Segment Reporting - Sales from Products (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Sales	$ 16,112	$ 15,035	$ 31,887	$ 29,522
Increase in hedge revenue			118	128
Revenue related to the sale of the marketing rights			76	54
U.S.
Segment Reporting Information [Line Items]
Sales	7,876	7,018	15,354	13,676
Non-US
Segment Reporting Information [Line Items]
Sales	8,236	8,018	16,533	15,846
Operating Segments
Segment Reporting Information [Line Items]
Sales	15,890	14,913	31,408	29,126
Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	7,854	7,045	15,265	13,644
Operating Segments \| Non-US
Segment Reporting Information [Line Items]
Sales	8,036	7,869	16,143	15,482
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Sales	222	122	479	396
Corporate, Non-Segment \| U.S.
Segment Reporting Information [Line Items]
Sales	22	(27)	89	32
Corporate, Non-Segment \| Non-US
Segment Reporting Information [Line Items]
Sales	200	149	390	364
Pharmaceutical \| Operating Segments
Segment Reporting Information [Line Items]
Sales	14,408	13,457	28,415	26,179
Pharmaceutical \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	7,399	6,570	14,336	12,688
Pharmaceutical \| Operating Segments \| Non-US
Segment Reporting Information [Line Items]
Sales	7,009	6,887	14,079	13,491
Pharmaceutical \| Operating Segments \| Keytruda
Segment Reporting Information [Line Items]
Sales	7,270	6,271	14,217	12,065
Pharmaceutical \| Operating Segments \| Keytruda \| U.S.
Segment Reporting Information [Line Items]
Sales	4,412	3,863	8,531	7,348
Pharmaceutical \| Operating Segments \| Keytruda \| Non-US
Segment Reporting Information [Line Items]
Sales	2,858	2,408	5,686	4,718
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza
Segment Reporting Information [Line Items]
Sales	317	310	609	585
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| U.S.
Segment Reporting Information [Line Items]
Sales	153	144	288	286
Pharmaceutical \| Operating Segments \| Alliance revenue - Lynparza \| Non-US
Segment Reporting Information [Line Items]
Sales	165	166	321	299
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima
Segment Reporting Information [Line Items]
Sales	249	242	504	474
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| U.S.
Segment Reporting Information [Line Items]
Sales	177	163	349	316
Pharmaceutical \| Operating Segments \| Alliance revenue - Lenvima \| Non-US
Segment Reporting Information [Line Items]
Sales	73	79	155	158
Pharmaceutical \| Operating Segments \| Welireg
Segment Reporting Information [Line Items]
Sales	126	50	211	92
Pharmaceutical \| Operating Segments \| Welireg \| U.S.
Segment Reporting Information [Line Items]
Sales	116	49	194	90
Pharmaceutical \| Operating Segments \| Welireg \| Non-US
Segment Reporting Information [Line Items]
Sales	10	2	17	3
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl
Segment Reporting Information [Line Items]
Sales	90	47	161	90
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| U.S.
Segment Reporting Information [Line Items]
Sales	75	36	133	66
Pharmaceutical \| Operating Segments \| Alliance Revenue - Reblozyl \| Non-US
Segment Reporting Information [Line Items]
Sales	15	11	28	24
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	2,478	2,458	4,727	4,430
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| U.S.
Segment Reporting Information [Line Items]
Sales	536	464	1,024	880
Pharmaceutical \| Operating Segments \| Gardasil/Gardasil 9 \| Non-US
Segment Reporting Information [Line Items]
Sales	1,941	1,994	3,702	3,550
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	617	582	1,187	1,109
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| U.S.
Segment Reporting Information [Line Items]
Sales	490	447	928	868
Pharmaceutical \| Operating Segments \| ProQuad/M-M-R II/Varivax \| Non-US
Segment Reporting Information [Line Items]
Sales	127	135	259	242
Pharmaceutical \| Operating Segments \| Vaxneuvance
Segment Reporting Information [Line Items]
Sales	189	168	408	274
Pharmaceutical \| Operating Segments \| Vaxneuvance \| U.S.
Segment Reporting Information [Line Items]
Sales	99	147	260	241
Pharmaceutical \| Operating Segments \| Vaxneuvance \| Non-US
Segment Reporting Information [Line Items]
Sales	90	20	148	33
Pharmaceutical \| Operating Segments \| RotaTeq
Segment Reporting Information [Line Items]
Sales	163	131	379	428
Pharmaceutical \| Operating Segments \| RotaTeq \| U.S.
Segment Reporting Information [Line Items]
Sales	107	93	257	273
Pharmaceutical \| Operating Segments \| RotaTeq \| Non-US
Segment Reporting Information [Line Items]
Sales	56	37	123	155
Pharmaceutical \| Operating Segments \| Pneumovax 23
Segment Reporting Information [Line Items]
Sales	59	92	120	188
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| U.S.
Segment Reporting Information [Line Items]
Sales	11	23	17	63
Pharmaceutical \| Operating Segments \| Pneumovax 23 \| Non-US
Segment Reporting Information [Line Items]
Sales	48	69	103	125
Pharmaceutical \| Operating Segments \| Bridion
Segment Reporting Information [Line Items]
Sales	455	502	895	989
Pharmaceutical \| Operating Segments \| Bridion \| U.S.
Segment Reporting Information [Line Items]
Sales	351	299	680	576
Pharmaceutical \| Operating Segments \| Bridion \| Non-US
Segment Reporting Information [Line Items]
Sales	104	203	215	413
Pharmaceutical \| Operating Segments \| Prevymis
Segment Reporting Information [Line Items]
Sales	188	143	362	273
Pharmaceutical \| Operating Segments \| Prevymis \| U.S.
Segment Reporting Information [Line Items]
Sales	90	61	165	116
Pharmaceutical \| Operating Segments \| Prevymis \| Non-US
Segment Reporting Information [Line Items]
Sales	98	82	197	157
Pharmaceutical \| Operating Segments \| Dificid
Segment Reporting Information [Line Items]
Sales	92	76	165	141
Pharmaceutical \| Operating Segments \| Dificid \| U.S.
Segment Reporting Information [Line Items]
Sales	79	68	147	130
Pharmaceutical \| Operating Segments \| Dificid \| Non-US
Segment Reporting Information [Line Items]
Sales	12	8	17	11
Pharmaceutical \| Operating Segments \| Zerbaxa
Segment Reporting Information [Line Items]
Sales	62	54	118	104
Pharmaceutical \| Operating Segments \| Zerbaxa \| U.S.
Segment Reporting Information [Line Items]
Sales	33	30	67	57
Pharmaceutical \| Operating Segments \| Zerbaxa \| Non-US
Segment Reporting Information [Line Items]
Sales	28	24	51	47
Pharmaceutical \| Operating Segments \| Noxafil
Segment Reporting Information [Line Items]
Sales	45	55	101	116
Pharmaceutical \| Operating Segments \| Noxafil \| U.S.
Segment Reporting Information [Line Items]
Sales	0	11	8	25
Pharmaceutical \| Operating Segments \| Noxafil \| Non-US
Segment Reporting Information [Line Items]
Sales	44	45	92	91
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo
Segment Reporting Information [Line Items]
Sales	106	68	203	167
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| U.S.
Segment Reporting Information [Line Items]
Sales	98	70	188	153
Pharmaceutical \| Operating Segments \| Alliance revenue - Adempas/Verquvo \| Non-US
Segment Reporting Information [Line Items]
Sales	8	(2)	16	14
Pharmaceutical \| Operating Segments \| Adempas
Segment Reporting Information [Line Items]
Sales	72	65	142	125
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	142	125
Pharmaceutical \| Operating Segments \| Winrevair
Segment Reporting Information [Line Items]
Sales	70	0	70	0
Pharmaceutical \| Operating Segments \| Winrevair \| U.S.
Segment Reporting Information [Line Items]
Sales	70	0	70	0
Pharmaceutical \| Operating Segments \| Winrevair \| Non-US
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Pharmaceutical \| Operating Segments \| Lagevrio
Segment Reporting Information [Line Items]
Sales	110	203	460	595
Pharmaceutical \| Operating Segments \| Lagevrio \| U.S.
Segment Reporting Information [Line Items]
Sales	15	2	60	0
Pharmaceutical \| Operating Segments \| Lagevrio \| Non-US
Segment Reporting Information [Line Items]
Sales	95	201	400	595
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	89	136	200	259
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| U.S.
Segment Reporting Information [Line Items]
Sales	43	56	93	108
Pharmaceutical \| Operating Segments \| Isentress/Isentress HD \| Non-US
Segment Reporting Information [Line Items]
Sales	46	80	107	151
Pharmaceutical \| Operating Segments \| Delstrigo
Segment Reporting Information [Line Items]
Sales	60	50	116	94
Pharmaceutical \| Operating Segments \| Delstrigo \| U.S.
Segment Reporting Information [Line Items]
Sales	14	13	26	24
Pharmaceutical \| Operating Segments \| Delstrigo \| Non-US
Segment Reporting Information [Line Items]
Sales	45	37	89	70
Pharmaceutical \| Operating Segments \| Pifeltro
Segment Reporting Information [Line Items]
Sales	39	38	81	72
Pharmaceutical \| Operating Segments \| Pifeltro \| U.S.
Segment Reporting Information [Line Items]
Sales	27	27	56	51
Pharmaceutical \| Operating Segments \| Pifeltro \| Non-US
Segment Reporting Information [Line Items]
Sales	12	11	25	21
Pharmaceutical \| Operating Segments \| Belsomra
Segment Reporting Information [Line Items]
Sales	53	63	99	119
Pharmaceutical \| Operating Segments \| Belsomra \| U.S.
Segment Reporting Information [Line Items]
Sales	19	21	33	37
Pharmaceutical \| Operating Segments \| Belsomra \| Non-US
Segment Reporting Information [Line Items]
Sales	34	42	66	82
Pharmaceutical \| Operating Segments \| Simponi
Segment Reporting Information [Line Items]
Sales	172	180	356	359
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	172	180	356	359
Pharmaceutical \| Operating Segments \| Remicade
Segment Reporting Information [Line Items]
Sales	35	48	74	99
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	35	48	74	99
Pharmaceutical \| Operating Segments \| Januvia
Segment Reporting Information [Line Items]
Sales	405	511	824	1,062
Pharmaceutical \| Operating Segments \| Januvia \| U.S.
Segment Reporting Information [Line Items]
Sales	177	243	361	514
Pharmaceutical \| Operating Segments \| Januvia \| Non-US
Segment Reporting Information [Line Items]
Sales	227	267	463	548
Pharmaceutical \| Operating Segments \| Janumet
Segment Reporting Information [Line Items]
Sales	224	354	475	683
Pharmaceutical \| Operating Segments \| Janumet \| U.S.
Segment Reporting Information [Line Items]
Sales	17	82	55	138
Pharmaceutical \| Operating Segments \| Janumet \| Non-US
Segment Reporting Information [Line Items]
Sales	208	272	420	544
Pharmaceutical \| Operating Segments \| Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	573	560	1,151	1,187
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| U.S.
Segment Reporting Information [Line Items]
Sales	190	158	346	328
Pharmaceutical \| Operating Segments \| Other pharmaceutical \| Non-US
Segment Reporting Information [Line Items]
Sales	386	403	807	857
Animal Health \| Operating Segments
Segment Reporting Information [Line Items]
Sales	1,482	1,456	2,993	2,947
Animal Health \| Operating Segments \| U.S.
Segment Reporting Information [Line Items]
Sales	455	475	929	956
Animal Health \| Operating Segments \| Non-US
Segment Reporting Information [Line Items]
Sales	1,027	982	2,064	1,991
Animal Health \| Operating Segments \| Livestock
Segment Reporting Information [Line Items]
Sales	837	807	1,686	1,656
Animal Health \| Operating Segments \| Livestock \| U.S.
Segment Reporting Information [Line Items]
Sales	168	165	334	338
Animal Health \| Operating Segments \| Livestock \| Non-US
Segment Reporting Information [Line Items]
Sales	669	643	1,352	1,318
Animal Health \| Operating Segments \| Companion Animal
Segment Reporting Information [Line Items]
Sales	645	649	1,307	1,291
Animal Health \| Operating Segments \| Companion Animal \| U.S.
Segment Reporting Information [Line Items]
Sales	287	310	595	618
Animal Health \| Operating Segments \| Companion Animal \| Non-US
Segment Reporting Information [Line Items]
Sales	$ 358	$ 339	$ 712	$ 673