Net Income Per Share Attributable to Gilead Common Stockholders Reconciliation of the Numerator and Denominator Used in the Calculation of Basic and Diluted EPS (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Debt Instrument [Line Items]
Net income attributable to Gilead	$ 4,333us-gaap_NetIncomeLoss	$ 2,227us-gaap_NetIncomeLoss
Shares used in per share calculation—basic (shares)	1,488	1,537
Stock options and equivalents (shares)	26	35
Warrants related to the May Notes (shares)	39	69
Shares used in per share calculation - diluted (shares)	1,569	1,680
Convertible Senior Notes Due May 2014
Debt Instrument [Line Items]
Conversion spread related to notes (shares)	0	7
Convertible Senior Notes Due May 2016
Debt Instrument [Line Items]
Conversion spread related to notes (shares)	16	32

Net Income Per Share Attributable to Gilead Common Stockholders Reconciliation of the Numerator and Denominator Used in the Calculation of Basic and Diluted EPS (Details) (USD $)
In Millions, unless otherwise specified

3 Months Ended

Mar. 31, 2015

Mar. 31, 2014

Debt Instrument [Line Items]

Net income attributable to Gilead

$ 4,333us-gaap_NetIncomeLoss

$ 2,227us-gaap_NetIncomeLoss

Shares used in per share calculation—basic (shares)

1,488us-gaap_WeightedAverageNumberOfSharesOutstandingBasic

1,537us-gaap_WeightedAverageNumberOfSharesOutstandingBasic

Stock options and equivalents (shares)

26us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

35us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

39us-gaap_IncrementalCommonSharesAttributableToCallOptionsAndWarrants

69us-gaap_IncrementalCommonSharesAttributableToCallOptionsAndWarrants

Shares used in per share calculation - diluted (shares)

1,569us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding

1,680us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding

Convertible Senior Notes Due May 2014

Debt Instrument [Line Items]

Conversion spread related to notes (shares)

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Convertible Senior Notes Due May 2016

Debt Instrument [Line Items]

Conversion spread related to notes (shares)

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