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Segment Reporting - Sales of Company's Products (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Sales	$ 11,402	$ 9,353	$ 22,029	$ 19,641
Operating Segments
Segment Reporting Information [Line Items]
Sales	11,452	9,279	22,108	19,420
Other
Segment Reporting Information [Line Items]
Sales	(50)	74	(79)	221
United States
Segment Reporting Information [Line Items]
Sales	5,100	4,322	9,890	9,053
United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	5,106	4,300	9,837	9,015
United States | Other
Segment Reporting Information [Line Items]
Sales	(6)	22	53	38
International
Segment Reporting Information [Line Items]
Sales	6,301	5,031	12,139	10,588
International | Operating Segments
Segment Reporting Information [Line Items]
Sales	6,345	4,979	12,271	10,406
International | Other
Segment Reporting Information [Line Items]
Sales	(44)	52	(132)	182
Total Pharmaceutical segment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	9,980	8,178	19,218	17,083
Total Pharmaceutical segment sales | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	4,176	3,388	8,076	6,672
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	248	178	475	323
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	181	151	310	279
Total Pharmaceutical segment sales | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	1,234	656	2,151	1,753
Total Pharmaceutical segment sales | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	516	378	965	813
Total Pharmaceutical segment sales | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	208	168	366	391
Total Pharmaceutical segment sales | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	152	117	323	373
Total Pharmaceutical segment sales | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	56	28	90	88
Total Pharmaceutical segment sales | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	387	224	727	524
Total Pharmaceutical segment sales | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	93	63	174	123
Total Pharmaceutical segment sales | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	66	73	133	168
Total Pharmaceutical segment sales | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	60	64	125	115
Total Pharmaceutical segment sales | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	54	43	111	98
Total Pharmaceutical segment sales | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	48	43	104	108
Total Pharmaceutical segment sales | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	(1)	32	(9)	69
Total Pharmaceutical segment sales | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	202	191	416	406
Total Pharmaceutical segment sales | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	75	73	160	160
Total Pharmaceutical segment sales | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	78	84	157	163
Total Pharmaceutical segment sales | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	192	196	401	441
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue-Adempas/Verquvo (2)
Segment Reporting Information [Line Items]
Sales	74	79	149	133
Total Pharmaceutical segment sales | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	74	57	129	113
Total Pharmaceutical segment sales | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	784	854	1,593	1,628
Total Pharmaceutical segment sales | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	477	490	962	993
Total Pharmaceutical segment sales | Operating Segments | Other pharmaceutical (3)
Segment Reporting Information [Line Items]
Sales	546	548	1,130	1,149
Total Pharmaceutical segment sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	4,647	3,958	8,941	8,266
Total Pharmaceutical segment sales | United States | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	2,347	2,043	4,528	3,949
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	124	105	242	190
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	88	98	173	188
Total Pharmaceutical segment sales | United States | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	454	168	766	629
Total Pharmaceutical segment sales | United States | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	386	263	718	596
Total Pharmaceutical segment sales | United States | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	111	100	229	241
Total Pharmaceutical segment sales | United States | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	100	21	173	203
Total Pharmaceutical segment sales | United States | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	22	17	47	47
Total Pharmaceutical segment sales | United States | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	197	107	364	250
Total Pharmaceutical segment sales | United States | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	37	28	72	55
Total Pharmaceutical segment sales | United States | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	14	6	29	14
Total Pharmaceutical segment sales | United States | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	0	1	0	1
Total Pharmaceutical segment sales | United States | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	1	(2)	3	1
Total Pharmaceutical segment sales | United States | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	(4)	0	0	6
Total Pharmaceutical segment sales | United States | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	(2)	17	(4)	37
Total Pharmaceutical segment sales | United States | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	14	22	32	49
Total Pharmaceutical segment sales | United States | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	74	76	145	151
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue-Adempas/Verquvo (2)
Segment Reporting Information [Line Items]
Sales	81	73	149	122
Total Pharmaceutical segment sales | United States | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	284	413	632	768
Total Pharmaceutical segment sales | United States | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	74	143	158	256
Total Pharmaceutical segment sales | United States | Operating Segments | Other pharmaceutical (3)
Segment Reporting Information [Line Items]
Sales	245	259	485	513
Total Pharmaceutical segment sales | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	5,333	4,220	10,277	8,818
Total Pharmaceutical segment sales | International | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	1,829	1,345	3,548	2,722
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	124	73	233	133
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	93	53	137	91
Total Pharmaceutical segment sales | International | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	781	488	1,385	1,124
Total Pharmaceutical segment sales | International | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	130	115	246	217
Total Pharmaceutical segment sales | International | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	97	68	137	150
Total Pharmaceutical segment sales | International | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	52	96	150	170
Total Pharmaceutical segment sales | International | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	34	11	43	41
Total Pharmaceutical segment sales | International | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	190	117	363	274
Total Pharmaceutical segment sales | International | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	56	35	103	68
Total Pharmaceutical segment sales | International | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	52	67	104	154
Total Pharmaceutical segment sales | International | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	60	63	125	114
Total Pharmaceutical segment sales | International | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	53	45	108	98
Total Pharmaceutical segment sales | International | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	52	43	104	102
Total Pharmaceutical segment sales | International | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	1	15	(5)	32
Total Pharmaceutical segment sales | International | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	202	191	416	406
Total Pharmaceutical segment sales | International | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	75	73	160	160
Total Pharmaceutical segment sales | International | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	63	61	125	114
Total Pharmaceutical segment sales | International | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	118	120	256	290
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue-Adempas/Verquvo (2)
Segment Reporting Information [Line Items]
Sales	(7)	6	0	11
Total Pharmaceutical segment sales | International | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	74	57	129	113
Total Pharmaceutical segment sales | International | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	500	441	961	860
Total Pharmaceutical segment sales | International | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	403	348	805	737
Total Pharmaceutical segment sales | International | Operating Segments | Other pharmaceutical (3)
Segment Reporting Information [Line Items]
Sales	301	289	644	637
Total Animal Health segment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,472	1,101	2,890	2,314
Total Animal Health segment sales | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	821	648	1,640	1,386
Total Animal Health segment sales | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	651	453	1,250	928
Total Animal Health segment sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	459	342	896	726
Total Animal Health segment sales | United States | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	161	122	318	284
Total Animal Health segment sales | United States | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	298	220	578	442
Total Animal Health segment sales | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,012	759	1,994	1,588
Total Animal Health segment sales | International | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	659	526	1,322	1,102
Total Animal Health segment sales | International | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	353	233	672	486
Other segment sales (4) | Operating Segments
Segment Reporting Information [Line Items]
Sales	0	0	0	23
Other segment sales (4) | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	0	0	0	23
Other segment sales (4) | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	$ 0	$ 0	$ 0	$ 0

X

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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