Selected Quarterly Financial Information (unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Data [Abstract]
Revenue, Net	$ 7,314	$ 6,042	$ 6,535	$ 4,999	$ 3,120	$ 2,783	$ 2,767	$ 2,532	$ 24,890	$ 11,202	$ 9,702
Gross Profit on Product Sales	6,159	4,981	5,488	4,058	2,185	2,028	1,973	1,759
Net income	3,462	2,724	3,650	2,223	787	784	768	718	12,059	3,057	2,574
Net Income Attributable to Gilead	$ 3,487	$ 2,731	$ 3,656	$ 2,227	$ 791	$ 789	$ 773	$ 722	$ 12,101	$ 3,075	$ 2,592
Net income per share attributable to Gilead common stockholders-basic (usd per share)	$ 2.32	$ 1.80	$ 2.39	$ 1.45	$ 0.52	$ 0.51	$ 0.51	$ 0.47	$ 7.95	$ 2.01	$ 1.71
Net income per share attributable to Gilead common stockholders-diluted (usd per share)	$ 2.18	$ 1.67	$ 2.20	$ 1.33	$ 0.47	$ 0.47	$ 0.46	$ 0.43	$ 7.35	$ 1.81	$ 1.64