460
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| U.S.
Segment Reporting Information [Line Items]
Sales	416	418
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| Int’l
Segment Reporting Information [Line Items]
Sales	1,556	1,042
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	528	470
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| U.S.
Segment Reporting Information [Line Items]
Sales	421	371
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| Int’l
Segment Reporting Information [Line Items]
Sales	107	99
Pharmaceutical \| Operating Segments \| RotaTeq
Segment Reporting Information [Line Items]
Sales	297	216
Pharmaceutical \| Operating Segments \| RotaTeq \| U.S.
Segment Reporting Information [Line Items]
Sales	180	175
Pharmaceutical \| Operating Segments \| RotaTeq \| Int’l
Segment Reporting Information [Line Items]
Sales	117	41
Pharmaceutical \| Operating Segments \| Vaxneuvance
Segment Reporting Information [Line Items]
Sales	106	5
Pharmaceutical \| Operating Segments \| Vaxneuvance \| U.S.
Segment Reporting Information [Line Items]
Sales	94	5
Pharmaceutical \| Operating Segments \| Vaxneuvance \| Int’l
Segment Reporting Information [Line Items]
Sales	13	0
Pharmaceutical \| Operating Segments \| Pneumovax 23
Segment Reporting Information [Line Items]
Sales	96	173
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| U.S.
Segment Reporting Information [Line Items]
Sales	40	118
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| Int’l
Segment Reporting Information [Line Items]
Sales	56	55
Pharmaceutical \| Operating Segments \| Vaqta
Segment Reporting Information [Line Items]
Sales	40	36
Pharmaceutical \| Operating Segments \| Vaqta \| U.S.
Segment Reporting Information [Line Items]
Sales	30	29
Pharmaceutical \| Operating Segments \| Vaqta \| Int’l
Segment Reporting Information [Line Items]
Sales	10	7
Pharmaceutical \| Operating Segments \| Bridion
Segment Reporting Information [Line Items]
Sales	487	395
Pharmaceutical \| Operating Segments \| Bridion \| U.S.
Segment Reporting Information [Line Items]
Sales	276	195
Pharmaceutical \| Operating Segments \| Bridion \| Int’l
Segment Reporting Information [Line Items]
Sales	210	199
Pharmaceutical \| Operating Segments \| Prevymis
Segment Reporting Information [Line Items]
Sales	129	94
Pharmaceutical \| Operating Segments \| Prevymis \| U.S.
Segment Reporting Information [Line Items]
Sales	54	40
Pharmaceutical \| Operating Segments \| Prevymis \| Int’l
Segment Reporting Information [Line Items]
Sales	75	54
Pharmaceutical \| Operating Segments \| Primaxin
Segment Reporting Information [Line Items]
Sales	80	58
Pharmaceutical \| Operating Segments \| Primaxin \| U.S.
Segment Reporting Information [Line Items]
Sales	4	1
Pharmaceutical \| Operating Segments \| Primaxin \| Int’l
Segment Reporting Information [Line Items]
Sales	76	58
Pharmaceutical \| Operating Segments \| Dificid
Segment Reporting Information [Line Items]
Sales	65	52
Pharmaceutical \| Operating Segments \| Dificid \| U.S.
Segment Reporting Information [Line Items]
Sales	62	49
Pharmaceutical \| Operating Segments \| Dificid \| Int’l
Segment Reporting Information [Line Items]
Sales	3	3
Pharmaceutical \| Operating Segments \| Noxafil
Segment Reporting Information [Line Items]
Sales	60	57
Pharmaceutical \| Operating Segments \| Noxafil \| U.S.
Segment Reporting Information [Line Items]
Sales	14	10
Pharmaceutical \| Operating Segments \| Noxafil \| Int’l
Segment Reporting Information [Line Items]
Sales	46	48
Pharmaceutical \| Operating Segments \| Zerbaxa
Segment Reporting Information [Line Items]
Sales	50	30
Pharmaceutical \| Operating Segments \| Zerbaxa \| U.S.
Segment Reporting Information [Line Items]
Sales	27	18
Pharmaceutical \| Operating Segments \| Zerbaxa \| Int’l
Segment Reporting Information [Line Items]
Sales	23	12
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo
Segment Reporting Information [Line Items]
Sales	99	72
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| U.S.
Segment Reporting Information [Line Items]
Sales	83	71
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| Int’l
Segment Reporting Information [Line Items]
Sales	16	1
Pharmaceutical \| Operating Segments \| Adempas
Segment Reporting Information [Line Items]
Sales	59	61
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	59	61
Pharmaceutical \| Operating Segments \| Lagevrio
Segment Reporting Information [Line Items]
Sales	392	3,247
Pharmaceutical \| Operating Segments \| Lagevrio \| U.S.
Segment Reporting Information [Line Items]
Sales	(2)	1,523
Pharmaceutical \| Operating Segments \| Lagevrio \| Int’l
Segment Reporting Information [Line Items]
Sales	394	1,723
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	123	158
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| U.S.
Segment Reporting Information [Line Items]
Sales	52	61
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| Int’l
Segment Reporting Information [Line Items]
Sales	71	97
Pharmaceutical \| Operating Segments \| Belsomra
Segment Reporting Information [Line Items]
Sales	56	69
Pharmaceutical \| Operating Segments \| Belsomra \| U.S.
Segment Reporting Information [Line Items]
Sales	16	20
Pharmaceutical \| Operating Segments \| Belsomra \| Int’l
Segment Reporting Information [Line Items]
Sales	40	48
Pharmaceutical \| Operating Segments \| Simponi
Segment Reporting Information [Line Items]
Sales	180	186
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	180	186
Pharmaceutical \| Operating Segments \| Remicade
Segment Reporting Information [Line Items]
Sales	51	61
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	51	61
Pharmaceutical \| Operating Segments \| Januvia
Segment Reporting Information [Line Items]
Sales	551	779
Pharmaceutical \| Operating Segments \| Januvia \| U.S.
Segment Reporting Information [Line Items]
Sales	271	325
Pharmaceutical \| Operating Segments \| Januvia \| Int’l
Segment Reporting Information [Line Items]
Sales	280	454
Pharmaceutical \| Operating Segments \| Janumet
Segment Reporting Information [Line Items]
Sales	329	454
Pharmaceutical \| Operating Segments \| Janumet \| U.S.
Segment Reporting Information [Line Items]
Sales	56	63
Pharmaceutical \| Operating Segments \| Janumet \| Int’l
Segment Reporting Information [Line Items]
Sales	272	391
Pharmaceutical \| Operating Segments \| Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	584	602
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| U.S.
Segment Reporting Information [Line Items]
Sales	172	160
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| Int’l
Segment Reporting Information [Line Items]
Sales	414	443
Animal Health \| Operating Segments
Segment Reporting Information [Line Items]
Sales	1,491	1,482
Animal Health \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	482	473
Animal Health \| Operating Segments \| Int’l
Segment Reporting Information [Line Items]
Sales	1,010	1,009
Animal Health \| Operating Segments \| Livestock
Segment Reporting Information [Line Items]
Sales	849	832
Animal Health \| Operating Segments \| Livestock \| U.S.
Segment Reporting Information [Line Items]
Sales	174	171
Animal Health \| Operating Segments \| Livestock \| Int’l
Segment Reporting Information [Line Items]
Sales	676	661
Animal Health \| Operating Segments \| Companion Animals
Segment Reporting Information [Line Items]
Sales	642	650
Animal Health \| Operating Segments \| Companion Animals \| U.S.
Segment Reporting Information [Line Items]
Sales	308	302
Animal Health \| Operating Segments \| Companion Animals \| Int’l
Segment Reporting Information [Line Items]
Sales	$ 334	$ 348