Segment Reporting - Sales from Products (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Segment Reporting Information [Line Items]
Sales	$ 16,657	$ 15,962	$ 48,544	$ 45,485
Increase in hedge revenue			156	173
Revenue related to the sale of the marketing rights			91	118
U.S.
Segment Reporting Information [Line Items]
Sales	8,736	7,715	24,089	21,393
Non-US
Segment Reporting Information [Line Items]
Sales	7,922	8,247	24,455	24,092
Operating Segments
Segment Reporting Information [Line Items]
Sales	16,430	15,663	47,838	44,789
Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	8,714	7,615	23,980	21,258
Operating Segments \| Non-US
Segment Reporting Information [Line Items]
Sales	7,716	8,048	23,858	23,531
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Sales	227	299	706	696
Corporate, Non-Segment \| U.S.
Segment Reporting Information [Line Items]
Sales	22	100	109	135
Corporate, Non-Segment \| Non-US
Segment Reporting Information [Line Items]
Sales	206	199	597	561
Pharmaceutical \| Operating Segments
Segment Reporting Information [Line Items]
Sales	14,943	14,263	43,358	40,442
Pharmaceutical \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	8,227	7,153	22,563	19,840
Pharmaceutical \| Operating Segments \| Non-US
Segment Reporting Information [Line Items]
Sales	6,717	7,110	20,795	20,602
Pharmaceutical \| Operating Segments \| Keytruda
Segment Reporting Information [Line Items]
Sales	7,429	6,338	21,646	18,403
Pharmaceutical \| Operating Segments \| Keytruda \| U.S.
Segment Reporting Information [Line Items]
Sales	4,500	3,795	13,031	11,142
Pharmaceutical \| Operating Segments \| Keytruda \| Non-US
Segment Reporting Information [Line Items]
Sales	2,929	2,543	8,614	7,261
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza
Segment Reporting Information [Line Items]
Sales	337	299	947	884
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| U.S.
Segment Reporting Information [Line Items]
Sales	161	153	449	439
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| Non-US
Segment Reporting Information [Line Items]
Sales	177	146	498	445
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima
Segment Reporting Information [Line Items]
Sales	251	260	755	734
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| U.S.
Segment Reporting Information [Line Items]
Sales	173	160	523	476
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| Non-US
Segment Reporting Information [Line Items]
Sales	78	100	233	258
Pharmaceutical \| Operating Segments \| Welireg
Segment Reporting Information [Line Items]
Sales	139	54	349	146
Pharmaceutical \| Operating Segments \| Welireg \| U.S.
Segment Reporting Information [Line Items]
Sales	127	51	320	141
Pharmaceutical \| Operating Segments \| Welireg \| Non-US
Segment Reporting Information [Line Items]
Sales	12	3	29	6
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl
Segment Reporting Information [Line Items]
Sales	100	52	261	142
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| U.S.
Segment Reporting Information [Line Items]
Sales	82	43	215	108
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| Non-US
Segment Reporting Information [Line Items]
Sales	18	10	45	33
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	2,306	2,585	7,032	7,015
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| U.S.
Segment Reporting Information [Line Items]
Sales	1,020	838	2,045	1,718
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| Non-US
Segment Reporting Information [Line Items]
Sales	1,285	1,746	4,988	5,297
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	703	713	1,891	1,823
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| U.S.
Segment Reporting Information [Line Items]
Sales	572	567	1,500	1,435
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| Non-US
Segment Reporting Information [Line Items]
Sales	131	146	391	388
Pharmaceutical \| Operating Segments \| Vaxneuvance
Segment Reporting Information [Line Items]
Sales	239	214	647	488
Pharmaceutical \| Operating Segments \| Vaxneuvance \| U.S.
Segment Reporting Information [Line Items]
Sales	137	182	397	423
Pharmaceutical \| Operating Segments \| Vaxneuvance \| Non-US
Segment Reporting Information [Line Items]
Sales	103	33	251	65
Pharmaceutical \| Operating Segments \| RotaTeq
Segment Reporting Information [Line Items]
Sales	193	156	572	584
Pharmaceutical \| Operating Segments \| RotaTeq \| U.S.
Segment Reporting Information [Line Items]
Sales	131	108	388	381
Pharmaceutical \| Operating Segments \| RotaTeq \| Non-US
Segment Reporting Information [Line Items]
Sales	62	48	185	203
Pharmaceutical \| Operating Segments \| Pneumovax 23
Segment Reporting Information [Line Items]
Sales	68	140	188	327
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| U.S.
Segment Reporting Information [Line Items]
Sales	19	42	36	105
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| Non-US
Segment Reporting Information [Line Items]
Sales	49	98	152	223
Pharmaceutical \| Operating Segments \| Bridion
Segment Reporting Information [Line Items]
Sales	420	424	1,315	1,413
Pharmaceutical \| Operating Segments \| Bridion \| U.S.
Segment Reporting Information [Line Items]
Sales	339	265	1,020	841
Pharmaceutical \| Operating Segments \| Bridion \| Non-US
Segment Reporting Information [Line Items]
Sales	81	159	296	572
Pharmaceutical \| Operating Segments \| Prevymis
Segment Reporting Information [Line Items]
Sales	208	157	570	430
Pharmaceutical \| Operating Segments \| Prevymis \| U.S.
Segment Reporting Information [Line Items]
Sales	101	70	265	186
Pharmaceutical \| Operating Segments \| Prevymis \| Non-US
Segment Reporting Information [Line Items]
Sales	107	87	305	244
Pharmaceutical \| Operating Segments \| Dificid
Segment Reporting Information [Line Items]
Sales	96	74	261	215
Pharmaceutical \| Operating Segments \| Dificid \| U.S.
Segment Reporting Information [Line Items]
Sales	83	69	231	199
Pharmaceutical \| Operating Segments \| Dificid \| Non-US
Segment Reporting Information [Line Items]
Sales	13	5	30	16
Pharmaceutical \| Operating Segments \| Zerbaxa
Segment Reporting Information [Line Items]
Sales	64	53	182	157
Pharmaceutical \| Operating Segments \| Zerbaxa \| U.S.
Segment Reporting Information [Line Items]
Sales	39	29	106	86
Pharmaceutical \| Operating Segments \| Zerbaxa \| Non-US
Segment Reporting Information [Line Items]
Sales	26	24	77	71
Pharmaceutical \| Operating Segments \| Noxafil
Segment Reporting Information [Line Items]
Sales	41	51	141	167
Pharmaceutical \| Operating Segments \| Noxafil \| U.S.
Segment Reporting Information [Line Items]
Sales	1	4	9	29
Pharmaceutical \| Operating Segments \| Noxafil \| Non-US
Segment Reporting Information [Line Items]
Sales	40	47	132	138
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo
Segment Reporting Information [Line Items]
Sales	102	92	306	259
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| U.S.
Segment Reporting Information [Line Items]
Sales	96	96	283	249
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| Non-US
Segment Reporting Information [Line Items]
Sales	7	(4)	22	10
Pharmaceutical \| Operating Segments \| Adempas
Segment Reporting Information [Line Items]
Sales	72	65	214	189
Pharmaceutical \| Operating Segments \| Adempas \| U.S.
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Pharmaceutical \| Operating Segments \| Adempas \| Non-US
Segment Reporting Information [Line Items]
Sales	72	65	214	189
Pharmaceutical \| Operating Segments \| Winrevair
Segment Reporting Information [Line Items]
Sales	149	0	219	0
Pharmaceutical \| Operating Segments \| Winrevair \| U.S.
Segment Reporting Information [Line Items]
Sales	147	0	216	0
Pharmaceutical \| Operating Segments \| Winrevair \| Non-US
Segment Reporting Information [Line Items]
Sales	3	0	3	0
Pharmaceutical \| Operating Segments \| Lagevrio
Segment Reporting Information [Line Items]
Sales	383	640	843	1,236
Pharmaceutical \| Operating Segments \| Lagevrio \| U.S.
Segment Reporting Information [Line Items]
Sales	84	0	144	0
Pharmaceutical \| Operating Segments \| Lagevrio \| Non-US
Segment Reporting Information [Line Items]
Sales	299	640	699	1,236
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	102	119	302	377
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| U.S.
Segment Reporting Information [Line Items]
Sales	54	58	147	165
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| Non-US
Segment Reporting Information [Line Items]
Sales	48	61	155	212
Pharmaceutical \| Operating Segments \| Delstrigo
Segment Reporting Information [Line Items]
Sales	65	54	180	148
Pharmaceutical \| Operating Segments \| Delstrigo \| U.S.
Segment Reporting Information [Line Items]
Sales	15	13	42	37
Pharmaceutical \| Operating Segments \| Delstrigo \| Non-US
Segment Reporting Information [Line Items]
Sales	50	40	139	110
Pharmaceutical \| Operating Segments \| Pifeltro
Segment Reporting Information [Line Items]
Sales	42	37	123	109
Pharmaceutical \| Operating Segments \| Pifeltro \| U.S.
Segment Reporting Information [Line Items]
Sales	31	27	86	78
Pharmaceutical \| Operating Segments \| Pifeltro \| Non-US
Segment Reporting Information [Line Items]
Sales	12	10	37	31
Pharmaceutical \| Operating Segments \| Belsomra
Segment Reporting Information [Line Items]
Sales	78	58	177	176
Pharmaceutical \| Operating Segments \| Belsomra \| U.S.
Segment Reporting Information [Line Items]
Sales	20	23	53	60
Pharmaceutical \| Operating Segments \| Belsomra \| Non-US
Segment Reporting Information [Line Items]
Sales	58	35	124	117
Pharmaceutical \| Operating Segments \| Simponi
Segment Reporting Information [Line Items]
Sales	189	179	545	539
Pharmaceutical \| Operating Segments \| Simponi \| U.S.
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Pharmaceutical \| Operating Segments \| Simponi \| Non-US
Segment Reporting Information [Line Items]
Sales	189	179	545	539
Pharmaceutical \| Operating Segments \| Remicade
Segment Reporting Information [Line Items]
Sales	41	45	115	144
Pharmaceutical \| Operating Segments \| Remicade \| U.S.
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Pharmaceutical \| Operating Segments \| Remicade \| Non-US
Segment Reporting Information [Line Items]
Sales	41	45	115	144
Pharmaceutical \| Operating Segments \| Januvia
Segment Reporting Information [Line Items]
Sales	278	581	1,102	1,642
Pharmaceutical \| Operating Segments \| Januvia \| U.S.
Segment Reporting Information [Line Items]
Sales	67	328	428	842
Pharmaceutical \| Operating Segments \| Januvia \| Non-US
Segment Reporting Information [Line Items]
Sales	211	252	674	800
Pharmaceutical \| Operating Segments \| Janumet
Segment Reporting Information [Line Items]
Sales	204	255	679	937
Pharmaceutical \| Operating Segments \| Janumet \| U.S.
Segment Reporting Information [Line Items]
Sales	15	43	70	182
Pharmaceutical \| Operating Segments \| Janumet \| Non-US
Segment Reporting Information [Line Items]
Sales	190	211	610	755
Pharmaceutical \| Operating Segments \| Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	644	568	1,796	1,758
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| U.S.
Segment Reporting Information [Line Items]
Sales	213	189	559	518
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| Non-US
Segment Reporting Information [Line Items]
Sales	426	381	1,232	1,239
Animal Health \| Operating Segments
Segment Reporting Information [Line Items]
Sales	1,487	1,400	4,480	4,347
Animal Health \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	487	462	1,417	1,418
Animal Health \| Operating Segments \| Non-US
Segment Reporting Information [Line Items]
Sales	999	938	3,063	2,929
Animal Health \| Operating Segments \| Livestock
Segment Reporting Information [Line Items]
Sales	886	874	2,573	2,530
Animal Health \| Operating Segments \| Livestock \| U.S.
Segment Reporting Information [Line Items]
Sales	194	205	529	543
Animal Health \| Operating Segments \| Livestock \| Non-US
Segment Reporting Information [Line Items]
Sales	692	669	2,044	1,987
Animal Health \| Operating Segments \| Companion Animal
Segment Reporting Information [Line Items]
Sales	601	526	1,907	1,817
Animal Health \| Operating Segments \| Companion Animal \| U.S.
Segment Reporting Information [Line Items]
Sales	293	257	888	875
Animal Health \| Operating Segments \| Companion Animal \| Non-US
Segment Reporting Information [Line Items]
Sales	$ 307	$ 269	$ 1,019	$ 942