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Segment Reporting - Sales of Company's Products (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Sales	$ 11,760	$ 10,465	$ 22,575	$ 20,502
Operating Segments
Segment Reporting Information [Line Items]
Sales	11,632	10,428	22,359	20,496
Other
Segment Reporting Information [Line Items]
Sales	128	37	216	6
United States
Segment Reporting Information [Line Items]
Sales	5,144	4,262	9,659	8,395
United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	5,140	4,208	9,647	8,315
United States | Other
Segment Reporting Information [Line Items]
Sales	4	54	12	80
International
Segment Reporting Information [Line Items]
Sales	6,616	6,203	12,917	12,107
International | Operating Segments
Segment Reporting Information [Line Items]
Sales	6,491	6,221	12,711	12,181
International | Other
Segment Reporting Information [Line Items]
Sales	125	(18)	206	(74)
Total Pharmaceutical segment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	10,460	9,282	20,123	18,201
Total Pharmaceutical segment sales | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	2,634	1,667	4,903	3,131
Total Pharmaceutical segment sales | Operating Segments | Emend
Segment Reporting Information [Line Items]
Sales	121	148	237	273
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue - Lynparza
Segment Reporting Information [Line Items]
Sales	111	44	190	76
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue - Lenvima
Segment Reporting Information [Line Items]
Sales	97	35	171	35
Total Pharmaceutical segment sales | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	886	608	1,724	1,269
Total Pharmaceutical segment sales | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	675	426	1,171	818
Total Pharmaceutical segment sales | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	172	156	383	349
Total Pharmaceutical segment sales | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	170	193	355	372
Total Pharmaceutical segment sales | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	58	65	105	101
Total Pharmaceutical segment sales | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	278	240	533	444
Total Pharmaceutical segment sales | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	193	188	383	363
Total Pharmaceutical segment sales | Operating Segments | Cubicin
Segment Reporting Information [Line Items]
Sales	67	94	155	192
Total Pharmaceutical segment sales | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	78	149	150	300
Total Pharmaceutical segment sales | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	71	68	130	140
Total Pharmaceutical segment sales | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	67	87	129	178
Total Pharmaceutical segment sales | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	214	233	422	464
Total Pharmaceutical segment sales | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	98	157	221	324
Total Pharmaceutical segment sales | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	76	71	143	125
Total Pharmaceutical segment sales | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	247	305	502	586
Total Pharmaceutical segment sales | Operating Segments | Zepatier
Segment Reporting Information [Line Items]
Sales	108	113	221	243
Total Pharmaceutical segment sales | Operating Segments | Zetia
Segment Reporting Information [Line Items]
Sales	156	226	296	531
Total Pharmaceutical segment sales | Operating Segments | Vytorin
Segment Reporting Information [Line Items]
Sales	76	155	174	322
Total Pharmaceutical segment sales | Operating Segments | Atozet
Segment Reporting Information [Line Items]
Sales	92	101	186	174
Total Pharmaceutical segment sales | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	104	75	194	143
Total Pharmaceutical segment sales | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	908	949	1,732	1,829
Total Pharmaceutical segment sales | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	533	585	1,063	1,129
Total Pharmaceutical segment sales | Operating Segments | NuvaRing
Segment Reporting Information [Line Items]
Sales	240	236	459	452
Total Pharmaceutical segment sales | Operating Segments | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	183	174	382	348
Total Pharmaceutical segment sales | Operating Segments | Singulair
Segment Reporting Information [Line Items]
Sales	160	185	352	360
Total Pharmaceutical segment sales | Operating Segments | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	109	125	213	245
Total Pharmaceutical segment sales | Operating Segments | Nasonex
Segment Reporting Information [Line Items]
Sales	72	81	168	203
Total Pharmaceutical segment sales | Operating Segments | Arcoxia
Segment Reporting Information [Line Items]
Sales	75	84	149	166
Total Pharmaceutical segment sales | Operating Segments | Follistim AQ
Segment Reporting Information [Line Items]
Sales	63	70	121	138
Total Pharmaceutical segment sales | Operating Segments | Other Pharmaceutical
Segment Reporting Information [Line Items]
Sales	1,268	1,189	2,406	2,378
Total Pharmaceutical segment sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	4,758	3,841	8,933	7,557
Total Pharmaceutical segment sales | United States | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	1,498	959	2,782	1,797
Total Pharmaceutical segment sales | United States | Operating Segments | Emend
Segment Reporting Information [Line Items]
Sales	67	89	130	168
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue - Lynparza
Segment Reporting Information [Line Items]
Sales	66	31	116	55
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue - Lenvima
Segment Reporting Information [Line Items]
Sales	54	19	104	19
Total Pharmaceutical segment sales | United States | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	456	302	818	682
Total Pharmaceutical segment sales | United States | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	500	356	843	668
Total Pharmaceutical segment sales | United States | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	104	99	258	250
Total Pharmaceutical segment sales | United States | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	123	122	248	234
Total Pharmaceutical segment sales | United States | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	38	42	67	60
Total Pharmaceutical segment sales | United States | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	129	95	248	175
Total Pharmaceutical segment sales | United States | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	100	87	191	168
Total Pharmaceutical segment sales | United States | Operating Segments | Cubicin
Segment Reporting Information [Line Items]
Sales	22	48	64	95
Total Pharmaceutical segment sales | United States | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	18	87	31	177
Total Pharmaceutical segment sales | United States | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	0	0	1	5
Total Pharmaceutical segment sales | United States | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	3	4	4	7
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	21	29	45	52
Total Pharmaceutical segment sales | United States | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	94	132	202	260
Total Pharmaceutical segment sales | United States | Operating Segments | Zepatier
Segment Reporting Information [Line Items]
Sales	39	(10)	72	(10)
Total Pharmaceutical segment sales | United States | Operating Segments | Zetia
Segment Reporting Information [Line Items]
Sales	6	8	6	25
Total Pharmaceutical segment sales | United States | Operating Segments | Vytorin
Segment Reporting Information [Line Items]
Sales	3	3	6	11
Total Pharmaceutical segment sales | United States | Operating Segments | Atozet
Segment Reporting Information [Line Items]
Sales	0	0	0	0
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	471	503	855	968
Total Pharmaceutical segment sales | United States | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	166	209	333	401
Total Pharmaceutical segment sales | United States | Operating Segments | NuvaRing
Segment Reporting Information [Line Items]
Sales	206	187	391	357
Total Pharmaceutical segment sales | United States | Operating Segments | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	136	114	285	242
Total Pharmaceutical segment sales | United States | Operating Segments | Singulair
Segment Reporting Information [Line Items]
Sales	8	5	13	11
Total Pharmaceutical segment sales | United States | Operating Segments | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	6	7	10	14
Total Pharmaceutical segment sales | United States | Operating Segments | Nasonex
Segment Reporting Information [Line Items]
Sales	(1)	0	(2)	2
Total Pharmaceutical segment sales | United States | Operating Segments | Arcoxia
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Follistim AQ
Segment Reporting Information [Line Items]
Sales	24	27	53	56
Total Pharmaceutical segment sales | United States | Operating Segments | Other Pharmaceutical
Segment Reporting Information [Line Items]
Sales	401	287	759	608
Total Pharmaceutical segment sales | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	5,702	5,442	11,190	10,644
Total Pharmaceutical segment sales | International | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	1,136	707	2,121	1,333
Total Pharmaceutical segment sales | International | Operating Segments | Emend
Segment Reporting Information [Line Items]
Sales	54	59	107	105
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue - Lynparza
Segment Reporting Information [Line Items]
Sales	45	13	74	22
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue - Lenvima
Segment Reporting Information [Line Items]
Sales	43	16	67	16
Total Pharmaceutical segment sales | International | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	430	306	906	586
Total Pharmaceutical segment sales | International | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	174	70	328	150
Total Pharmaceutical segment sales | International | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	68	57	125	99
Total Pharmaceutical segment sales | International | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	47	71	107	137
Total Pharmaceutical segment sales | International | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	20	23	39	42
Total Pharmaceutical segment sales | International | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	149	145	285	269
Total Pharmaceutical segment sales | International | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	93	100	192	195
Total Pharmaceutical segment sales | International | Operating Segments | Cubicin
Segment Reporting Information [Line Items]
Sales	45	46	91	97
Total Pharmaceutical segment sales | International | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	60	63	118	123
Total Pharmaceutical segment sales | International | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	70	68	129	135
Total Pharmaceutical segment sales | International | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	64	83	125	171
Total Pharmaceutical segment sales | International | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	214	233	422	464
Total Pharmaceutical segment sales | International | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	98	157	221	324
Total Pharmaceutical segment sales | International | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	55	42	98	73
Total Pharmaceutical segment sales | International | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	153	174	300	326
Total Pharmaceutical segment sales | International | Operating Segments | Zepatier
Segment Reporting Information [Line Items]
Sales	68	123	149	253
Total Pharmaceutical segment sales | International | Operating Segments | Zetia
Segment Reporting Information [Line Items]
Sales	150	218	290	505
Total Pharmaceutical segment sales | International | Operating Segments | Vytorin
Segment Reporting Information [Line Items]
Sales	73	152	167	311
Total Pharmaceutical segment sales | International | Operating Segments | Atozet
Segment Reporting Information [Line Items]
Sales	92	101	186	174
Total Pharmaceutical segment sales | International | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	104	75	194	143
Total Pharmaceutical segment sales | International | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	437	446	877	862
Total Pharmaceutical segment sales | International | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	366	377	730	729
Total Pharmaceutical segment sales | International | Operating Segments | NuvaRing
Segment Reporting Information [Line Items]
Sales	34	49	68	95
Total Pharmaceutical segment sales | International | Operating Segments | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	48	60	98	106
Total Pharmaceutical segment sales | International | Operating Segments | Singulair
Segment Reporting Information [Line Items]
Sales	153	180	338	350
Total Pharmaceutical segment sales | International | Operating Segments | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	103	118	202	231
Total Pharmaceutical segment sales | International | Operating Segments | Nasonex
Segment Reporting Information [Line Items]
Sales	73	81	170	201
Total Pharmaceutical segment sales | International | Operating Segments | Arcoxia
Segment Reporting Information [Line Items]
Sales	75	84	149	166
Total Pharmaceutical segment sales | International | Operating Segments | Follistim AQ
Segment Reporting Information [Line Items]
Sales	39	43	67	81
Total Pharmaceutical segment sales | International | Operating Segments | Other Pharmaceutical
Segment Reporting Information [Line Items]
Sales	869	902	1,650	1,770
Total Animal Health segment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,124	1,090	2,149	2,155
Total Animal Health segment sales | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	671	633	1,282	1,286
Total Animal Health segment sales | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	453	457	867	869
Total Animal Health segment sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	335	311	628	618
Total Animal Health segment sales | United States | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	145	107	261	231
Total Animal Health segment sales | United States | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	190	204	367	387
Total Animal Health segment sales | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	789	779	1,521	1,537
Total Animal Health segment sales | International | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	526	526	1,021	1,055
Total Animal Health segment sales | International | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	263	253	500	482
Other segment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	48	56	87	140
Other segment sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	47	56	86	140
Other segment sales | 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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