Gilead Sciences (GILD) 10-Q 7 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document	3 Months Ended
	Mar. 31, 2014	Apr. 25, 2014
Document And Entity Information [Abstract]	'	'
Entity Registrant Name	'Gilead Sciences Inc	'
Entity Central Index Key	'0000882095	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	1,535,682,107
Entity Current Reporting Status	'Yes	'

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets, Current [Abstract]	'	'
Cash and cash equivalents	$6,404,153	$2,112,806
Short-term marketable securities	64,877	18,756
Accounts receivable, net	3,236,195	2,100,286
Inventories	2,140,228	2,055,788
Deferred tax assets	348,942	330,530
Prepaid taxes	367,993	398,010
Prepaid expenses	207,230	165,652
Other current assets	201,011	91,925
Total current assets	12,970,629	7,273,753
Assets, Noncurrent [Abstract]	'	'
Property, plant and equipment, net	1,303,029	1,166,181
Long-term portion of prepaid royalties	191,345	198,766
Long-term deferred tax assets	138,966	154,765
Long-term marketable securities	389,871	439,028
Intangible assets, net	11,707,830	11,900,106
Goodwill	1,171,561	1,169,023
Other long-term assets	204,461	195,163
Total assets	28,077,692	22,496,785
Liabilities, Current [Abstract]	'	'
Accounts payable	1,234,507	1,255,914
Accrued government rebates	1,139,093	983,490
Accrued compensation and employee benefits	181,799	243,540
Income taxes payable	152,953	10,855
Other accrued liabilities	1,222,821	1,023,938
Deferred revenues	111,792	110,640
Current portion of long-term debt and other obligations, net	1,871,811	2,697,044
Total current liabilities	5,914,776	6,325,421
Liabilities, Noncurrent [Abstract]	'	'
Long-term debt, net	7,932,032	3,938,708
Long-term income taxes payable	226,018	162,412
Long-term deferred tax liabilities	81,960	83,286
Other long-term obligations	174,945	178,626
Commitments and Contingencies	'	'
Equity Component of Currently Redeemable Convertible Notes [Abstract]	'	'
Equity component of currently redeemable convertible notes	45,767	63,831
Stockholders' Equity [Abstract]	'	'
Preferred stock, par value $0.001 per share; 5,000 shares authorized; none outstanding	0	0
Common stock, par value $0.001 per share; shares authorized of 5,600,000; shares issued and outstanding of 1,537,642 and 1,534,414	1,538	1,534
Additional paid-in capital	5,746,574	5,386,735
Accumulated other comprehensive loss	-95,769	-124,446
Retained earnings	7,734,979	6,105,244
Total Gilead stockholders’ equity	13,387,322	11,369,067
Noncontrolling interest	314,872	375,434
Total stockholders’ equity	13,702,194	11,744,501
Total liabilities and stockholders’ equity	$28,077,692	$22,496,785

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets Paranthetical (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, except Per Share data, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Preferred Stock, Par Value (usd per share)	$0.00	$0.00
Preferred Stock, Shares Authorized	5,000	5,000
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par Value (usd per share)	$0.00	$0.00
Common Stock, Shares Authorized	5,600,000	5,600,000
Common Stock, Shares Issued	1,537,642	1,534,414
Common Stock, Shares Outstanding	1,537,642	1,534,414

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Income (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Revenues [Abstract]	'	'
Product sales	$4,870,974	$2,393,568
Royalty, contract and other revenues	127,982	138,067
Total revenues	4,998,956	2,531,635
Costs and Expenses [Abstract]	'	'
Cost of goods sold	813,205	634,448
Research and development	594,978	497,632
Selling, general and administrative	548,123	374,296
Total costs and expenses	1,956,306	1,506,376
Income from operations	3,042,650	1,025,259
Interest expense	-76,269	-81,787
Other income (expense), net	-17,912	-3,324
Income before provision for income taxes	2,948,469	940,148
Provision for income taxes	725,882	222,438
Net income	2,222,587	717,710
Net loss attributable to noncontrolling interest	4,823	4,476
Net income attributable to Gilead	$2,227,410	$722,186
Net income per share attributable to Gilead common stockholders—basic	$1.45	$0.47
Shares used in per share calculation—basic	1,536,525	1,521,372
Net income per share attributable to Gilead common stockholders—diluted	$1.33	$0.43
Shares used in per share calculation—diluted	1,679,871	1,665,060

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'
Net income	$2,222,587	$717,710
Other Comprehensive Income [Abstract]	'	'
Change in foreign currency translation gain (loss), net of tax	5,783	-8,956
Available-for-sale Securities [Abstract]	'	'
Change in net unrealized gains (losses), net of tax impact of $82 and $(1,016)	147	1,785
Reclassifications to net income, net of tax impact of $(114) and $(9)	-199	-17
Net change	-52	1,768
Cash Flow Hedges [Abstract]	'	'
Change in net unrealized gains (losses), net of tax impact of $1,732 and $(1,849)	1,265	74,060
Reclassifications to net income, net of tax impact of $(990) and $(11)	21,681	-451
Net change	22,946	73,609
Other comprehensive income	28,677	66,421
Comprehensive income	2,251,264	784,131
Comprehensive loss attributable to noncontrolling interest	-4,823	-4,476
Comprehensive income attributable to Gilead	$2,256,087	$788,607

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Comprehensive Income Consolidated Statements of Comprehensive Income Paranthetical (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Available-for-sale Securities [Abstract]	'	'
Net Unrealized Gains, Tax Impact	$82	($1,016)
Reclassification Adjustments, Tax Impact	-114	-9
Cash Flow Hedges [Abstract]	'	'
Net Unrealized Losses, Tax Impact	1,732	-1,849
Reclassification Adjustments, Tax Impact	($990)	($11)

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating Activities [Abstract]	'	'
Net income	$2,222,587	$717,710
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities [Abstract]	'	'
Depreciation expense	24,510	23,973
Amortization expense	216,530	50,353
Stock-based compensation expense	82,181	61,767
Excess tax benefits from stock-based compensation	-156,695	-40,746
Tax benefits from employee stock plans	157,654	38,905
Deferred income taxes	-3,321	39,301
Change in Fair Value of Contingent Consideration	2,678	6,024
Other	3,120	8,262
Changes in Operating Assets and Liabilities [Abstract]	'	'
Accounts receivable, net	-1,117,620	-231,781
Inventories	-84,611	-57,109
Prepaid expenses and other assets	-169,380	-187,304
Accounts payable	-20,117	30,792
Income taxes payable	240,973	12,056
Accrued liabilities	166,263	167,018
Deferred revenues	3,266	32,880
Net cash provided by operating activities	1,568,018	672,101
Investing Activities [Abstract]	'	'
Purchases of marketable securities	-94,340	-62,604
Proceeds from sales of marketable securities	83,224	65,985
Proceeds from maturities of marketable securities	13,666	6,862
Acquisitions, net of cash acquired	0	-378,645
Capital expenditures	-163,490	-38,854
Net cash used in investing activities	-160,940	-407,256
Financing Activities [Abstract]	'	'
Proceeds from debt financing, net of issuance costs	3,967,914	0
Proceeds from convertible note hedges	601,591	100,771
Purchases of convertible note hedges	-26,249	0
Proceeds from issuances of common stock	108,727	86,049
Repurchases of common stock	-450,087	-82,239
Repayments of debt and other long-term obligations	-1,418,716	-347,916
Excess tax benefits from stock-based compensation	156,695	40,746
Contributions from (distributions to) noncontrolling interest	-55,739	3,588
Net cash provided by (used in) financing activities	2,884,136	-199,001
Effect of exchange rate changes on cash	133	-5,566
Net change in cash and cash equivalents	4,291,347	60,278
Cash and Cash Equivalents at beginning of period	2,112,806	1,803,694
Cash and Cash Equivalents at end of period	$6,404,153	$1,863,972

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies [Text Block]	'
	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Basis of Presentation
	The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with U.S. generally accepted accounting principles for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of Gilead Sciences, Inc. (Gilead, we or us) believes are necessary for a fair presentation of the periods presented. These interim financial results are not necessarily indicative of results expected for the full fiscal year or for any subsequent interim period.
	The accompanying Condensed Consolidated Financial Statements include the accounts of Gilead, our wholly-owned subsidiaries and our joint ventures with Bristol-Myers Squibb Company (BMS), for which we are the primary beneficiary. We record a noncontrolling interest in our Condensed Consolidated Financial Statements to reflect BMS’s interest in the joint ventures. All intercompany transactions have been eliminated. The Condensed Consolidated Financial Statements include the results of companies acquired by us from the date of each acquisition for the applicable reporting periods. Certain prior period amounts within our Condensed Consolidated Financial Statements and related notes have been reclassified to conform to the current presentation.
	The accompanying Condensed Consolidated Financial Statements and related Notes to Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and the related notes thereto for the year ended December 31, 2013, included in our Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.
	Significant Accounting Policies, Estimates and Judgments
	The preparation of these Condensed Consolidated Financial Statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures. On an ongoing basis, management evaluates its significant accounting policies or estimates. We base our estimates on historical experience and on various market specific and other relevant assumptions that we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ significantly from these estimates.
	Concentrations of Risk
	We are subject to credit risk from our portfolio of cash equivalents and marketable securities. Under our investment policy, we limit amounts invested in such securities by credit rating, maturity, industry group, investment type and issuer, except for securities issued by the U.S. government. We are not exposed to any significant concentrations of credit risk from these financial instruments. The goals of our investment policy, in order of priority, are as follows: safety and preservation of principal and diversification of risk; liquidity of investments sufficient to meet cash flow requirements; and a competitive after-tax rate of return.
	We are also subject to credit risk from our accounts receivable related to our product sales. The majority of our trade accounts receivable arises from product sales in the United States and Europe.
	As of March 31, 2014, our accounts receivable in Southern Europe, specifically Greece, Italy, Portugal and Spain, totaled approximately $602.8 million, of which $156.8 million were greater than 120 days past due and $50.6 million were greater than 365 days past due. To date, we have not experienced significant losses with respect to the collection of our accounts receivable. We believe that our allowance for doubtful accounts was adequate at March 31, 2014.
	Recent Accounting Pronouncements
	There have been no new accounting pronouncements during the three months ended March 31, 2014 that we believe would have a material impact on our financial position or results of operations.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'
Fair Value Disclosures [Text Block]	'
	FAIR VALUE MEASUREMENTS
	We determine the fair value of financial and non-financial assets and liabilities using the fair value hierarchy, which establishes three levels of inputs that may be used to measure fair value, as follows:
	•	Level 1 inputs which include quoted prices in active markets for identical assets or liabilities;
	•	Level 2 inputs which include observable inputs other than Level 1 inputs, such as quoted prices for similar assets or liabilities; quoted prices for identical or similar assets or liabilities in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the asset or liability. For our marketable securities, we review trading activity and pricing as of the measurement date. When sufficient quoted pricing for identical securities is not available, we use market pricing and other observable market inputs for similar securities obtained from various third-party data providers. These inputs either represent quoted prices for similar assets in active markets or have been derived from observable market data; and
	•	Level 3 inputs which include unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the underlying asset or liability. Our level 3 liabilities include those whose fair value measurements are determined using pricing models, discounted cash flow methodologies or similar valuation techniques and significant management judgment or estimation.
	Our financial instruments consist principally of cash and cash equivalents, marketable securities, accounts receivable, foreign currency exchange contracts, accounts payable and short-term and long-term debt. Cash and cash equivalents, marketable securities and foreign currency exchange contracts that hedge accounts receivable and forecasted sales are reported at their respective fair values on our Condensed Consolidated Balance Sheets. Short-term and long-term debt are reported at their amortized cost on our Condensed Consolidated Balance Sheets. The remaining financial instruments are reported on our Condensed Consolidated Balances Sheets at amounts that approximate current fair values.
	The fair values of our convertible senior notes and senior unsecured notes were determined using Level 2 inputs based on their quoted market values. The following table summarizes the carrying values and fair values of our convertible senior notes and senior unsecured notes (in thousands):
					31-Mar-14						December 31, 2013
	Type of Borrowing		Description		Carrying Value			Fair Value			Carrying Value			Fair Value
	Convertible Senior		May 2014 Notes		$	208,471		$	637,224		$	234,217		$	783,651
	Convertible Senior		May 2016 Notes		913,478			2,947,013			1,113,043			3,871,516
	Senior Unsecured		April 2021 Notes		993,996			1,096,750			993,781			1,075,480
	Senior Unsecured		December 2014 Notes		749,789			759,983			749,710			762,637
	Senior Unsecured		December 2016 Notes		699,384			737,961			699,326			740,705
	Senior Unsecured		December 2021 Notes		1,247,788			1,358,275			1,247,716			1,336,738
	Senior Unsecured		December 2041 Notes		997,904			1,148,870			997,885			1,118,660
	Senior Unsecured(1)		April 2019 Notes		499,146			496,485			—			—
	Senior Unsecured(1)		April 2024 Notes		1,747,201			1,763,825			—			—
	Senior Unsecured(1)		April 2044 Notes		1,746,613			1,811,250			—			—
	(1) See Note 8, Debt and Credit Facility for discussion of March 2014 financing.
	The following table summarizes, for assets or liabilities recorded at fair value, the respective fair value and the classification by level of input within the fair value hierarchy previously defined (in thousands):
		31-Mar-14													December 31, 2013
		Level 1				Level 2			Level 3			Total			Level 1		Level 2		Level 3		Total
	Assets:
	Debt securities:
	Money market funds	$	5,056,350			$	—		$	—		$	5,056,350		$	1,490,964	$	—	$	—	$	1,490,964
	Corporate debt securities	—				221,734			—			221,734			—		220,025		—		220,025
	U.S. treasury securities	105,291				—			—			105,291			85,403		—		—		85,403
	U.S. government agencies securities	—				72,830			—			72,830			—		93,350		—		93,350
	Residential mortgage and asset-backed securities	—				45,647			—			45,647			—		46,941		—		46,941
	Municipal debt securities	—				9,246			—			9,246			—		12,065		—		12,065
	Total debt securities	5,161,641				349,457			—			5,511,098			1,576,367		372,381		—		1,948,748
	Deferred compensation plan	47,913				—			—			47,913			44,461		—		—		44,461
	Derivatives	—				11,032			—			11,032			—		13,879		—		13,879
		$	5,209,554			$	360,489		$	—		$	5,570,043		$	1,620,828	$	386,260	$	—	$	2,007,088
	Liabilities:
	Contingent consideration	$	—			$	—		$	266,438		$	266,438		$	—	$	—	$	263,760	$	263,760
	Derivatives	—				72,366			—			72,366			—		99,057		—		99,057
	Deferred compensation plan	47,913				—			—			47,913			44,461		—		—		44,461
		$	47,913			$	72,366		$	266,438		$	386,717		$	44,461	$	99,057	$	263,760	$	407,278
	Level 2 Inputs
	We estimate the fair values of our government agency securities, corporate debt, residential mortgage and asset-backed securities by taking into consideration valuations obtained from third-party pricing services. The pricing services utilize industry standard valuation models, including both income- and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities; issuer credit spreads; benchmark securities; prepayment/default projections based on historical data and other observable inputs.
	Substantially all of our foreign currency derivative contracts have maturities primarily over an 18-month time horizon and all are with counterparties that have a minimum credit rating of A- or equivalent by Standard & Poor's, Moody's Investors Service, Inc. or Fitch, Inc. We estimate the fair values of these contracts by taking into consideration valuations obtained from a third-party valuation service that utilizes an income-based industry standard valuation model for which all significant inputs are observable, either directly or indirectly. These inputs include foreign currency rates, London Interbank Offered Rates (LIBOR) and swap rates. These inputs, where applicable, are at commonly quoted intervals.
	Level 3 Inputs
	As of March 31, 2014 and December 31, 2013, the only assets or liabilities that were measured using Level 3 inputs were contingent consideration liabilities. Our policy is to recognize transfers into or out of Level 3 classification as of the actual date of the event or change in circumstances that caused the transfer.
	Contingent Consideration Liabilities
	In connection with certain acquisitions, we may be required to pay future consideration that is contingent upon the achievement of specified development, regulatory approval or sales-based milestone events. We estimate the fair value of the contingent consideration liabilities on the acquisition date and each reporting period thereafter using a probability-weighted income approach, which reflects the probability and timing of future payments. This fair value measurement is based on significant Level 3 inputs such as the anticipated timelines and probability of achieving development, regulatory approval or sales-based milestone events and projected revenues. The resulting probability-weighted cash flows are discounted using credit-risk adjusted interest rates.
	Each reporting period thereafter, we revalue these obligations by performing a review of the assumptions listed above and record increases or decreases in the fair value of these contingent consideration obligations in research and development (R&D) expenses within our Condensed Consolidated Statements of Income until such time that the related product candidate receives marketing approval. In the absence of any significant changes in key assumptions, the quarterly determination of fair values of these contingent consideration obligations would primarily reflect the passage of time.
	Significant judgment is employed in determining Level 3 inputs and fair value measurements as of the acquisition date and for each subsequent period. Updates to assumptions could have a significant impact on our results of operations in any given period and actual results may differ from estimates. For example, significant increases in the probability of achieving a milestone or projected revenues would result in a significantly higher fair value measurement while significant decreases in the estimated probability of achieving a milestone or projected revenues would result in a significantly lower fair value measurement. Significant increases in the discount rate or in the anticipated timelines would result in a significantly lower fair value measurement while significant decreases in the discount rate or anticipated timelines would result in a significantly higher fair value measurement.
	The potential contingent consideration payments required upon achievement of development or regulatory approval-based milestones related to our CGI Pharmaceuticals, Inc. and Calistoga Pharmaceuticals, Inc. acquisitions range from no payment if none of the milestones are achieved to an estimated maximum of $254.0 million (undiscounted), of which we had accrued $221.6 million as of March 31, 2014 and $220.5 million as of December 31, 2013. The remainder of the contingent consideration liabilities accrual as of March 31, 2014 and December 31, 2013 relates to potential future payments resulting from the acquisition of Arresto Biosciences, Inc. for royalty obligations on future sales once specified sales-based milestones are achieved.
	The following table provides a rollforward of our contingent consideration liabilities, which are recorded as part of other accrued liabilities and other long-term obligations in our Condensed Consolidated Balance Sheets (in thousands):
	Balance at December 31, 2013		$	263,760
	Additions from new acquisitions		—
	Net changes in valuation		2,678
	Balance at March 31, 2014		$	266,438

AvailableforSale_Securities

Available-for-Sale Securities	3 Months Ended
	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]	'
Available-for-Sale Securities Disclosure [Text Block]	'
	AVAILABLE-FOR-SALE SECURITIES
	Estimated fair values of available-for-sale securities are generally based on prices obtained from commercial pricing services. The following table is a summary of available-for-sale debt securities recorded in cash and cash equivalents or marketable securities in our Condensed Consolidated Balance Sheets (in thousands):
		31-Mar-14											December 31, 2013
		Amortized			Gross			Gross			Estimated		Amortized			Gross		Gross			Estimated
		Cost			Unrealized			Unrealized			Fair Value		Cost			Unrealized		Unrealized			Fair Value
					Gains			Losses								Gains		Losses
	Debt securities:
	Money market funds	$	5,056,350		$	—		$	—		$	5,056,350	$	1,490,964		$	—	$	—		$	1,490,964
	Corporate debt securities	220,999			801			(66		)	221,734		219,242			885		(102		)	220,025
	U.S. Treasury securities	105,330			75			(114		)	105,291		85,337			94		(28		)	85,403
	U.S. government agencies securities	72,654			176			—			72,830		93,211			156		(17		)	93,350
	Residential mortgage and asset-backed securities	45,624			59			(36		)	45,647		46,969			37		(65		)	46,941
	Municipal debt securities	9,175			71			—			9,246		12,009			56		—			12,065
	Total	$	5,510,132		$	1,182		$	(216	)	$	5,511,098	$	1,947,732		$	1,228	$	(212	)	$	1,948,748
	The following table summarizes the classification of the available-for-sale debt securities on our Condensed Consolidated Balance Sheets (in thousands):
		31-Mar-14			December 31, 2013
	Cash and cash equivalents	$	5,056,350		$	1,490,964
	Short-term marketable securities	64,877			18,756
	Long-term marketable securities	389,871			439,028
	Total	$	5,511,098		$	1,948,748
	Cash and cash equivalents in the table above exclude cash of $1.35 billion as of March 31, 2014 and $621.8 million as of December 31, 2013.
	The following table summarizes our portfolio of available-for-sale debt securities by contractual maturity (in thousands):
		31-Mar-14
		Amortized Cost			Fair Value
	Less than one year	$	5,121,014		$	5,121,227
	Greater than one year but less than five years	383,960			384,741
	Greater than five years but less than ten years	—			—
	Greater than ten years	5,158			5,130
	Total	$	5,510,132		$	5,511,098
	The following table summarizes the gross realized gains and losses related to sales of marketable securities (in thousands):
		Three Months Ended
		March 31,
		2014			2013
	Gross realized gains on sales	$	338		$	182
	Gross realized losses on sales	$	(25	)	$	(156	)
	The cost of securities sold was determined based on the specific identification method.
	The following table summarizes our available-for-sale debt securities that were in a continuous unrealized loss position, but were not deemed to be other-than-temporarily impaired (in thousands):
		Less Than 12 Months						12 Months or Greater					Total
		Gross			Estimated			Gross			Estimated		Gross			Estimated
		Unrealized			Fair Value			Unrealized			Fair Value		Unrealized			Fair Value
		Losses						Losses					Losses
	31-Mar-14
	Debt securities:
	U.S. treasury securities	$	(114	)	$	44,014		$	—		$	—	$	(114	)	$	44,014
	Corporate debt securities	(66		)	37,719			—			—		(66		)	37,719
	Residential mortgage and asset-backed securities	(17		)	15,248			(19		)	3,655		(36		)	18,903
	U.S. government agencies securities	—			—			—			—		—			—
	Total	$	(197	)	$	96,981		$	(19	)	$	3,655	$	(216	)	$	100,636
	December 31, 2013
	Debt securities:
	U.S. treasury securities	$	(28	)	$	24,562		$	—		$	—	$	(28	)	$	24,562
	Corporate debt securities	(102		)	37,076			—			1,505		(102		)	38,581
	Residential mortgage and asset-backed securities	(38		)	19,563			(27		)	6,731		(65		)	26,294
	U.S. government agencies securities	(17		)	10,858			—			—		(17		)	10,858
	Total	$	(185	)	$	92,059		$	(27	)	$	8,236	$	(212	)	$	100,295
	We held a total of 40 securities as of March 31, 2014 and December 31, 2013 that were in an unrealized loss position. Based on our review of these securities, we believe we had no other-than-temporary impairments on these securities as of March 31, 2014 and December 31, 2013, because we do not intend to sell these securities and we believe it is not more likely than not that we will be required to sell these securities before the recovery of their amortized cost basis.

Derivative_Financial_Instrumen

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Financial Instruments	'
		DERIVATIVE FINANCIAL INSTRUMENTS
	We operate in foreign countries, which exposes us to market risk associated with foreign currency exchange rate fluctuations between the U.S. dollar and various foreign currencies, the most significant of which is the Euro. In order to manage this risk, we may hedge a portion of our foreign currency exposures related to outstanding monetary assets and liabilities as well as forecasted product sales using foreign currency exchange forward or option contracts. In general, the market risk related to these contracts is offset by corresponding gains and losses on the hedged transactions. The credit risk associated with these contracts is driven by changes in interest and currency exchange rates and, as a result, varies over time. By working only with major banks and closely monitoring current market conditions, we seek to limit the risk that counterparties to these contracts may be unable to perform. We also seek to limit our risk of loss by entering into contracts that permit net settlement at maturity. Therefore, our overall risk of loss in the event of a counterparty default is limited to the amount of any unrecognized gains on outstanding contracts (i.e. those contracts that have a positive fair value) at the date of default. We do not enter into derivative contracts for trading purposes.
	We hedge our exposure to foreign currency exchange rate fluctuations for certain monetary assets and liabilities of our foreign subsidiaries that are denominated in a non-functional currency. The derivative instruments we use to hedge this exposure are not designated as hedges, and as a result, changes in their fair value are recorded in other income (expense), net on our Condensed Consolidated Statements of Income.
	We hedge our exposure to foreign currency exchange rate fluctuations for forecasted product sales that are denominated in a non-functional currency. The derivative instruments we use to hedge this exposure are designated as cash flow hedges and have maturity dates of 18 months or less. Upon executing a hedging contract and quarterly thereafter, we assess prospective hedge effectiveness using a regression analysis which calculates the change in cash flow as a result of the hedge instrument. On a monthly basis, we assess retrospective hedge effectiveness using a dollar offset approach. We exclude time value from our effectiveness testing and recognize changes in the time value of the hedge in other income (expense), net. The effective component of our hedge is recorded as an unrealized gain or loss on the hedging instrument in accumulated other comprehensive income (OCI) within stockholders' equity. When the hedged forecasted transaction occurs, the hedge is de-designated and the unrealized gains or losses are reclassified into product sales. The majority of gains and losses related to the hedged forecasted transactions reported in accumulated OCI at March 31, 2014 will be reclassified to product sales within 12 months.
	The cash flow effects of our derivatives contracts for the three months ended March 31, 2014 and 2013 are included within net cash provided by operating activities in the Condensed Consolidated Statements of Cash Flows.
	We had notional amounts on foreign currency exchange contracts outstanding of $4.04 billion at March 31, 2014 and $4.28 billion at December 31, 2013.
	While all of our derivative contracts allow us the right to offset assets or liabilities, we have presented amounts on a gross basis. Under the International Swap Dealers Association, Inc. master agreements with the respective counterparties of the foreign currency exchange contracts, subject to applicable requirements, we are allowed to net settle transactions of the same currency with a single net amount payable by one party to the other. The following table summarizes the location and fair values of derivative instruments on our Condensed Consolidated Balance Sheets (in thousands):
			31-Mar-14
			Asset Derivatives						Liability Derivatives
			Classification		Fair Value				Classification	Fair Value
	Derivatives designated as hedges:
	Foreign currency exchange contracts		Other current assets		$	10,451			Other accrued liabilities	$	65,965
	Foreign currency exchange contracts		Other long-term assets		580				Other long-term obligations	6,321
	Total derivatives designated as hedges				11,031					72,286
	Derivatives not designated as hedges:
	Foreign currency exchange contracts		Other current assets		1				Other accrued liabilities	80
	Total derivatives not designated as hedges				1					80
	Total derivatives				$	11,032				$	72,366
			December 31, 2013
			Asset Derivatives						Liability Derivatives
			Classification		Fair Value				Classification	Fair Value
	Derivatives designated as hedges:
	Foreign currency exchange contracts		Other current assets		$	12,647			Other accrued liabilities	$	85,541
	Foreign currency exchange contracts		Other long-term assets		1,229				Other long-term obligations	13,299
	Total derivatives designated as hedges				13,876					98,840
	Derivatives not designated as hedges:
	Foreign currency exchange contracts		Other current assets		3				Other accrued liabilities	217
	Total derivatives not designated as hedges				3					217
	Total derivatives				$	13,879				$	99,057
	The following table summarizes the effect of our foreign currency exchange contracts on our Condensed Consolidated Statements of Income (in thousands):
			Three Months Ended
			March 31,
			2014				2013
	Derivatives designated as hedges:
	Gains recognized in OCI (effective portion)		$	2,997			$	70,860
	Gains (losses) reclassified from accumulated OCI into product sales (effective portion)		$	(20,691	)		$	462
	Gains (losses) recognized in other income (expense), net (ineffective portion and amounts excluded from effectiveness testing)		$	84			$	(2,132	)
	Derivatives not designated as hedges:
	Gains recognized in other income (expense), net		$	1,103			$	32,620
	From time to time, we may discontinue cash flow hedges and as a result, record related amounts in other income (expense), net on our Condensed Consolidated Statements of Income. There were no material amounts recorded in other income (expense), net for the three months ended March 31, 2014 and 2013 as a result of the discontinuance of cash flow hedges.
	As of March 31, 2014 and December 31, 2013, we held one type of financial instrument, derivative contracts related to foreign currency exchange contracts. The following table summarizes the potential effect of offsetting derivatives by type of financial instrument on our Condensed Consolidated Balance Sheets (in thousands):
	31-Mar-14
	Offsetting of Derivative Assets/Liabilities
													Gross Amounts Not Offset
													in the Condensed
													Consolidated Balance Sheet
	Description		Gross Amounts of Recognized Assets/Liabilities				Gross Amounts Offset in the Condensed Consolidated Balance Sheet			Amounts of Assets/Liabilities Presented			Derivative Financial Instruments			Cash Collateral Received/Pledged		Net Amount (Legal Offset)
										in the Condensed Consolidated
										Balance Sheet
	Derivative assets		$	11,032			$	—		$	11,032		$	(11,032	)	$	—	$	—
	Derivative liabilities		(72,366		)		—			(72,366		)	11,032			—		(61,334		)
	December 31, 2013
	Offsetting of Derivative Assets/Liabilities
													Gross Amounts Not Offset in the Consolidated Balance Sheet
	Description		Gross Amounts of Recognized Assets/Liabilities				Gross Amounts Offset in the Consolidated Balance Sheet			Amounts of Assets/Liabilities Presented in the Consolidated Balance Sheet			Derivative Financial Instruments			Cash Collateral Received/Pledged		Net Amount (Legal Offset)
	Derivative assets		$	13,879			$	—		$	13,879		$	(13,879	)	$	—	$	—
	Derivative liabilities		(99,057		)		—			(99,057		)	13,879			—		(85,178		)

Inventories

Inventories	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Inventories	'
	INVENTORIES
	Inventories are summarized as follows (in thousands):
		March 31, 2014		December 31, 2013
	Raw materials	$	999,667	$	1,049,403
	Work in process	592,897		412,945
	Finished goods	547,664		593,440
	Total	$	2,140,228	$	2,055,788
	The joint ventures formed by Gilead and BMS (See Note 7, Collaborative Arrangements), which are included in our Condensed Consolidated Financial Statements, held efavirenz active pharmaceutical ingredient in inventory. This efavirenz inventory was purchased from BMS at BMS's estimated net selling price of efavirenz and totaled $1.32 billion as of March 31, 2014 and $1.28 billion as of December 31, 2013.

Intangible_Assets_and_Goodwill

Intangible Assets and Goodwill	3 Months Ended
	Mar. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill and Intangible Assets Disclosure [Text Block]	'
	INTANGIBLE ASSETS AND GOODWILL
	Intangible Assets
	The following table summarizes the carrying amount of our intangible assets (in thousands):
		31-Mar-14		December 31, 2013
	Finite-lived intangible assets	$	11,126,240	$	11,325,751
	Indefinite-lived intangible assets	581,590		574,355
	Total intangible assets	$	11,707,830	$	11,900,106
	Finite-Lived Intangible Assets
	The following table summarizes our finite-lived intangible assets (in thousands):
		31-Mar-14					December 31, 2013
		Gross Carrying		Accumulated			Gross Carrying		Accumulated
		Amount		Amortization			Amount		Amortization
	Intangible asset - sofosbuvir	$	10,720,000	$	233,043		$	10,720,000	$	58,261
	Intangible asset - Ranexa	688,400		208,466			688,400		190,849
	Other	305,795		146,446			305,795		139,334
	Total	$	11,714,195	$	587,955		$	11,714,195	$	388,444
	Upon U.S. Food and Drug Administration (FDA) approval and commercial launch of Sovaldi in December 2013, we reclassified the IPR&D related to sofosbuvir to finite-lived intangible assets. Amortization expense related to finite-lived intangible assets included primarily in cost of goods sold in our Condensed Consolidated Statements of Income totaled $199.5 million for the three months ended March 31, 2014 and $21.5 million for the three months ended March 31, 2013. The weighted-average amortization period for all finite-lived intangible assets is approximately 15 years. As of March 31, 2014, the estimated future amortization expense associated with our intangible assets for the remaining nine months of 2014 and each of the five succeeding fiscal years is as follows (in thousands):
	Fiscal Year	Amount
	2014 (remaining nine months)	$	598,533
	2015	803,496
	2016	811,428
	2017	815,871
	2018	827,980
	2019	792,823
	Total	$	4,650,131
	Indefinite-Lived Intangible Assets
	The following table summarizes our indefinite-lived intangible assets (in thousands):
		31-Mar-14		December 31, 2013
	Indefinite-lived intangible asset - momelotinib (formerly CYT387)	$	308,155	$	362,700
	Indefinite-lived intangible assets - other	266,200		266,200
		574,355		628,900
	Foreign currency translation adjustment	7,235		(54,545		)
	Total	$	581,590	$	574,355
	Goodwill
	The following table summarizes the changes in the carrying amount of goodwill (in thousands):
	Balance at December 31, 2013	$	1,169,023
	Foreign currency translation adjustment	2,538
	Balance at March 31, 2014	$	1,171,561

Collaborative_Arrangements

Collaborative Arrangements	3 Months Ended
	Mar. 31, 2014
Collaborative Arrangements [Abstract]	'
Collaborative Arrangement Disclosure [Text Block]	'
	COLLABORATIVE ARRANGEMENTS
	From time to time, as a result of entering into strategic collaborations, we may hold investments in non-public companies. We review our interests in investee companies for consolidation and/or disclosure based on applicable guidance. For variable interest entities (VIEs), we may be required to consolidate an entity if the contractual terms of the arrangement essentially provide us with control over the entity, even if we do not have a majority voting interest. We assess whether we are the primary beneficiary of a VIE based on our power to direct the activities of the VIE that most significantly impact the VIE's economic performance and our obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. As of March 31, 2014, we determined that certain of our investee companies are VIEs; however, other than with respect to our joint ventures with BMS, we are not the primary beneficiary and therefore do not consolidate these investees.
	Bristol-Myers Squibb Company
	North America
	In 2004, we entered into a collaboration arrangement with BMS to develop and commercialize a single tablet regimen containing our Truvada and BMS's Sustiva (efavirenz) in the United States. This combination was approved for use in the United States in 2006 and is sold under the brand name Atripla. We and BMS structured this collaboration as a joint venture that operates as a limited liability company named Bristol-Myers Squibb & Gilead Sciences, LLC, which we consolidate. We and BMS granted royalty free sublicenses to the joint venture for the use of our respective company owned technologies and, in return, were granted a license by the joint venture to use any intellectual property that results from the collaboration. In 2006, we and BMS amended the joint venture's collaboration agreement to allow the joint venture to sell Atripla in Canada. The economic interests of the joint venture held by us and BMS (including share of revenues and out-of-pocket expenses) are based on the portion of the net selling price of Atripla attributable to efavirenz and Truvada. Since the net selling price for Truvada may change over time relative to the net selling price of efavirenz, both our and BMS's respective economic interests in the joint venture may vary annually.
	We and BMS shared marketing and sales efforts. Starting in the second quarter of 2011, except for a limited number of activities that will be jointly managed, the parties no longer coordinate detailing and promotional activities in the United States, and the parties have begun to reduce their joint promotional efforts since we launched Complera in August 2011 and Stribild in August 2012. The parties will continue to collaborate on activities such as manufacturing, regulatory, compliance and pharmacovigilance. The daily operations of the joint venture are governed by four primary joint committees formed by both BMS and Gilead. We are responsible for accounting, financial reporting, tax reporting, manufacturing and product distribution for the joint venture. Both parties provide their respective bulk active pharmaceutical ingredients to the joint venture at their approximate market values. The agreement will continue until terminated by the mutual agreement of the parties. In addition, either party may terminate the other party's participation in the collaboration within 30 days after the launch of at least one generic version of such other party's single agent products (or the double agent products). The terminating party then has the right to continue to sell Atripla and become the continuing party, but will be obligated to pay the terminated party certain royalties for a three-year period following the effective date of the termination.
	As of March 31, 2014 and December 31, 2013, the joint venture held efavirenz active pharmaceutical ingredient which it purchased from BMS at BMS's estimated net selling price of efavirenz in the U.S. market. These amounts are included in inventories on our Condensed Consolidated Balance Sheets. As of March 31, 2014, total assets held by the joint venture were $2.24 billion and consisted primarily of cash and cash equivalents of $200.4 million, accounts receivable of $252.8 million and inventories of $1.76 billion; total liabilities were $1.41 billion and consisted primarily of accounts payable of $1.04 billion and other accrued expenses of $370.9 million. As of December 31, 2013, total assets held by the joint venture were $2.24 billion and consisted primarily of cash and cash equivalents of $245.7 million, accounts receivable of $275.3 million and inventories of $1.72 billion; total liabilities were $1.26 billion and consisted primarily of accounts payable of $915.4 million and other accrued expenses of $341.2 million. These asset and liability amounts do not reflect the impact of intercompany eliminations that are included in our Condensed Consolidated Balance Sheets. Although we consolidate the joint venture, the legal structure of the joint venture limits the recourse that its creditors will have over our general credit or assets. Similarly, the assets held in the joint venture can be used only to settle obligations of the joint venture.
	Europe
	In 2007, Gilead Sciences Limited, our wholly-owned subsidiary in Ireland, and BMS entered into a collaboration agreement with BMS which sets forth the terms and conditions under which we and BMS will commercialize and distribute Atripla in the European Union, Iceland, Liechtenstein, Norway and Switzerland (collectively, the European Territory). The parties formed a limited liability company which we consolidate, to manufacture Atripla for distribution in the European Territory using efavirenz that it purchases from BMS at BMS's estimated net selling price of efavirenz in the European Territory. We are responsible for manufacturing, product distribution, inventory management and warehousing. Through our local subsidiaries, we have primary responsibility for order fulfillment, collection of receivables, customer relations and handling of sales returns in all the territories where we and BMS promote Atripla. In general, the parties share revenues and out-of-pocket expenses in proportion to the net selling prices of the components of Atripla, Truvada and efavirenz.
	Starting in 2012, except for a limited number of activities that will be jointly managed, the parties no longer coordinate detailing and promotional activities in the region. We are responsible for accounting, financial reporting and tax reporting for the collaboration. As of March 31, 2014 and December 31, 2013, efavirenz purchased from BMS at BMS's estimated net selling price of efavirenz in the European Territory is included in inventories on our Condensed Consolidated Balance Sheets.
	The parties also formed a limited liability company to hold the marketing authorization for Atripla in Europe. We have primary responsibility for regulatory activities. In the major market countries, both parties have agreed to independently continue to use commercially reasonable efforts to promote Atripla.
	The agreement will terminate upon the expiration of the last-to-expire patent which affords market exclusivity to Atripla or one of its components in the European Territory. In addition, starting December 31, 2013, either party may terminate the agreement for any reason and such termination will be effective two calendar quarters after notice of termination. The non-terminating party has the right to continue to sell Atripla and become the continuing party, but will be obligated to pay the terminating party certain royalties for a three-year period following the effective date of the termination. In the event the continuing party decides not to sell Atripla, the effective date of the termination will be the date Atripla is withdrawn in each country or the date on which a third party assumes distribution of Atripla, whichever is earlier.

Debt_and_Credit_Facility

Debt and Credit Facility	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Long-Term Obligations [Text Block]	'
	DEBT AND CREDIT FACILITY
	Financing Arrangements
	The following table summarizes the carrying amount of our borrowings under various financing arrangements (in thousands):
	Type of Borrowing	Description	Issue Date	Due Date	Interest Rate	March 31,		December 31, 2013
						2014
	Convertible Senior	May 2014 Notes	Jul-10	May-14	1.00%	$	208,471	$	234,217
	Convertible Senior	May 2016 Notes	Jul-10	May-16	1.63%	913,478		1,113,043
	Senior Unsecured	April 2021 Notes	Mar-11	Apr-21	4.50%	993,996		993,781
	Senior Unsecured	December 2014 Notes	Dec-11	Dec-14	2.40%	749,789		749,710
	Senior Unsecured	December 2016 Notes	Dec-11	Dec-16	3.05%	699,384		699,326
	Senior Unsecured	December 2021 Notes	Dec-11	Dec-21	4.40%	1,247,788		1,247,716
	Senior Unsecured	December 2041 Notes	Dec-11	Dec-41	5.65%	997,904		997,885
	Senior Unsecured	April 2019 Notes	Mar-14	Apr-19	2.05%	499,146		—
	Senior Unsecured	April 2024 Notes	Mar-14	Apr-24	3.70%	1,747,201		—
	Senior Unsecured	April 2044 Notes	Mar-14	Apr-44	4.80%	1,746,613		—
	Credit Facility	Five-Year Revolver	Jan-12	Jan-17	Variable	—		600,000
	Total debt, net					$	9,803,770	$	6,635,678
	Less current portion					1,871,738		2,696,970
	Total long-term debt, net					$	7,932,032	$	3,938,708
	Convertible Senior Notes
	During the three months ended March 31, 2014, a portion of our convertible senior notes due in May 2014 (May 2014 Notes) and May 2016 (May 2016 Notes) (together, the Notes) was converted. We repaid $243.4 million of principal balance, primarily comprised of May 2016 Notes. We also paid $575.3 million in cash related to the conversion spread of the Notes, which represents the conversion value in excess of the principal amount, and received $575.3 million in cash from the convertible note hedges related to the Notes.
	As of March 31, 2014, the May 2014 Notes were classified as current given their maturity date and the May 2016 Notes were classified as current given that the conversion criteria had been met. As a result, the related unamortized discount of $45.8 million was classified as equity component of currently redeemable convertible notes on our Condensed Consolidated Balance Sheet.
	April 2019, 2024 and 2044 Senior Unsecured Notes
	In March 2014, we issued senior unsecured notes in a registered offering for a total aggregate principal amount of $4.00 billion. We issued senior unsecured notes due in April 2019 (April 2019 Notes) for $500.0 million that pay interest at fixed annual rate of 2.05%, senior unsecured notes due in April 2024 (April 2024 Notes) for $1.75 billion that pay interest at a fixed annual rate of 3.70% and senior unsecured notes due in April 2044 (April 2044 Notes) for $1.75 billion that pay interest at a fixed annual rate of 4.80%. Debt issuance costs incurred in connection with the issuance of this debt totaled approximately $27.5 million and are being amortized to interest expense over the contractual term of each of the respective notes.
	These notes may be redeemed at our option at any time or from time to time, at a redemption price equal to the greater of (i) 100% of the principal amount of the notes to be redeemed and (ii) the sum, as determined by an independent investment banker, of the present values of the remaining scheduled payments of principal and interest on the notes to be redeemed (exclusive of interest accrued to the date of redemption) discounted to the redemption date on a semiannual basis at the Treasury Rate plus 10 basis points in the case of the April 2019 Notes, 15 basis points in case of the April 2024 Notes and 20 basis points in the case of the April 2044 Notes plus, in each case, accrued and unpaid interest on the notes to be redeemed to the date of redemption.
	At any time on or after the date that is three months prior to the maturity date of the April 2024 Notes, we may redeem the notes, in whole or in part, at 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest to the date of redemption. At any time on or after the date that is six months prior to the maturity date of the April 2044 Notes, we may redeem the notes, in whole or in part, at 100% of the principal amount of the notes to be redeemed, plus accrued and unpaid interest to the date of redemption.
	In the event of the occurrence of both a change in control and a downgrade in the rating of a series of notes below an investment grade rating by Standard & Poor's Ratings Services and Moody's Investors Service, Inc., the holders of such series of notes may require us to purchase all or a portion of their notes of such series at a price equal to 101% of the aggregate principal amount of the notes repurchased, plus accrued and unpaid interest.
	Credit Facility
	During the first quarter of 2014, we repaid the remaining balance of $600.0 million that was outstanding under the revolving credit facility credit agreement.
	We are required to comply with certain covenants under the credit agreement and note indentures and as of March 31, 2014, we believe we were in compliance with all such covenants.

Commitment_and_Contingencies

Commitment and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies Disclosure [Text Block]	'
		COMMITMENTS AND CONTINGENCIES
	Legal Proceedings
	Litigation Related to Sofosbuvir
	In January 2012, we acquired Pharmasset, Inc. (Pharmasset). Through the acquisition, we acquired sofosbuvir, a nucleotide analog that acts to inhibit the replication of the hepatitis C virus (HCV). In December 2013, we received FDA approval of sofosbuvir, now known commercially as Sovaldi. We have received a number of contractual and intellectual property claims regarding sofosbuvir. We have carefully considered these claims both prior to and following the acquisition and believe they are without merit.
	Contract Arbitration with Jeremy Clark
	In March 2012, Jeremy Clark, a former employee of Pharmasset and inventor of U.S. Patent No. 7,429,572, filed a demand for arbitration in his lawsuit against Pharmasset and Dr. Raymond Schinazi. Mr. Clark initially filed the lawsuit against Pharmasset and Dr. Schinazi in the U.S. District Court for the Northern District of Alabama in February 2008 seeking to void the assignment provision in his employment agreement and assert ownership of U.S. Patent No. 7,429,572, which claims metabolites of sofosbuvir and RG7128. In December 2008, the court ordered a stay of the litigation pending the outcome of an arbitration proceeding required by Mr. Clark's employment agreement. Instead of proceeding with arbitration, Mr. Clark filed two additional lawsuits in September 2009 and June 2010, both of which the court subsequently dismissed. In September 2010, Mr. Clark filed a motion seeking reconsideration of the court's December 2008 order which the court denied. In December 2011, Mr. Clark filed a motion to appoint a special prosecutor. In February 2012, the court issued an order requiring Mr. Clark to enter arbitration or risk dismissal of his case. Mr. Clark filed a demand for arbitration in March 2012. The arbitration panel held a hearing in April 2013. In June 2013, the arbitration panel issued its decision in favor of Pharmasset (now Gilead) and Dr. Schinazi. In August 2013, Gilead and Dr. Schinazi filed a motion in the U.S. District Court for the Northern District of Alabama seeking to have the court confirm the arbitration decision and Mr. Clark filed a motion seeking to vacate the arbitration decision. On April 9, 2014, the court granted our motion, confirmed the arbitration award and denied Mr. Clark’s motion.
	Arbitration with F. Hoffman-La Roche Ltd and Hoffman-La Roche Inc. (collectively, Roche)
	Gilead (as successor to Pharmasset) is a party to an October 29, 2004 collaboration agreement with Roche. The agreement granted Roche rights to develop PSI-6130, a cytidine analog, and its prodrugs, for the treatment of HCV infection. The collaborative research efforts under the agreement ended on December 31, 2006. Roche later asked Pharmasset to consider whether Roche may have contributed to the inventorship of sofosbuvir and whether Pharmasset has complied with the confidentiality provisions of the collaboration agreement. Pharmasset advised us that it carefully considered the issues raised by Roche and that it believed any such issues are without merit. We have also considered these issues and reached the same conclusion. In March 2013, Roche initiated an arbitration against us and Pharmasset, predecessor to Gilead Pharmasset LLC, regarding the collaboration agreement. In the arbitration demand, Roche asserts that it has an exclusive license to sofosbuvir pursuant to the collaboration agreement because sofosbuvir, a prodrug of a uridine monophosphate analog, is allegedly a prodrug of PSI-6130, a cytidine analog. Roche further claims that, because it has exclusive rights to sofosbuvir, it also has an exclusive license to a patent covering sofosbuvir, and that we will infringe that patent by selling and offering for sale products containing sofosbuvir. Gilead and Gilead Pharmasset LLC filed their response to Roche's arbitration demand in April 2013. We expect a decision in the arbitration by the end of 2014.
	Interference Proceedings and Litigation with Idenix Pharmaceuticals, Inc. (Idenix)
	In February 2012, we received notice that the U.S. Patent and Trademark Office (USPTO) had declared Interference No. 105,871 (First Idenix Interference) between our U.S. Patent No. 7,429,572 and Idenix's pending U.S. Patent Application No. 12/131,868. An interference is an administrative proceeding before the USPTO designed to determine who was the first to invent the subject matter claimed by both parties. Our patent covers metabolites of sofosbuvir and RG7128, a prodrug of a cytidine nucleoside analog that Pharmasset licensed to Roche. Idenix is attempting to patent a class of compounds, including these metabolites. The purpose of the First Idenix Interference was to determine who was first to invent these compounds and therefore who is entitled to the patent claiming these compounds. In March 2013, the USPTO Patent Trials and Appeal Board (the Board) determined that Idenix is not entitled to the benefit of any of its early application filing dates because none of those patent applications, including the application that led to Idenix’s U.S. Patent No. 7,608,600 (the ‘600 patent), taught how to make the compounds in dispute. The Board also determined that because we are entitled to the filing date of our earliest application, we were first to file the patent application on the compounds in dispute, and we were therefore the “senior party” in the First Idenix Interference. On January 29, 2014, the Board determined that Pharmasset and not Idenix was the first to invent the compounds in dispute and accordingly Gilead prevailed. In its decision, the Board held that Idenix failed to prove that it was first to conceive of any of the compounds in dispute. Specifically, Idenix failed to prove that the Idenix inventors had identified the structure, a method of making and a use for any of the disputed compounds. The Board went on to conclude that Idenix failed to work diligently toward making and testing the compounds in dispute during the relevant time period. Idenix has appealed the Board’s decisions to the U.S. District Court for the District of Delaware. If either or both of the Board’s decisions are reversed on appeal and the court determines that Idenix is entitled to their patent claims, and it is determined that we have infringed those claims, we may be required to obtain a license from and pay royalties to Idenix to commercialize sofosbuvir and RG7128 in the United States. A decision by the District Court can be appealed by either party to the U.S. Court of Appeals for the Federal Circuit (CAFC).
	We believe the claims in the Idenix application involved in the First Idenix Interference, and similar U.S. and foreign patents claiming the same compounds and metabolites, are invalid. As a result, we filed an Impeachment Action in the Federal Court of Canada to invalidate Idenix Canadian Patent No. 2,490,191 (the ‘191 patent), which is the Canadian patent that corresponds to the ‘600 patent and the Idenix patent application that is the subject of the First Idenix Interference. Idenix has now asserted that the commercialization of Sovaldi in Canada will infringe its ‘191 patent and that our Canadian Patent No. 2,527,657, corresponding to our U.S. Patent No. 7,429,572 in the First Idenix Interference, is invalid.
	We filed a similar legal action in Norway in the Oslo District Court seeking to invalidate Idenix's corresponding Norwegian patent. In September 2013, Idenix filed an invalidation action in the Norwegian proceedings against our Norwegian Patent No. 333700 patent, which corresponds to our U.S. Patent No. 7,429,572. The trial was held in November 2013. On March 21, 2014, the Norwegian court found all claims in the Idenix Norwegian patent to be invalid and upheld the validity of all claims in the challenged Gilead patent. Additionally, the Norwegian court ordered Idenix to pay us over $2.0 million in attorney fees as the losing party to the litigation. Idenix has indicated that it will appeal the Norwegian court’s decision. Idenix’s obligation to pay our attorneys’ fees will be stayed during the pendency of the appeal.
	In August 2013, Idenix also filed a request for invalidation with the Chinese Patent Office of our Chinese Patent CN ZL200480019148.4, which corresponds to our U.S. Patent No. 7,429,572.
	We filed a legal action in the Federal Court of Australia seeking to invalidate Idenix’s Australian patent corresponding to the ‘600 patent. In April 2013, Idenix asserted that the commercialization of sofosbuvir will infringe the Australian patent corresponding to the ‘600 patent. We may bring similar action in other countries in the future.
	On March 12, 2014, the European Patent Office (EPO) granted Idenix European Patent No. 1 523 489 (the ‘489 patent), which corresponds to the ‘600 patent. The same day that the ‘489 patent granted, we filed an opposition with the EPO seeking to revoke the ‘489 patent. Also on March 12, 2014, Idenix initiated infringement proceedings against us in the United Kingdom, Germany and France alleging that the commercialization of Sovaldi in those countries would infringe the respective national counterparts of the ‘489 patent. In the United Kingdom, the court has ordered an October 2014 trial date to determine the issues of infringement and validity of the Idenix United Kingdom patent. In Germany, the court in Düsseldorf has ordered a hearing date of December 2, 2014 to determine the issue of infringement of the Idenix German patent. We do not have a trial date for the French lawsuit.
	Idenix has not been awarded patents corresponding to the ‘600 patent in Japan or China. In the event such patents issue, we expect to challenge them in proceedings similar to those we invoked in Canada, Norway and Australia. If the courts hearing these proceedings determine that Idenix is entitled to their patent claims and it is determined that we have infringed those claims, we may be required to obtain a license from and pay royalties to Idenix to commercialize sofosbuvir and RG7128 in that country.
	In December 2013, after receiving Gilead’s request to do so, the USPTO declared Interference No. 105,981 (Second Idenix Interference) between our pending U.S. Patent Application No. 11/854,218 and the ‘600 patent. The ‘600 patent includes claims directed to methods of treating HCV with nucleoside compounds similar to those which were involved in the First Idenix Interference. The Second Idenix Interference will determine who was first to invent the claimed methods of treating HCV. In the declaration of the Second Idenix Interference, the USPTO has initially designated Gilead as the junior party based upon the patent application filing dates appearing on the face of the ‘600 patent. On February 5, 2014, the USPTO issued an Order to Show Cause against Idenix in the Second Idenix Interference. The Order requires Idenix to explain why judgment should not be entered against it in the Second Idenix Interference in favor of Gilead based upon the outcome of the First Idenix Interference. On April 11, 2014, the USPTO declined to enter judgment against Idenix in the Second Idenix Interference based upon the Order to Show Cause, but we will have the opportunity to prove that Gilead should be the senior party for the same reasons we were declared the senior party in the First Idenix Interference. We believe the Board’s determination in the First Idenix Interference that Idenix is not entitled to the benefit of any of its earlier application filing dates, including the filing date of the ‘600 patent, will be equally applicable to the Second Idenix Interference. If we are correct, the Board may conclude that Gilead is the senior party in the Second Idenix Interference, consistent with the determination in the First Idenix Interference. In light of the Board’s conclusion in the First Idenix Interference that the application that led to the ‘600 patent does not teach how to make the claimed compounds, it is possible that the Board will make the same determination in the Second Idenix Interference and eliminate the need for the Board to address who was the first to invent the claimed methods of treating HCV. However, if the Board does consider who was the first to invent the claimed methods of treating HCV and ultimately concludes that Gilead was first, the claims in the ‘600 patent may be revoked. If the Board determines that Idenix was first to invent and is entitled to these patent claims, and it is determined in other proceedings that we have infringed those claims, we may be required to obtain a license from and pay royalties to Idenix to commercialize sofosbuvir and RG7128. Any determination by the Board can be appealed by either party to U.S. federal court.
	In December 2013, Idenix, Universita Degli Studi di Cagliari (UDSG), Centre National de la Recherche Scientifique and L’Université Montpellier II sued us in U.S. District Court for the District of Delaware alleging that the commercialization of sofosbuvir will infringe the ‘600 patent and that an interference exists between the ‘600 patent and our U.S. Patent No. 8,415,322. We believe that the claims in the ‘600 patent are invalid and that we have the sole right to commercialize sofosbuvir. However, if the court disagrees with our view and further determines that the ‘600 patent is infringed, we may be required to obtain a license from and pay royalties to Idenix to commercialize sofosbuvir. A decision by the District Court can be appealed by either party to the CAFC.
	Also in December 2013, Idenix and UDSG sued us in the U.S. District Court for the District of Massachusetts alleging that the commercialization of sofosbuvir will infringe U.S. Patent Nos. 6,914,054 and 7,608,597. We believe that Idenix’s patents are invalid and would not be infringed by our commercialization of sofosbuvir and that we have the sole right to commercialize sofosbuvir. However, if the court disagrees with our view and determines that these patents are infringed, we may be required to obtain a license from and pay royalties to Idenix to commercialize sofosbuvir. A decision by the District Court can be appealed by either party to the CAFC.
	We have an expansive patent portfolio covering NS5A inhibitors for the treatment of HCV. Following the recent disclosure of the structure of Idenix’s NS5A inhibitor, samatasvir (also known as IDX-719), we are evaluating the compound in light of the claims of our granted U.S. Patent No. 8,669,234.
	Litigation with Merck & Co., Inc. (Merck)
	In August 2013, Merck contacted us requesting that we pay royalties on the sales of sofosbuvir and take a license to U.S. Patent Nos. 7,105,499 and 8,481,712, which it co-owns with Isis Pharmaceuticals, Inc. We believe that Merck’s patents are invalid and would not be infringed by our commercialization of sofosbuvir and that we have the sole right to commercialize sofosbuvir. Accordingly, in August 2013, we filed a lawsuit in the U.S. District Court for the Northern District of California seeking declaratory judgment that the Merck patents are invalid and not infringed. Merck’s U.S. Patent Nos. 7,105,499 and 8,481,712 cover compounds which do not include, but may relate to, sofosbuvir. During patent prosecution, Merck amended its patent application in an attempt to cover compounds related to sofosbuvir and ultimately extract royalty payments for sofosbuvir’s commercialization, or to exclude it from the market. If the court determines that Merck’s patents are valid and that we have infringed those claims, we may be required to obtain a license from and pay royalties to Merck to commercialize sofosbuvir. Either party can appeal a decision by the District Court to the CAFC.
	Litigation with AbbVie, Inc. (AbbVie)
	AbbVie has obtained U.S. Patent Nos. 8,466,159, 8,492,386, 8,680,106 and 8,685,984, which purport to claim the use of a combination of LDV/SOF for the treatment of HCV. We own published and pending patent applications directed to the use of combinations for the treatment of HCV, and, specifically, to combinations of ledipasvir and sofosbuvir. Certain of those applications were filed before AbbVie’s patents. For this reason and others, we believe AbbVie’s patents are invalid.
	Accordingly, in December 2013, we filed a lawsuit in the U.S. District Court for the District of Delaware seeking declaratory judgment that the AbbVie patents are invalid and unenforceable, as well as other relief. We believe that Abbott Laboratories, Inc. and AbbVie conspired to eliminate competition in the HCV market by falsely representing to the USPTO that they, and not Gilead, invented methods of treating HCV using a combination of LDV/SOF. In February 2014, AbbVie responded to our lawsuit by filing a lawsuit also in the U.S. District Court for the District of Delaware alleging that our LDV/SOF product will infringe their patents. We do not expect AbbVie’s patents to block or delay the commercialization of our combination products. If the court determines that AbbVie’s patents are valid and that we have infringed those claims, we may be required to obtain a license from and pay royalties to AbbVie to commercialize sofosbuvir combination products. Either party can appeal a decision by the District Court to the CAFC.
	We cannot predict the ultimate outcome of contractual and intellectual property claims related to sofosbovir, and we may spend significant resources enforcing and defending these patents. If these parties successfully obtain valid and enforceable patents, and successfully prove infringement of those patents by sofosbuvir, we could be prevented from selling sofosbuvir unless we were able to obtain a license under such patents. Such a license may not be available on commercially reasonable terms or at all. Further, if any party is successful in establishing exclusive rights to sofosbuvir, our expected revenues and earnings from the sale of sofosbuvir would be adversely affected. A range of losses cannot be estimated at this time.
	Litigation with Generic Manufacturers
	As part of the approval process for some of our products, the FDA granted a New Chemical Entity (NCE) exclusivity period during which other manufacturers' applications for approval of generic versions of our product will not be approved. Generic manufacturers may challenge the patents protecting products that have been granted NCE exclusivity one year prior to the end of the NCE exclusivity period. Generic manufacturers have sought and may continue to seek FDA approval for a similar or identical drug through an abbreviated new drug application (ANDA), the application form typically used by manufacturers seeking approval of a generic drug. We received notices that generic manufacturers have submitted ANDAs to manufacture a generic version of Atripla, Truvada, Viread, Emtriva, Ranexa and Tamiflu in the United States and Atripla, Truvada and Viread in Canada. In April 2013, we and Teva Pharmaceuticals (Teva) reached an agreement to settle the ongoing patent litigation concerning the four patents that protect tenofovir disoproxil fumarate in our Atripla, Truvada and Viread products. Under the agreement, Teva will be allowed to launch a generic version of Viread on December 15, 2017.
	In March 2011, we and F. Hoffmann-La Roche Ltd. (Roche) filed a lawsuit against Natco Pharma Ltd. (Natco) in U.S. District Court for the District of New Jersey for infringement of one of the patents associated with Tamiflu. In December 2012, the court issued a ruling in favor of Gilead and Roche, that our patent is not invalid for the reasons stated in Natco’s notice letter. Natco has appealed this decision to the CAFC. In April 2014, the court issued a decision which will allow Natco’s patent invalidity challenge to proceed on remand to the District Court of New Jersey for a full trial on the merits. We are currently evaluating our response to this decision.
	In August 2013, we and Lupin Limited (Lupin) reached an agreement to settle the patent litigation concerning ten of the patents that protect Ranexa. Under the agreement, Lupin would be allowed to launch a generic version of Ranexa on February 27, 2019.
	In February 2014, we and Teva reached an agreement in principle to settle the ongoing patent litigation concerning the emtricitabine patents that protect Atripla and Truvada. The terms of the settlement agreement are confidential. The settlement agreement will be filed with the Federal Trade Commission and Department of Justice as required by law.
	Also in August 2012, Teva filed an Impeachment Action in the Federal Court of Canada seeking invalidation of our two Canadian patents associated with Viread. In September 2013, a hearing on the consolidated requests for orders of prohibition in connection with all three of Teva’s abbreviated new drug submission (ANDS) filings to the Canadian Minister of Health (for Teva’s generic versions of Viread, Truvada, and Atripla) took place. In December 2013, the court issued our requested order prohibiting the Canadian Ministry of Health from issuing a Notice of Compliance for Teva’s generic versions of our Viread, Truvada, and Atripla products until expiry of our patent in July 2017. Teva appealed this decision and this decision of the court does not ultimately resolve the validity challenges raised by Teva in the Impeachment Action. If Teva is successful in invalidating our patents, Teva may be able to launch generic versions of our Viread, Truvada and Atripla products prior to the expiry of our patents. A trial in the Impeachment Action is scheduled for January 2015.
	We anticipate trials related to Lupin's ANDAs requesting permission to make a generic version of Truvada and Viread and Cipla's ANDA requesting permission to make generic versions of Emtriva and Viread to take place in the fourth quarter of 2014.
	We cannot predict the ultimate outcome of these actions, and we may spend significant resources enforcing and defending these patents. If we are unsuccessful in these lawsuits, some or all of our original claims in the patents may be narrowed or invalidated and the patent protection for Atripla, Truvada, Viread, Emtriva, Ranexa and Tamiflu in the United States and Atripla, Truvada and Viread in Canada could be substantially shortened. Further, if all of the patents covering one or more products are invalidated, the FDA or Canadian Minister of Health could approve the requests to manufacture a generic version of such products in the United States or Canada, respectively, prior to the expiration date of those patents. The sale of generic versions of these products earlier than their patent expiration would have a significant negative effect on our revenues and results of operations.
	Department of Justice Investigation
	In June 2011, we received a subpoena from the U.S. Attorney's Office for the Northern District of California requesting documents related to the manufacture, and related quality and distribution practices, of Complera, Atripla, Truvada, Viread, Emtriva, Hepsera and Letairis. We cooperated with the government’s inquiry. On April 16, 2014, the United States Department of Justice informed us that, following an investigation, it declined to intervene in a False Claims Act lawsuit filed by two former employees. We intend to move to dismiss the complaint.
	Other Matters
	We are a party to various legal actions that arose in the ordinary course of our business. We do not believe that these other legal actions will have a material adverse impact on our consolidated business, financial position or results of operations.

Stockholders_Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2014
Stockholders' Equity Attributable to Parent [Abstract]	'
Stockholders' Equity Note Disclosure [Text Block]	'
	STOCKHOLDERS’ EQUITY
	Stock Repurchase Program
	During the three months ended March 31, 2014, we repurchased a total of $450.1 million or 5.7 million shares of common stock under our January 2011 stock repurchase program.
	Accumulated Other Comprehensive Income (Loss)
	The following table summarizes the changes in accumulated OCI by component, net of tax (in thousands):
		Foreign Currency Items			Unrealized Gains and Losses on Available-for-Sale Securities			Unrealized Gains and Losses on Cash Flow Hedges			Total
	Balance at December 31, 2013	$	(45,860	)	$	11,907		$	(90,493	)	$	(124,446	)
	Other comprehensive income before reclassifications	5,783			147			1,265			7,195
	Amounts reclassified from accumulated other comprehensive income (loss)	—			(199		)	21,681			21,482
	Net current period other comprehensive income (loss)	5,783			(52		)	22,946			28,677
	Balance at March 31, 2014	$	(40,077	)	$	11,855		$	(67,547	)	$	(95,769	)
	Amounts reclassified for gains (losses) on cash flow hedges were recorded as part of product sales on our Condensed Consolidated Statements of Income. Amounts reclassified for unrealized gains (losses) on available-for-sale securities were recorded as part of other income (expense), net on our Condensed Consolidated Statements of Income.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2014
Share-based Compensation [Abstract]	'
Stock-Based Compensation Disclosure [Text Block]	'
	STOCK-BASED COMPENSATION
	The following table summarizes the stock-based compensation expense included in our Condensed Consolidated Statements of Income (in thousands):
		Three Months Ended
		March 31,
		2014			2013
	Cost of goods sold	$	2,642		$	1,841
	Research and development expenses	34,350			26,875
	Selling, general and administrative expenses	45,233			33,051
	Stock-based compensation expense included in total costs and expenses	82,225			61,767
	Income tax effect	(19,089		)	(16,387		)
	Stock-based compensation expense, net of tax	$	63,136		$	45,380

Net_Income_Per_Share_Attributa

Net Income Per Share Attributable to Gilead Common Stockholders	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share [Text Block]	'
	NET INCOME PER SHARE ATTRIBUTABLE TO GILEAD COMMON STOCKHOLDERS
	Basic net income per share attributable to Gilead common stockholders is calculated based on the weighted-average number of shares of our common stock outstanding during the period. Diluted net income per share attributable to Gilead common stockholders is calculated based on the weighted-average number of shares of our common stock outstanding and other dilutive securities outstanding during the period. The potential dilutive shares of our common stock resulting from the assumed exercise of outstanding stock options, performance shares and the assumed exercise of warrants relating to the convertible senior notes due in May 2013 (May 2013 Notes), May 2014 Notes and May 2016 Notes (collectively, the Convertible Notes) are determined under the treasury stock method.
	Because the principal amount of the Convertible Notes will be settled in cash, only the conversion spread relating to the Convertible Notes is included in our calculation of diluted net income per share attributable to Gilead common stockholders. Our common stock resulting from the assumed settlement of the conversion spread of the Convertible Notes has a dilutive effect when the average market price of our common stock during the period exceeds the conversion price of $22.54 for the May 2014 Notes and $22.71 for the May 2016 Notes. Warrants relating to the Convertible Notes have a dilutive effect when the average market price of our common stock during the period exceeds the warrants’ exercise price of $28.38 for the May 2014 Notes and $30.05 for the May 2016 Notes.
	Our May 2013 Notes matured and as a result, we have only included their impact for the period they were outstanding on our net income per share calculations for the three months ended March 31, 2013. Our common stock resulting from the assumed settlement of the conversion spread of the May 2013 Notes had a dilutive effect when the average market price of our common stock during the period exceeded the conversion price of $19.05. Warrants related to our May 2013 Notes settled in August 2013 and as a result, we have only included their impact for the period they were outstanding on our net income per share calculation for the three months ended March 31, 2013. The related warrants had a dilutive effect when the average market price of our common stock during the period exceeded the warrants’ exercise price of $26.95.
	We have excluded stock options to purchase approximately 0.7 million weighted-average shares of our common stock that were outstanding during the three months ended March 31, 2014 and 1.3 million shares during the three months ended March 31, 2013 in the computation of diluted net income per share attributable to Gilead common stockholders because their effect was antidilutive.
	The following table is a reconciliation of the numerator and denominator used in the calculation of basic and diluted net income per share attributable to Gilead common stockholders (in thousands):
		Three Months Ended
		March 31,
		2014		2013
	Numerator:
	Net income attributable to Gilead	$	2,227,410	$	722,186
	Denominator:
	Weighted-average shares of common stock outstanding used in the calculation of basic net income per share attributable to Gilead common stockholders	1,536,525		1,521,372
	Effect of dilutive securities:
	Stock options and equivalents	35,024		36,812
	Conversion spread related to the May 2013 Notes	—		10,703
	Conversion spread related to the May 2014 Notes	7,036		25,554
	Conversion spread related to the May 2016 Notes	31,936		25,140
	Warrants related to the Convertible Notes	69,350		45,479
	Weighted-average shares of common stock outstanding used in the calculation of diluted net income per share attributable to Gilead common stockholders	1,679,871		1,665,060

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Segment Reporting Disclosure [Text Block]	'
	SEGMENT INFORMATION
	We operate in one business segment, which primarily focuses on the discovery, development and commercialization of innovative medicines in areas of unmet medical need. All products are included in one segment, because the majority of our products have similar economic and other characteristics, including the nature of the products and production processes, type of customers, distribution methods and regulatory environment. Total product sales on an individual product basis are summarized in the following table (in thousands):
		Three Months Ended
		March 31,
		2014			2013
	Antiviral products:
	Sovaldi	$	2,274,349		$	—
	Atripla	779,594			877,073
	Truvada	759,700			700,242
	Complera/Eviplera	250,733			148,189
	Stribild	215,271			92,148
	Viread	210,625			210,332
	Hepsera	11,723			26,423
	Emtriva	6,502			6,671
	Total antiviral products	4,508,497			2,061,078
	Letairis	122,885			118,107
	Ranexa	111,618			96,286
	AmBisome	92,093			85,275
	Other products	35,881			32,822
	Total product sales	$	4,870,974		$	2,393,568
	The following table summarizes revenues from each of our customers who individually accounted for 10% or more of our total revenues (as a percentage of total revenues):
		Three Months Ended
		March 31,
		2014		2013
	AmerisourceBergen Corp.	27	%	11	%
	McKesson Corp.	23	%	14	%
	Cardinal Health, Inc.	13	%	19	%
	The change in the percentage of total revenues was due primarily to sales of Sovaldi, the majority of which represent sales in the United States.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]	'
Income Tax Disclosure [Text Block]	'
	INCOME TAXES
	Our income tax rate of 24.6% for the three months ended March 31, 2014, differed from the U.S. federal statutory rate of 35% due primarily to tax credits and certain operating earnings from non-U.S. subsidiaries that are considered indefinitely reinvested, partially offset by state taxes, our portion of the non-deductible pharmaceutical excise tax and amortization expense of the intangible asset related to sofosbuvir for which we receive no tax benefit. We do not provide for U.S. income taxes on undistributed earnings of our foreign operations that are intended to be indefinitely reinvested in our foreign subsidiaries.
	We file federal, state and foreign income tax returns in many jurisdictions in the United States and abroad. For federal income tax purposes, the statute of limitations is open for 2008 and onwards. For certain acquired entities, the statute of limitations is open for all years from inception due to our utilization of their net operating losses and credits carried over from prior years. For California income tax purposes, the statute of limitations is open for 2008 and onwards.
	Our income tax returns are audited by federal, state and foreign tax authorities. We are currently under examination by the Internal Revenue Service (IRS) for the 2010, 2011 and 2012 tax years and by various state and foreign jurisdictions. There are differing interpretations of tax laws and regulations, and as a result, significant disputes may arise with these tax authorities involving issues of the timing and amount of deductions and allocations of income among various tax jurisdictions. We periodically evaluate our exposures associated with our tax filing positions.
	As of March 31, 2014, we believe that it is reasonably possible that our unrecognized tax benefits will decrease by approximately $12.0 million in the next 12 months as we expect to have clarification from the IRS and other tax authorities regarding our uncertain tax positions. With respect to the remaining unrecognized tax benefits, we are currently unable to make a reasonable estimate as to the period of cash settlement, if any, with the respective tax authorities.
	We record liabilities related to uncertain tax positions in accordance with the income tax guidance which clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements by prescribing a minimum recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We do not believe any of our uncertain tax positions will have a material adverse effect on our Condensed Consolidated Financial Statements, although an adverse resolution of one or more of these uncertain tax positions in any period could have a material impact on the results of operations for that period.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Basis of Presentation [Policy Text Block]	'
	Basis of Presentation
	The accompanying unaudited Condensed Consolidated Financial Statements have been prepared in accordance with U.S. generally accepted accounting principles for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of Gilead Sciences, Inc. (Gilead, we or us) believes are necessary for a fair presentation of the periods presented. These interim financial results are not necessarily indicative of results expected for the full fiscal year or for any subsequent interim period.
	The accompanying Condensed Consolidated Financial Statements include the accounts of Gilead, our wholly-owned subsidiaries and our joint ventures with Bristol-Myers Squibb Company (BMS), for which we are the primary beneficiary. We record a noncontrolling interest in our Condensed Consolidated Financial Statements to reflect BMS’s interest in the joint ventures. All intercompany transactions have been eliminated. The Condensed Consolidated Financial Statements include the results of companies acquired by us from the date of each acquisition for the applicable reporting periods. Certain prior period amounts within our Condensed Consolidated Financial Statements and related notes have been reclassified to conform to the current presentation.
	The accompanying Condensed Consolidated Financial Statements and related Notes to Condensed Consolidated Financial Statements should be read in conjunction with the audited Consolidated Financial Statements and the related notes thereto for the year ended December 31, 2013, included in our Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.
Significant Accounting Policies, Estimates and Judgments [Policy Text Block]	'
	Significant Accounting Policies, Estimates and Judgments
	The preparation of these Condensed Consolidated Financial Statements requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures. On an ongoing basis, management evaluates its significant accounting policies or estimates. We base our estimates on historical experience and on various market specific and other relevant assumptions that we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ significantly from these estimates.
Concentrations of Risk [Policy Text Block]	'
	Concentrations of Risk
	We are subject to credit risk from our portfolio of cash equivalents and marketable securities. Under our investment policy, we limit amounts invested in such securities by credit rating, maturity, industry group, investment type and issuer, except for securities issued by the U.S. government. We are not exposed to any significant concentrations of credit risk from these financial instruments. The goals of our investment policy, in order of priority, are as follows: safety and preservation of principal and diversification of risk; liquidity of investments sufficient to meet cash flow requirements; and a competitive after-tax rate of return.
	We are also subject to credit risk from our accounts receivable related to our product sales. The majority of our trade accounts receivable arises from product sales in the United States and Europe.
	As of March 31, 2014, our accounts receivable in Southern Europe, specifically Greece, Italy, Portugal and Spain, totaled approximately $602.8 million, of which $156.8 million were greater than 120 days past due and $50.6 million were greater than 365 days past due. To date, we have not experienced significant losses with respect to the collection of our accounts receivable. We believe that our allowance for doubtful accounts was adequate at March 31, 2014.
Recent Accounting Pronouncement [Policy Text Block]	'
	Recent Accounting Pronouncements
	There have been no new accounting pronouncements during the three months ended March 31, 2014 that we believe would have a material impact on our financial position or results of operations.

Fair_value_measurements_Tables

Fair value measurements (Tables)	3 Months Ended
	Mar. 31, 2014
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]	'
	The following table summarizes the carrying values and fair values of our convertible senior notes and senior unsecured notes (in thousands):
					31-Mar-14						December 31, 2013
	Type of Borrowing		Description		Carrying Value			Fair Value			Carrying Value			Fair Value
	Convertible Senior		May 2014 Notes		$	208,471		$	637,224		$	234,217		$	783,651
	Convertible Senior		May 2016 Notes		913,478			2,947,013			1,113,043			3,871,516
	Senior Unsecured		April 2021 Notes		993,996			1,096,750			993,781			1,075,480
	Senior Unsecured		December 2014 Notes		749,789			759,983			749,710			762,637
	Senior Unsecured		December 2016 Notes		699,384			737,961			699,326			740,705
	Senior Unsecured		December 2021 Notes		1,247,788			1,358,275			1,247,716			1,336,738
	Senior Unsecured		December 2041 Notes		997,904			1,148,870			997,885			1,118,660
	Senior Unsecured(1)		April 2019 Notes		499,146			496,485			—			—
	Senior Unsecured(1)		April 2024 Notes		1,747,201			1,763,825			—			—
	Senior Unsecured(1)		April 2044 Notes		1,746,613			1,811,250			—			—
	(1) See Note 8, Debt and Credit Facility for discussion of March 2014 financing.
Schedule of fair value, assets and liabilities measured on recurring basis [Table Text Block]	'
	The following table summarizes, for assets or liabilities recorded at fair value, the respective fair value and the classification by level of input within the fair value hierarchy previously defined (in thousands):
		31-Mar-14													December 31, 2013
		Level 1				Level 2			Level 3			Total			Level 1		Level 2		Level 3		Total
	Assets:
	Debt securities:
	Money market funds	$	5,056,350			$	—		$	—		$	5,056,350		$	1,490,964	$	—	$	—	$	1,490,964
	Corporate debt securities	—				221,734			—			221,734			—		220,025		—		220,025
	U.S. treasury securities	105,291				—			—			105,291			85,403		—		—		85,403
	U.S. government agencies securities	—				72,830			—			72,830			—		93,350		—		93,350
	Residential mortgage and asset-backed securities	—				45,647			—			45,647			—		46,941		—		46,941
	Municipal debt securities	—				9,246			—			9,246			—		12,065		—		12,065
	Total debt securities	5,161,641				349,457			—			5,511,098			1,576,367		372,381		—		1,948,748
	Deferred compensation plan	47,913				—			—			47,913			44,461		—		—		44,461
	Derivatives	—				11,032			—			11,032			—		13,879		—		13,879
		$	5,209,554			$	360,489		$	—		$	5,570,043		$	1,620,828	$	386,260	$	—	$	2,007,088
	Liabilities:
	Contingent consideration	$	—			$	—		$	266,438		$	266,438		$	—	$	—	$	263,760	$	263,760
	Derivatives	—				72,366			—			72,366			—		99,057		—		99,057
	Deferred compensation plan	47,913				—			—			47,913			44,461		—		—		44,461
		$	47,913			$	72,366		$	266,438		$	386,717		$	44,461	$	99,057	$	263,760	$	407,278
Fair value, liabilities measured on recurring basis, unobservable input reconciliation [Table Text Block]	'
	The following table provides a rollforward of our contingent consideration liabilities, which are recorded as part of other accrued liabilities and other long-term obligations in our Condensed Consolidated Balance Sheets (in thousands):
	Balance at December 31, 2013		$	263,760
	Additions from new acquisitions		—
	Net changes in valuation		2,678
	Balance at March 31, 2014		$	266,438

Availableforsale_securities_Ta

Available-for-sale securities (Tables)	3 Months Ended
	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]	'
Summary of Available-for-Sale Securities at Estimated Fair Value [Table Text Block]	'
	The following table is a summary of available-for-sale debt securities recorded in cash and cash equivalents or marketable securities in our Condensed Consolidated Balance Sheets (in thousands):
		31-Mar-14											December 31, 2013
		Amortized			Gross			Gross			Estimated		Amortized			Gross		Gross			Estimated
		Cost			Unrealized			Unrealized			Fair Value		Cost			Unrealized		Unrealized			Fair Value
					Gains			Losses								Gains		Losses
	Debt securities:
	Money market funds	$	5,056,350		$	—		$	—		$	5,056,350	$	1,490,964		$	—	$	—		$	1,490,964
	Corporate debt securities	220,999			801			(66		)	221,734		219,242			885		(102		)	220,025
	U.S. Treasury securities	105,330			75			(114		)	105,291		85,337			94		(28		)	85,403
	U.S. government agencies securities	72,654			176			—			72,830		93,211			156		(17		)	93,350
	Residential mortgage and asset-backed securities	45,624			59			(36		)	45,647		46,969			37		(65		)	46,941
	Municipal debt securities	9,175			71			—			9,246		12,009			56		—			12,065
	Total	$	5,510,132		$	1,182		$	(216	)	$	5,511,098	$	1,947,732		$	1,228	$	(212	)	$	1,948,748
Summary of the Classification of Available-for-Sale Securities [Table Text Block]	'
	The following table summarizes the classification of the available-for-sale debt securities on our Condensed Consolidated Balance Sheets (in thousands):
		31-Mar-14			December 31, 2013
	Cash and cash equivalents	$	5,056,350		$	1,490,964
	Short-term marketable securities	64,877			18,756
	Long-term marketable securities	389,871			439,028
	Total	$	5,511,098		$	1,948,748
Summary of Available-for-Sale Securities by Contractual Maturity [Table Text Block]	'
	The following table summarizes our portfolio of available-for-sale debt securities by contractual maturity (in thousands):
		31-Mar-14
		Amortized Cost			Fair Value
	Less than one year	$	5,121,014		$	5,121,227
	Greater than one year but less than five years	383,960			384,741
	Greater than five years but less than ten years	—			—
	Greater than ten years	5,158			5,130
	Total	$	5,510,132		$	5,511,098
Summary of Gross Realized Gains (Losses) Related to Sales of Marketable Securities [Table Text Block]	'
	The following table summarizes the gross realized gains and losses related to sales of marketable securities (in thousands):
		Three Months Ended
		March 31,
		2014			2013
	Gross realized gains on sales	$	338		$	182
	Gross realized losses on sales	$	(25	)	$	(156	)
Summary of Available-for-Sale Securities in a Continuous Loss Position Deemed not to be Other-than-Temporarily Impaired [Table Text Block]	'
	The following table summarizes our available-for-sale debt securities that were in a continuous unrealized loss position, but were not deemed to be other-than-temporarily impaired (in thousands):
		Less Than 12 Months						12 Months or Greater					Total
		Gross			Estimated			Gross			Estimated		Gross			Estimated
		Unrealized			Fair Value			Unrealized			Fair Value		Unrealized			Fair Value
		Losses						Losses					Losses
	31-Mar-14
	Debt securities:
	U.S. treasury securities	$	(114	)	$	44,014		$	—		$	—	$	(114	)	$	44,014
	Corporate debt securities	(66		)	37,719			—			—		(66		)	37,719
	Residential mortgage and asset-backed securities	(17		)	15,248			(19		)	3,655		(36		)	18,903
	U.S. government agencies securities	—			—			—			—		—			—
	Total	$	(197	)	$	96,981		$	(19	)	$	3,655	$	(216	)	$	100,636
	December 31, 2013
	Debt securities:
	U.S. treasury securities	$	(28	)	$	24,562		$	—		$	—	$	(28	)	$	24,562
	Corporate debt securities	(102		)	37,076			—			1,505		(102		)	38,581
	Residential mortgage and asset-backed securities	(38		)	19,563			(27		)	6,731		(65		)	26,294
	U.S. government agencies securities	(17		)	10,858			—			—		(17		)	10,858
	Total	$	(185	)	$	92,059		$	(27	)	$	8,236	$	(212	)	$	100,295

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Fair Values of Derivative Instruments on Condensed Consolidated Balance Sheets	'
	The following table summarizes the location and fair values of derivative instruments on our Condensed Consolidated Balance Sheets (in thousands):
		31-Mar-14
		Asset Derivatives						Liability Derivatives
		Classification		Fair Value				Classification	Fair Value
	Derivatives designated as hedges:
	Foreign currency exchange contracts	Other current assets		$	10,451			Other accrued liabilities	$	65,965
	Foreign currency exchange contracts	Other long-term assets		580				Other long-term obligations	6,321
	Total derivatives designated as hedges			11,031					72,286
	Derivatives not designated as hedges:
	Foreign currency exchange contracts	Other current assets		1				Other accrued liabilities	80
	Total derivatives not designated as hedges			1					80
	Total derivatives			$	11,032				$	72,366
		December 31, 2013
		Asset Derivatives						Liability Derivatives
		Classification		Fair Value				Classification	Fair Value
	Derivatives designated as hedges:
	Foreign currency exchange contracts	Other current assets		$	12,647			Other accrued liabilities	$	85,541
	Foreign currency exchange contracts	Other long-term assets		1,229				Other long-term obligations	13,299
	Total derivatives designated as hedges			13,876					98,840
	Derivatives not designated as hedges:
	Foreign currency exchange contracts	Other current assets		3				Other accrued liabilities	217
	Total derivatives not designated as hedges			3					217
	Total derivatives			$	13,879				$	99,057
Summary of the Effect of Foreign Currency Exchange Contracts on Condensed Consolidated Statements of Income	'
	The following table summarizes the effect of our foreign currency exchange contracts on our Condensed Consolidated Statements of Income (in thousands):
		Three Months Ended
		March 31,
		2014				2013
	Derivatives designated as hedges:
	Gains recognized in OCI (effective portion)	$	2,997			$	70,860
	Gains (losses) reclassified from accumulated OCI into product sales (effective portion)	$	(20,691	)		$	462
	Gains (losses) recognized in other income (expense), net (ineffective portion and amounts excluded from effectiveness testing)	$	84			$	(2,132	)
	Derivatives not designated as hedges:
	Gains recognized in other income (expense), net	$	1,103			$	32,620
Derivatives Netting Tabular Disclosure [Table Text Block]	'
	The following table summarizes the potential effect of offsetting derivatives by type of financial instrument on our Condensed Consolidated Balance Sheets (in thousands):
	31-Mar-14
	Offsetting of Derivative Assets/Liabilities
												Gross Amounts Not Offset
												in the Condensed
												Consolidated Balance Sheet
	Description	Gross Amounts of Recognized Assets/Liabilities				Gross Amounts Offset in the Condensed Consolidated Balance Sheet			Amounts of Assets/Liabilities Presented			Derivative Financial Instruments			Cash Collateral Received/Pledged		Net Amount (Legal Offset)
									in the Condensed Consolidated
									Balance Sheet
	Derivative assets	$	11,032			$	—		$	11,032		$	(11,032	)	$	—	$	—
	Derivative liabilities	(72,366		)		—			(72,366		)	11,032			—		(61,334		)
	December 31, 2013
	Offsetting of Derivative Assets/Liabilities
												Gross Amounts Not Offset in the Consolidated Balance Sheet
	Description	Gross Amounts of Recognized Assets/Liabilities				Gross Amounts Offset in the Consolidated Balance Sheet			Amounts of Assets/Liabilities Presented in the Consolidated Balance Sheet			Derivative Financial Instruments			Cash Collateral Received/Pledged		Net Amount (Legal Offset)
	Derivative assets	$	13,879			$	—		$	13,879		$	(13,879	)	$	—	$	—
	Derivative liabilities	(99,057		)		—			(99,057		)	13,879			—		(85,178		)

Inventories_Tables

Inventories (Tables)	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Schedule of Inventories	'
	Inventories are summarized as follows (in thousands):
		March 31, 2014		December 31, 2013
	Raw materials	$	999,667	$	1,049,403
	Work in process	592,897		412,945
	Finished goods	547,664		593,440
	Total	$	2,140,228	$	2,055,788

Intangible_Assets_and_Goodwill1

Intangible Assets and Goodwill (Tables)	3 Months Ended
	Mar. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of Intangible Assets [Table Text Block]	'
	The following table summarizes the carrying amount of our intangible assets (in thousands):
		31-Mar-14		December 31, 2013
	Finite-lived intangible assets	$	11,126,240	$	11,325,751
	Indefinite-lived intangible assets	581,590		574,355
	Total intangible assets	$	11,707,830	$	11,900,106
Schedule of Finite-Lived Intangible Assets [Table Text Block]	'
	The following table summarizes our finite-lived intangible assets (in thousands):
		31-Mar-14					December 31, 2013
		Gross Carrying		Accumulated			Gross Carrying		Accumulated
		Amount		Amortization			Amount		Amortization
	Intangible asset - sofosbuvir	$	10,720,000	$	233,043		$	10,720,000	$	58,261
	Intangible asset - Ranexa	688,400		208,466			688,400		190,849
	Other	305,795		146,446			305,795		139,334
	Total	$	11,714,195	$	587,955		$	11,714,195	$	388,444
Estimated Future Amortization Expense [Table Text Block]	'
	As of March 31, 2014, the estimated future amortization expense associated with our intangible assets for the remaining nine months of 2014 and each of the five succeeding fiscal years is as follows (in thousands):
	Fiscal Year	Amount
	2014 (remaining nine months)	$	598,533
	2015	803,496
	2016	811,428
	2017	815,871
	2018	827,980
	2019	792,823
	Total	$	4,650,131
Schedule of Indefinite-Lived Intangible Assets [Table Text Block]	'
	The following table summarizes our indefinite-lived intangible assets (in thousands):
		31-Mar-14		December 31, 2013
	Indefinite-lived intangible asset - momelotinib (formerly CYT387)	$	308,155	$	362,700
	Indefinite-lived intangible assets - other	266,200		266,200
		574,355		628,900
	Foreign currency translation adjustment	7,235		(54,545		)
	Total	$	581,590	$	574,355
Schedule of Goodwill [Table Text Block]	'
	The following table summarizes the changes in the carrying amount of goodwill (in thousands):
	Balance at December 31, 2013	$	1,169,023
	Foreign currency translation adjustment	2,538
	Balance at March 31, 2014	$	1,171,561

Debt_and_Credit_Facility_Table

Debt and Credit Facility (Tables)	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Schedule of Debt Instruments [Table Text Block]	'
	The following table summarizes the carrying amount of our borrowings under various financing arrangements (in thousands):
	Type of Borrowing	Description	Issue Date	Due Date	Interest Rate	March 31,		December 31, 2013
						2014
	Convertible Senior	May 2014 Notes	Jul-10	May-14	1.00%	$	208,471	$	234,217
	Convertible Senior	May 2016 Notes	Jul-10	May-16	1.63%	913,478		1,113,043
	Senior Unsecured	April 2021 Notes	Mar-11	Apr-21	4.50%	993,996		993,781
	Senior Unsecured	December 2014 Notes	Dec-11	Dec-14	2.40%	749,789		749,710
	Senior Unsecured	December 2016 Notes	Dec-11	Dec-16	3.05%	699,384		699,326
	Senior Unsecured	December 2021 Notes	Dec-11	Dec-21	4.40%	1,247,788		1,247,716
	Senior Unsecured	December 2041 Notes	Dec-11	Dec-41	5.65%	997,904		997,885
	Senior Unsecured	April 2019 Notes	Mar-14	Apr-19	2.05%	499,146		—
	Senior Unsecured	April 2024 Notes	Mar-14	Apr-24	3.70%	1,747,201		—
	Senior Unsecured	April 2044 Notes	Mar-14	Apr-44	4.80%	1,746,613		—
	Credit Facility	Five-Year Revolver	Jan-12	Jan-17	Variable	—		600,000
	Total debt, net					$	9,803,770	$	6,635,678
	Less current portion					1,871,738		2,696,970
	Total long-term debt, net					$	7,932,032	$	3,938,708

Stockholders_Equity_Table_of_C

Stockholders' Equity Table of Changes in Accumulated Comprehensive Income by Component (Tables)	3 Months Ended
	Mar. 31, 2014
Stockholders' Equity Attributable to Parent [Abstract]	'
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	'
	The following table summarizes the changes in accumulated OCI by component, net of tax (in thousands):
		Foreign Currency Items			Unrealized Gains and Losses on Available-for-Sale Securities			Unrealized Gains and Losses on Cash Flow Hedges			Total
	Balance at December 31, 2013	$	(45,860	)	$	11,907		$	(90,493	)	$	(124,446	)
	Other comprehensive income before reclassifications	5,783			147			1,265			7,195
	Amounts reclassified from accumulated other comprehensive income (loss)	—			(199		)	21,681			21,482
	Net current period other comprehensive income (loss)	5,783			(52		)	22,946			28,677
	Balance at March 31, 2014	$	(40,077	)	$	11,855		$	(67,547	)	$	(95,769	)

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Share-based Compensation [Abstract]	'
Schedule of Stock-Based Compensation Expenses Included in Consolidated Statement of Income [Text Block]	'
	The following table summarizes the stock-based compensation expense included in our Condensed Consolidated Statements of Income (in thousands):
		Three Months Ended
		March 31,
		2014			2013
	Cost of goods sold	$	2,642		$	1,841
	Research and development expenses	34,350			26,875
	Selling, general and administrative expenses	45,233			33,051
	Stock-based compensation expense included in total costs and expenses	82,225			61,767
	Income tax effect	(19,089		)	(16,387		)
	Stock-based compensation expense, net of tax	$	63,136		$	45,380

Net_Income_Per_Share_Attributa1

Net Income Per Share Attributable to Gilead Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	'
	The following table is a reconciliation of the numerator and denominator used in the calculation of basic and diluted net income per share attributable to Gilead common stockholders (in thousands):
		Three Months Ended
		March 31,
		2014		2013
	Numerator:
	Net income attributable to Gilead	$	2,227,410	$	722,186
	Denominator:
	Weighted-average shares of common stock outstanding used in the calculation of basic net income per share attributable to Gilead common stockholders	1,536,525		1,521,372
	Effect of dilutive securities:
	Stock options and equivalents	35,024		36,812
	Conversion spread related to the May 2013 Notes	—		10,703
	Conversion spread related to the May 2014 Notes	7,036		25,554
	Conversion spread related to the May 2016 Notes	31,936		25,140
	Warrants related to the Convertible Notes	69,350		45,479
	Weighted-average shares of common stock outstanding used in the calculation of diluted net income per share attributable to Gilead common stockholders	1,679,871		1,665,060

Segment_information_Tables

Segment information (Tables)	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Product Sales by Product [Table Text Block]	'
	Total product sales on an individual product basis are summarized in the following table (in thousands):
		Three Months Ended
		March 31,
		2014			2013
	Antiviral products:
	Sovaldi	$	2,274,349		$	—
	Atripla	779,594			877,073
	Truvada	759,700			700,242
	Complera/Eviplera	250,733			148,189
	Stribild	215,271			92,148
	Viread	210,625			210,332
	Hepsera	11,723			26,423
	Emtriva	6,502			6,671
	Total antiviral products	4,508,497			2,061,078
	Letairis	122,885			118,107
	Ranexa	111,618			96,286
	AmBisome	92,093			85,275
	Other products	35,881			32,822
	Total product sales	$	4,870,974		$	2,393,568
Schedule of Revenue by Major Customers [Table Text Block]	'
	The following table summarizes revenues from each of our customers who individually accounted for 10% or more of our total revenues (as a percentage of total revenues):
		Three Months Ended
		March 31,
		2014		2013
	AmerisourceBergen Corp.	27	%	11	%
	McKesson Corp.	23	%	14	%
	Cardinal Health, Inc.	13	%	19	%

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details) (USD $)	Mar. 31, 2014
In Millions, unless otherwise specified
Accounting Policies [Abstract]	'
Total Southern European Accounts Receivable	$602.80
Total Southern European Accounts Receivable Greater Than 120 Days Past Due	156.8
Total Southern European Accounts Receivable Greater Than 365 Days Past Due	$50.60

Fair_Value_and_Carrying_Value_

Fair Value and Carrying Value of Debt (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Convertible Senior Notes Due In May 2014 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Convertible Senior Notes, Carrying Value	$208,471		$234,217
Debt Instruments, Fair Value	637,224		783,651
Convertible Senior Notes Due In May 2016 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Convertible Senior Notes, Carrying Value	913,478		1,113,043
Debt Instruments, Fair Value	2,947,013		3,871,516
Senior Unsecured Notes Due In April 2021 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Senior Unsecured Notes, Carrying Value	993,996		993,781
Debt Instruments, Fair Value	1,096,750		1,075,480
Senior Unsecured Notes Due In December 2014 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Senior Unsecured Notes, Carrying Value	749,789		749,710
Debt Instruments, Fair Value	759,983		762,637
Senior Unsecured Notes Due In December 2016 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Senior Unsecured Notes, Carrying Value	699,384		699,326
Debt Instruments, Fair Value	737,961		740,705
Senior Unsecured Notes Due In December 2021 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Senior Unsecured Notes, Carrying Value	1,247,788		1,247,716
Debt Instruments, Fair Value	1,358,275		1,336,738
Senior Unsecured Notes Due In December 2041 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Senior Unsecured Notes, Carrying Value	997,904		997,885
Debt Instruments, Fair Value	1,148,870		1,118,660
Senior Unsecured Notes Due in April 2019 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Senior Unsecured Notes, Carrying Value	499,146	[1]	0	[1]
Debt Instruments, Fair Value	496,485	[1]	0	[1]
Senior Unsecured Notes Due in April 2024 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Senior Unsecured Notes, Carrying Value	1,747,201	[1]	0	[1]
Debt Instruments, Fair Value	1,763,825	[1]	0	[1]
Senior Unsecured Notes Due in April 2044 [Member]	'		'
Fair Value and Carrying Value of Debt [Line Items]	'		'
Senior Unsecured Notes, Carrying Value	1,746,613	[1]	0	[1]
Debt Instruments, Fair Value	$1,811,250	[1]	$0	[1]
[1]	See Note 8, Debt and Credit Facility for discussion of March 2014 financing.

Fair_value_measurements_Summar

Fair value measurements (Summary of assets and liabilities recorded at fair value) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	$5,511,098	$1,948,748
Contingent Consideration	266,438	263,760
Level 1 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	5,161,641	1,576,367
Fair Value of Deferred Compensation Plan, Assets	47,913	44,461
Derivatives, assets	0	0
Fair value, Assets, Total	5,209,554	1,620,828
Contingent Consideration	0	0
Derivatives, liabilities	0	0
Fair Value of Deferred Compensation Plan, Liabilities	47,913	44,461
Fair value, Liabilities, Total	47,913	44,461
Level 1 [Member] | Money Market Funds [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	5,056,350	1,490,964
Level 1 [Member] | Corporate Debt Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 1 [Member] | US Treasury Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	105,291	85,403
Level 1 [Member] | U.S. government agencies securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 1 [Member] | Residential Mortgage and Asset-Backed Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 1 [Member] | Municipal Debt Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 2 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	349,457	372,381
Fair Value of Deferred Compensation Plan, Assets	0	0
Derivatives, assets	11,032	13,879
Fair value, Assets, Total	360,489	386,260
Contingent Consideration	0	0
Derivatives, liabilities	72,366	99,057
Fair Value of Deferred Compensation Plan, Liabilities	0	0
Fair value, Liabilities, Total	72,366	99,057
Level 2 [Member] | Money Market Funds [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 2 [Member] | Corporate Debt Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	221,734	220,025
Level 2 [Member] | US Treasury Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 2 [Member] | U.S. government agencies securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	72,830	93,350
Level 2 [Member] | Residential Mortgage and Asset-Backed Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	45,647	46,941
Level 2 [Member] | Municipal Debt Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	9,246	12,065
Level 3 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Fair Value of Deferred Compensation Plan, Assets	0	0
Derivatives, assets	0	0
Fair value, Assets, Total	0	0
Contingent Consideration	266,438	263,760
Derivatives, liabilities	0	0
Fair Value of Deferred Compensation Plan, Liabilities	0	0
Fair value, Liabilities, Total	266,438	263,760
Level 3 [Member] | Money Market Funds [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | Corporate Debt Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | US Treasury Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | U.S. government agencies securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | Residential Mortgage and Asset-Backed Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | Municipal Debt Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	0	0
Estimate of Fair Value Measurement [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	5,511,098	1,948,748
Fair Value of Deferred Compensation Plan, Assets	47,913	44,461
Derivatives, assets	11,032	13,879
Fair value, Assets, Total	5,570,043	2,007,088
Contingent Consideration	266,438	263,760
Derivatives, liabilities	72,366	99,057
Fair Value of Deferred Compensation Plan, Liabilities	47,913	44,461
Fair value, Liabilities, Total	386,717	407,278
Estimate of Fair Value Measurement [Member] | Money Market Funds [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	5,056,350	1,490,964
Estimate of Fair Value Measurement [Member] | Corporate Debt Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	221,734	220,025
Estimate of Fair Value Measurement [Member] | US Treasury Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	105,291	85,403
Estimate of Fair Value Measurement [Member] | U.S. government agencies securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	72,830	93,350
Estimate of Fair Value Measurement [Member] | Residential Mortgage and Asset-Backed Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	45,647	46,941
Estimate of Fair Value Measurement [Member] | Municipal Debt Securities [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Estimated Fair Value	$9,246	$12,065

Contingent_Consideration_Rollf

Contingent Consideration Rollforward (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Balance as of December 31, 2013	$263,760	'
Additions from new acquisitions	0	'
Net changes in valuation	2,678	6,024
Balance as of March 31, 2014	$266,438	'

Fair_value_measurements_Narrat

Fair value measurements Narrative (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Contingent Consideration	$266,438,000	$263,760,000
CGI and Calistoga [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, Low	0	'
Business combination, contingent consideration arrangements, range of outcomes, value, high	254,000,000	'
Contingent Consideration	$221,600,000	$220,500,000

AvailableforSale_Securities_Su

Available-for-Sale Securities Summary of Available-for-Sale Securities at Estimated Fair Value (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-Sale Securities [Line Items]	'	'
Amortized Cost	$5,510,132	$1,947,732
Available for Sale Securities Gross Unreal Gains	1,182	1,228
Available for Sale Securities - Gross Unrealized Losses	-216	-212
Total	5,511,098	1,948,748
Money Market Funds [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Amortized Cost	5,056,350	1,490,964
Available for Sale Securities Gross Unreal Gains	0	0
Available for Sale Securities - Gross Unrealized Losses	0	0
Total	5,056,350	1,490,964
Corporate Debt Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Amortized Cost	220,999	219,242
Available for Sale Securities Gross Unreal Gains	801	885
Available for Sale Securities - Gross Unrealized Losses	-66	-102
Total	221,734	220,025
US Treasury Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Amortized Cost	105,330	85,337
Available for Sale Securities Gross Unreal Gains	75	94
Available for Sale Securities - Gross Unrealized Losses	-114	-28
Total	105,291	85,403
US Government Agencies Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Amortized Cost	72,654	93,211
Available for Sale Securities Gross Unreal Gains	176	156
Available for Sale Securities - Gross Unrealized Losses	0	-17
Total	72,830	93,350
Residential Mortgage and Asset-Backed Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Amortized Cost	45,624	46,969
Available for Sale Securities Gross Unreal Gains	59	37
Available for Sale Securities - Gross Unrealized Losses	-36	-65
Total	45,647	46,941
Municipal Debt Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Amortized Cost	9,175	12,009
Available for Sale Securities Gross Unreal Gains	71	56
Available for Sale Securities - Gross Unrealized Losses	0	0
Total	$9,246	$12,065

AvailableforSale_Securities_Su1

Available-for-Sale Securities Summary of the Classification of Available-for-Sale Securities (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]	'	'
Cash And Cash Equivalents	$5,056,350	$1,490,964
Short-term marketable securities	64,877	18,756
Long-term marketable securities	389,871	439,028
Total	$5,511,098	$1,948,748

AvailableforSale_Securities_Su2

Available-for-Sale Securities Summary of Available-for-Sale Securities by Contractual Maturity (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]	'	'
Less than 1 Year, Amortized Cost	$5,121,014	'
Greater than 1 Year but Less than 5 Years, Amortized Cost	383,960	'
Greater than 5 Years but Less than 10 Years, Amortized Cost	0	'
Greater than 10 Years, Amortized Cost	5,158	'
Total Amortized Cost	5,510,132	'
Less than 1 Year, Fair Value	5,121,227	'
Greater than 1 Year but Less than 5 Years, Fair Value	384,741	'
Greater than 5 Years but Less than 10 Years, Fair Value	0	'
Greater than 10 Years, Fair Value	5,130	'
Total	$5,511,098	$1,948,748

AvailableforSale_Securities_Su3

Available-for-Sale Securities Summary of Gross Realized Gains and Losses Related to Sales of Marketable Securities (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Investments, Debt and Equity Securities [Abstract]	'	'
Gross realized gains on sales	$338	$182
Gross realized losses on sales	($25)	($156)

AvailableforSale_Securities_Su4

Available-for-Sale Securities Summary of Available-for-Sale Securities in a Continuous Unrealized Loss Position Deemed not to be Other-than-Temporarily Impaired (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	($216)	($212)
Continuous Unrealized Loss Position, Estimated Fair Value	100,636	100,295
Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-197	-185
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	96,981	92,059
Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-19	-27
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	3,655	8,236
US Treasury Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-114	-28
Continuous Unrealized Loss Position, Estimated Fair Value	44,014	24,562
US Treasury Securities [Member] | Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-114	-28
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	44,014	24,562
US Treasury Securities [Member] | Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	0	0
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	0	0
Corporate Debt Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-66	-102
Continuous Unrealized Loss Position, Estimated Fair Value	37,719	38,581
Corporate Debt Securities [Member] | Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-66	-102
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	37,719	37,076
Corporate Debt Securities [Member] | Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	0	0
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	0	1,505
Residential Mortgage and Asset-Backed Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-36	-65
Continuous Unrealized Loss Position, Estimated Fair Value	18,903	26,294
Residential Mortgage and Asset-Backed Securities [Member] | Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-17	-38
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	15,248	19,563
Residential Mortgage and Asset-Backed Securities [Member] | Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-19	-27
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	3,655	6,731
US Government Agencies Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	0	-17
Continuous Unrealized Loss Position, Estimated Fair Value	0	10,858
US Government Agencies Securities [Member] | Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	0	-17
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	0	10,858
US Government Agencies Securities [Member] | Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	0	0
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	$0	$0

AvailableforSale_Securities_Na

Available-for-Sale Securities Narrative (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]	'	'
Cash Excluded from Available-for-Sale Debt Securities Table	$1,350,000,000	$621,800,000
Available-for-Sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions (securities)	40	40
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities	$0	$0

Derivative_Financial_Instrumen2

Derivative Financial Instruments Summary of Information about the Fair Values of Derivative Instruments on Condensed Consolidated Balance Sheets (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	$11,032	$13,879
Derivative Liability, Fair Value	72,366	99,057
Designated as Hedging Instrument [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	11,031	13,876
Derivative Liability, Fair Value	72,286	98,840
Not Designated as Hedging Instrument [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	1	3
Derivative Liability, Fair Value	80	217
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	10,451	12,647
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value	65,965	85,541
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Long-Term Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	580	1,229
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Long-Term Obligations [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value	6,321	13,299
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	1	3
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value	$80	$217

Derivative_Financial_Instrumen3

Derivative Financial Instruments Summary of the effect of foreign currency exchange contracts on condensed consolidated statements of income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'	'
Gains recognized in OCI (effective portion)	$2,997	$70,860
Gains (losses) reclassified from accumulated OCI into product sales (effective portion)	-20,691	462
Gains (losses) recognized in other income (expense), net (ineffective portion and amounts excluded from effectiveness testing)	84	-2,132
Gains recognized in other income (expense), net	$1,103	$32,620

Derivative_Financial_Instrumen4

Derivative Financial Instruments Table of Offsetting Derivative Assets and Liabilities (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative Asset [Abstract]	'	'
Gross Amounts of Recognized Assets	$11,032	$13,879
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Amount of Assets Presented in the Condensed Consolidated Balance Sheet	11,032	13,879
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheet - Derivative Financial Instruments	-11,032	-13,879
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheet - Cash Collateral Received/Pledged	0	0
Net Amount (Legal Offset)	0	0
Derivative Liability [Abstract]	'	'
Gross Amount of Recognized Liabilities	-72,366	-99,057
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheet	-72,366	-99,057
Gross Amount Not Offset in the Condensed Consolidated Balance Sheet - Derivative Financial Instruments	11,032	13,879
Gross Amount Not Offset in the Condensed Consolidated Balance Sheet - Cash Collateral Received/Pledged	0	0
Net Amount (Legal Offset)	($61,334)	($85,178)

Derivative_Financial_Instrumen5

Derivative Financial Instruments Derivative financial instruments Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'	'	'
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	$0	$0	'
Derivative, Notional Amount	$4,040,000,000	'	$4,280,000,000

Inventories_Schedule_of_invent

Inventories Schedule of inventories (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Raw materials	$999,667	$1,049,403
Work in process	592,897	412,945
Finished goods	547,664	593,440
Total	$2,140,228	$2,055,788

Inventories_Narrative_Details

Inventories (Narrative) (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory [Line Items]	'	'
Inventories	$2,140,228	$2,055,788
Efavirenz [Member] | Bristol-Myers Squibb Company [Member]	'	'
Inventory [Line Items]	'	'
Inventories	$1,320,000	$1,280,000

Intangible_Assets_and_Goodwill2

Intangible Assets and Goodwill Schedule of Carrying Amount of Intangible Assets (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]	'	'
Finite-lived intangible assets	$11,126,240	$11,325,751
Indefinite-lived intangible assets	581,590	574,355
Total intangible assets	$11,707,830	$11,900,106

Intangible_Assets_and_Goodwill3

Intangible Assets and Goodwill Schedule of Finite Lived Intangible Assets (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Finite Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross Carrying Amount	$11,714,195	$11,714,195
Finite-Lived Intangible Assets, Accumulated Amortization	587,955	388,444
Sofosbuvir [Member]	'	'
Finite Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross Carrying Amount	10,720,000	10,720,000
Finite-Lived Intangible Assets, Accumulated Amortization	233,043	58,261
Ranexa [Member]	'	'
Finite Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross Carrying Amount	688,400	688,400
Finite-Lived Intangible Assets, Accumulated Amortization	208,466	190,849
Other [Member]	'	'
Finite Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross Carrying Amount	305,795	305,795
Finite-Lived Intangible Assets, Accumulated Amortization	$146,446	$139,334

Intangible_Assets_and_Goodwill4

Intangible Assets and Goodwill Schedule of Future Amortization Expense (Details) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]	'
2014 (remaining nine months)	$598,533
2015	803,496
2016	811,428
2017	815,871
2018	827,980
2019	792,823
Total	$4,650,131

Intangible_Assets_and_Goodwill5

Intangible Assets and Goodwill Schedule of Indefinite Lived Intangible Assets (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Indefinite-lived Intangible Assets [Line Items]	'	'
Indefinite-lived Intangible Assets	$581,590	$574,355
Indefinite-Lived Intangible Assets (Excluding Goodwill), Gross	574,355	628,900
Indefinite-lived Intangible Assets, Translation Adjustments	7,235	-54,545
Momelotinib (formerly CYT387) [Member]	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'
Indefinite-lived Intangible Assets	308,155	362,700
Other [Member]	'	'
Indefinite-lived Intangible Assets [Line Items]	'	'
Indefinite-lived Intangible Assets	$266,200	$266,200

Intangible_Assets_and_Goodwill6

Intangible Assets and Goodwill Goodwill Rollforward (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Goodwill [Roll Forward]	'
Balance at December 31, 2013	$1,169,023
Foreign currency translation adjustment	2,538
Balance at March 31, 2014	$1,171,561

Intangible_Assets_and_Goodwill7

Intangible Assets and Goodwill (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Acquired Indefinite-lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Asset, Useful Life	'15 years	'
Cost of Sales [Member]	'	'
Acquired Indefinite-lived Intangible Assets [Line Items]	'	'
Amortization of Finite-Lived Intangible Assets	$199.50	$21.50

Collaborative_Arrangements_Nar

Collaborative Arrangements Narrative (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Variable Interest Entity [Line Items]	'	'	'	'
Variable Interest Entity, Cash and Cash Equivalents	$6,404,153,000	$2,112,806,000	$1,863,972,000	$1,803,694,000
Variable Interest Entity, Accounts Receivable	3,236,195,000	2,100,286,000	'	'
Variable Interest Entity, Inventories	2,140,228,000	2,055,788,000	'	'
Variable Interest Entity, Accounts Payable	1,234,507,000	1,255,914,000	'	'
Variable Interest Entity, Other Accrued Expenses	1,222,821,000	1,023,938,000	'	'
Bristol-Myers Squibb Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]	'	'	'	'
Variable Interest Entity [Line Items]	'	'	'	'
Variable Interest Entity, Total Assets	2,240,000,000	2,240,000,000	'	'
Variable Interest Entity, Cash and Cash Equivalents	200,400,000	245,700,000	'	'
Variable Interest Entity, Accounts Receivable	252,800,000	275,300,000	'	'
Variable Interest Entity, Inventories	1,760,000,000	1,720,000,000	'	'
Variable Interest Entity Total Liabilities	1,410,000,000	1,260,000,000	'	'
Variable Interest Entity, Accounts Payable	1,040,000,000	915,400,000	'	'
Variable Interest Entity, Other Accrued Expenses	$370,900,000	$341,200,000	'	'

Debt_and_Credit_Facility_Sched

Debt and Credit Facility Schedule of Carrying Amounts of Senior Notes (Details) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'		'
Total Debt, Net	$9,803,770		$6,635,678
Less Current Portion	1,871,738		2,696,970
Total Long-Term Debt, Net	7,932,032		3,938,708
Convertible Senior Notes Due In May 2014 Member	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	1.00%		'
Convertible Senior Notes	208,471		234,217
Convertible Senior Notes Due In May 2016 [Member]	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	1.63%		'
Convertible Senior Notes	913,478		1,113,043
Senior Unsecured Notes Due In April 2021 [Member]	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	4.50%		'
Senior Unsecured Notes	993,996		993,781
Senior Unsecured Notes Due December 2014 [Member]	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	2.40%		'
Senior Unsecured Notes	749,789		749,710
Senior Unsecured Notes Due In December 2016 [Member]	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	3.05%		'
Senior Unsecured Notes	699,384		699,326
Senior Unsecured Notes Due In December 2021 [Member]	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	4.40%		'
Senior Unsecured Notes	1,247,788		1,247,716
Senior Unsecured Notes Due In December 2041 [Member]	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	5.65%		'
Senior Unsecured Notes	997,904		997,885
Senior Unsecured Notes Due in April 2019 [Member]	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	2.05%		'
Senior Unsecured Notes	499,146	[1]	0	[1]
Senior Unsecured Notes Due in April 2024 [Member]	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	3.70%		'
Senior Unsecured Notes	1,747,201	[1]	0	[1]
Senior Unsecured Notes Due in April 2044 [Member]	'		'
Debt Instrument [Line Items]	'		'
Debt Instrument, Interest Rate, Stated Percentage	4.80%		'
Senior Unsecured Notes	1,746,613	[1]	0	[1]
Credit Facility Due In January 2017 [Member]	'		'
Debt Instrument [Line Items]	'		'
Credit Facility, Amount Outstanding	$0		$600,000
[1]	See Note 8, Debt and Credit Facility for discussion of March 2014 financing.

Debt_and_Credit_Facility_Debt_

Debt and Credit Facility Debt and Credity Facility (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]	'	'
Proceeds from convertible note hedges	$601,591,000	$100,771,000
Debt Instrument, Face Amount	4,000,000,000	'
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	100.00%	'
Debt Instrument, Redemption Price, Percentage	101.00%	'
Debt Principal Repayment, Conversion	243,400,000	'
Debt Instrument, Unamortized Discount	45,800,000	'
Debt Issuance Cost	27,500,000	'
Repayment of Credit Facility	600,000,000	'
Convertible Senior Notes Due May 2014 and May 2016 [Member]	'	'
Debt Instrument [Line Items]	'	'
Conversion Value In Excess of Principal Amount	575,300,000	'
Proceeds from convertible note hedges	575,300,000	'
Senior Unsecured Notes Due in April 2019 [Member]	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Face Amount	500,000,000	'
Basis Points	10	'
Senior Unsecured Notes Due in April 2024 [Member]	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Face Amount	1,750,000,000	'
Basis Points	15	'
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	100.00%	'
Senior Unsecured Notes Due in April 2044 [Member]	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Face Amount	$1,750,000,000	'
Basis Points	20	'
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	100.00%	'

Stockholders_Equity_Schedule_o

Stockholders' Equity Schedule of Accumulated Comprehensive Income (loss) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'
Balance at December 31, 2013	($124,446)	'
Other comprehensive income before reclassifications	7,195	'
Amounts reclassified from accumulated other comprehensive income (loss)	-21,482	'
Net current period other comprehensive income (loss)	28,677	66,421
Balance at March 31, 2014	-95,769	'
Accumulated Translation Adjustment [Member]	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'
Balance at December 31, 2013	-45,860	'
Other comprehensive income before reclassifications	5,783	'
Amounts reclassified from accumulated other comprehensive income (loss)	0	'
Net current period other comprehensive income (loss)	5,783	'
Balance at March 31, 2014	-40,077	'
Accumulated Net Unrealized Investment Gain (Loss) [Member]	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'
Balance at December 31, 2013	11,907	'
Other comprehensive income before reclassifications	147	'
Amounts reclassified from accumulated other comprehensive income (loss)	199	'
Net current period other comprehensive income (loss)	-52	'
Balance at March 31, 2014	11,855	'
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'
Balance at December 31, 2013	-90,493	'
Other comprehensive income before reclassifications	1,265	'
Amounts reclassified from accumulated other comprehensive income (loss)	-21,681	'
Net current period other comprehensive income (loss)	22,946	'
Balance at March 31, 2014	($67,547)	'

Stockholders_Equity_Narrative_

Stockholders' Equity Narrative (Details) (USD $)	3 Months Ended
In Thousands, except Share data in Millions, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Stockholders' Equity Attributable to Parent [Abstract]	'	'
Payments for Repurchase of Common Stock	$450,087	$82,239
Stock Repurchased During Period, Shares	5.7	'

StockBased_Compensation_Summar

Stock-Based Compensation Summary of Stock-Based Compensation (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expense included in total costs and expenses	$82,225	$61,767
Income tax effect	-19,089	-16,387
Stock-based compensation expense, net of tax	63,136	45,380
Cost of Goods Sold [Member]	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expense included in total costs and expenses	2,642	1,841
Research and Development Expenses [Member]	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expense included in total costs and expenses	34,350	26,875
Selling, General and Administrative Expenses [Member]	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Stock-based compensation expense included in total costs and expenses	$45,233	$33,051

Net_Income_Per_Share_Attributa2

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 $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Debt Instrument [Line Items]	'	'
Net income attributable to Gilead	$2,227,410	$722,186
Weighted Average Number of Shares Outstanding, Basic	1,536,525	1,521,372
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	35,024	36,812
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants	69,350	45,479
Weighted Average Number of Shares Outstanding, Diluted	1,679,871	1,665,060
Convertible Senior Notes Due May 2013 [Member]	'	'
Debt Instrument [Line Items]	'	'
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	0	10,703
Convertible Senior Notes Due May 2014 [Member]	'	'
Debt Instrument [Line Items]	'	'
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	7,036	25,554
Convertible Senior Notes Due May 2016 [Member]	'	'
Debt Instrument [Line Items]	'	'
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	31,936	25,140

Net_Income_Per_Share_Attributa3

Net Income Per Share Attributable to Gilead Common Stockholders (Narrative) (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Debt Instrument, Redemption [Line Items]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0.7	1.3
Convertible Senior Notes Due In May 2013 [Member]	'	'
Debt Instrument, Redemption [Line Items]	'	'
Debt Instrument, Convertible, Conversion Price	19.05	'
Class of Warrant or Right, Exercise Price of Warrants or Rights	26.95	'
Convertible Senior Notes Due In May 2014 [Member]	'	'
Debt Instrument, Redemption [Line Items]	'	'
Debt Instrument, Convertible, Conversion Price	22.54	'
Class of Warrant or Right, Exercise Price of Warrants or Rights	28.38	'
Convertible Senior Notes Due In May 2016 [Member]	'	'
Debt Instrument, Redemption [Line Items]	'	'
Debt Instrument, Convertible, Conversion Price	22.71	'
Class of Warrant or Right, Exercise Price of Warrants or Rights	30.05	'

Segment_Information_Segment_re

Segment Information Segment reporting information, revenue for reportable segment (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Revenue from External Customer [Line Items]	'	'
Product sales	$4,870,974	$2,393,568
Sovaldi [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	2,274,349	0
Atripla [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	779,594	877,073
Truvada [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	759,700	700,242
Complera Eviplera [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	250,733	148,189
Stribild [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	215,271	92,148
Viread [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	210,625	210,332
Hepsera [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	11,723	26,423
Emtriva [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	6,502	6,671
Antiviral Products [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	4,508,497	2,061,078
Letairis [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	122,885	118,107
Ranexa [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	111,618	96,286
Ambisome [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	92,093	85,275
Other Products [Member]	'	'
Revenue from External Customer [Line Items]	'	'
Product sales	$35,881	$32,822

Segment_Information_Schedule_o

Segment Information Schedule of revenue by major customers (Details)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
AmerisourceBergen Corp. [Member]	'	'
Revenue, Major Customer [Line Items]	'	'
Percentage of Revenues	27.00%	11.00%
McKesson Corp. [Member]	'	'
Revenue, Major Customer [Line Items]	'	'
Percentage of Revenues	23.00%	14.00%
Cardinal Health, Inc. [Member]	'	'
Revenue, Major Customer [Line Items]	'	'
Percentage of Revenues	13.00%	19.00%

Segment_information_narrative_

Segment information narrative (Details)	3 Months Ended
	Mar. 31, 2014
Segment Reporting Information, Revenue for Reportable Segment [Abstract]	'
Major Customers Percentage Of Total Revenues Minimum	10.00%

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]	'
Effective Income Tax Rate, Continuing Operations	24.60%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	$12