Segment Reporting - Sales of Company's Products (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Sales	$ 10,536	$ 10,073	$ 29,692	$ 29,283
corticotropin marketing rights
Segment Reporting Information [Line Items]
Proceeds from sale of marketing rights			75
Operating Segments
Segment Reporting Information [Line Items]
Sales	10,420	9,828	29,109	28,500
Operating Segments | Total Pharmaceutical segment sales
Segment Reporting Information [Line Items]
Sales	9,443	8,925	26,247	25,755
Operating Segments | Total Pharmaceutical segment sales | Zetia
Segment Reporting Information [Line Items]
Sales	671	633	1,985	1,836
Operating Segments | Total Pharmaceutical segment sales | Vytorin
Segment Reporting Information [Line Items]
Sales	273	302	843	942
Operating Segments | Total Pharmaceutical segment sales | Januvia
Segment Reporting Information [Line Items]
Sales	1,006	1,014	2,976	2,942
Operating Segments | Total Pharmaceutical segment sales | Janumet
Segment Reporting Information [Line Items]
Sales	548	562	1,624	1,625
Operating Segments | Total Pharmaceutical segment sales | NuvaRing
Segment Reporting Information [Line Items]
Sales	195	190	571	538
Operating Segments | Total Pharmaceutical segment sales | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	148	176	446	437
Operating Segments | Total Pharmaceutical segment sales | Dulera
Segment Reporting Information [Line Items]
Sales	97	133	331	383
Operating Segments | Total Pharmaceutical segment sales | Follistim AQ
Segment Reporting Information [Line Items]
Sales	101	95	268	288
Operating Segments | Total Pharmaceutical segment sales | Zepatier
Segment Reporting Information [Line Items]
Sales	164	0	326	0
Operating Segments | Total Pharmaceutical segment sales | Isentress
Segment Reporting Information [Line Items]
Sales	372	377	1,050	1,137
Operating Segments | Total Pharmaceutical segment sales | Cubicin
Segment Reporting Information [Line Items]
Sales	320	325	969	805
Operating Segments | Total Pharmaceutical segment sales | Noxafil
Segment Reporting Information [Line Items]
Sales	147	132	434	360
Operating Segments | Total Pharmaceutical segment sales | Invanz
Segment Reporting Information [Line Items]
Sales	152	153	409	424
Operating Segments | Total Pharmaceutical segment sales | Cancidas
Segment Reporting Information [Line Items]
Sales	142	139	406	436
Operating Segments | Total Pharmaceutical segment sales | Bridion
Segment Reporting Information [Line Items]
Sales	139	89	343	262
Operating Segments | Total Pharmaceutical segment sales | Primaxin
Segment Reporting Information [Line Items]
Sales	77	75	231	228
Operating Segments | Total Pharmaceutical segment sales | Remicade
Segment Reporting Information [Line Items]
Sales	311	442	999	1,398
Operating Segments | Total Pharmaceutical segment sales | Simponi
Segment Reporting Information [Line Items]
Sales	193	178	581	505
Operating Segments | Total Pharmaceutical segment sales | Keytruda
Segment Reporting Information [Line Items]
Sales	356	159	919	352
Operating Segments | Total Pharmaceutical segment sales | Emend
Segment Reporting Information [Line Items]
Sales	137	141	405	396
Operating Segments | Total Pharmaceutical segment sales | Temodar
Segment Reporting Information [Line Items]
Sales	78	83	216	238
Operating Segments | Total Pharmaceutical segment sales | Singulair
Segment Reporting Information [Line Items]
Sales	239	201	705	658
Operating Segments | Total Pharmaceutical segment sales | Nasonex
Segment Reporting Information [Line Items]
Sales	94	121	425	625
Operating Segments | Total Pharmaceutical segment sales | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	131	150	389	524
Operating Segments | Total Pharmaceutical segment sales | Arcoxia
Segment Reporting Information [Line Items]
Sales	114	123	342	361
Operating Segments | Total Pharmaceutical segment sales | Fosamax
Segment Reporting Information [Line Items]
Sales	68	86	217	277
Operating Segments | Total Pharmaceutical segment sales | Zocor
Segment Reporting Information [Line Items]
Sales	54	56	150	168
Operating Segments | Total Pharmaceutical segment sales | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	860	625	1,631	1,410
Operating Segments | Total Pharmaceutical segment sales | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	496	390	1,236	1,096
Operating Segments | Total Pharmaceutical segment sales | RotaTeq
Segment Reporting Information [Line Items]
Sales	171	160	489	441
Operating Segments | Total Pharmaceutical segment sales | Zostavax
Segment Reporting Information [Line Items]
Sales	190	179	464	503
Operating Segments | Total Pharmaceutical segment sales | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	175	138	403	354
Operating Segments | Total Pharmaceutical segment sales | Other Pharmaceutical
Segment Reporting Information [Line Items]
Sales	1,224	1,298	3,464	3,806
Operating Segments | Other segment sales
Segment Reporting Information [Line Items]
Sales	977	903	2,862	2,745
Other
Segment Reporting Information [Line Items]
Sales	$ 116	$ 245	$ 583	$ 783