Segment Reporting - Sales from Products (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Sales	$ 15,962	$ 14,959	$ 45,485	$ 45,453
Increase in hedge revenue			173	533
Revenue related to the sale of the marketing rights			118	156
U.S.
Segment Reporting Information [Line Items]
Sales	7,715	7,322	21,393	20,927
Int’l
Segment Reporting Information [Line Items]
Sales	8,247	7,637	24,092	24,526
Operating Segments
Segment Reporting Information [Line Items]
Sales	15,663	14,334	44,789	44,146
Operating Segments | U.S.
Segment Reporting Information [Line Items]
Sales	7,615	7,095	21,258	20,544
Operating Segments | Int’l
Segment Reporting Information [Line Items]
Sales	8,048	7,239	23,531	23,601
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Sales	299	625	696	1,307
Corporate, Non-Segment | U.S.
Segment Reporting Information [Line Items]
Sales	100	227	135	383
Corporate, Non-Segment | Int’l
Segment Reporting Information [Line Items]
Sales	199	398	561	925
Pharmaceutical | Operating Segments
Segment Reporting Information [Line Items]
Sales	14,263	12,963	40,442	39,826
Pharmaceutical | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Sales	7,153	6,620	19,840	19,119
Pharmaceutical | Operating Segments | Int’l
Segment Reporting Information [Line Items]
Sales	7,110	6,343	20,602	20,707
Pharmaceutical | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	6,338	5,426	18,403	15,487
Pharmaceutical | Operating Segments | Keytruda | U.S.
Segment Reporting Information [Line Items]
Sales	3,795	3,331	11,142	9,307
Pharmaceutical | Operating Segments | Keytruda | Int’l
Segment Reporting Information [Line Items]
Sales	2,543	2,095	7,261	6,180
Pharmaceutical | Operating Segments | Alliance revenue - Lynparza
Segment Reporting Information [Line Items]
Sales	299	284	884	825
Pharmaceutical | Operating Segments | Alliance revenue - Lynparza | U.S.
Segment Reporting Information [Line Items]
Sales	153	144	439	427
Pharmaceutical | Operating Segments | Alliance revenue - Lynparza | Int’l
Segment Reporting Information [Line Items]
Sales	146	140	445	397
Pharmaceutical | Operating Segments | Alliance revenue - Lenvima
Segment Reporting Information [Line Items]
Sales	260	202	734	660
Pharmaceutical | Operating Segments | Alliance revenue - Lenvima | U.S.
Segment Reporting Information [Line Items]
Sales	160	142	476	426
Pharmaceutical | Operating Segments | Alliance revenue - Lenvima | Int’l
Segment Reporting Information [Line Items]
Sales	100	60	258	235
Pharmaceutical | Operating Segments | Welireg
Segment Reporting Information [Line Items]
Sales	54	38	146	83
Pharmaceutical | Operating Segments | Welireg | U.S.
Segment Reporting Information [Line Items]
Sales	51	38	141	83
Pharmaceutical | Operating Segments | Welireg | Int’l
Segment Reporting Information [Line Items]
Sales	3	0	6	0
Pharmaceutical | Operating Segments | Alliance Revenue - Reblozyl
Segment Reporting Information [Line Items]
Revenue from collaborative arrangement	52	39	142	124
Pharmaceutical | Operating Segments | Alliance Revenue - Reblozyl | U.S.
Segment Reporting Information [Line Items]
Sales	43	32	108	87
Pharmaceutical | Operating Segments | Alliance Revenue - Reblozyl | Int’l
Segment Reporting Information [Line Items]
Sales	10	7	33	37
Pharmaceutical | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	2,585	2,294	7,015	5,428
Pharmaceutical | Operating Segments | Gardasil/Gardasil 9 | U.S.
Segment Reporting Information [Line Items]
Sales	838	957	1,718	1,803
Pharmaceutical | Operating Segments | Gardasil/Gardasil 9 | Int’l
Segment Reporting Information [Line Items]
Sales	1,746	1,337	5,297	3,624
Pharmaceutical | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	713	668	1,823	1,716
Pharmaceutical | Operating Segments | ProQuad/M-M-R II/Varivax | U.S.
Segment Reporting Information [Line Items]
Sales	567	532	1,435	1,337
Pharmaceutical | Operating Segments | ProQuad/M-M-R II/Varivax | Int’l
Segment Reporting Information [Line Items]
Sales	146	136	388	379
Pharmaceutical | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	156	256	584	644
Pharmaceutical | Operating Segments | RotaTeq | U.S.
Segment Reporting Information [Line Items]
Sales	108	154	381	427
Pharmaceutical | Operating Segments | RotaTeq | Int’l
Segment Reporting Information [Line Items]
Sales	48	102	203	218
Pharmaceutical | Operating Segments | Vaxneuvance
Segment Reporting Information [Line Items]
Sales	214	16	488	32
Pharmaceutical | Operating Segments | Vaxneuvance | U.S.
Segment Reporting Information [Line Items]
Sales	182	15	423	31
Pharmaceutical | Operating Segments | Vaxneuvance | Int’l
Segment Reporting Information [Line Items]
Sales	33	1	65	1
Pharmaceutical | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	140	131	327	457
Pharmaceutical | Operating Segments | Pneumovax 23 | U.S.
Segment Reporting Information [Line Items]
Sales	42	68	105	280
Pharmaceutical | Operating Segments | Pneumovax 23 | Int’l
Segment Reporting Information [Line Items]
Sales	98	63	223	177
Pharmaceutical | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	69	64	151	134
Pharmaceutical | Operating Segments | Vaqta | U.S.
Segment Reporting Information [Line Items]
Sales	32	27	91	72
Pharmaceutical | Operating Segments | Vaqta | Int’l
Segment Reporting Information [Line Items]
Sales	37	36	60	62
Pharmaceutical | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	424	423	1,413	1,244
Pharmaceutical | Operating Segments | Bridion | U.S.
Segment Reporting Information [Line Items]
Sales	265	233	841	665
Pharmaceutical | Operating Segments | Bridion | Int’l
Segment Reporting Information [Line Items]
Sales	159	190	572	579
Pharmaceutical | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	157	114	430	310
Pharmaceutical | Operating Segments | Prevymis | U.S.
Segment Reporting Information [Line Items]
Sales	70	49	186	136
Pharmaceutical | Operating Segments | Prevymis | Int’l
Segment Reporting Information [Line Items]
Sales	87	64	244	174
Pharmaceutical | Operating Segments | Dificid
Segment Reporting Information [Line Items]
Sales	74	77	215	196
Pharmaceutical | Operating Segments | Dificid | U.S.
Segment Reporting Information [Line Items]
Sales	69	72	199	184
Pharmaceutical | Operating Segments | Dificid | Int’l
Segment Reporting Information [Line Items]
Sales	5	6	16	12
Pharmaceutical | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	41	63	174	185
Pharmaceutical | Operating Segments | Primaxin | U.S.
Segment Reporting Information [Line Items]
Sales	0	0	2	1
Pharmaceutical | Operating Segments | Primaxin | Int’l
Segment Reporting Information [Line Items]
Sales	41	63	173	185
Pharmaceutical | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	51	62	167	180
Pharmaceutical | Operating Segments | Noxafil | U.S.
Segment Reporting Information [Line Items]
Sales	4	13	29	39
Pharmaceutical | Operating Segments | Noxafil | Int’l
Segment Reporting Information [Line Items]
Sales	47	49	138	141
Pharmaceutical | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	53	43	157	120
Pharmaceutical | Operating Segments | Zerbaxa | U.S.
Segment Reporting Information [Line Items]
Sales	29	24	86	64
Pharmaceutical | Operating Segments | Zerbaxa | Int’l
Segment Reporting Information [Line Items]
Sales	24	19	71	55
Pharmaceutical | Operating Segments | Alliance revenue - Adempas/Verquvo
Segment Reporting Information [Line Items]
Sales	92	88	259	258
Pharmaceutical | Operating Segments | Alliance revenue - Adempas/Verquvo | U.S.
Segment Reporting Information [Line Items]
Sales	96	85	249	244
Pharmaceutical | Operating Segments | Alliance revenue - Adempas/Verquvo | Int’l
Segment Reporting Information [Line Items]
Sales	(4)	3	10	14
Pharmaceutical | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	65	57	189	181
Pharmaceutical | Operating Segments | Adempas | U.S.
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Pharmaceutical | Operating Segments | Adempas | Int’l
Segment Reporting Information [Line Items]
Sales	65	57	189	181
Pharmaceutical | Operating Segments | Lagevrio
Segment Reporting Information [Line Items]
Sales	640	436	1,236	4,859
Pharmaceutical | Operating Segments | Lagevrio | U.S.
Segment Reporting Information [Line Items]
Sales	0	0	0	1,523
Pharmaceutical | Operating Segments | Lagevrio | Int’l
Segment Reporting Information [Line Items]
Sales	640	436	1,236	3,336
Pharmaceutical | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	119	161	377	466
Pharmaceutical | Operating Segments | Isentress/Isentress HD | U.S.
Segment Reporting Information [Line Items]
Sales	58	68	165	196
Pharmaceutical | Operating Segments | Isentress/Isentress HD | Int’l
Segment Reporting Information [Line Items]
Sales	61	93	212	270
Pharmaceutical | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	58	62	176	199
Pharmaceutical | Operating Segments | Belsomra | U.S.
Segment Reporting Information [Line Items]
Sales	23	20	60	60
Pharmaceutical | Operating Segments | Belsomra | Int’l
Segment Reporting Information [Line Items]
Sales	35	42	117	139
Pharmaceutical | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	179	173	539	540
Pharmaceutical | Operating Segments | Simponi | U.S.
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Pharmaceutical | Operating Segments | Simponi | Int’l
Segment Reporting Information [Line Items]
Sales	179	173	539	540
Pharmaceutical | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	45	49	144	163
Pharmaceutical | Operating Segments | Remicade | U.S.
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Pharmaceutical | Operating Segments | Remicade | Int’l
Segment Reporting Information [Line Items]
Sales	45	49	144	163
Pharmaceutical | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	581	717	1,642	2,252
Pharmaceutical | Operating Segments | Januvia | U.S.
Segment Reporting Information [Line Items]
Sales	328	332	842	958
Pharmaceutical | Operating Segments | Januvia | Int’l
Segment Reporting Information [Line Items]
Sales	252	385	800	1,294
Pharmaceutical | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	255	417	937	1,347
Pharmaceutical | Operating Segments | Janumet | U.S.
Segment Reporting Information [Line Items]
Sales	43	90	182	258
Pharmaceutical | Operating Segments | Janumet | Int’l
Segment Reporting Information [Line Items]
Sales	211	327	755	1,089
Pharmaceutical | Operating Segments | Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	549	603	1,690	1,736
Pharmaceutical | Operating Segments | Other pharmaceutical | U.S.
Segment Reporting Information [Line Items]
Sales	197	194	540	511
Pharmaceutical | Operating Segments | Other pharmaceutical | Int’l
Segment Reporting Information [Line Items]
Sales	353	410	1,147	1,225
Animal Health | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,400	1,371	4,347	4,320
Animal Health | Operating Segments | U.S.
Segment Reporting Information [Line Items]
Sales	462	475	1,418	1,425
Animal Health | Operating Segments | Int’l
Segment Reporting Information [Line Items]
Sales	938	896	2,929	2,894
Animal Health | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	874	829	2,530	2,486
Animal Health | Operating Segments | Livestock | U.S.
Segment Reporting Information [Line Items]
Sales	205	186	543	521
Animal Health | Operating Segments | Livestock | Int’l
Segment Reporting Information [Line Items]
Sales	669	643	1,987	1,965
Animal Health | Operating Segments | Companion Animal
Segment Reporting Information [Line Items]
Sales	526	542	1,817	1,834
Animal Health | Operating Segments | Companion Animal | U.S.
Segment Reporting Information [Line Items]
Sales	257	289	875	904
Animal Health | Operating Segments | Companion Animal | Int’l
Segment Reporting Information [Line Items]
Sales	$ 269	$ 253	$ 942	$ 929