Gilead Sciences (GILD) 10-Q 5 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information Document	9 Months Ended
	Sep. 30, 2014	Oct. 31, 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	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Entity Well-known Seasoned Issuer	'Yes	'
Entity Voluntary Filers	'No	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	1,508,664,333
Entity Current Reporting Status	'Yes	'

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets, Current [Abstract]	'	'
Cash and cash equivalents	$6,209,060	$2,112,806
Short-term marketable securities	107,266	18,756
Accounts receivable, net	2,850,367	2,100,286
Inventories	1,909,584	2,055,788
Deferred tax assets	384,588	330,530
Prepaid taxes	599,117	398,010
Prepaid expenses	234,802	165,652
Other current assets	267,247	91,925
Total current assets	12,562,031	7,273,753
Assets, Noncurrent [Abstract]	'	'
Property, plant and equipment, net	1,509,796	1,166,181
Long-term portion of prepaid royalties	487,852	198,766
Long-term deferred tax assets	163,720	154,765
Long-term marketable securities	1,375,400	439,028
Intangible assets, net	11,306,547	11,900,106
Goodwill	1,171,561	1,169,023
Other long-term assets	267,486	195,163
Total assets	28,844,393	22,496,785
Liabilities, Current [Abstract]	'	'
Accounts payable	1,182,917	1,255,914
Accrued government rebates	1,741,829	983,490
Accrued compensation and employee benefits	267,599	243,540
Income taxes payable	43,781	10,855
Other accrued liabilities	1,224,864	1,023,938
Deferred revenues	116,880	110,640
Current portion of long-term debt and other obligations, net	1,477,082	2,697,044
Total current liabilities	6,054,952	6,325,421
Liabilities, Noncurrent [Abstract]	'	'
Long-term debt, net	7,933,040	3,938,708
Long-term income taxes payable	417,434	162,412
Long-term deferred tax liabilities	65,433	83,286
Other long-term obligations	482,542	178,626
Commitments and Contingencies	'	'
Equity Component of Currently Redeemable Convertible Notes [Abstract]	'	'
Equity component of currently redeemable convertible notes	27,382	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 1,513,593 at September 30, 2014 and 1,534,414 at December 31, 2013	1,514	1,534
Additional paid-in capital	2,143,092	5,386,735
Accumulated other comprehensive income (loss)	173,962	-124,446
Retained earnings	11,247,655	6,105,244
Total Gilead stockholders’ equity	13,566,223	11,369,067
Noncontrolling interest	297,387	375,434
Total stockholders’ equity	13,863,610	11,744,501
Total liabilities and stockholders’ equity	$28,844,393	$22,496,785

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets Paranthetical (USD $)	Sep. 30, 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	1,513,593	1,534,414
Common Stock, Shares Outstanding	1,513,593	1,534,414

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues [Abstract]	'	'	'	'
Product sales	$5,968,208	$2,709,652	$17,252,119	$7,760,505
Royalty, contract and other revenues	73,624	73,181	323,612	321,357
Total revenues	6,041,832	2,782,833	17,575,731	8,081,862
Costs and Expenses [Abstract]	'	'	'	'
Cost of goods sold	987,306	681,868	2,725,220	2,000,979
Research and development	630,466	546,244	1,809,368	1,567,778
Selling, general and administrative	944,837	406,860	2,106,515	1,186,147
Total costs and expenses	2,562,609	1,634,972	6,641,103	4,754,904
Income from operations	3,479,223	1,147,861	10,934,628	3,326,958
Interest expense	-103,366	-73,949	-281,639	-233,744
Other income (expense), net	-5,037	5,777	-26,594	2,222
Income before provision for income taxes	3,370,820	1,079,689	10,626,395	3,095,436
Provision for income taxes	646,557	294,473	2,029,060	824,892
Net income	2,724,263	785,216	8,597,335	2,270,544
Net loss attributable to noncontrolling interest	7,011	3,390	16,942	12,853
Net income attributable to Gilead	$2,731,274	$788,606	$8,614,277	$2,283,397
Net income per share attributable to Gilead common stockholders—basic	$1.80	$0.51	$5.64	$1.50
Shares used in per share calculation—basic	1,513,899	1,532,105	1,527,633	1,526,847
Net income per share attributable to Gilead common stockholders—diluted	$1.67	$0.47	$5.18	$1.35
Shares used in per share calculation—diluted	1,636,530	1,691,898	1,662,281	1,689,647

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net income	$2,724,263	$785,216	$8,597,335	$2,270,544
Other Comprehensive Income [Abstract]	'	'	'	'
Change in foreign currency translation gain (loss), net of tax	-10,031	2,381	-3,062	5,155
Available-for-sale Securities [Abstract]	'	'	'	'
Change in net unrealized gains (losses), net of tax impact of $(481), $2,182, $697 and $2,310	-831	4,316	995	4,082
Reclassifications to net income, net of tax impact of $(29), $(38), $(253) and $(79)	-51	-65	-437	-140
Net change	-882	4,251	558	3,942
Cash Flow Hedges [Abstract]	'	'	'	'
Change in net unrealized gains (losses), net of tax impact of $6,462, $6,083, $6,288 and $2,504	223,886	-82,453	256,772	-3,371
Reclassifications to net income, net of tax impact of $(640), $(358), $(2,702) and $(610)	2,449	3,380	44,140	-2,181
Net change	226,335	-79,073	300,912	-5,552
Other comprehensive income (loss)	215,422	-72,441	298,408	3,545
Comprehensive income	2,939,685	712,775	8,895,743	2,274,089
Comprehensive loss attributable to noncontrolling interest	7,011	3,390	16,942	12,853
Comprehensive income attributable to Gilead	$2,946,696	$716,165	$8,912,685	$2,286,942

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income Paranthetical (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Available-for-sale Securities [Abstract]	'	'	'	'
Net Unrealized Gains, Tax Impact	($481)	$2,182	$697	$2,310
Reclassification Adjustments, Tax Impact	-29	-38	-253	-79
Cash Flow Hedges [Abstract]	'	'	'	'
Net Unrealized Losses, Tax Impact	6,462	6,083	6,288	2,504
Reclassification Adjustments, Tax Impact	($640)	($358)	($2,702)	($610)

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating Activities [Abstract]	'	'
Net income	$8,597,335	$2,270,544
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities [Abstract]	'	'
Depreciation expense	93,669	76,046
Amortization expense	680,950	140,699
Stock-based compensation expense	264,583	180,293
Excess tax benefits from stock-based compensation	-357,928	-168,728
Tax benefits from exercise and vesting of stock-based awards	360,336	169,916
Deferred income taxes	-67,061	-12,400
Change in fair value of contingent consideration	-4,119	47,442
Other	54,791	45,116
Changes in Operating Assets and Liabilities [Abstract]	'	'
Accounts receivable, net	-826,970	-226,308
Inventories	100,828	-216,650
Prepaid expenses and other assets	-428,969	-111,199
Accounts payable	-74,599	23,131
Income taxes payable	135,672	-87,081
Accrued liabilities	1,256,505	218,323
Deferred revenues	12,310	29,057
Net cash provided by operating activities	9,797,333	2,378,201
Investing Activities [Abstract]	'	'
Purchases of marketable securities	-1,532,426	-254,657
Proceeds from sales of marketable securities	477,152	226,291
Proceeds from maturities of marketable securities	26,582	57,556
Acquisitions, net of cash acquired	0	-378,645
Capital expenditures	-389,549	-121,310
Net cash used in investing activities	-1,418,241	-470,765
Financing Activities [Abstract]	'	'
Proceeds from debt financing, net of issuance costs	3,965,446	0
Proceeds from convertible note hedges	1,629,483	1,257,869
Purchases of convertible note hedges	-26,249	0
Proceeds from issuances of common stock	275,074	240,671
Repurchases of common stock	-3,348,477	-182,259
Repayments of debt and other long-term obligations	-2,859,872	-2,224,782
Payments to settle warrants	-4,092,758	-1,039,695
Excess tax benefits from stock-based compensation	357,928	168,728
Payment of contingent consideration	-98,346	0
Contributions from (distributions to) noncontrolling interest	-61,105	80,586
Net cash used in financing activities	-4,258,876	-1,698,882
Effect of exchange rate changes on cash and cash equivalents	-23,962	-1,512
Net change in cash and cash equivalents	4,096,254	207,042
Cash and cash equivalents at beginning of period	2,112,806	1,803,694
Cash and cash equivalents at end of period	$6,209,060	$2,010,736

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 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.
	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 September 30, 2014, our accounts receivable in Southern Europe, specifically Greece, Italy, Portugal and Spain, totaled approximately $587.2 million, of which $154.5 million were greater than 120 days past due and $52.0 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 September 30, 2014.
	Branded Prescription Drug Fee
	We, along with other pharmaceutical manufacturers of branded drug products, are required to pay a portion of the Branded Prescription Drug (BPD) Fee, which is calculated based on select government sales during each calendar year as a percentage of total industry government sales. During the third quarter of 2014, the IRS issued final regulations which required manufacturers to recognize an additional year of expense, which for us resulted in a cumulative catch-up of $337 million within the quarter. The IRS is expected to communicate the final BPD fee amounts due for 2013 sales during the third quarter of 2015 and for 2014 sales during the third quarter of 2016. As of September 30, 2014, our BPD fee accrual totaled $343 million, of which $304 million was included in other long-term obligations on our Condensed Consolidated Balance Sheet.
	Recent Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board, jointly with the International Accounting Standards Board, issued a comprehensive new standard on revenue recognition from contracts with customers. The standard's core principle is that a reporting entity will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In applying this new guidance to contracts within its scope, an entity will: (1) identify the contract(s) with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) the entity satisfies a performance obligation. Additionally, this new guidance will require significantly expanded revenue recognition disclosures. This guidance will become effective for us beginning in the first quarter of 2017. Early application is not permitted. Entities have the option of using either a full retrospective or a modified retrospective approach to adopt this new guidance. We are currently evaluating the impact of our pending adoption of this standard on our Condensed Consolidated Financial Statements.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2014
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'
Fair Value Measurements [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):
					30-Sep-14						December 31, 2013
	Type of Borrowing		Description		Carrying Value			Fair Value			Carrying Value			Fair Value
	Convertible Senior		May 2014 Notes		$	—		$	—		$	234,217		$	783,651
	Convertible Senior		May 2016 Notes		727,072			3,517,174			1,113,043			3,871,516
	Senior Unsecured		April 2021 Notes		994,425			1,093,710			993,781			1,075,480
	Senior Unsecured		December 2014 Notes		749,947			752,820			749,710			762,637
	Senior Unsecured		December 2016 Notes		699,499			729,603			699,326			740,705
	Senior Unsecured		December 2021 Notes		1,247,933			1,358,813			1,247,716			1,336,738
	Senior Unsecured		December 2041 Notes		997,942			1,186,550			997,885			1,118,660
	Senior Unsecured		April 2019 Notes		499,232			496,065			—			—
	Senior Unsecured		April 2024 Notes		1,747,340			1,782,900			—			—
	Senior Unsecured		April 2044 Notes		1,746,669			1,848,333			—			—
	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):
		30-Sep-14													December 31, 2013
		Level 1				Level 2			Level 3			Total			Level 1		Level 2		Level 3		Total
	Assets:
	Debt securities:
	Money market funds	$	5,049,683			$	—		$	—		$	5,049,683		$	1,490,964	$	—	$	—	$	1,490,964
	Corporate debt securities	—				675,745			—			675,745			—		220,025		—		220,025
	U.S. treasury securities	520,208				—			—			520,208			85,403		—		—		85,403
	U.S. government agencies securities	—				131,417			—			131,417			—		93,350		—		93,350
	Residential mortgage and asset-backed securities	—				151,287			—			151,287			—		46,941		—		46,941
	Municipal debt securities	—				9,209			—			9,209			—		12,065		—		12,065
	Total debt securities	5,569,891				967,658			—			6,537,549			1,576,367		372,381		—		1,948,748
	Deferred compensation plan	52,261				—			—			52,261			44,461		—		—		44,461
	Foreign currency derivative contracts	—				215,911			—			215,911			—		13,879		—		13,879
		$	5,622,152			$	1,183,569		$	—		$	6,805,721		$	1,620,828	$	386,260	$	—	$	2,007,088
	Liabilities:
	Contingent consideration	$	—			$	—		$	94,899		$	94,899		$	—	$	—	$	263,760	$	263,760
	Foreign currency derivative contracts	—				3,696			—			3,696			—		99,057		—		99,057
	Deferred compensation plan	52,261				—			—			52,261			44,461		—		—		44,461
		$	52,261			$	3,696		$	94,899		$	150,856		$	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 September 30, 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. (Calistoga) 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 $47.4 million as of September 30, 2014 and $220.5 million as of December 31, 2013. In July 2014, upon receiving U.S. Food and Drug Administration (FDA) approval of Zydelig, certain regulatory approval-based milestones related to our Calistoga acquisition were met and as a result, we made contingent consideration payments totaling $175.0 million in the third quarter of 2014. The remainder of the contingent consideration liabilities as of September 30, 2014 and December 31, 2013 relate 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
	Milestone payments		(175,000		)
	Net changes in valuation		6,139
	Balance at September 30, 2014		$	94,899

AvailableforSale_Securities

Available-for-Sale Securities	9 Months Ended
	Sep. 30, 2014
Investments, Debt and Equity Securities [Abstract]	'
Available-for-Sale Securities [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):
		30-Sep-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	$	5,049,683		$	—		$	—		$	5,049,683		$	1,490,964		$	—	$	—		$	1,490,964
	Corporate debt securities	676,599			474			(1,328		)	675,745			219,242			885		(102		)	220,025
	U.S. treasury securities	520,243			250			(285		)	520,208			85,337			94		(28		)	85,403
	U.S. government agencies securities	131,396			94			(73		)	131,417			93,211			156		(17		)	93,350
	Residential mortgage and asset-backed securities	151,359			51			(123		)	151,287			46,969			37		(65		)	46,941
	Municipal debt securities	9,175			34			—			9,209			12,009			56		—			12,065
	Total	$	6,538,455		$	903		$	(1,809	)	$	6,537,549		$	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):
		30-Sep-14			December 31, 2013
	Cash and cash equivalents	$	5,054,883		$	1,490,964
	Short-term marketable securities	107,266			18,756
	Long-term marketable securities	1,375,400			439,028
	Total	$	6,537,549		$	1,948,748
	Cash and cash equivalents in the table above exclude cash of $1.15 billion as of September 30, 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):
		30-Sep-14
		Amortized Cost			Fair Value
	Less than one year	$	5,161,903		$	5,162,149
	Greater than one year but less than five years	1,366,482			1,365,350
	Greater than five years but less than ten years	5,618			5,607
	Greater than ten years	4,452			4,443
	Total	$	6,538,455		$	6,537,549
	The following table summarizes the gross realized gains and losses related to sales of marketable securities (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Gross realized gains on sales	$	164		$	269		$	865		$	652
	Gross realized losses on sales	$	(84	)	$	(166	)	$	(175	)	$	(433	)
	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
	30-Sep-14
	Debt securities:
	U.S. treasury securities	$	(285	)	$	230,148		$	—		$	—		$	(285	)	$	230,148
	Corporate debt securities	(1,328		)	494,142			—			—			(1,328		)	494,142
	Residential mortgage and asset-backed securities	(110		)	100,094			(13		)	811			(123		)	100,905
	U.S. government agencies securities	(73		)	49,849			—			—			$	(73	)	$	49,849
	Total	$	(1,796	)	$	874,233		$	(13	)	$	811		$	(1,809	)	$	875,044
	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 317 securities as of September 30, 2014 and 40 securities as of 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 September 30, 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	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative Financial Instruments [Text Block]	'
	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 (loss) (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 September 30, 2014 will be reclassified to product sales within 12 months.
	The cash flow effects of our derivative contracts for the nine months ended September 30, 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 $5.56 billion at September 30, 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):
		30-Sep-14
		Asset Derivatives						Liability Derivatives
		Classification		Fair Value				Classification	Fair Value
	Derivatives designated as hedges:
	Foreign currency exchange contracts	Other current assets		$	179,891			Other accrued liabilities	$	3,545
	Foreign currency exchange contracts	Other long-term assets		36,016				Other long-term obligations	79
	Total derivatives designated as hedges			215,907					3,624
	Derivatives not designated as hedges:
	Foreign currency exchange contracts	Other current assets		4				Other accrued liabilities	72
	Total derivatives not designated as hedges			4					72
	Total derivatives			$	215,911				$	3,696
		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 Financial Statements (in thousands):
		Three Months Ended							Nine Months Ended
		September 30,							September 30,
		2014				2013			2014			2013
	Derivatives designated as hedges:
	Gains (losses) recognized in OCI (effective portion)	$	230,348			$	(83,528	)	$	263,060		$	(867	)
	Gains (losses) reclassified from accumulated OCI into product sales (effective portion)	$	(1,810	)		$	(3,022	)	$	(41,439	)	$	2,791
	Gains (losses) recognized in other income (expense), net (ineffective portion and amounts excluded from effectiveness testing)	$	(2,626	)		$	1,105		$	(6,525	)	$	881
	Derivatives not designated as hedges:
	Gains (losses) recognized in other income (expense), net	$	73,489			$	(41,929	)	$	82,600		$	(232	)
	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 and nine months ended September 30, 2014 and 2013 as a result of the discontinuance of cash flow hedges.
	As of September 30, 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):
	30-Sep-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	$	215,911			$	—		$	215,911		$	(3,688	)	$	—	$	212,223
	Derivative liabilities	$	(3,696	)		$	—		$	(3,696	)	$	3,688		$	—	$	(8	)
	December 31, 2013
	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	$	13,879			$	—		$	13,879		$	(13,879	)	$	—	$	—
	Derivative liabilities	$	(99,057	)		$	—		$	(99,057	)	$	13,879		$	—	$	(85,178	)

Inventories

Inventories	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Inventories [Text Block]	'
	INVENTORIES
	Inventories are summarized as follows (in thousands):
		September 30, 2014		December 31, 2013
	Raw materials	$	956,842	$	1,049,403
	Work in process	501,856		412,945
	Finished goods	450,886		593,440
	Total	$	1,909,584	$	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 $1.01 billion as of September 30, 2014 and $1.28 billion as of December 31, 2013.

Intangible_Assets_and_Goodwill

Intangible Assets and Goodwill	9 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Intangible Assets and Goodwill [Text Block]	'
	INTANGIBLE ASSETS AND GOODWILL
	Intangible Assets
	The following table summarizes the carrying amount of our intangible assets (in thousands):
		30-Sep-14		December 31, 2013
	Finite-lived intangible assets	$	10,874,157	$	11,325,751
	Indefinite-lived intangible assets	432,390		574,355
	Total intangible assets	$	11,306,547	$	11,900,106
	Finite-Lived Intangible Assets
	The following table summarizes our finite-lived intangible assets (in thousands):
		30-Sep-14					December 31, 2013
		Gross Carrying		Accumulated			Gross Carrying		Accumulated
		Amount		Amortization			Amount		Amortization
	Intangible asset - sofosbuvir	$	10,720,000	$	582,609		$	10,720,000	$	58,261
	Intangible asset - Ranexa	688,400		243,697			688,400		190,849
	Other	454,995		162,932			305,795		139,334
	Total	$	11,863,395	$	989,238		$	11,714,195	$	388,444
	Upon FDA approval and commercial launch of Sovaldi in December 2013, we reclassified the in-process R&D related to sofosbuvir to finite-lived intangible assets. After receiving FDA approval in July 2014, we launched Zydelig and reclassified the in-process R&D related to idelalisib to finite-lived intangibles. Amortization expense related to finite-lived intangible assets are included primarily in cost of goods sold in our Condensed Consolidated Statements of Income which totaled $201.8 million and $600.8 million for the three and nine months ended September 30, 2014 and $21.3 million and $63.8 million for the three and nine months ended September 30, 2013. As of September 30, 2014, the estimated future amortization expense associated with our intangible assets for the remaining three months of 2014 and each of the five succeeding fiscal years is as follows (in thousands):
	Fiscal Year	Amount
	2014 (remaining three months)	$	202,902
	2015	817,060
	2016	824,992
	2017	829,435
	2018	841,543
	2019	806,386
	Total	$	4,322,318
	Indefinite-Lived Intangible Assets
	The following table summarizes our indefinite-lived intangible assets (in thousands):
		30-Sep-14		December 31, 2013
	Indefinite-lived intangible asset - momelotinib (formerly CYT387)	$	308,155	$	362,700
	Indefinite-lived intangible assets - other	117,000		266,200
		425,155		628,900
	Foreign currency translation adjustment	7,235		(54,545		)
	Total	$	432,390	$	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 September 30, 2014	$	1,171,561

Collaborative_Arrangements

Collaborative Arrangements	9 Months Ended
	Sep. 30, 2014
Collaborative Arrangements [Abstract]	'
Collaborative Arrangements [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 September 30, 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 September 30, 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 September 30, 2014, total assets held by the joint venture were $2.26 billion and consisted primarily of cash and cash equivalents of $213.9 million, accounts receivable of $257.5 million and inventories of $1.77 billion; total liabilities were $1.47 billion and consisted primarily of accounts payable of $1.08 billion and other accrued expenses of $393.9 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 Ireland Unlimited Company, our wholly-owned subsidiary in Ireland, formerly known as Gilead Sciences Limited, and BMS entered into a collaboration agreement with BMS which sets forth the terms and conditions under which we and BMS 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 September 30, 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	9 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Debt and Credit Facility [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	September 30,		December 31, 2013
						2014
	Convertible Senior	May 2014 Notes	Jul-10	May-14	1.00%	$	—	$	234,217
	Convertible Senior	May 2016 Notes	Jul-10	May-16	1.63%	727,072		1,113,043
	Senior Unsecured	April 2021 Notes	Mar-11	Apr-21	4.50%	994,425		993,781
	Senior Unsecured	December 2014 Notes	Dec-11	Dec-14	2.40%	749,947		749,710
	Senior Unsecured	December 2016 Notes	Dec-11	Dec-16	3.05%	699,499		699,326
	Senior Unsecured	December 2021 Notes	Dec-11	Dec-21	4.40%	1,247,933		1,247,716
	Senior Unsecured	December 2041 Notes	Dec-11	Dec-41	5.65%	997,942		997,885
	Senior Unsecured	April 2019 Notes	Mar-14	Apr-19	2.05%	499,232		—
	Senior Unsecured	April 2024 Notes	Mar-14	Apr-24	3.70%	1,747,340		—
	Senior Unsecured	April 2044 Notes	Mar-14	Apr-44	4.80%	1,746,669		—
	Credit Facility	Five-Year Revolver	Jan-12	Jan-17	Variable	—		600,000
	Total debt, net					9,410,059		6,635,678
	Less current portion					1,477,019		2,696,970
	Total long-term debt, net					$	7,933,040	$	3,938,708
	Convertible Senior Notes
	During the nine months ended September 30, 2014, our convertible senior notes due in May 2014 (May 2014 Notes) matured and a portion of our convertible senior notes due in May 2016 (May 2016 Notes) (together, the Notes) were converted. During the nine months ended September 30, 2014, we repaid $656.6 million of principal balance relating to the Notes. We also paid $1.60 billion in cash related to the conversion spread of the Notes, which represents the conversion value in excess of the principal amount, and received $1.60 billion in cash from the convertible note hedges related to the Notes.
	As of September 30, 2014, the May 2016 Notes were classified as current given that their conversion criteria had been met. As a result, the related unamortized discount of $27.4 million was classified as equity component of currently redeemable convertible notes on our Condensed Consolidated Balance Sheet.
	During the third quarter of 2014, we exercised our option to settle in cash the warrants expiring in 2014 (the 2014 Warrants). As result, we paid $4.09 billion to settle the warrants as the market value of our common stock at the time of the exercise of the warrants exceeds their strike price. There were 55.5 million shares of our common stock underlying the 2014 Warrants, which had a strike price of $28.38 per share and expired during the 40 trading-day period commencing August 1, 2014 and ending on September 26, 2014. Because the warrants could have been settled, at our option, in cash or shares of our common stock, and the related contracts met all of the applicable criteria for equity classification, the settlement was recorded as a reduction of additional paid-in capital in our Condensed Consolidated Balance Sheet.
	There are 55.1 million shares of our common stock underlying our warrants expiring in 2016 (the 2016 Warrants). The 2016 Warrants have a strike price of $30.05 per share and are exercisable only on their expiration date. If the market value of our common stock at the time of the exercise of the warrants exceeds their strike price, we will be required to net settle in cash or shares of our common stock, at our option, for the value of the warrants in excess of the warrant strike price.
	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 a 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 the 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. There were no amounts outstanding under the revolving credit facility credit agreement as of September 30, 2014.
	We are required to comply with certain covenants under the credit agreement and note indentures and as of September 30, 2014, we were not in violation with any covenants.

Commitment_and_Contingencies

Commitment and Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies [Text Block]	'
	COMMITMENTS AND CONTINGENCIES
	We are a party to various legal actions. The most significant of these are described below. It is not possible to determine the outcome of these matters, and we cannot reasonably estimate the maximum potential exposure or the range of possible loss.
	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 U.S. Food and Drug Administration (FDA) approval of sofosbuvir, now known commercially as Sovaldi. In October 2014, we also received approval of the fixed dose combination of ledipasvir and sofosbuvir (LDV/SOF), now known commercially as Harvoni. We own patents that claim sofosbuvir as a chemical entity and its metabolites. However, the existence of patents does not necessarily guarantee our right to practice the patented technology or commercialize the patented product. Third parties may have, or may obtain rights to, patents that allegedly could be used to prevent or attempt to prevent us from commercializing sofosbuvir. For example, we are aware of patents and patent applications owned by other parties that may be alleged by such parties to cover the use of sofosbuvir. 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. We cannot predict the ultimate outcome of the intellectual property claims related to sofosbuvir and may spend significant resources enforcing and defending our patents. Any range of loss cannot be estimated at this time.
	Current legal proceedings of significance regarding sofosbuvir include:
	Arbitration with F. Hoffman-La Roche Ltd and Hoffman-La Roche Inc. (collectively, Roche)
	Gilead (as successor to Pharmasset) is a party to a 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 in 2006. In March 2013, Roche served an arbitration against us and Pharmasset, predecessor to Gilead Pharmasset LLC. In the arbitration demand, Roche asserted that it had an exclusive license to sofosbuvir pursuant to the collaboration agreement because sofosbuvir, a prodrug of a uridine analog, is allegedly a prodrug of PSI-6130, a cytidine analog. Roche further claimed that, because it had exclusive rights to sofosbuvir, it also had an exclusive license to a patent covering sofosbuvir, and that we infringed 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. The arbitration hearing was held in June 2014. In August 2014, the arbitration panel determined that Roche failed to establish any of their claims and ruled in favor of us. As a result, Roche is not entitled to any damages or other relief.
	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 Trial 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.
	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 was 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. A trial on these issues is scheduled to commence in January 2015 in Toronto.
	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. A trial on these issues is scheduled to commence in September 2015 in Sydney.
	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 that day, Idenix initiated infringement proceedings against Gilead 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, a trial was held in October 2014 to determine the issues of infringement and validity of the Idenix United Kingdom patent. A decision is expected in the fourth quarter of 2014. 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 Europe, Canada, Norway and Australia.
	In December 2013, after receiving our 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. 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.
	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.
	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. On June 30, 2014, the court in Massachusetts granted our request and transferred the Massachusetts litigation to the U.S. District Court for the District of Delaware. 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.
	On June 9, 2014, Merck & Co. Inc. (Merck) and Idenix announced that the companies had entered into a definitive agreement under which Merck would acquire Idenix. While the acquisition of Idenix Pharmaceuticals, Inc. by Merck in August 2014 does not change our view of the lack of merit in the claims made by Idenix, Merck has greater resources than Idenix and may therefore choose to fund the litigation at higher levels than Idenix.
	Litigation with Merck
	In August 2013, Merck contacted us requesting that we pay royalties on the sales of sofosbuvir and obtain 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 a 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. The court has set a trial date of March 7, 2016 for this litigation.
	Litigation with AbbVie, Inc. (AbbVie)
	AbbVie has obtained U.S. Patent Nos. 8,466,159, 8,492,386, 8,680,106, 8,685,984, and 8,809,265 which purport to cover the use of a combination of LDV/SOF for the treatment of HCV. Gilead is aware that AbbVie has pending patent applications in other countries. We own published and pending patent applications directed to the use of combinations for the treatment of HCV, and, specifically, to the combination 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 and March 2014, AbbVie responded to our lawsuit by filing two lawsuits also in the U.S. District Court for the District of Delaware alleging that our fixed-dose combination of LDV/SOF will infringe its patents. All of those lawsuits have been consolidated into a single action. AbbVie’s patents have not blocked or delayed the commercialization of our combination product in the United States, and we do not expect any foreign counterparts to block or delay the commercialization around the world.
	Litigation with Generic Manufacturers
	As part of the approval process for some of our products, the FDA granted us 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 cannot predict the ultimate outcome of the foregoing actions and other litigation with generic manufacturers, 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 Truvada and Viread 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.
	Current legal proceedings of significance with some of our generic manufacturers include:
	Mylan Inc. (Mylan)
	In April 2014, we received notice that Mylan submitted an ANDA to the FDA requesting permission to manufacture and market a generic version of Truvada. In the notice, Mylan alleges that two of the patents associated with emtricitabine and one of our patents associated with the fixed-dose combination of emtricitabine with tenofovir disoproxil fumarate are invalid, unenforceable and/or will not be infringed by Mylan's manufacture, use or sale of a generic version of Truvada. In June 2014, we filed a lawsuit against Mylan in U.S. District Court for the Northern District of West Virginia for infringement of our patents. In June 2014, we received notice that Mylan Inc. submitted petitions for Inter Partes Review (IPR) to the Board alleging that four patents associated with tenofovir disoproxil fumarate are invalid. We are opposing Mylan’s petitions. We anticipate that the Board will issue a decision on whether to institute an IPR by December 2014. If the Board institutes an IPR, we anticipate a final decision by December 2015.
	Apotex Corp. (Apotex)
	In June 2014, we received notice that Apotex submitted an ANDS to the Canadian Minister of Health requesting permission to manufacture and market a generic fixed-dose combination of emtricitabine and tenofovir disoproxil fumarate and a separate ANDS requesting permission to manufacture and market a generic version of Viread. In the notice, Apotex alleges that three of the patents associated with Truvada and two of the patents associated with Viread are invalid, unenforceable and/or will not be infringed by Apotex's manufacture, use or sale of a generic version of Truvada or Viread. In August 2014, we filed a lawsuit against Apotex in the Federal Court of Canada seeking an order of prohibition against approval of this ANDS.
	Teva Pharmaceuticals (Teva)
	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 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 Minister 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 the decision of the court prohibiting the Minister of Heath from issuing the Notices of Compliance until expiry of our patent in July 2017. This decision did not rule on the validity of the patents and accordingly the only issue on appeal is whether the Minister of Health should be prohibited from issuing the Notices of Compliance for Teva’s products. Separately, the court will determine the validity of the patents in the pending Impeachment Action. A trial in the Impeachment Action is scheduled for March 2015.
	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 have moved to dismiss the complaint.

Stockholders_Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity Attributable to Parent [Abstract]	'
Stockholders' Equity [Text Block]	'
	STOCKHOLDERS’ EQUITY
	Stock Repurchase Program
	During the third quarter of 2014, we completed the stock repurchase program authorized in January 2011 (2011 Program). We repurchased a total of $1.70 billion or 19.1 million shares of common stock during the three months ended September 30, 2014, and a total of $3.35 billion or 40.0 million shares of common stock during the nine months ended September 30, 2014. In May 2014, our Board of Directors authorized a new stock repurchase program of up to $5.00 billion of our common stock. As of September 30, 2014, there were no shares repurchased under this new 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 (loss) before reclassifications	(3,062		)	995			256,772			254,705
	Amounts reclassified from accumulated other comprehensive income (loss)	—			(437		)	44,140			43,703
	Net current period other comprehensive income (loss)	(3,062		)	558			300,912			298,408
	Balance at September 30, 2014	$	(48,922	)	$	12,465		$	210,419		$	173,962
	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	9 Months Ended
	Sep. 30, 2014
Share-based Compensation [Abstract]	'
Stock-Based Compensation [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						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Cost of goods sold	$	2,726		$	1,823		$	7,933		$	6,296
	Research and development expenses	40,312			27,740			111,295			79,261
	Selling, general and administrative expenses	56,298			33,010			145,466			94,736
	Stock-based compensation expense included in total costs and expenses	99,336			62,573			264,694			180,293
	Income tax effect	(18,075		)	(15,997		)	(48,098		)	(47,958		)
	Stock-based compensation expense, net of tax	$	81,261		$	46,576		$	216,596		$	132,335

Net_Income_Per_Share_Attributa

Net Income Per Share Attributable to Gilead Common Stockholders	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Net Income Per Share Attributable to Gilead Common Stockholders [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 May 2016 Notes has a dilutive effect when the average market price of our common stock during the period exceeds the conversion price of $22.71 for the May 2016 Notes. Warrants relating to the May 2016 Notes have a dilutive effect when the average market price of our common stock during the period exceeds the warrants’ exercise price of $30.05.
	Our May 2013 Notes and May 2014 Notes matured and as a result, we have only included their impact for the periods they were outstanding on our net income per share calculations for the periods shown. Our common stock resulting from the assumed settlement of the conversion spread of the May 2013 Notes and May 2014 Notes had a dilutive effect when the average market price of our common stock during the period exceeded the conversion price of $19.05 for the May 2013 Notes and $22.54 for the May 2014 Notes. 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 and nine months ended September 30, 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. Warrants related to our May 2014 Notes settled in August and September 2014 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 and nine months ended September 30, 2014. 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 $28.38.
	We have excluded stock options to purchase approximately 1.1 million and 1.0 million weighted-average shares of our common stock that were outstanding during the three and nine months ended September 30, 2014, and approximately 0.1 million and 0.9 million weighted-average shares of our common stock that were outstanding during the three and nine months ended September 30, 2013. These shares were excluded 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				Nine Months Ended
		September 30,				September 30,
		2014		2013		2014		2013
	Net income attributable to Gilead	$	2,731,274	$	788,606	$	8,614,277	$	2,283,397
	Shares used in per share calculation - basic	1,513,899		1,532,105		1,527,633		1,526,847
	Effect of dilutive securities:
	Stock options and equivalents	31,727		38,575		33,769		39,085
	Conversion spread related to the May 2013 Notes	—		—		—		5,268
	Conversion spread related to the May 2014 Notes	—		24,335		3,138		27,435
	Conversion spread related to the May 2016 Notes	27,178		33,873		29,633		30,587
	Warrants related to the Convertible Notes	63,726		63,010		68,108		60,425
	Shares used in per share calculation - diluted	1,636,530		1,691,898		1,662,281		1,689,647

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Information [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							Nine Months Ended
		September 30,							September 30,
		2014			2013				2014			2013
	Antiviral products:
	Sovaldi	$	2,796,093		$	—			$	8,550,768		$	—
	Atripla	894,787			899,669				2,545,089			2,714,850
	Truvada	875,454			813,652				2,441,764			2,321,673
	Complera/Eviplera	330,263			210,736				880,460			547,608
	Stribild	328,035			143,953				812,826			335,495
	Viread	275,637			231,555				746,996			692,075
	Harvoni	19,966			—				20,405			—
	Other antiviral products	24,278			27,162				66,846			89,643
	Total antiviral products	5,544,513			2,326,727				16,065,154			6,701,344
	Letairis	146,415			135,072				414,016			381,436
	Ranexa	132,510			115,815				366,084			318,698
	AmBisome	98,108			97,812				284,995			258,224
	Zydelig	5,862			—				5,862			—
	Other products	40,800			34,226				116,008			100,803
	Total product sales	$	5,968,208		$	2,709,652			$	17,252,119		$	7,760,505
	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					Nine Months Ended
		September 30,					September 30,
		2014		2013			2014			2013
	AmerisourceBergen Corp.	23	%	15	%		25	%		13	%
	McKesson Corp.	24	%	16	%		24	%		16	%
	Cardinal Health, Inc.	15	%	16	%		13	%		18	%

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]	'
Income Taxes[Text Block]	'
	INCOME TAXES
	Our income tax rates of 19.2% and 19.1% for the three and nine months ended September 30, 2014, differed from the U.S. federal statutory rate of 35% due primarily to certain operating earnings from non-U.S. subsidiaries that are considered indefinitely reinvested and tax credits, partially offset by state taxes, our portion of the non-tax deductible Branded Prescription Drug Fee, also known as the 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 2010 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 September 30, 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)	9 Months Ended
	Sep. 30, 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.
	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 September 30, 2014, our accounts receivable in Southern Europe, specifically Greece, Italy, Portugal and Spain, totaled approximately $587.2 million, of which $154.5 million were greater than 120 days past due and $52.0 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 September 30, 2014.
Branded Prescription Drug Fee [Policy Text Block]	'
	Branded Prescription Drug Fee
	We, along with other pharmaceutical manufacturers of branded drug products, are required to pay a portion of the Branded Prescription Drug (BPD) Fee, which is calculated based on select government sales during each calendar year as a percentage of total industry government sales. During the third quarter of 2014, the IRS issued final regulations which required manufacturers to recognize an additional year of expense, which for us resulted in a cumulative catch-up of $337 million within the quarter. The IRS is expected to communicate the final BPD fee amounts due for 2013 sales during the third quarter of 2015 and for 2014 sales during the third quarter of 2016. As of September 30, 2014, our BPD fee accrual totaled $343 million, of which $304 million was included in other long-term obligations on our Condensed Consolidated Balance Sheet.
Recent Accounting Pronouncement [Policy Text Block]	'
	Recent Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board, jointly with the International Accounting Standards Board, issued a comprehensive new standard on revenue recognition from contracts with customers. The standard's core principle is that a reporting entity will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In applying this new guidance to contracts within its scope, an entity will: (1) identify the contract(s) with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) the entity satisfies a performance obligation. Additionally, this new guidance will require significantly expanded revenue recognition disclosures. This guidance will become effective for us beginning in the first quarter of 2017. Early application is not permitted. Entities have the option of using either a full retrospective or a modified retrospective approach to adopt this new guidance. We are currently evaluating the impact of our pending adoption of this standard on our Condensed Consolidated Financial Statements.

Fair_value_measurements_Tables

Fair value measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'
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):
					30-Sep-14						December 31, 2013
	Type of Borrowing		Description		Carrying Value			Fair Value			Carrying Value			Fair Value
	Convertible Senior		May 2014 Notes		$	—		$	—		$	234,217		$	783,651
	Convertible Senior		May 2016 Notes		727,072			3,517,174			1,113,043			3,871,516
	Senior Unsecured		April 2021 Notes		994,425			1,093,710			993,781			1,075,480
	Senior Unsecured		December 2014 Notes		749,947			752,820			749,710			762,637
	Senior Unsecured		December 2016 Notes		699,499			729,603			699,326			740,705
	Senior Unsecured		December 2021 Notes		1,247,933			1,358,813			1,247,716			1,336,738
	Senior Unsecured		December 2041 Notes		997,942			1,186,550			997,885			1,118,660
	Senior Unsecured		April 2019 Notes		499,232			496,065			—			—
	Senior Unsecured		April 2024 Notes		1,747,340			1,782,900			—			—
	Senior Unsecured		April 2044 Notes		1,746,669			1,848,333			—			—
Schedule of Fair Value Classified by Level of Input [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):
		30-Sep-14													December 31, 2013
		Level 1				Level 2			Level 3			Total			Level 1		Level 2		Level 3		Total
	Assets:
	Debt securities:
	Money market funds	$	5,049,683			$	—		$	—		$	5,049,683		$	1,490,964	$	—	$	—	$	1,490,964
	Corporate debt securities	—				675,745			—			675,745			—		220,025		—		220,025
	U.S. treasury securities	520,208				—			—			520,208			85,403		—		—		85,403
	U.S. government agencies securities	—				131,417			—			131,417			—		93,350		—		93,350
	Residential mortgage and asset-backed securities	—				151,287			—			151,287			—		46,941		—		46,941
	Municipal debt securities	—				9,209			—			9,209			—		12,065		—		12,065
	Total debt securities	5,569,891				967,658			—			6,537,549			1,576,367		372,381		—		1,948,748
	Deferred compensation plan	52,261				—			—			52,261			44,461		—		—		44,461
	Foreign currency derivative contracts	—				215,911			—			215,911			—		13,879		—		13,879
		$	5,622,152			$	1,183,569		$	—		$	6,805,721		$	1,620,828	$	386,260	$	—	$	2,007,088
	Liabilities:
	Contingent consideration	$	—			$	—		$	94,899		$	94,899		$	—	$	—	$	263,760	$	263,760
	Foreign currency derivative contracts	—				3,696			—			3,696			—		99,057		—		99,057
	Deferred compensation plan	52,261				—			—			52,261			44,461		—		—		44,461
		$	52,261			$	3,696		$	94,899		$	150,856		$	44,461	$	99,057	$	263,760	$	407,278
CGI and Calistoga [Member]	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'
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
	Milestone payments		(175,000		)
	Net changes in valuation		6,139
	Balance at September 30, 2014		$	94,899

Availableforsale_securities_Ta

Available-for-sale securities (Tables)	9 Months Ended
	Sep. 30, 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):
		30-Sep-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	$	5,049,683		$	—		$	—		$	5,049,683		$	1,490,964		$	—	$	—		$	1,490,964
	Corporate debt securities	676,599			474			(1,328		)	675,745			219,242			885		(102		)	220,025
	U.S. treasury securities	520,243			250			(285		)	520,208			85,337			94		(28		)	85,403
	U.S. government agencies securities	131,396			94			(73		)	131,417			93,211			156		(17		)	93,350
	Residential mortgage and asset-backed securities	151,359			51			(123		)	151,287			46,969			37		(65		)	46,941
	Municipal debt securities	9,175			34			—			9,209			12,009			56		—			12,065
	Total	$	6,538,455		$	903		$	(1,809	)	$	6,537,549		$	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):
		30-Sep-14			December 31, 2013
	Cash and cash equivalents	$	5,054,883		$	1,490,964
	Short-term marketable securities	107,266			18,756
	Long-term marketable securities	1,375,400			439,028
	Total	$	6,537,549		$	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):
		30-Sep-14
		Amortized Cost			Fair Value
	Less than one year	$	5,161,903		$	5,162,149
	Greater than one year but less than five years	1,366,482			1,365,350
	Greater than five years but less than ten years	5,618			5,607
	Greater than ten years	4,452			4,443
	Total	$	6,538,455		$	6,537,549
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						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Gross realized gains on sales	$	164		$	269		$	865		$	652
	Gross realized losses on sales	$	(84	)	$	(166	)	$	(175	)	$	(433	)
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
	30-Sep-14
	Debt securities:
	U.S. treasury securities	$	(285	)	$	230,148		$	—		$	—		$	(285	)	$	230,148
	Corporate debt securities	(1,328		)	494,142			—			—			(1,328		)	494,142
	Residential mortgage and asset-backed securities	(110		)	100,094			(13		)	811			(123		)	100,905
	U.S. government agencies securities	(73		)	49,849			—			—			$	(73	)	$	49,849
	Total	$	(1,796	)	$	874,233		$	(13	)	$	811		$	(1,809	)	$	875,044
	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)	9 Months Ended
	Sep. 30, 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):
		30-Sep-14
		Asset Derivatives						Liability Derivatives
		Classification		Fair Value				Classification	Fair Value
	Derivatives designated as hedges:
	Foreign currency exchange contracts	Other current assets		$	179,891			Other accrued liabilities	$	3,545
	Foreign currency exchange contracts	Other long-term assets		36,016				Other long-term obligations	79
	Total derivatives designated as hedges			215,907					3,624
	Derivatives not designated as hedges:
	Foreign currency exchange contracts	Other current assets		4				Other accrued liabilities	72
	Total derivatives not designated as hedges			4					72
	Total derivatives			$	215,911				$	3,696
		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 Financial Statements (in thousands):
		Three Months Ended							Nine Months Ended
		September 30,							September 30,
		2014				2013			2014			2013
	Derivatives designated as hedges:
	Gains (losses) recognized in OCI (effective portion)	$	230,348			$	(83,528	)	$	263,060		$	(867	)
	Gains (losses) reclassified from accumulated OCI into product sales (effective portion)	$	(1,810	)		$	(3,022	)	$	(41,439	)	$	2,791
	Gains (losses) recognized in other income (expense), net (ineffective portion and amounts excluded from effectiveness testing)	$	(2,626	)		$	1,105		$	(6,525	)	$	881
	Derivatives not designated as hedges:
	Gains (losses) recognized in other income (expense), net	$	73,489			$	(41,929	)	$	82,600		$	(232	)
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):
	30-Sep-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	$	215,911			$	—		$	215,911		$	(3,688	)	$	—	$	212,223
	Derivative liabilities	$	(3,696	)		$	—		$	(3,696	)	$	3,688		$	—	$	(8	)
	December 31, 2013
	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	$	13,879			$	—		$	13,879		$	(13,879	)	$	—	$	—
	Derivative liabilities	$	(99,057	)		$	—		$	(99,057	)	$	13,879		$	—	$	(85,178	)

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2014
Inventory Disclosure [Abstract]	'
Schedule of Inventories	'
	Inventories are summarized as follows (in thousands):
		September 30, 2014		December 31, 2013
	Raw materials	$	956,842	$	1,049,403
	Work in process	501,856		412,945
	Finished goods	450,886		593,440
	Total	$	1,909,584	$	2,055,788

Intangible_Assets_and_Goodwill1

Intangible Assets and Goodwill (Tables)	9 Months Ended
	Sep. 30, 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):
		30-Sep-14		December 31, 2013
	Finite-lived intangible assets	$	10,874,157	$	11,325,751
	Indefinite-lived intangible assets	432,390		574,355
	Total intangible assets	$	11,306,547	$	11,900,106
Schedule of Finite-Lived Intangible Assets [Table Text Block]	'
	The following table summarizes our finite-lived intangible assets (in thousands):
		30-Sep-14					December 31, 2013
		Gross Carrying		Accumulated			Gross Carrying		Accumulated
		Amount		Amortization			Amount		Amortization
	Intangible asset - sofosbuvir	$	10,720,000	$	582,609		$	10,720,000	$	58,261
	Intangible asset - Ranexa	688,400		243,697			688,400		190,849
	Other	454,995		162,932			305,795		139,334
	Total	$	11,863,395	$	989,238		$	11,714,195	$	388,444
Estimated Future Amortization Expense [Table Text Block]	'
	As of September 30, 2014, the estimated future amortization expense associated with our intangible assets for the remaining three months of 2014 and each of the five succeeding fiscal years is as follows (in thousands):
	Fiscal Year	Amount
	2014 (remaining three months)	$	202,902
	2015	817,060
	2016	824,992
	2017	829,435
	2018	841,543
	2019	806,386
	Total	$	4,322,318
Schedule of Indefinite-Lived Intangible Assets [Table Text Block]	'
	The following table summarizes our indefinite-lived intangible assets (in thousands):
		30-Sep-14		December 31, 2013
	Indefinite-lived intangible asset - momelotinib (formerly CYT387)	$	308,155	$	362,700
	Indefinite-lived intangible assets - other	117,000		266,200
		425,155		628,900
	Foreign currency translation adjustment	7,235		(54,545		)
	Total	$	432,390	$	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 September 30, 2014	$	1,171,561

Debt_and_Credit_Facility_Table

Debt and Credit Facility (Tables)	9 Months Ended
	Sep. 30, 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	September 30,		December 31, 2013
						2014
	Convertible Senior	May 2014 Notes	Jul-10	May-14	1.00%	$	—	$	234,217
	Convertible Senior	May 2016 Notes	Jul-10	May-16	1.63%	727,072		1,113,043
	Senior Unsecured	April 2021 Notes	Mar-11	Apr-21	4.50%	994,425		993,781
	Senior Unsecured	December 2014 Notes	Dec-11	Dec-14	2.40%	749,947		749,710
	Senior Unsecured	December 2016 Notes	Dec-11	Dec-16	3.05%	699,499		699,326
	Senior Unsecured	December 2021 Notes	Dec-11	Dec-21	4.40%	1,247,933		1,247,716
	Senior Unsecured	December 2041 Notes	Dec-11	Dec-41	5.65%	997,942		997,885
	Senior Unsecured	April 2019 Notes	Mar-14	Apr-19	2.05%	499,232		—
	Senior Unsecured	April 2024 Notes	Mar-14	Apr-24	3.70%	1,747,340		—
	Senior Unsecured	April 2044 Notes	Mar-14	Apr-44	4.80%	1,746,669		—
	Credit Facility	Five-Year Revolver	Jan-12	Jan-17	Variable	—		600,000
	Total debt, net					9,410,059		6,635,678
	Less current portion					1,477,019		2,696,970
	Total long-term debt, net					$	7,933,040	$	3,938,708

Stockholders_Equity_Table_of_C

Stockholders' Equity Table of Changes in Accumulated Comprehensive Income by Component (Tables)	9 Months Ended
	Sep. 30, 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 (loss) before reclassifications	(3,062		)	995			256,772			254,705
	Amounts reclassified from accumulated other comprehensive income (loss)	—			(437		)	44,140			43,703
	Net current period other comprehensive income (loss)	(3,062		)	558			300,912			298,408
	Balance at September 30, 2014	$	(48,922	)	$	12,465		$	210,419		$	173,962

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 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						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Cost of goods sold	$	2,726		$	1,823		$	7,933		$	6,296
	Research and development expenses	40,312			27,740			111,295			79,261
	Selling, general and administrative expenses	56,298			33,010			145,466			94,736
	Stock-based compensation expense included in total costs and expenses	99,336			62,573			264,694			180,293
	Income tax effect	(18,075		)	(15,997		)	(48,098		)	(47,958		)
	Stock-based compensation expense, net of tax	$	81,261		$	46,576		$	216,596		$	132,335

Net_Income_Per_Share_Attributa1

Net Income Per Share Attributable to Gilead Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 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				Nine Months Ended
		September 30,				September 30,
		2014		2013		2014		2013
	Net income attributable to Gilead	$	2,731,274	$	788,606	$	8,614,277	$	2,283,397
	Shares used in per share calculation - basic	1,513,899		1,532,105		1,527,633		1,526,847
	Effect of dilutive securities:
	Stock options and equivalents	31,727		38,575		33,769		39,085
	Conversion spread related to the May 2013 Notes	—		—		—		5,268
	Conversion spread related to the May 2014 Notes	—		24,335		3,138		27,435
	Conversion spread related to the May 2016 Notes	27,178		33,873		29,633		30,587
	Warrants related to the Convertible Notes	63,726		63,010		68,108		60,425
	Shares used in per share calculation - diluted	1,636,530		1,691,898		1,662,281		1,689,647

Segment_information_Tables

Segment information (Tables)	9 Months Ended
	Sep. 30, 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							Nine Months Ended
		September 30,							September 30,
		2014			2013				2014			2013
	Antiviral products:
	Sovaldi	$	2,796,093		$	—			$	8,550,768		$	—
	Atripla	894,787			899,669				2,545,089			2,714,850
	Truvada	875,454			813,652				2,441,764			2,321,673
	Complera/Eviplera	330,263			210,736				880,460			547,608
	Stribild	328,035			143,953				812,826			335,495
	Viread	275,637			231,555				746,996			692,075
	Harvoni	19,966			—				20,405			—
	Other antiviral products	24,278			27,162				66,846			89,643
	Total antiviral products	5,544,513			2,326,727				16,065,154			6,701,344
	Letairis	146,415			135,072				414,016			381,436
	Ranexa	132,510			115,815				366,084			318,698
	AmBisome	98,108			97,812				284,995			258,224
	Zydelig	5,862			—				5,862			—
	Other products	40,800			34,226				116,008			100,803
	Total product sales	$	5,968,208		$	2,709,652			$	17,252,119		$	7,760,505
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					Nine Months Ended
		September 30,					September 30,
		2014		2013			2014			2013
	AmerisourceBergen Corp.	23	%	15	%		25	%		13	%
	McKesson Corp.	24	%	16	%		24	%		16	%
	Cardinal Health, Inc.	15	%	16	%		13	%		18	%

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Accounting Policies [Abstract]	'
Total Southern European Accounts Receivable	$587.20
Total Southern European Accounts Receivable Greater Than 120 Days	154.5
Total Southern European Accounts Receivable Greater Than 365 Days Past Due	52
Branded Prescription Drug Fee	337
Branded Prescription Drug Fee Accrued	343
Branded Prescription Drug Fee Accrued Non-Current	$304

Fair_Value_and_Carrying_Value_

Fair Value and Carrying Value of Debt (Details) (USD $)	Sep. 30, 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	$0	$234,217
Debt Instruments, Fair Value	0	783,651
Convertible Senior Notes Due In May 2016 [Member]	'	'
Fair Value and Carrying Value of Debt [Line Items]	'	'
Convertible Senior Notes, Carrying Value	727,072	1,113,043
Debt Instruments, Fair Value	3,517,174	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	994,425	993,781
Debt Instruments, Fair Value	1,093,710	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	749,947	749,710
Debt Instruments, Fair Value	752,820	762,637
Senior Unsecured Notes Due In December 2016 [Member]	'	'
Fair Value and Carrying Value of Debt [Line Items]	'	'
Senior Unsecured Notes, Carrying Value	699,499	699,326
Debt Instruments, Fair Value	729,603	740,705
Senior Unsecured Notes Due In December 2021 [Member]	'	'
Fair Value and Carrying Value of Debt [Line Items]	'	'
Senior Unsecured Notes, Carrying Value	1,247,933	1,247,716
Debt Instruments, Fair Value	1,358,813	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	997,942	997,885
Debt Instruments, Fair Value	1,186,550	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	499,232	0
Debt Instruments, Fair Value	496,065	0
Senior Unsecured Notes Due in April 2024 [Member]	'	'
Fair Value and Carrying Value of Debt [Line Items]	'	'
Senior Unsecured Notes, Carrying Value	1,747,340	0
Debt Instruments, Fair Value	1,782,900	0
Senior Unsecured Notes Due in April 2044 [Member]	'	'
Fair Value and Carrying Value of Debt [Line Items]	'	'
Senior Unsecured Notes, Carrying Value	1,746,669	0
Debt Instruments, Fair Value	$1,848,333	$0

Fair_value_measurements_Summar

Fair value measurements (Summary of assets and liabilities recorded at fair value) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	$6,537,549	$1,948,748
Contingent consideration	94,899	263,760
Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	5,569,891	1,576,367
Deferred compensation plan	52,261	44,461
Foreign currency derivative contracts	0	0
Fair value, Assets, Total	5,622,152	1,620,828
Contingent consideration	0	0
Foreign currency derivative contracts	0	0
Deferred compensation plan	52,261	44,461
Fair value, Liabilities, Total	52,261	44,461
Level 1 [Member] | Money Market Funds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	5,049,683	1,490,964
Level 1 [Member] | Corporate Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 1 [Member] | US Treasury Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	520,208	85,403
Level 1 [Member] | US Government Corporations and Agencies Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 1 [Member] | Residential mortgage and asset-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 1 [Member] | Municipal Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	967,658	372,381
Deferred compensation plan	0	0
Foreign currency derivative contracts	215,911	13,879
Fair value, Assets, Total	1,183,569	386,260
Contingent consideration	0	0
Foreign currency derivative contracts	3,696	99,057
Deferred compensation plan	0	0
Fair value, Liabilities, Total	3,696	99,057
Level 2 [Member] | Money Market Funds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 2 [Member] | Corporate Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	675,745	220,025
Level 2 [Member] | US Treasury Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 2 [Member] | US Government Corporations and Agencies Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	131,417	93,350
Level 2 [Member] | Residential mortgage and asset-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	151,287	46,941
Level 2 [Member] | Municipal Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	9,209	12,065
Level 3 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Deferred compensation plan	0	0
Foreign currency derivative contracts	0	0
Fair value, Assets, Total	0	0
Contingent consideration	94,899	263,760
Foreign currency derivative contracts	0	0
Deferred compensation plan	0	0
Fair value, Liabilities, Total	94,899	263,760
Level 3 [Member] | Money Market Funds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | Corporate Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | US Treasury Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | US Government Corporations and Agencies Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | Residential mortgage and asset-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Level 3 [Member] | Municipal Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	0	0
Estimate of Fair Value Measurement [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	6,537,549	1,948,748
Deferred compensation plan	52,261	44,461
Foreign currency derivative contracts	215,911	13,879
Fair value, Assets, Total	6,805,721	2,007,088
Contingent consideration	94,899	263,760
Foreign currency derivative contracts	3,696	99,057
Deferred compensation plan	52,261	44,461
Fair value, Liabilities, Total	150,856	407,278
Estimate of Fair Value Measurement [Member] | Money Market Funds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	5,049,683	1,490,964
Estimate of Fair Value Measurement [Member] | Corporate Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	675,745	220,025
Estimate of Fair Value Measurement [Member] | US Treasury Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	520,208	85,403
Estimate of Fair Value Measurement [Member] | US Government Corporations and Agencies Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	131,417	93,350
Estimate of Fair Value Measurement [Member] | Residential mortgage and asset-backed securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	151,287	46,941
Estimate of Fair Value Measurement [Member] | Municipal Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Estimated Fair Value	$9,209	$12,065

Contingent_Consideration_Rollf

Contingent Consideration Rollforward (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'
Net changes in valuation	($4,119)	$47,442
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Balance at December 31, 2013	263,760	'
Milestone payments	-175,000	'
Balance at September 30, 2014	94,899	'
CGI and Calistoga [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'
Net changes in valuation	6,139	'
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'
Balance at December 31, 2013	220,500	'
Balance at September 30, 2014	$47,400	'

Fair_value_measurements_Narrat

Fair value measurements Narrative (Details) (USD $)	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Contingent consideration	$94,899,000	$263,760,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	175,000,000	'
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	$47,400,000	$220,500,000

AvailableforSale_Securities_Su

Available-for-Sale Securities Summary of Available-for-Sale Securities at Estimated Fair Value (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-Sale Securities [Line Items]	'	'
Total Amortized Cost	$6,538,455	$1,947,732
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	903	1,228
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	-1,809	-212
Total	6,537,549	1,948,748
Money Market Funds [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Total Amortized Cost	5,049,683	1,490,964
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	0	0
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Total	5,049,683	1,490,964
Corporate Debt Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Total Amortized Cost	676,599	219,242
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	474	885
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	-1,328	-102
Total	675,745	220,025
US Treasury Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Total Amortized Cost	520,243	85,337
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	250	94
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	-285	-28
Total	520,208	85,403
US Government Agencies Debt Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Total Amortized Cost	131,396	93,211
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	94	156
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	-73	-17
Total	131,417	93,350
Residential mortgage and asset-backed securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Total Amortized Cost	151,359	46,969
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	51	37
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	-123	-65
Total	151,287	46,941
Municipal Debt Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Total Amortized Cost	9,175	12,009
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	34	56
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Total	$9,209	$12,065

AvailableforSale_Securities_Su1

Available-for-Sale Securities Summary of the Classification of Available-for-Sale Securities (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]	'	'
Cash And Cash Equivalents	$5,054,883	$1,490,964
Short-term marketable securities	107,266	18,756
Long-term marketable securities	1,375,400	439,028
Total	$6,537,549	$1,948,748

AvailableforSale_Securities_Su2

Available-for-Sale Securities Summary of Available-for-Sale Securities by Contractual Maturity (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Investments, Debt and Equity Securities [Abstract]	'	'
Less than 1 Year, Amortized Cost	$5,161,903	'
Greater than 1 Year but Less than 5 Years, Amortized Cost	1,366,482	'
Greater than 5 Years but Less than 10 Years, Amortized Cost	5,618	'
Greater than 10 Years, Amortized Cost	4,452	'
Total Amortized Cost	6,538,455	1,947,732
Less than 1 Year, Fair Value	5,162,149	'
Greater than 1 Year but Less than 5 Years, Fair Value	1,365,350	'
Greater than 5 Years but Less than 10 Years, Fair Value	5,607	'
Greater than 10 Years, Fair Value	4,443	'
Total	$6,537,549	$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		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Investments, Debt and Equity Securities [Abstract]	'	'	'	'
Gross realized gains on sales	$164	$269	$865	$652
Gross realized losses on sales	($84)	($166)	($175)	($433)

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 $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	($1,809)	($212)
Continuous Unrealized Loss Position, Estimated Fair Value	875,044	100,295
Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	874,233	92,059
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	-1,796	-185
Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available-for-sale Securities, Gross Unrealized Loss	-13	-27
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	811	8,236
U.S. treasury securities	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-285	-28
Continuous Unrealized Loss Position, Estimated Fair Value	230,148	24,562
U.S. treasury securities | Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	230,148	24,562
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	-285	-28
U.S. treasury securities | Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available-for-sale Securities, Gross Unrealized Loss	0	0
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	0	0
Corporate debt securities	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-1,328	-102
Continuous Unrealized Loss Position, Estimated Fair Value	494,142	38,581
Corporate debt securities | Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	494,142	37,076
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	-1,328	-102
Corporate debt securities | Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available-for-sale Securities, Gross Unrealized Loss	0	0
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	0	1,505
Residential mortgage and asset-backed securities	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-123	-65
Continuous Unrealized Loss Position, Estimated Fair Value	100,905	26,294
Residential mortgage and asset-backed securities | Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	100,094	19,563
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	-110	-38
Residential mortgage and asset-backed securities | Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available-for-sale Securities, Gross Unrealized Loss	-13	-27
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	811	6,731
US Government Agencies Securities [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available for Sale Securities - Gross Unrealized Losses	-73	-17
Continuous Unrealized Loss Position, Estimated Fair Value	49,849	10,858
US Government Agencies Securities [Member] | Less Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	49,849	10,858
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	-73	-17
US Government Agencies Securities [Member] | Greater Than 12 Months [Member]	'	'
Schedule of Available-for-Sale Securities [Line Items]	'	'
Available-for-sale Securities, Gross Unrealized Loss	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 $)	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]	'	'
Cash Excluded from Available-for-Sale Debt Securities Table	$1,150,000,000	$621,800,000
Available-for-Sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions (securities)	317	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 $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	$215,911	$13,879
Derivative Liability, Fair Value	3,696	99,057
Designated as Hedging Instrument [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	215,907	13,876
Derivative Liability, Fair Value	3,624	98,840
Not Designated as Hedging Instrument [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	4	3
Derivative Liability, Fair Value	72	217
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Current Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Asset Fair Value	179,891	12,647
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value	3,545	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	36,016	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	79	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	4	3
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Accrued Liabilities [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative Liability, Fair Value	$72	$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		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'	'	'	'
Gains (losses) recognized in OCI (effective portion)	$230,348	($83,528)	$263,060	($867)
Gains (losses) reclassified from accumulated OCI into product sales (effective portion)	-1,810	-3,022	-41,439	2,791
Gains (losses) recognized in other income (expense), net (ineffective portion and amounts excluded from effectiveness testing)	-2,626	1,105	-6,525	881
Gains (losses) recognized in other income (expense), net	$73,489	($41,929)	$82,600	($232)

Derivative_Financial_Instrumen4

Derivative Financial Instruments Table of Offsetting Derivative Assets and Liabilities (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative Asset [Abstract]	'	'
Gross Amounts of Recognized Assets	$215,911	$13,879
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Amount of Assets Presented in the Condensed Consolidated Balance Sheet	215,911	13,879
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheet - Derivative Financial Instruments	-3,688	-13,879
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheet - Cash Collateral Received/Pledged	0	0
Net Amount (Legal Offset)	212,223	0
Derivative Liability [Abstract]	'	'
Gross Amount of Recognized Liabilities	-3,696	-99,057
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheet	-3,696	-99,057
Gross Amount Not Offset in the Condensed Consolidated Balance Sheet - Derivative Financial Instruments	3,688	13,879
Gross Amount Not Offset in the Condensed Consolidated Balance Sheet - Cash Collateral Received/Pledged	0	0
Net Amount (Legal Offset)	($8)	($85,178)

Derivative_Financial_Instrumen5

Derivative Financial Instruments Derivative financial instruments Narrative (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Billions, unless otherwise specified
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'	'
Derivative, Notional Amount	$5.56	$4.28

Inventories_Schedule_of_invent

Inventories Schedule of inventories (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Raw materials	$956,842	$1,049,403
Work in process	501,856	412,945
Finished goods	450,886	593,440
Total	$1,909,584	$2,055,788

Inventories_Narrative_Details

Inventories (Narrative) (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory [Line Items]	'	'
Inventories	$1,909,584	$2,055,788
Efavirenz [Member] | Bristol-Myers Squibb Company [Member]	'	'
Inventory [Line Items]	'	'
Inventories	$1,010,000	$1,280,000

Intangible_Assets_and_Goodwill2

Intangible Assets and Goodwill Schedule of Carrying Amount of Intangible Assets (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]	'	'
Finite-lived intangible assets	$10,874,157	$11,325,751
Indefinite-lived intangible assets	432,390	574,355
Total intangible assets	$11,306,547	$11,900,106

Intangible_Assets_and_Goodwill3

Intangible Assets and Goodwill Schedule of Finite Lived Intangible Assets (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Finite Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross Carrying Amount	$11,863,395	$11,714,195
Finite-Lived Intangible Assets, Accumulated Amortization	989,238	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	582,609	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	243,697	190,849
Other [Member]	'	'
Finite Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross Carrying Amount	454,995	305,795
Finite-Lived Intangible Assets, Accumulated Amortization	$162,932	$139,334

Intangible_Assets_and_Goodwill4

Intangible Assets and Goodwill Schedule of Future Amortization Expense (Details) (USD $)	Sep. 30, 2014
In Thousands, unless otherwise specified
Goodwill and Intangible Assets Disclosure [Abstract]	'
2014 (remaining three months)	$202,902
2015	817,060
2016	824,992
2017	829,435
2018	841,543
2019	806,386
Total	$4,322,318

Intangible_Assets_and_Goodwill5

Intangible Assets and Goodwill Schedule of Indefinite Lived Intangible Assets (Details) (USD $)	9 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Indefinite-lived Intangible Assets [Line Items]	'	'
Indefinite-lived Intangible Assets	$432,390	$574,355
Indefinite-Lived Intangible Assets (Excluding Goodwill), Gross	425,155	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	$117,000	$266,200

Intangible_Assets_and_Goodwill6

Intangible Assets and Goodwill Goodwill Rollforward (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014
Goodwill [Roll Forward]	'
Balance at December 31, 2013	$1,169,023
Foreign currency translation adjustment	2,538
Balance at September 30, 2014	$1,171,561

Intangible_Assets_and_Goodwill7

Intangible Assets and Goodwill (Narrative) (Details) (Cost of Sales [Member], USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Cost of Sales [Member]	'	'	'	'
Acquired Indefinite-lived Intangible Assets [Line Items]	'	'	'	'
Amortization of Finite-Lived Intangible Assets	$201.80	$21.30	$600.80	$63.80

Collaborative_Arrangements_Nar

Collaborative Arrangements Narrative (Details) (Bristol-Myers Squibb Company [Member], USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Variable Interest Entity, Primary Beneficiary [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity, Assets	$2,260	$2,240
Variable Interest Entity, Liabilities	1,470	1,260
Cash and Cash Equivalents [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity, Assets	213.9	245.7
Accounts Receivable [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity, Assets	257.5	275.3
Inventories [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity, Assets	1,770	1,720
Accounts Payable [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity, Liabilities	1,080	915.4
Other Accrued Liabilities [Member]	'	'
Variable Interest Entity [Line Items]	'	'
Variable Interest Entity, Liabilities	$393.90	$341.20

Debt_and_Credit_Facility_Sched

Debt and Credit Facility Schedule of Carrying Amounts of Senior Notes (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Debt Instrument [Line Items]	'	'
Total Debt, Net	$9,410,059	$6,635,678
Less Current Portion	1,477,019	2,696,970
Total Long-Term Debt, Net	7,933,040	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	0	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	727,072	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	994,425	993,781
Senior Unsecured Notes Due December 2014 [Member]	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Interest Rate, Stated Percentage	2.40%	'
Senior Unsecured Notes	749,947	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	699,499	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	1,247,933	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	997,942	997,885
Senior Unsecured Notes Due in April 2019 [Member]	'	'
Debt Instrument [Line Items]	'	'
Senior Unsecured Notes	499,232	0
Senior Unsecured Notes Due in April 2024 [Member]	'	'
Debt Instrument [Line Items]	'	'
Senior Unsecured Notes	1,747,340	0
Senior Unsecured Notes Due in April 2044 [Member]	'	'
Debt Instrument [Line Items]	'	'
Senior Unsecured Notes	1,746,669	0
Credit Facility Due In January 2017 [Member]	'	'
Debt Instrument [Line Items]	'	'
Credit Facility, Amount Outstanding	$0	$600,000

Debt_and_Credit_Facility_Debt_

Debt and Credit Facility Debt and Credity Facility (Narrative) (Details) (USD $)	9 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Debt Instrument [Line Items]	'	'
Debt Principal Repayment, Conversion	$656,600,000	'
Proceeds from convertible note hedges	1,629,483,000	1,257,869,000
Debt Instrument, Unamortized Discount	27,400,000	'
Payment to Settle Warrants Related to Convertible Notes	4,092,758,000	1,039,695,000
Debt Instrument, Face Amount	4,000,000,000	'
Debt Issuance Cost	27,500,000	'
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	100.00%	'
Debt Instrument, Redemption Price, Percentage	101.00%	'
Repayment of Credit Facility	600,000,000	'
Senior Unsecured Notes Due in April 2019 [Member]	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Face Amount	500,000,000	'
Debt Instrument, Interest Rate, Stated Percentage	2.05%	'
Senior Unsecured Notes Due in April 2024 [Member]	'	'
Debt Instrument [Line Items]	'	'
Debt Instrument, Face Amount	1,750,000,000	'
Debt Instrument, Interest Rate, Stated Percentage	3.70%	'
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	'
Debt Instrument, Interest Rate, Stated Percentage	4.80%	'
Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed	100.00%	'
Convertible Senior Notes Due May 2014 and May 2016 [Member]	'	'
Debt Instrument [Line Items]	'	'
Conversion Value In Excess of Principal Amount	1,600,000,000	'
Proceeds from convertible note hedges	$1,600,000,000	'
2014 Warrants [Member]	'	'
Debt Instrument [Line Items]	'	'
Common Stock Underlying Warrants	55.5	'
Class of Warrant or Right, Exercise Price of Warrants or Rights	$28.38	'
2016 Warrants [Member]	'	'
Debt Instrument [Line Items]	'	'
Common Stock Underlying Warrants	55.1	'
Class of Warrant or Right, Exercise Price of Warrants or Rights	$30.05	'
Treasury Rate [Member] | Senior Unsecured Notes Due in April 2019 [Member]	'	'
Debt Instrument [Line Items]	'	'
Basis Points	0.10%	'
Treasury Rate [Member] | Senior Unsecured Notes Due in April 2024 [Member]	'	'
Debt Instrument [Line Items]	'	'
Basis Points	0.15%	'
Treasury Rate [Member] | Senior Unsecured Notes Due in April 2044 [Member]	'	'
Debt Instrument [Line Items]	'	'
Basis Points	0.20%	'

Stockholders_Equity_Schedule_o

Stockholders' Equity Schedule of Accumulated Comprehensive Income (loss) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'
Balance at December 31, 2013	'	'	($124,446)	'
Other comprehensive income (loss) before reclassifications	'	'	254,705	'
Amounts reclassified from accumulated other comprehensive income (loss)	'	'	43,703	'
Net current period other comprehensive income (loss)	215,422	-72,441	298,408	3,545
Balance at September 30, 2014	173,962	'	173,962	'
Accumulated Translation Adjustment [Member]	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'
Balance at December 31, 2013	'	'	-45,860	'
Other comprehensive income (loss) before reclassifications	'	'	-3,062	'
Amounts reclassified from accumulated other comprehensive income (loss)	'	'	0	'
Net current period other comprehensive income (loss)	'	'	-3,062	'
Balance at September 30, 2014	-48,922	'	-48,922	'
Accumulated Net Unrealized Investment Gain (Loss) [Member]	'	'	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'
Balance at December 31, 2013	'	'	11,907	'
Other comprehensive income (loss) before reclassifications	'	'	995	'
Amounts reclassified from accumulated other comprehensive income (loss)	'	'	-437	'
Net current period other comprehensive income (loss)	'	'	558	'
Balance at September 30, 2014	12,465	'	12,465	'
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 (loss) before reclassifications	'	'	256,772	'
Amounts reclassified from accumulated other comprehensive income (loss)	'	'	44,140	'
Net current period other comprehensive income (loss)	'	'	300,912	'
Balance at September 30, 2014	$210,419	'	$210,419	'

Stockholders_Equity_Narrative_

Stockholders' Equity Narrative (Details) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013
Equity, Class of Treasury Stock [Line Items]	'	'	'
Stock Repurchased During Period, Shares	19,100,000	40,000,000	'
Payments for Repurchase of Common Stock	$1,700,000,000	$3,348,477,000	$182,259,000
Stock Repurchase Program, Authorized Amount	$5,000,000,000	$5,000,000,000	'
2014 Stock Repurchase Program [Member]	'	'	'
Equity, Class of Treasury Stock [Line Items]	'	'	'
Stock Repurchased During Period, Shares	'	0	'

StockBased_Compensation_Summar

Stock-Based Compensation Summary of Stock-Based Compensation (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'	'	'
Stock-based compensation expense included in total costs and expenses	$99,336	$62,573	$264,694	$180,293
Income tax effect	-18,075	-15,997	-48,098	-47,958
Stock-based compensation expense, net of tax	81,261	46,576	216,596	132,335
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	2,726	1,823	7,933	6,296
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	40,312	27,740	111,295	79,261
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	$56,298	$33,010	$145,466	$94,736

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		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Debt Instrument [Line Items]	'	'	'	'
Net income attributable to Gilead	$2,731,274	$788,606	$8,614,277	$2,283,397
Shares used in per share calculation - basic	1,513,899	1,532,105	1,527,633	1,526,847
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	31,727	38,575	33,769	39,085
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants	63,726	63,010	68,108	60,425
Shares used in per share calculation - diluted	1,636,530	1,691,898	1,662,281	1,689,647
Convertible Senior Notes Due May 2013 [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	0	0	0	5,268
Convertible Senior Notes Due May 2014 [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	0	24,335	3,138	27,435
Convertible Senior Notes Due May 2016 [Member]	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities	27,178	33,873	29,633	30,587

Net_Income_Per_Share_Attributa3

Net Income Per Share Attributable to Gilead Common Stockholders (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Debt Instrument, Redemption [Line Items]	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1.1	0.1	1	0.9
Convertible Senior Notes Due In May 2013 [Member]	'	'	'	'
Debt Instrument, Redemption [Line Items]	'	'	'	'
Debt Instrument, Convertible, Conversion Price	19.05	'	19.05	'
Class of Warrant or Right, Exercise Price of Warrants or Rights	26.95	'	26.95	'
Convertible Senior Notes Due In May 2014 [Member]	'	'	'	'
Debt Instrument, Redemption [Line Items]	'	'	'	'
Debt Instrument, Convertible, Conversion Price	22.54	'	22.54	'
Class of Warrant or Right, Exercise Price of Warrants or Rights	28.38	'	28.38	'
Convertible Senior Notes Due In May 2016 [Member]	'	'	'	'
Debt Instrument, Redemption [Line Items]	'	'	'	'
Debt Instrument, Convertible, Conversion Price	22.71	'	22.71	'
Class of Warrant or Right, Exercise Price of Warrants or Rights	30.05	'	30.05	'

Segment_Information_Segment_re

Segment Information Segment reporting information, revenue for reportable segment (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	$5,968,208	$2,709,652	$17,252,119	$7,760,505
Antiviral Products [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	5,544,513	2,326,727	16,065,154	6,701,344
Sovaldi [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	2,796,093	0	8,550,768	0
Atripla [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	894,787	899,669	2,545,089	2,714,850
Truvada [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	875,454	813,652	2,441,764	2,321,673
Complera Eviplera [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	330,263	210,736	880,460	547,608
Stribild [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	328,035	143,953	812,826	335,495
Viread [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	275,637	231,555	746,996	692,075
Harvoni [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	19,966	0	20,405	0
Other antiviral products [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	24,278	27,162	66,846	89,643
Letairis [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	146,415	135,072	414,016	381,436
Ranexa [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	132,510	115,815	366,084	318,698
Ambisome [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	98,108	97,812	284,995	258,224
Zydelig [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	5,862	0	5,862	0
Other Products [Member]	'	'	'	'
Revenue from External Customer [Line Items]	'	'	'	'
Product sales	$40,800	$34,226	$116,008	$100,803

Segment_Information_Schedule_o

Segment Information Schedule of revenue by major customers (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
AmerisourceBergen Corp. [Member]	'	'	'	'
Revenue, Major Customer [Line Items]	'	'	'	'
Percentage of Revenues	23.00%	15.00%	25.00%	13.00%
McKesson Corp. [Member]	'	'	'	'
Revenue, Major Customer [Line Items]	'	'	'	'
Percentage of Revenues	24.00%	16.00%	24.00%	16.00%
Cardinal Health, Inc. [Member]	'	'	'	'
Revenue, Major Customer [Line Items]	'	'	'	'
Percentage of Revenues	15.00%	16.00%	13.00%	18.00%

Income_Taxes_Narrative_Details

Income Taxes (Narrative) (Details) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2014
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]	'	'
Effective Income Tax Rate, Continuing Operations	19.20%	19.10%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	'	35.00%
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	$12	$12