Segment Information Segment reporting information, revenue for reportable segment (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Revenue from External Customer [Line Items]
Product sales	$ 7,405	$ 4,871
Total antiviral products
Revenue from External Customer [Line Items]
Product sales	6,988	4,509
Harvoni
Revenue from External Customer [Line Items]
Product sales	3,579	0
Sovaldi
Revenue from External Customer [Line Items]
Product sales	972	2,274
Truvada
Revenue from External Customer [Line Items]
Product sales	771	760
Atripla
Revenue from External Customer [Line Items]
Product sales	734	780
Stribild
Revenue from External Customer [Line Items]
Product sales	356	215
Complera/Eviplera
Revenue from External Customer [Line Items]
Product sales	320	251
Viread
Revenue from External Customer [Line Items]
Product sales	234	211
Other antiviral
Revenue from External Customer [Line Items]
Product sales	22	18
Letairis
Revenue from External Customer [Line Items]
Product sales	151	123
Ranexa
Revenue from External Customer [Line Items]
Product sales	117	111
AmBisome
Revenue from External Customer [Line Items]
Product sales	85	92
Zydelig
Revenue from External Customer [Line Items]
Product sales	26	0
Other
Revenue from External Customer [Line Items]
Product sales	$ 38	$ 36