Schedule of Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 18,154	$ 11,863
Accumulated Amortization	3,804	2,892
Total	14,350	8,971
Intangible Asset - Sofosbuvir [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	10,720	10,720
Accumulated Amortization	2,855	2,156
Total	7,865	8,564
axicabtagene ciloleucel (DLBCL) [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	6,200	0
Accumulated Amortization	72	0
Total	6,128	0
Intangible Asset - Ranexa [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	688	688
Accumulated Amortization	566	467
Total	122	221
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	546	455
Accumulated Amortization	311	269
Total	$ 235	$ 186