Gilead Sciences (GILD) 10-Q 6 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 29, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	Gilead Sciences Inc
Entity Central Index Key	882,095
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Amendment Flag	false
Entity Common Stock, Shares Outstanding		1,331,821,506

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 6,315	$ 12,851
Short-term marketable securities	2,004	1,756
Accounts receivable, net of allowances of $1,277 at March 31, 2016 and $1,032 at December 31, 2015	6,163	5,854
Inventories	1,880	1,955
Deferred tax assets	830	828
Prepaid and other current assets	2,075	1,518
Total current assets	19,267	24,762
Property, plant and equipment, net	2,431	2,276
Long-term portion of prepaid royalties	383	400
Long-term deferred tax assets	292	324
Long-term marketable securities	13,003	11,601
Intangible assets, net	9,923	10,247
Goodwill	1,172	1,172
Other long-term assets	1,294	934
Total assets	47,765	51,716
Current liabilities:
Accounts payable	945	1,178
Accrued government and other rebates	4,766	4,118
Other accrued liabilities	2,925	3,172
Deferred revenues	529	440
Current portion of long-term debt and other obligations, net	1,745	982
Total current liabilities	10,910	9,890
Long-term debt, net	21,077	21,073	[1]
Long-term income taxes payable	1,385	1,243
Other long-term obligations	$ 374	$ 395
Commitments and contingencies (Note 9)
Equity component of currently redeemable convertible notes	$ 0	$ 2
Stockholders’ equity:
Preferred stock, par value $0.001 per share; 5 shares authorized; none outstanding	0	0
Common stock, par value $0.001 per share; shares authorized of 5,600 at March 31, 2016 and December 31, 2015; shares issued and outstanding of 1,348 at March 31, 2016 and 1,422 at December 31, 2015	1	1
Additional paid-in capital	516	444
Accumulated other comprehensive income (loss)	(164)	88
Retained earnings	13,045	18,001
Total Gilead stockholders’ equity	13,398	18,534
Noncontrolling interest	621	579
Total stockholders’ equity	14,019	19,113
Total liabilities and stockholders’ equity	$ 47,765	$ 51,716
[1]	In connection with our adoption of the ASU relating to the presentation of debt issuance costs during the first quarter of 2016, debt balances at December 31, 2015 have been retrospectively adjusted by $123 million to include unamortized debt issuance costs. Prior to our adoption of the ASU, these unamortized debt issuance costs were included in prepaid and other current assets and other long-term assets in our Condensed Consolidated Balance Sheets.

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (unaudited) Parenthetical - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Allowance for accounts receivable and chargebacks	$ 1,277	$ 1,032
Preferred Stock, Par Value (usd per share)	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Shares Outstanding	0	0
Common Stock, Par Value (usd per share)	$ 0.001	$ 0.001
Common Stock, Shares Authorized	5,600,000,000	5,600,000,000
Common Stock, Shares Issued	1,348,000,000	1,422,000,000
Common Stock, Shares Outstanding	1,348,000,000	1,422,000,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues:
Product sales	$ 7,681	$ 7,405
Royalty, contract and other revenues	113	189
Total revenues	7,794	7,594
Cost of goods sold
Cost of goods sold	1,193	882
Research and development expenses	1,265	696
Selling, general and administrative expenses	685	645
Total costs and expenses	3,143	2,223
Income from operations	4,651	5,371
Interest expense	(230)	(153)
Other income (expense), net	81	21
Income before provision for income taxes	4,502	5,239
Provision for income taxes	935	907
Net income	3,567	4,332
Net income (loss) attributable to noncontrolling interest	1	(1)
Net income attributable to Gilead	$ 3,566	$ 4,333
Net income per share attributable to Gilead common stockholders - basic (in dollars per share)	$ 2.58	$ 2.91
Shares used in per share calculation - basic (in shares)	1,383	1,488
Net income per share attributable to Gilead common stockholders - diluted (in dollars per share)	$ 2.53	$ 2.76
Shares used in per share calculation - diluted (in shares)	1,412	1,569
Cash dividends declared per share	$ 0.43	$ 0

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 3,567	$ 4,332
Other comprehensive income (loss):
Net foreign currency translation gain (loss), net of tax	2	(10)
Available-for-sale securities:
Net unrealized gain (loss), net of tax impact of $30 and $3	(24)	6
Net change	(24)	6
Cash flow hedges:
Net unrealized gain (loss), net of tax impact of $(10) and $6	(150)	383
Reclassifications to net income, net of tax impact of $(6) and $(4)	(80)	(141)
Net change	(230)	242
Other comprehensive income (loss)	(252)	238
Comprehensive income	3,315	4,570
Comprehensive income (loss) attributable to noncontrolling interest	1	(1)
Comprehensive income attributable to Gilead	$ 3,314	$ 4,571

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income Parenthetical - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Available-for-sale securities:
Net Unrealized Gains, Tax Impact	$ 30	$ 3
Cash flow hedges:
Net Unrealized Losses, Tax Impact	(10)	6
Reclassification Adjustments, Tax Impact	$ (6)	$ (4)

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities
Net income	$ 3,567	$ 4,332
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	42	37
Amortization expense	241	232
Stock-based compensation expense	88	92
Excess tax benefits from stock-based compensation	(89)	(186)
Tax benefits from exercise and vesting of stock-based awards	87	186
Deferred income taxes	15	(121)
In-process research and development impairment	114	0
Other	(19)	(3)
Changes in operating assets and liabilities:
Accounts receivable, net	(191)	(348)
Inventories	(14)	(370)
Prepaid expenses and other assets	(126)	52
Accounts payable	(239)	58
Income taxes payable	205	149
Accrued liabilities	195	1,530
Deferred revenues	37	61
Net cash provided by operating activities	3,913	5,701
Investing Activities:
Purchases of marketable securities	(4,977)	(2,462)
Proceeds from sales of marketable securities	2,959	249
Proceeds from maturities of marketable securities	443	38
Other investments	(357)	0
Capital expenditures	(177)	(124)
Net cash used in investing activities	(2,109)	(2,299)
Financing Activities:
Proceeds from convertible note hedges	95	154
Repayments of debt and other obligations	(126)	(199)
Proceeds from issuances of common stock	92	118
Repurchases of common stock	(8,000)	(3,001)
Payments of dividends	(587)	0
Excess tax benefits from stock-based compensation	89	186
Contributions from noncontrolling interest	41	20
Net cash used in financing activities	(8,396)	(2,722)
Effect of exchange rate changes on cash and cash equivalents	56	(72)
Net change in cash and cash equivalents	(6,536)	608
Cash and cash equivalents at beginning of period	12,851	10,027
Cash and cash equivalents at end of period	$ 6,315	$ 10,635

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	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 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 certain variable interest entities for which we are the primary beneficiary. All intercompany transactions have been eliminated. For consolidated entities where we own or are exposed to less than 100% of the economics, we record Net income (loss) attributable to noncontrolling interest in our Condensed Consolidated Statements of Income equal to the percentage of the economic or ownership interest retained in such entities by the respective noncontrolling parties. We assess whether we are the primary beneficiary of a variable interest entity (VIE) at the inception of the arrangement and at each reporting date. This assessment is based on our power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and our obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. As of March 31, 2016 , the only material VIE was our joint venture with Bristol-Myers Squibb Company (BMS) which is described in Note 7 , Collaborative Arrangements. 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, 2015 , 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, we evaluate our significant accounting policies and 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. Estimates are assessed each period and updated to reflect current information. Actual results may differ significantly from these estimates. Concentrations of Risk We are subject to credit risk from our portfolio of cash, 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. 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. As of March 31, 2016, approximately 15% of our cash, cash equivalents and marketable securities were held at one financial institution. We mitigate risk by depositing funds with reputable institutions and by monitoring their risk profiles. To date, losses with respect to our concentrations of risk related to our cash, cash equivalents and marketable securities have been immaterial. 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, Europe and Japan. As of March 31, 2016 , our accounts receivable in Southern Europe, specifically Greece, Italy, Portugal and Spain, totaled approximately $819 million , of which $237 million were greater than 120 days past due, including $32 million greater than 365 days past due. To date, we have not experienced significant losses with respect to the collection of our accounts receivable. We believe that our allowance for doubtful accounts was adequate at March 31, 2016 . Recent Accounting Pronouncements In April 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update No. 2015-03 (ASU 2015-03) "Simplifying the Presentation of Debt Issuance Costs." ASU 2015-03 requires the presentation of debt issuance costs as a direct deduction from the carrying amount of a recognized debt liability on the balance sheet. We adopted this ASU with retrospective application in the first quarter of 2016. The adoption of this standard did not have a material impact on our Condensed Consolidated Financial Statements. See Note 8 , Debt and Credit Facility for further information. In May 2014, the FASB issued Accounting Standard Update No. 2014-09 (ASU 2014-09) "Revenue 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. The standard will become effective for us beginning in the first quarter of 2018. Early adoption is permitted in 2017. Entities have the option of using either a full retrospective or a modified retrospective approach to adopt this new guidance. In March and April 2016, the FASB issued ASU 2016-08 "Revenue From Contracts With Customers: Principal vs. Agent Considerations" and ASU 2016-10 “Revenue From Contracts with Customers: Identifying Performance Obligations and Licensing” to provide supplemental adoption guidance and clarification to ASU 2014-09. We are evaluating the impact of the adoption of these standards on our Condensed Consolidated Financial Statements. In November 2015, the FASB issued Accounting Standard Update No. 2015-17 (ASU 2015-17) "Balance Sheet Classification of Deferred Taxes." ASU 2015-17 requires that deferred tax liabilities and assets be classified as noncurrent on the balance sheet. Previous guidance required deferred tax liabilities and assets to be separated into current and noncurrent amounts on the balance sheet. The guidance will become effective for us beginning in the first quarter of 2017 and may be applied either prospectively or retrospectively. Early adoption is permitted. At the time of adoption, we will reclassify current deferred tax amounts on our Consolidated Balance Sheets as noncurrent. We are evaluating the impact of the method of adoption of this standard on our Condensed Consolidated Financial Statements . In January 2016, the FASB issued Accounting Standard Update No. 2016-01(ASU 2016-01) "Recognition and Measurement of Financial Assets and Financial Liabilities." ASU 2016-01 changes accounting for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. In addition, it clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. The guidance will become effective for us beginning in the first quarter of 2018. Early adoption is permitted. We are evaluating the impact of the adoption of this standard on our Condensed Consolidated Financial Statements . In February 2016, the FASB issued Accounting Standard Update No. 2016-02 (ASU 2016-02) "Leases." ASU 2016-02 amends a number of aspects of lease accounting, including requiring lessees to recognize almost all leases with a term greater than one year as a right-of-use asset and corresponding liability, measured at the present value of the lease payments. The guidance will become effective for us beginning in the first quarter of 2019 and is required to be adopted using a modified retrospective approach. Early adoption is permitted. We are evaluating the impact of the adoption of this standard on our Condensed Consolidated Financial Statements . In March 2016, the FASB issued Accounting Standard Update No. 2016-09 (ASU 2016-09) "Improvements to Employee Share-Based Payment Accounting." ASU 2016-09 simplifies several aspects of employee share-based payment accounting, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. This guidance will become effective for us beginning in the first quarter of 2017. Early adoption is permitted. We are evaluating the impact of the adoption of this standard on our Condensed Consolidated Financial Statements .

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2016
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Fair Value Measurements	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 primarily of cash and cash equivalents, marketable securities, accounts receivable, foreign currency exchange contracts, equity securities, accounts payable and short-term and long-term debt. Cash and cash equivalents, marketable securities, foreign currency exchange contracts and equity securities are reported at their respective fair values in our Condensed Consolidated Balance Sheets. Short-term and long-term debt are reported at their amortized cost in our Condensed Consolidated Balance Sheets. The remaining financial instruments are reported in our Condensed Consolidated Balance Sheets at amounts that approximate current fair values. There were no transfers between Level 1, Level 2 and Level 3 in the periods presented. The following table summarizes the types of assets and liabilities measured at fair value on a recurring basis, by level, within the fair value hierarchy (in millions): March 31, 2016 December 31, 2015 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Money market funds $ 2,128 $ — $ — $ 2,128 $ 10,161 $ — $ — $ 10,161 Corporate debt securities — 7,284 — 7,284 — 5,773 — 5,773 U.S. treasury securities 3,987 — — 3,987 4,389 — — 4,389 Residential mortgage and asset-backed securities — 2,233 — 2,233 — 1,695 — 1,695 U.S. government agencies securities — 775 — 775 — 707 — 707 Certificates of deposit — 364 — 364 — 448 — 448 Non-U.S. government securities — 378 — 378 — 313 — 313 Municipal debt securities — 34 — 34 — 34 — 34 Equity securities 280 — — 280 — — — — Convertible note hedges (1) — 792 — 792 — — — — Foreign currency derivative contracts — 74 — 74 — 210 — 210 Deferred compensation plan 74 — — 74 66 — — 66 $ 6,469 $ 11,934 $ — $ 18,403 $ 14,616 $ 9,180 $ — $ 23,796 Liabilities: Conversion spread of convertible senior notes (1) $ — $ 792 $ — $ 792 $ — $ — $ — $ — Contingent consideration — — 33 33 — — 59 59 Deferred compensation plan 74 — — 74 66 — — 66 Foreign currency derivative contracts — 140 — 140 — 41 — 41 $ 74 $ 932 $ 33 $ 1,039 $ 66 $ 41 $ 59 $ 166 _________________________________________ (1) See Note 4, Derivative Financial Instruments for further information. Level 2 Inputs We estimate the fair values of Level 2 instruments 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 within an 18 months 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. The total estimated fair values of our convertible senior notes and senior unsecured notes, determined using Level 2 inputs based on their quoted market values, were approximately $24.7 billion at March 31, 2016 and $23.7 billion at December 31, 2015 , and the carrying values were $22.0 billion at March 31, 2016 and $22.1 billion at December 31, 2015 . Level 3 Inputs As of March 31, 2016 and December 31, 2015 , the only assets or liabilities that were measured using Level 3 inputs were our contingent consideration liabilities, which were immaterial as of March 31, 2016 and December 31, 2015 . 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.

Available-for-Sale Securities

Available-for-Sale Securities	3 Months Ended
	Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Available-for-Sale Securities	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 our available-for-sale securities (in millions): March 31, 2016 December 31, 2015 Amortized Gross Gross Estimated Amortized Gross Gross Estimated Money market funds $ 2,128 $ — $ — $ 2,128 $ 10,161 $ — $ — $ 10,161 Corporate debt securities 7,261 28 (5 ) 7,284 5,795 1 (23 ) 5,773 U.S. treasury securities 3,980 8 (1 ) 3,987 4,407 — (18 ) 4,389 Residential mortgage and asset-backed securities 2,229 5 (1 ) 2,233 1,701 — (6 ) 1,695 U.S. government agencies securities 774 1 — 775 709 — (2 ) 707 Certificates of deposit 364 — — 364 448 — — 448 Non-U.S. government securities 378 — — 378 315 — (2 ) 313 Municipal debt securities 34 — — 34 34 — — 34 Equity securities 357 — (77 ) 280 — — — — Total $ 17,505 $ 42 $ (84 ) $ 17,463 $ 23,570 $ 1 $ (51 ) $ 23,520 The following table summarizes the classification of the available-for-sale securities in our Condensed Consolidated Balance Sheets (in millions): March 31, 2016 December 31, 2015 Cash and cash equivalents $ 2,176 $ 10,163 Short-term marketable securities 2,004 1,756 Long-term marketable securities 13,003 11,601 Other long-term assets 280 — Total $ 17,463 $ 23,520 Cash and cash equivalents in the table above exclude cash of $4.1 billion as of March 31, 2016 and $2.7 billion as of December 31, 2015 . The following table summarizes our portfolio of available-for-sale debt securities by contractual maturity (in millions): March 31, 2016 Amortized Cost Fair Value Less than one year $ 4,180 $ 4,180 Greater than one year but less than five years 12,750 12,785 Greater than five years but less than ten years 185 185 Greater than ten years 33 33 Total $ 17,148 $ 17,183 The following table summarizes our available-for-sale securities that were in a continuous unrealized loss position, but were not deemed to be other-than-temporarily impaired (in millions): Less Than 12 Months 12 Months or Greater Total Gross Estimated Gross Estimated Gross Estimated March 31, 2016 Corporate debt securities $ (5 ) $ 1,834 $ — $ 50 $ (5 ) $ 1,884 U.S. treasury securities (1 ) 1,075 — — (1 ) 1,075 Residential mortgage and asset-backed securities (1 ) 667 — 24 (1 ) 691 U.S. government agencies securities — 116 — — — 116 Non-U.S. government securities — 221 — — — 221 Equity securities (77 ) 280 — — (77 ) 280 Total $ (84 ) $ 4,193 $ — $ 74 $ (84 ) $ 4,267 December 31, 2015 Corporate debt securities $ (23 ) $ 4,891 $ — $ 43 $ (23 ) $ 4,934 U.S. treasury securities (18 ) 4,342 — — (18 ) 4,342 Residential mortgage and asset-backed securities (6 ) 1,626 — 20 (6 ) 1,646 U.S. government agencies securities (2 ) 707 — — (2 ) 707 Non-U.S. government securities (2 ) 313 — — (2 ) 313 Municipal debt securities — 21 — — — 21 Total $ (51 ) $ 11,900 $ — $ 63 $ (51 ) $ 11,963 We held a total of 1,073 positions as of March 31, 2016 and 2,742 positions as of December 31, 2015 related to our debt securities that were in an unrealized loss position. Based on our review of our available-for-sale securities, we believe we had no other-than-temporary impairments on these securities as of March 31, 2016 and December 31, 2015 , because we do not intend to sell these securities nor do we believe that we will be required to sell these securities before the recovery of their amortized cost basis. Gross realized gains and gross realized losses were immaterial for the three months ended March 31, 2016 and 2015 .

Derivative Financial Instrument

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	DERIVATIVE FINANCIAL INSTRUMENTS Foreign Currency Exposure Our operations in foreign countries expose 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 are the Euro and Yen. 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 entities 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 in 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 regression analysis which calculates the change in cash flow as a result of the hedge instrument. On a quarterly 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) (AOCI) 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 AOCI at March 31, 2016 are expected to be reclassified to product sales within 12 months. The cash flow effects of our derivative contracts for the three months ended March 31, 2016 and 2015 are included within Net cash provided by operating activities in our Condensed Consolidated Statements of Cash Flows. We had notional amounts on foreign currency exchange contracts outstanding of $9.9 billion at March 31, 2016 and $9.1 billion at December 31, 2015 . 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 classification and fair values of derivative instruments in our Condensed Consolidated Balance Sheets (in millions): March 31, 2016 Asset Derivatives Liability Derivatives Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Other current assets $ 71 Other accrued liabilities $ (121 ) Foreign currency exchange contracts Other long-term assets 2 Other long-term obligations (18 ) Total derivatives designated as hedges 73 (139 ) Derivatives not designated as hedges: Foreign currency exchange contracts Other current assets 1 Other accrued liabilities (1 ) Total derivatives not designated as hedges 1 (1 ) Total derivatives $ 74 $ (140 ) December 31, 2015 Asset Derivatives Liability Derivatives Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Other current assets $ 200 Other accrued liabilities $ (32 ) Foreign currency exchange contracts Other long-term assets 9 Other long-term obligations (8 ) Total derivatives designated as hedges 209 (40 ) Derivatives not designated as hedges: Foreign currency exchange contracts Other current assets 1 Other accrued liabilities (1 ) Total derivatives not designated as hedges 1 (1 ) Total derivatives $ 210 $ (41 ) The following table summarizes the effect of our foreign currency exchange contracts in our Condensed Consolidated Financial Statements (in millions): Three Months Ended March 31, 2016 2015 Derivatives designated as hedges: Gains (losses) recognized in AOCI (effective portion) $ (160 ) $ 389 Gains reclassified from AOCI into product sales (effective portion) $ 86 $ 145 Gains recognized in Other income (expense), net (ineffective portion and amounts excluded from effectiveness testing) $ 14 $ 1 Derivatives not designated as hedges: Gains (losses) recognized in Other income (expense), net $ (151 ) $ 108 From time to time, we may discontinue cash flow hedges and as a result, record related amounts in Other income (expense), net in our Condensed Consolidated Statements of Income. There were no material amounts recorded in Other income (expense), net for the three months ended March 31, 2016 and 2015 as a result of the discontinuance of cash flow hedges. As of March 31, 2016 and December 31, 2015 , 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 in our Condensed Consolidated Balance Sheets (in millions): 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 in the Condensed Consolidated Balance Sheet Derivative Financial Instruments Cash Collateral Received/Pledged Net Amount (Legal Offset) As of March 31, 2016 Derivative assets $ 74 $ — $ 74 $ (66 ) $ — $ 8 Derivative liabilities (140 ) — (140 ) 66 — (74 ) As of December 31, 2015 Derivative assets $ 210 $ — $ 210 $ (38 ) $ — $ 172 Derivative liabilities (41 ) — (41 ) 38 — (3 ) May 2016 Convertible Senior Notes and Convertible Note Hedges In March 2016, we exercised our option to elect cash for the settlement of the conversion value in excess of the principal amount (the conversion spread) of our remaining convertible senior notes due in May 2016 (the May 2016 Notes) and for the related convertible note hedges. Until our cash settlement election, the conversion spread of the May 2016 Notes and the convertible note hedges met the applicable criteria for equity classification and were therefore recorded in stockholders’ equity in our Condensed Consolidated Balance Sheets. Upon our cash settlement election, we reclassified $733 million of the fair value of the conversion spread from stockholders’ equity to Current portion of long-term debt and other obligations, net , and reclassified $733 million of the fair value of the convertible note hedges from Stockholders’ equity to Prepaid and other current assets in our Condensed Consolidated Balance Sheets. At March 31, 2016, we revalued both the conversion spread and the convertible note hedges at $792 million , respectively, and recorded a loss of $59 million on the conversion spread and a gain of $59 million on the convertible note hedges in our Condensed Consolidated Statements of Income. Both the conversion spread and the convertible note hedges associated with our May 2016 Notes will be settled during the second quarter of 2016 when the May 2016 Notes are due.

Other Financial Information

Other Financial Information	3 Months Ended
	Mar. 31, 2016
Other Financial Information [Abstract]
Other Financial Information	OTHER FINANCIAL INFORMATION Inventories Inventories are summarized as follows (in millions): March 31, 2016 December 31, 2015 Raw materials $ 1,239 $ 1,332 Work in process 761 542 Finished goods 731 852 Total $ 2,731 $ 2,726 Reported as: Inventories $ 1,880 $ 1,955 Other long-term assets 851 771 Total $ 2,731 $ 2,726 Amounts reported as Other long-term assets primarily consisted of raw materials as of March 31, 2016 and December 31, 2015 . The joint ventures formed by Gilead Sciences, LLC and BMS, 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 $1.3 billion as of March 31, 2016 and December 31, 2015 . See Note 7, Collaborative Arrangements for further information. Prepaid and other current assets The components of Prepaid and other current assets are summarized as follows (in millions): March 31, 2016 December 31, 2015 Convertible note hedges $ 792 $ — Prepaid taxes 705 773 Other prepaid expenses 319 240 Other current assets 259 505 Total prepaid and other current assets $ 2,075 $ 1,518 Other accrued liabilities The components of Other accrued liabilities are summarized as follows (in millions): March 31, 2016 December 31, 2015 Accrued royalties $ 190 $ 237 Branded Prescription Drug fee 513 649 Compensation and employee benefits 235 380 Income taxes payable 51 65 Other accrued expenses 1,936 1,841 Total other accrued liabilities $ 2,925 $ 3,172

Intangible Assets

Intangible Assets	3 Months Ended
	Mar. 31, 2016
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	INTANGIBLE ASSETS The following table summarizes the carrying amounts of our Intangible assets, net (in millions): March 31, 2016 December 31, 2015 Finite-lived intangible assets $ 9,605 $ 9,815 Indefinite-lived intangible assets 318 432 Total intangible assets $ 9,923 $ 10,247 Finite-Lived Intangible Assets The following table summarizes our finite-lived intangible assets (in millions): March 31, 2016 December 31, 2015 Gross Carrying Amount Accumulated Amortization Gross Carrying Amount Accumulated Amortization Intangible asset - sofosbuvir $ 10,720 $ 1,631 $ 10,720 $ 1,456 Intangible asset - Ranexa 688 388 688 363 Other 455 239 455 229 Total $ 11,863 $ 2,258 $ 11,863 $ 2,048 Amortization expense related to finite-lived intangible assets included primarily in Cost of goods sold in our Condensed Consolidated Statements of Income totaled $210 million and $206 million for the three months ended March 31, 2016 and 2015, respectively. As of March 31, 2016 , the estimated future amortization expense associated with our finite-lived intangible assets for the remaining nine months of 2016 and each of the five succeeding fiscal years is expected as follows (in millions): Fiscal Year Amount 2016 (remaining nine months) $ 629 2017 844 2018 849 2019 741 2020 713 2021 and thereafter 5,829 Total $ 9,605 Indefinite-Lived Intangible Assets The following table summarizes our indefinite-lived intangible assets (in-process research and development) (in millions): March 31, 2016 December 31, 2015 Indefinite-lived intangible asset - momelotinib $ 201 $ 315 Indefinite-lived intangible assets - Other 117 117 Total $ 318 $ 432 In the first quarter of 2016, the estimated fair value of the intangible asset related to momelotinib declined to $201 million due to changes in the clinical development plans and as a result, we recorded an impairment charge of $114 million within Research and development expenses in our Condensed Consolidated Statements of Income.

Collaborative Arrangements

Collaborative Arrangements	3 Months Ended
	Mar. 31, 2016
Collaborative Arrangements [Abstract]
Collaborative Arrangements	COLLABORATIVE ARRANGEMENTS We enter into collaborative arrangements with third parties for the development and commercialization of certain products. Both parties are active participants in the operating activities of the collaboration and exposed to significant risks and rewards depending on the commercial success of the activities. Selected information related to our collaborative arrangements follows. 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 a 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 are jointly managed, the parties no longer coordinate detailing and promotional activities in the United States, and the parties reduced their joint promotional efforts since we launched Complera in August 2011 and Stribild in August 2012. The parties continue to collaborate on activities such as manufacturing, regulatory, compliance and pharmacovigilance. The daily operations of the joint venture are governed by four primary joint committees formed by both BMS and Gilead. We are responsible for accounting, financial reporting, tax reporting, manufacturing and product distribution for the joint venture. Both parties provide their respective bulk active pharmaceutical ingredients to the joint venture at their approximate market values. The agreement will continue until terminated by the mutual agreement of the parties. In addition, either party may terminate the other party’s participation in the collaboration within 30 days after the launch of at least one generic version of such other party’s single agent products (or the double agent products). The terminating party then has the right to continue to sell Atripla and become the continuing party, but will be obligated to pay the terminated party certain royalties for a three-year period following the effective date of the termination. As of March 31, 2016 and December 31, 2015 , 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 were primarily included in Inventories in our Condensed Consolidated Balance Sheets. Selected financial information for the joint venture was as follows (in millions): March 31, 2016 December 31, 2015 Total assets $ 2,441 $ 2,464 Cash and cash equivalents 132 166 Accounts receivable, net 251 269 Inventories 2,056 2,027 Total liabilities 929 1,055 Accounts payable 544 606 Other accrued liabilities 385 449 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 UC, our wholly-owned subsidiary, 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 are jointly managed, the parties no longer coordinate detailing and promotional activities in the European Territory. We are responsible for accounting, financial reporting and tax reporting for the collaboration. As of March 31, 2016 and December 31, 2015 , efavirenz purchased from BMS at BMS’s estimated net selling price of efavirenz in the European Territory is included in Inventories in our Condensed Consolidated Balance Sheets. The parties also formed a limited liability company to hold the marketing authorization for Atripla in European Territory. 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, since 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. Galapagos NV We entered into a license and collaboration agreement with Galapagos NV (Galapagos), a clinical-stage biotechnology company based in Belgium, for the development and commercialization of filgotinib, a JAK1-selective inhibitor being evaluated in phase II trials for inflammatory disease indications. Upon closing of the license and collaboration agreement in January 2016, we made an upfront license fee payment of $300 million and a $425 million equity investment in Galapagos by subscribing for new shares at a price of €58 per share, including issuance premium. As a result, Gilead received 6.8 million new shares of Galapagos, representing 14.75% of their outstanding share capital. The license fee payment of $300 million and the issuance premium on the equity investment of $68 million were recorded as Research and development expenses in our Condensed Consolidated Statements of Income. The equity investment, net of issuance premium, of $357 million was recorded as an available-for-sale security in Other long-term assets in our Condensed Consolidated Balance Sheets. Galapagos is eligible to receive development and regulatory milestone-based payments of up to $755 million , sales-based milestone payments of up to $600 million , plus tiered royalties on global sales starting at 20%, with the exception of certain co-promotion territories where profits would be shared equally. Under the terms of the agreement, we have an exclusive, worldwide, royalty-bearing, sublicensable license for filgotinib and products containing filgotinib. Gilead is primarily responsible for development and seeking regulatory approval related to filgotinib. Gilead is responsible for 80% and Galapagos is responsible for 20% of the development costs incurred. Gilead is responsible for the manufacturing and commercialization activities. Galapagos has the option to co-promote filgotinib in certain territories, in which case, we and Galapagos will share profits equally.

Debt and Credit Facility

Debt and Credit Facility	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Debt and Credit Facility	DEBT AND CREDIT FACILITY Financing Arrangements The following table summarizes the carrying amount of our borrowings under various financing arrangements (in millions): Type of Borrowing Issue Date Due Date Interest Rate March 31, 2016 December 31, 2015 (1) Convertible Senior July 2010 May 2016 1.625% $ 254 $ 283 Senior Unsecured December 2011 December 2016 3.05% 699 699 Senior Unsecured September 2015 September 2018 1.85% 997 997 Senior Unsecured March 2014 April 2019 2.05% 498 498 Senior Unsecured November 2014 February 2020 2.35% 498 497 Senior Unsecured September 2015 September 2020 2.55% 1,990 1,989 Senior Unsecured March 2011 April 2021 4.50% 993 992 Senior Unsecured December 2011 December 2021 4.40% 1,244 1,244 Senior Unsecured September 2015 September 2022 3.25% 995 995 Senior Unsecured March 2014 April 2024 3.70% 1,740 1,740 Senior Unsecured November 2014 February 2025 3.50% 1,742 1,742 Senior Unsecured September 2015 March 2026 3.65% 2,724 2,724 Senior Unsecured September 2015 September 2035 4.60% 988 988 Senior Unsecured December 2011 December 2041 5.65% 995 995 Senior Unsecured March 2014 April 2044 4.80% 1,732 1,732 Senior Unsecured November 2014 February 2045 4.50% 1,728 1,728 Senior Unsecured September 2015 March 2046 4.75% 2,213 2,212 Total debt, net 22,030 22,055 Less current portion 953 982 Total long-term debt, net $ 21,077 $ 21,073 _____________________________ (1) In connection with our adoption of the ASU relating to the presentation of debt issuance costs during the first quarter of 2016, debt balances at December 31, 2015 have been retrospectively adjusted by $123 million to include unamortized debt issuance costs. Prior to our adoption of the ASU, these unamortized debt issuance costs were included in prepaid and other current assets and other long-term assets in our Condensed Consolidated Balance Sheets. Convertible Senior Notes During the three months ended March 31, 2016 , a portion of our May 2016 Notes were converted and we repaid $31 million of principal balance related to these notes. We also paid $95 million in cash related to the conversion option value in excess of the principal amount (the conversion spread), and received $95 million in cash from the convertible note hedges related to the May 2016 Notes. The initial conversion rate for the May 2016 Notes was 44.0428 shares per $1,000 principal amount (which represented an initial conversion price of approximately $22.71 per share). The conversion rate for the May 2016 Notes is adjusted in connection with our quarterly cash dividend. As of March 31, 2016 , the conversion rate was 44.7828 (which represented a conversion price of approximately $22.33 per share). In March 2016, we exercised our option to elect cash settlement for both the conversion spread of the remaining May 2016 Notes and our convertible note hedges associated with the May 2016 Notes. See Note 4, Derivative Financial Instruments for further information. As of March 31, 2016 , there were 9 million shares of our common stock underlying our warrants associated with our May 2016 Notes (the 2016 Warrants). The 2016 Warrants expire in 2016 and have a strike price of $28.33 per share. Under the terms of the original agreements, the 2016 Warrants had a strike price of $30.05 per share and are due to expire during the 40 trading-day period commencing August 1, 2016. The strike price of the 2016 Warrants is adjusted in connection with our quarterly cash dividend. Credit Facility As of March 31, 2016 , there were no amounts outstanding under the revolving credit facility credit agreement. We are required to comply with certain covenants under the credit agreement and note indentures governing our senior notes. As of March 31, 2016 , we were not in violation of any covenants.

Commitment and Contingencies

Commitment and Contingencies	3 Months Ended
	Mar. 31, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	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 have received a number of contractual and intellectual property claims regarding sofosbuvir. While we have carefully considered these claims both prior to and following the acquisition and believe they are without merit, we cannot predict the ultimate outcome of such claims or range of loss. We own patents and patent applications that claim sofosbuvir (Sovaldi) as a chemical entity and its metabolites and the fixed-dose combination of ledipasvir and sofosbuvir (Harvoni). Third parties may have, or may obtain rights to, patents that allegedly could be used to prevent or attempt to prevent us from commercializing Sovaldi or Harvoni. For example, we are aware of patents and patent applications owned by other parties that have been or may in the future be alleged by such parties to cover the use of Sovaldi and Harvoni. We cannot predict the ultimate outcome of intellectual property claims related to Sovaldi or Harvoni. We have spent, and will continue to spend, significant resources defending against these claims. If third parties successfully obtain valid and enforceable patents, and successfully prove infringement of those patents by Sovaldi and/or Harvoni, we could be prevented from selling these products 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. 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 (the ’572 patent) and Idenix ’ s pending U.S. Patent Application No. 12/131,868. An interference is a proceeding before the USPTO designed to determine who was the first to invent the subject matter claimed by both parties. In January 2014, the USPTO Patent Trial and Appeal Board (PTAB) determined that Pharmasset and not Idenix was the first to invent the compounds in dispute and accordingly we prevailed in the First Idenix Interference. Idenix has appealed the PTAB’s decisions to the U.S. District Court for the District of Delaware. 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 Idenix’s U.S. Patent No. 7,608,600 (the ’600 patent). The ’600 patent is related to the Idenix patent application at issue in the First Idenix Interference and includes claims directed to methods of treating HCV with nucleoside compounds. The purpose of the Second Idenix Interference was to determine who was first to invent the claimed methods of treating HCV with compounds similar to those which were involved in the First Idenix Interference. In March 2015, the PTAB determined that Pharmasset and not Idenix was the first to invent the claimed methods of treating HCV. Idenix appealed this decision in both the U.S. District Court for the District of Delaware and the U.S. Court of Appeal for the Federal Circuit (CAFC). We have filed a motion to dismiss the appeal in Delaware and have responded to the appeal filed in the CAFC. The CAFC has not yet set a hearing date for this appeal. The Delaware court has stayed the appeal relating to the Second Idenix Interference. We believe that the Idenix claims involved in the First and Second Idenix Interferences, and similar U.S. and foreign patents claiming the same compounds, metabolites and uses thereof, 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. Idenix asserted that the commercialization of Sovaldi in Canada will infringe its ’191 patent and that our Canadian Patent No. 2,527,657, corresponding to the ’572 patent involved in the First Idenix Interference, is invalid. In November 2015, the Canadian court held that Idenix’s patent is invalid and that Gilead’s patent is valid. Idenix appealed the decision to the Canadian Federal Court of Appeal in November 2015. We filed a similar legal action in Norway in the Oslo District Court seeking to invalidate Idenix’s Norwegian patent corresponding to the ’600 patent. In September 2013, Idenix filed an invalidation action in the Norwegian proceedings against our Norwegian Patent No. 333700 patent, which corresponds to the ’572 patent. In March 2014, the Norwegian court found all claims in the Idenix Norwegian patent to be invalid and upheld the validity of all claims in the challenged Gilead patent. Idenix appealed the decision to the Norwegian Court of Appeal. In April 2016, the Court of Appeal issued its decision invalidating the Idenix patent and upholding the Gilead patent. In January 2013, 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 Sovaldi in Australia infringes its Australian patent corresponding to the ’600 patent. In March 2016, the Australia court revoked Idenix’s Australian patent. We expect that Idenix will appeal this decision. In March 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 was granted, we filed an opposition with the EPO seeking to revoke the ’489 patent. An opposition hearing was held in February 2016, and the EPO ruled in our favor and revoked the ’489 patent. In March 2014, Idenix also initiated infringement proceedings against us in the United Kingdom (UK), Germany and France alleging that the commercialization of Sovaldi would infringe the UK, German and French counterparts of the ’489 patent. A trial was held in the UK in October 2014 to determine the issues of infringement and validity of the Idenix UK patent. In December 2014, the High Court of Justice of England and Wales (UK Court) invalidated all challenged claims of the ’489 patent on multiple grounds. Idenix appealed. The appeal hearing is scheduled for July 2016. In March 2015, the German court in Düsseldorf determined that the Idenix patent was highly likely to be invalid and stayed the infringement proceedings pending the outcome of the opposition hearing held by the EPO in February 2016. Idenix has not appealed this decision of the German court staying the proceedings. Upon Idenix’s request, the French proceedings have been stayed; however, in March 2016, Idenix requested that the French litigation be reactivated. Idenix has not been awarded patents corresponding to the ’600 patent in Japan or China. In the event such patents are issued, we expect to challenge them in proceedings similar to those we invoked in other countries. 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. 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. In June 2014, the court transferred the Massachusetts litigation to the U.S. District Court for the District of Delaware. The Delaware district court has set trial dates in October 2016 and December 2016 for resolution of these issues. A decision by the district court may be appealed by either party to the CAFC. Idenix was acquired by Merck & Co. Inc. (Merck) in August 2014, and Merck continues to pursue the Idenix claims described herein. 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. Merck’s U.S. Patent Nos. 7,105,499 and 8,481,712 cover compounds which do not include, but may relate to, sofosbuvir. We filed a lawsuit in August 2013 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. During patent prosecution, Merck amended its patent application in an attempt to cover compounds related to sofosbuvir. In March 2016, a jury in the case rendered a verdict that we had not established that Merck’s patents are invalid for lack of written description or lack of enablement. The court also ruled that Merck’s patents are infringed by our commercialization of sofosbuvir-containing products. The jury awarded Merck $200 million in damages for sales of our sofosbuvir-containing products from launch through December 2015. As a result, we accrued a $200 million litigation reserve, which was recorded in Cost of goods sold in our Condensed Consolidated Statements of Income during the first quarter of 2016. We are currently waiting for the court’s decision on our equitable defenses and our request for judgment as a matter of law. If the jury’s verdict stands, we may be required to pay a royalty on sales of sofosbuvir-containing products following the verdict. The judge has indicated that she will determine the amount of the royalty, if necessary, at the conclusion of any appeal in this case. It may take several months for the court to rule on these defenses before the case is ready for appeal. Either party may appeal a District Court decision to the Court of Appeals for the Federal Circuit. 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 (AbbVie Patents) which purport to cover the use of a combination of LDV/SOF (or Harvoni) for the treatment of HCV. We are aware that AbbVie has pending patent applications in the United States and granted and pending 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 LDV/SOF. Certain of our applications were filed before the AbbVie Patents. For this reason and others, we believe the AbbVie 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 also filing two lawsuits 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. In the United States, either party may appeal a decision by the District Court to the CAFC. The AbbVie Patents have not blocked or delayed the commercialization of our combination product in the United States, Canada, or Europe. We do not expect any other foreign patents to block or delay the commercialization around the world. The court has set a trial date of September 12, 2016 for this lawsuit. Additionally, AbbVie has obtained U.S. Patent No. 9,034,832 which purports to cover a solid oral dosage form containing ledipasvir. Accordingly, in May 2015, we filed a lawsuit in the U.S. District Court for the District of Delaware seeking declaratory judgment that AbbVie’s patent is invalid, as well as other relief. We do not expect AbbVie’s patent to block the commercialization of our combination product. The court has set a trial date of July 31, 2017. In August 2015, we filed an impeachment action against AbbVie seeking a declaration that AbbVie’s Canadian Patent No. 2,811,250 (’250 Patent), which purports to cover the use of a combination of LDV/SOF for the treatment of HCV, is invalid. On the same day, AbbVie filed an infringement action against us asserting that commercialization of Harvoni in Canada will infringe its ’250 Patent. The impeachment action has been stayed and we have counterclaimed for invalidity in the infringement proceeding. A trial date has not been set. Additionally, AbbVie has obtained Canadian Patent No. 2,857,339 which purports to cover a solid composition that contains ledipasvir. In November 2015, AbbVie filed an infringement action against us asserting that commercialization of Harvoni in Canada infringes its ’339 Patent. We have filed a counterclaim asserting the invalidity of AbbVie’s patent. A trial date has not been set. In November 2015, AbbVie filed a lawsuit against us in the Regional Court Düsseldorf for infringement of two quasi-patents, known as “utility models.” Utility models are unexamined IP rights and are not the same as standard patents. One utility model, DE 20 2012 013 117, purports to cover the use of a combination of direct-acting antivirals which includes at least an HCV polymerase inhibitor and an HCV NS5A inhibitor in the treatment of HCV; the other utility model, DE 21 2012 000 197, purports to cover a solid dispersion that includes ledipasvir. A trial date has not been set. European Patent Claims In February 2015, several parties filed oppositions in the EPO requesting revocation of our granted European patent covering sofosbuvir that expires in 2028. In January 2016, several parties filed oppositions in the EPO requesting revocation of our granted European patent covering tenofovir alafenamide (TAF) that expires in 2021. In March 2016, two parties filed oppositions in the EPO requesting revocation of our granted European patent covering cobicistat that expires in 2027. While we are confident in the strength of our patents, we cannot predict the ultimate outcome of these oppositions. If we are unsuccessful in defending these oppositions, some or all of our patent claims may be narrowed or revoked and the patent protection for sofosbuvir, TAF and cobicistat in Europe could be substantially shortened or eliminated entirely. If our patents are revoked, and no other European patents are granted covering these compounds, our exclusivity may be based entirely on regulatory exclusivity granted by the European Medicines Agency. Sovaldi has been granted regulatory exclusivity that will prevent generic sofosbuvir from entering the European Union for 10 years following approval of Sovaldi, or January 2024. If we lose exclusivity for Sovaldi prior to 2028, our expected revenues and results of operation could be negatively impacted for the years including and succeeding the year in which such exclusivity is lost, which may cause our stock price to decline. Litigation with Generic Manufacturers As part of the approval process for some of our products, 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. The sale of generic versions of our 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: HIV Products In November 2011, December 2011 and August 2012, we received notices that Teva Pharmaceuticals (Teva) submitted an abbreviated new drug submission (ANDS) to the Canadian Minister of Health requesting permission to manufacture and market generic versions of Truvada, Atripla and Viread. In the notices, Teva alleges that the patents associated with Truvada, Atripla and Viread are invalid, unenforceable and/or will not be infringed by Teva’s manufacture, use or sale of generic versions of those products. We filed lawsuits against Teva in the Federal Court of Canada seeking an order of prohibition against approval of these applications. In December 2013, the court issued an order prohibiting the Canadian Minister of Health from approving Teva’s generic versions of our Viread, Truvada and Atripla products until expiry of our patents in July 2017. Teva has appealed that decision. The court’s decision did not rule on the validity of the patents and accordingly the only issue on appeal is whether the Canadian Minister of Health should be prohibited from approving Teva’s products. The appeal will be heard by the Canadian Federal Court of Appeal after the trial in the Impeachment Action filed by Teva in August 2012 seeking invalidation of our Canadian patents associated with Viread. The court will determine the validity of the patents in the pending Impeachment Action. A trial in the Impeachment Action is scheduled for November 2016. If Teva is successful in invalidating our patents, Teva may be able to launch generic versions of our Viread, Truvada and Atripla products in Canada prior to the expiry of our patents. In June 2014, we received notice that Apotex Inc. (Apotex) submitted an ANDS to the Canadian Minister of Health requesting permission to manufacture and market a generic version of Truvada 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 lawsuits against Apotex in the Federal Court of Canada seeking orders of prohibition against approval of these ANDSs. A hearing in those cases was held in April 2016. We expect a decision from the court prior to July 31, 2016. Letairis In February 2015, we received notice that Watson Laboratories, Inc. (Watson) submitted an ANDA to FDA requesting permission to manufacture and market a generic version of Letairis. In the notice, Watson alleges that one of the patents associated with ambrisentan tablets is invalid, unenforceable and/or will not be infringed by Watson’s manufacture, use or sale of a generic version of Letairis. In April 2015, we filed a lawsuit against Watson in the U.S. District Court for the District of New Jersey for infringement of our patents. In June 2015, we received notice that SigmaPharm Laboratories, LLC (SigmaPharm) submitted an ANDA to FDA requesting permission to manufacture and market a generic version of Letairis. In the notice, SigmaPharm alleges that one of the patents associated with ambrisentan tablets is invalid, unenforceable and/or will not be infringed by SigmaPharm’s manufacture, use or sale of a generic version of Letairis. In June 2015, we filed a lawsuit against SigmaPharm in the U.S. District Court for the District of New Jersey for infringement of our patents. We cannot predict the ultimate outcome of these actions, and we may spend significant resources enforcing and defending these patents. If we are unsuccessful in these lawsuits, some or all of our claims in the patents may be narrowed or invalidated and the patent protection for our products could be substantially shortened. Further, if all of the patents covering one or more products are invalidated, FDA or the 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. TAF Litigation In January 2016, AIDS Healthcare Foundation, Inc. (AHF) filed a complaint with the U.S. District Court for the Northern District of California against Gilead, Japan Tobacco, Inc., Japan Tobacco International, U.S.A. (together, Japan Tobacco), and Emory University (Emory). In April 2016, AHF amended its complaint to add Akros Pharma, Inc. (Akros), Janssen Sciences Ireland UC (Janssen) and Johnson & Johnson Inc. (J&J) as defendants. AHF claims that U.S. Patent Nos. 7,390,791; 7,800,788; 8,754,065; 8,148,374; and 8,633,219 are invalid under 35 U.S.C. §§ 101 et seq. In addition, AHF claims that Gilead, independently and together with Japan Tobacco, Akros, Janssen and J&J, is violating federal and state antitrust and unfair competition laws in the market for sales of TAF by offering TAF as part of a fixed-dose combination product with elvitegravir, cobicistat and emtricitabine (Genvoya), a fixed-dose combination product with elvitegravir and rilpivirine (Odefsey) and in a fixed-dosed combination product with elvitegravir (Descovy). AHF seeks a declaratory judgment of invalidity against each of the patents as well as monetary damages. Department of Justice Investigations 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. In April 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. In April 2014, the former employees served a First Amended Complaint. In January 2015, the federal district court issued an order granting in its entirety, without prejudice, our motion to dismiss the First Amended Complaint. In February 2015, the plaintiffs filed a Second Amended Complaint and in June 2015, the federal district court issued an order granting our motion to dismiss the Second Amended Complaint. In July 2015, the plaintiffs filed a notice of appeal in the U.S. Court of Appeals for Ninth Circuit. In February 2016, we received a subpoena from the U.S. Attorney’s Office for the District of Massachusetts requesting documents related to our support of 501(c)(3) organizations that provide financial assistance to patients, and for our HCV products, documents concerning our provision of financial assistance to patients. Other companies have disclosed similar inquiries. We are cooperating with this inquiry. Massachusetts Attorney General Investigation In January 2016, we received a letter from the Massachusetts Attorney General that their office is considering whether our pricing of Sovaldi and Harvoni may constitute an unfair trade practice in violation of Massachusetts law. In February 2016, the Massachusetts Attorney General’s office served us with a Civil Investigative Demand requesting that we produce documents related to our HCV products. We are cooperating with this inquiry. Other Matters We are a party to various legal actions that arose in the ordinary course of our business. We do not believe that these other legal actions will have a material adverse impact on our consolidated business, financial position or results of operations.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY The following table summarizes the changes in stockholders’ equity (in millions): Gilead Stockholders’ Equity Noncontrolling Interest Total Common Stock Additional Paid-In Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings Shares Amount Balance at December 31, 2015 1,422 $ 1 $ 444 $ 88 $ 18,001 $ 579 $ 19,113 Net income — — — — 3,566 1 3,567 Other comprehensive loss, net of tax — — — (252 ) — — (252 ) Change in noncontrolling interest — — — — — 41 41 Issuances under employee stock purchase plan 1 — 48 — — — 48 Issuances under equity incentive plans 6 — 40 — — — 40 Stock-based compensation — — 88 — — — 88 Tax benefits from employee stock plans — — 87 — — — 87 Repurchases of common stock (81 ) — (193 ) — (7,935 ) — (8,128 ) Convertible senior notes settlement — — (95 ) — — — (95 ) Convertible notes hedge settlement — — 95 — — — 95 Dividends declared — — — — (587 ) — (587 ) Reclassification of conversion spread of senior convertible notes — — (733 ) — — — (733 ) Reclassification of convertible notes hedges — — 733 — — — 733 Reclassification to equity component of currently redeemable convertible senior notes — — 2 — — — 2 Balance at March 31, 2016 1,348 $ 1 $ 516 $ (164 ) $ 13,045 $ 621 $ 14,019 Accumulated Other Comprehensive Income (Loss) The following table summarizes the changes in AOCI by component, net of tax (in millions): 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, 2015 $ (45 ) $ (16 ) $ 149 $ 88 Other comprehensive income (loss) before reclassifications 2 (24 ) (150 ) (172 ) Amounts reclassified from AOCI — — (80 ) (80 ) Net current period other comprehensive income (loss) 2 (24 ) (230 ) (252 ) Balance at March 31, 2016 $ (43 ) $ (40 ) $ (81 ) $ (164 ) Amounts reclassified for gains (losses) on cash flow hedges are recorded as part of Product sales in our Condensed Consolidated Statements of Income. Amounts reclassified for gains (losses) on available-for-sale securities are recorded as part of Other income (expense), net in our Condensed Consolidated Statements of Income. Stock Repurchase Programs In February 2016, we entered into an accelerated stock repurchase program (ASR) to repurchase $5.0 billion of our common stock under the $15.0 billion stock repurchase program announced in January 2015 (2015 Program). We made an upfront payment of $5.0 billion and received 46 million shares of our common stock. The 46 million shares represented approximately 80% of the total shares calculated based on our common stock closing price of $86.68 per share on the date we entered into the ASR. In April 2016, the ASR was settled and we received an additional 8 million shares of our common stock based on the average price of our common stock during the ASR purchase period less a predetermined discount. As a result, the average purchase price of our common stock from the ASR was $92.09 per share. We accounted for the ASR as two separate transactions: (a) as shares of common stock acquired in a treasury stock transaction recorded on the transaction date and (b) as a forward contract indexed to our own common stock. As such, the up-front payment of $5.0 billion was accounted for as a reduction to stockholders’ equity in our Condensed Consolidated Balance Sheets in the period the payment was made. The ASR met all of the applicable criteria for equity classification, and therefore was not accounted for as a derivative instrument. The shares received under the ASR were retired in the periods they were received. During the first quarter of 2016 , we also repurchased and retired 34 million shares of our common stock for an aggregate purchase price of $3.0 billion through open market transactions under the 2015 Program. In February 2016, our Board of Directors authorized a $12.0 billion share repurchase program (2016 Program) under which repurchases may be made in the open market or in privately negotiated transactions. As of March 31, 2016 , we had not made any stock repurchases under the 2016 Program.

Net Income Per Share Attributab

Net Income Per Share Attributable to Gilead Common Stockholders	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Net Income Per Share Attributable to Gilead Common Stockholders	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 and equivalents, the assumed conversion of our outstanding May 2016 Notes and the 2016 Warrants were determined under the treasury stock method. Because the principal amount of the May 2016 Notes has been or will be settled in cash, only the conversion spread relating to the May 2016 Notes has been included in our calculation of diluted net income per share attributable to Gilead common stockholders. In March 2016, we exercised our option to elect cash settlement for the conversion spread of the remaining May 2016 Notes. Prior to our cash settlement election, our common stock resulting from the assumed settlement of the conversion spread of the May 2016 Notes had a dilutive effect when the average market price of our common stock during the period exceeded the conversion price for the May 2016 Notes. As a result, we included their dilutive impact in our net income per share calculations. Additionally, the 2016 Warrants have a dilutive effect when the average market price of our common stock during the period exceeded the warrants’ exercise price. See Note 8 , Debt and Credit Facility for additional information. Our ASR was reflected as repurchases of our common stock upon the receipt of shares and as forward contracts indexed to our common stock. We excluded the forward contracts from the computation of diluted net income per share attributable to Gilead common shareholders because their effect was antidilutive. We have excluded stock options and equivalents of approximately 4 million and 1 million weighted-average shares of our common stock that were outstanding for the three months ended March 31, 2016 and 2015 , respectively, from 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 denominator used in the calculation of basic and diluted net income per share attributable to Gilead common stockholders (in millions): Three Months Ended March 31, 2016 2015 Net income attributable to Gilead $ 3,566 $ 4,333 Shares used in per share calculation - basic 1,383 1,488 Effect of dilutive securities: Stock options and equivalents 16 26 Conversion spread related to the May 2016 Notes 7 16 Warrants related to the May 2016 Notes 6 39 Shares used in per share calculation - diluted 1,412 1,569 Net income per share attributable to Gilead common stockholders - basic $ 2.58 $ 2.91 Net income per share attributable to Gilead common stockholders - diluted $ 2.53 $ 2.76

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Segment Information	SEGMENT INFORMATION We have one operating segment, which primarily focuses on the discovery, development and commercialization of innovative medicines in areas of unmet medical need. Therefore, our results of operations are reported on a consolidated basis consistent with internal management reporting reviewed by our chief operating decision maker, our chief executive officer. Total product sales on an individual product basis are summarized in the following table (in millions): Three Months Ended March 31, 2016 2015 Antiviral products: Harvoni $ 3,017 $ 3,579 Sovaldi 1,277 972 Truvada 898 771 Atripla 675 734 Stribild 477 356 Complera/Eviplera 381 320 Viread 272 234 Genvoya 158 — Other antiviral 28 22 Total antiviral products 7,183 6,988 Other products: Letairis 175 151 Ranexa 144 117 AmBisome 86 85 Zydelig 49 26 Other 44 38 Total product sales $ 7,681 $ 7,405 The following table summarizes revenues from each of our customers who individually accounted for 10% or more of our total revenues (as a percentage of total revenues): Three Months Ended March 31, 2016 2015 McKesson Corp. 21 % 25 % AmerisourceBergen Corp. 17 % 21 % Cardinal Health, Inc. 16 % 17 %

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Our income tax rate of 20.8% for the three months ended March 31, 2016 , 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 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 and California 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. Our income tax returns are subject to audit by federal, state and foreign tax authorities. We are currently under examination by the Internal Revenue Service 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. 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. Resolution of one or more of these uncertain tax positions in any period may have a material impact on the results of operations for that period.

Summary of Significant Accoun21

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation	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 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 certain variable interest entities for which we are the primary beneficiary. All intercompany transactions have been eliminated. For consolidated entities where we own or are exposed to less than 100% of the economics, we record Net income (loss) attributable to noncontrolling interest in our Condensed Consolidated Statements of Income equal to the percentage of the economic or ownership interest retained in such entities by the respective noncontrolling parties. We assess whether we are the primary beneficiary of a variable interest entity (VIE) at the inception of the arrangement and at each reporting date. This assessment is based on our power to direct the activities of the VIE that most significantly impact the VIE’s economic performance and our obligation to absorb losses or the right to receive benefits from the VIE that could potentially be significant to the VIE. As of March 31, 2016 , the only material VIE was our joint venture with Bristol-Myers Squibb Company (BMS) which is described in Note 7 , Collaborative Arrangements. 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, 2015 , included in our Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission.
Significant Accounting Policies, Estimates and Judgments	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, we evaluate our significant accounting policies and 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. Estimates are assessed each period and updated to reflect current information. Actual results may differ significantly from these estimates.
Concentrations of Risk	Concentrations of Risk We are subject to credit risk from our portfolio of cash, 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. 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. As of March 31, 2016, approximately 15% of our cash, cash equivalents and marketable securities were held at one financial institution. We mitigate risk by depositing funds with reputable institutions and by monitoring their risk profiles. To date, losses with respect to our concentrations of risk related to our cash, cash equivalents and marketable securities have been immaterial. 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, Europe and Japan. As of March 31, 2016 , our accounts receivable in Southern Europe, specifically Greece, Italy, Portugal and Spain, totaled approximately $819 million , of which $237 million were greater than 120 days past due, including $32 million greater than 365 days past due. To date, we have not experienced significant losses with respect to the collection of our accounts receivable. We believe that our allowance for doubtful accounts was adequate at March 31, 2016 .
Recent Accounting Pronouncement	Recent Accounting Pronouncements In April 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update No. 2015-03 (ASU 2015-03) "Simplifying the Presentation of Debt Issuance Costs." ASU 2015-03 requires the presentation of debt issuance costs as a direct deduction from the carrying amount of a recognized debt liability on the balance sheet. We adopted this ASU with retrospective application in the first quarter of 2016. The adoption of this standard did not have a material impact on our Condensed Consolidated Financial Statements. See Note 8 , Debt and Credit Facility for further information. In May 2014, the FASB issued Accounting Standard Update No. 2014-09 (ASU 2014-09) "Revenue 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. The standard will become effective for us beginning in the first quarter of 2018. Early adoption is permitted in 2017. Entities have the option of using either a full retrospective or a modified retrospective approach to adopt this new guidance. In March and April 2016, the FASB issued ASU 2016-08 "Revenue From Contracts With Customers: Principal vs. Agent Considerations" and ASU 2016-10 “Revenue From Contracts with Customers: Identifying Performance Obligations and Licensing” to provide supplemental adoption guidance and clarification to ASU 2014-09. We are evaluating the impact of the adoption of these standards on our Condensed Consolidated Financial Statements. In November 2015, the FASB issued Accounting Standard Update No. 2015-17 (ASU 2015-17) "Balance Sheet Classification of Deferred Taxes." ASU 2015-17 requires that deferred tax liabilities and assets be classified as noncurrent on the balance sheet. Previous guidance required deferred tax liabilities and assets to be separated into current and noncurrent amounts on the balance sheet. The guidance will become effective for us beginning in the first quarter of 2017 and may be applied either prospectively or retrospectively. Early adoption is permitted. At the time of adoption, we will reclassify current deferred tax amounts on our Consolidated Balance Sheets as noncurrent. We are evaluating the impact of the method of adoption of this standard on our Condensed Consolidated Financial Statements . In January 2016, the FASB issued Accounting Standard Update No. 2016-01(ASU 2016-01) "Recognition and Measurement of Financial Assets and Financial Liabilities." ASU 2016-01 changes accounting for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements for financial instruments. In addition, it clarified guidance related to the valuation allowance assessment when recognizing deferred tax assets resulting from unrealized losses on available-for-sale debt securities. The guidance will become effective for us beginning in the first quarter of 2018. Early adoption is permitted. We are evaluating the impact of the adoption of this standard on our Condensed Consolidated Financial Statements . In February 2016, the FASB issued Accounting Standard Update No. 2016-02 (ASU 2016-02) "Leases." ASU 2016-02 amends a number of aspects of lease accounting, including requiring lessees to recognize almost all leases with a term greater than one year as a right-of-use asset and corresponding liability, measured at the present value of the lease payments. The guidance will become effective for us beginning in the first quarter of 2019 and is required to be adopted using a modified retrospective approach. Early adoption is permitted. We are evaluating the impact of the adoption of this standard on our Condensed Consolidated Financial Statements . In March 2016, the FASB issued Accounting Standard Update No. 2016-09 (ASU 2016-09) "Improvements to Employee Share-Based Payment Accounting." ASU 2016-09 simplifies several aspects of employee share-based payment accounting, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. This guidance will become effective for us beginning in the first quarter of 2017. Early adoption is permitted. We are evaluating the impact of the adoption of this standard on our Condensed Consolidated Financial Statements .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
Schedule of Fair Value Classified by Level of Input	The following table summarizes the types of assets and liabilities measured at fair value on a recurring basis, by level, within the fair value hierarchy (in millions): March 31, 2016 December 31, 2015 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Money market funds $ 2,128 $ — $ — $ 2,128 $ 10,161 $ — $ — $ 10,161 Corporate debt securities — 7,284 — 7,284 — 5,773 — 5,773 U.S. treasury securities 3,987 — — 3,987 4,389 — — 4,389 Residential mortgage and asset-backed securities — 2,233 — 2,233 — 1,695 — 1,695 U.S. government agencies securities — 775 — 775 — 707 — 707 Certificates of deposit — 364 — 364 — 448 — 448 Non-U.S. government securities — 378 — 378 — 313 — 313 Municipal debt securities — 34 — 34 — 34 — 34 Equity securities 280 — — 280 — — — — Convertible note hedges (1) — 792 — 792 — — — — Foreign currency derivative contracts — 74 — 74 — 210 — 210 Deferred compensation plan 74 — — 74 66 — — 66 $ 6,469 $ 11,934 $ — $ 18,403 $ 14,616 $ 9,180 $ — $ 23,796 Liabilities: Conversion spread of convertible senior notes (1) $ — $ 792 $ — $ 792 $ — $ — $ — $ — Contingent consideration — — 33 33 — — 59 59 Deferred compensation plan 74 — — 74 66 — — 66 Foreign currency derivative contracts — 140 — 140 — 41 — 41 $ 74 $ 932 $ 33 $ 1,039 $ 66 $ 41 $ 59 $ 166 _________________________________________ (1) See Note 4, Derivative Financial Instruments for further information.

Available-for-Sale Securities (

Available-for-Sale Securities (Tables)	3 Months Ended
	Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-Sale Securities at Estimated Fair Value	The following table is a summary of our available-for-sale securities (in millions): March 31, 2016 December 31, 2015 Amortized Gross Gross Estimated Amortized Gross Gross Estimated Money market funds $ 2,128 $ — $ — $ 2,128 $ 10,161 $ — $ — $ 10,161 Corporate debt securities 7,261 28 (5 ) 7,284 5,795 1 (23 ) 5,773 U.S. treasury securities 3,980 8 (1 ) 3,987 4,407 — (18 ) 4,389 Residential mortgage and asset-backed securities 2,229 5 (1 ) 2,233 1,701 — (6 ) 1,695 U.S. government agencies securities 774 1 — 775 709 — (2 ) 707 Certificates of deposit 364 — — 364 448 — — 448 Non-U.S. government securities 378 — — 378 315 — (2 ) 313 Municipal debt securities 34 — — 34 34 — — 34 Equity securities 357 — (77 ) 280 — — — — Total $ 17,505 $ 42 $ (84 ) $ 17,463 $ 23,570 $ 1 $ (51 ) $ 23,520
Summary of the Classification of Available-for-Sale Securities	The following table summarizes the classification of the available-for-sale securities in our Condensed Consolidated Balance Sheets (in millions): March 31, 2016 December 31, 2015 Cash and cash equivalents $ 2,176 $ 10,163 Short-term marketable securities 2,004 1,756 Long-term marketable securities 13,003 11,601 Other long-term assets 280 — Total $ 17,463 $ 23,520
Summary of Available-for-Sale Securities by Contractual Maturity	The following table summarizes our portfolio of available-for-sale debt securities by contractual maturity (in millions): March 31, 2016 Amortized Cost Fair Value Less than one year $ 4,180 $ 4,180 Greater than one year but less than five years 12,750 12,785 Greater than five years but less than ten years 185 185 Greater than ten years 33 33 Total $ 17,148 $ 17,183
Summary of Available-for-Sale Securities in a Continuous Loss Position Deemed not to be Other-than-Temporarily Impaired	The following table summarizes our available-for-sale securities that were in a continuous unrealized loss position, but were not deemed to be other-than-temporarily impaired (in millions): Less Than 12 Months 12 Months or Greater Total Gross Estimated Gross Estimated Gross Estimated March 31, 2016 Corporate debt securities $ (5 ) $ 1,834 $ — $ 50 $ (5 ) $ 1,884 U.S. treasury securities (1 ) 1,075 — — (1 ) 1,075 Residential mortgage and asset-backed securities (1 ) 667 — 24 (1 ) 691 U.S. government agencies securities — 116 — — — 116 Non-U.S. government securities — 221 — — — 221 Equity securities (77 ) 280 — — (77 ) 280 Total $ (84 ) $ 4,193 $ — $ 74 $ (84 ) $ 4,267 December 31, 2015 Corporate debt securities $ (23 ) $ 4,891 $ — $ 43 $ (23 ) $ 4,934 U.S. treasury securities (18 ) 4,342 — — (18 ) 4,342 Residential mortgage and asset-backed securities (6 ) 1,626 — 20 (6 ) 1,646 U.S. government agencies securities (2 ) 707 — — (2 ) 707 Non-U.S. government securities (2 ) 313 — — (2 ) 313 Municipal debt securities — 21 — — — 21 Total $ (51 ) $ 11,900 $ — $ 63 $ (51 ) $ 11,963

Derivative Financial Instrume24

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Values of Derivative Instruments on Condensed Consolidated Balance Sheets	The following table summarizes the classification and fair values of derivative instruments in our Condensed Consolidated Balance Sheets (in millions): March 31, 2016 Asset Derivatives Liability Derivatives Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Other current assets $ 71 Other accrued liabilities $ (121 ) Foreign currency exchange contracts Other long-term assets 2 Other long-term obligations (18 ) Total derivatives designated as hedges 73 (139 ) Derivatives not designated as hedges: Foreign currency exchange contracts Other current assets 1 Other accrued liabilities (1 ) Total derivatives not designated as hedges 1 (1 ) Total derivatives $ 74 $ (140 ) December 31, 2015 Asset Derivatives Liability Derivatives Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Other current assets $ 200 Other accrued liabilities $ (32 ) Foreign currency exchange contracts Other long-term assets 9 Other long-term obligations (8 ) Total derivatives designated as hedges 209 (40 ) Derivatives not designated as hedges: Foreign currency exchange contracts Other current assets 1 Other accrued liabilities (1 ) Total derivatives not designated as hedges 1 (1 ) Total derivatives $ 210 $ (41 )
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 in our Condensed Consolidated Financial Statements (in millions): Three Months Ended March 31, 2016 2015 Derivatives designated as hedges: Gains (losses) recognized in AOCI (effective portion) $ (160 ) $ 389 Gains reclassified from AOCI into product sales (effective portion) $ 86 $ 145 Gains recognized in Other income (expense), net (ineffective portion and amounts excluded from effectiveness testing) $ 14 $ 1 Derivatives not designated as hedges: Gains (losses) recognized in Other income (expense), net $ (151 ) $ 108
Derivatives Netting Tabular Disclosure	The following table summarizes the potential effect of offsetting derivatives by type of financial instrument in our Condensed Consolidated Balance Sheets (in millions): 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 in the Condensed Consolidated Balance Sheet Derivative Financial Instruments Cash Collateral Received/Pledged Net Amount (Legal Offset) As of March 31, 2016 Derivative assets $ 74 $ — $ 74 $ (66 ) $ — $ 8 Derivative liabilities (140 ) — (140 ) 66 — (74 ) As of December 31, 2015 Derivative assets $ 210 $ — $ 210 $ (38 ) $ — $ 172 Derivative liabilities (41 ) — (41 ) 38 — (3 )

Other Financial Information (Ta

Other Financial Information (Tables)	3 Months Ended
	Mar. 31, 2016
Other Financial Information [Abstract]
Schedule of Inventories	Inventories are summarized as follows (in millions): March 31, 2016 December 31, 2015 Raw materials $ 1,239 $ 1,332 Work in process 761 542 Finished goods 731 852 Total $ 2,731 $ 2,726 Reported as: Inventories $ 1,880 $ 1,955 Other long-term assets 851 771 Total $ 2,731 $ 2,726
Schedule of Prepaid and Other Current Assets	The components of Prepaid and other current assets are summarized as follows (in millions): March 31, 2016 December 31, 2015 Convertible note hedges $ 792 $ — Prepaid taxes 705 773 Other prepaid expenses 319 240 Other current assets 259 505 Total prepaid and other current assets $ 2,075 $ 1,518
Schedule of Other Accrued Liabilities	The components of Other accrued liabilities are summarized as follows (in millions): March 31, 2016 December 31, 2015 Accrued royalties $ 190 $ 237 Branded Prescription Drug fee 513 649 Compensation and employee benefits 235 380 Income taxes payable 51 65 Other accrued expenses 1,936 1,841 Total other accrued liabilities $ 2,925 $ 3,172

Intangible Assets (Tables)

Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2016
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Schedule of Intangible Assets	The following table summarizes the carrying amounts of our Intangible assets, net (in millions): March 31, 2016 December 31, 2015 Finite-lived intangible assets $ 9,605 $ 9,815 Indefinite-lived intangible assets 318 432 Total intangible assets $ 9,923 $ 10,247
Schedule of Finite-Lived Intangible Assets	The following table summarizes our finite-lived intangible assets (in millions): March 31, 2016 December 31, 2015 Gross Carrying Amount Accumulated Amortization Gross Carrying Amount Accumulated Amortization Intangible asset - sofosbuvir $ 10,720 $ 1,631 $ 10,720 $ 1,456 Intangible asset - Ranexa 688 388 688 363 Other 455 239 455 229 Total $ 11,863 $ 2,258 $ 11,863 $ 2,048
Estimated Future Amortization Expense	As of March 31, 2016 , the estimated future amortization expense associated with our finite-lived intangible assets for the remaining nine months of 2016 and each of the five succeeding fiscal years is expected as follows (in millions): Fiscal Year Amount 2016 (remaining nine months) $ 629 2017 844 2018 849 2019 741 2020 713 2021 and thereafter 5,829 Total $ 9,605
Schedule of Indefinite-Lived Intangible Assets	The following table summarizes our indefinite-lived intangible assets (in-process research and development) (in millions): March 31, 2016 December 31, 2015 Indefinite-lived intangible asset - momelotinib $ 201 $ 315 Indefinite-lived intangible assets - Other 117 117 Total $ 318 $ 432

Collaborative Arrangements (Tab

Collaborative Arrangements (Tables)	3 Months Ended
	Mar. 31, 2016
Collaborative Arrangements [Abstract]
Schedule of Variable Interest Entities	Selected financial information for the joint venture was as follows (in millions): March 31, 2016 December 31, 2015 Total assets $ 2,441 $ 2,464 Cash and cash equivalents 132 166 Accounts receivable, net 251 269 Inventories 2,056 2,027 Total liabilities 929 1,055 Accounts payable 544 606 Other accrued liabilities 385 449

Debt and Credit Facility (Table

Debt and Credit Facility (Tables)	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Schedule of Debt Instruments	The following table summarizes the carrying amount of our borrowings under various financing arrangements (in millions): Type of Borrowing Issue Date Due Date Interest Rate March 31, 2016 December 31, 2015 (1) Convertible Senior July 2010 May 2016 1.625% $ 254 $ 283 Senior Unsecured December 2011 December 2016 3.05% 699 699 Senior Unsecured September 2015 September 2018 1.85% 997 997 Senior Unsecured March 2014 April 2019 2.05% 498 498 Senior Unsecured November 2014 February 2020 2.35% 498 497 Senior Unsecured September 2015 September 2020 2.55% 1,990 1,989 Senior Unsecured March 2011 April 2021 4.50% 993 992 Senior Unsecured December 2011 December 2021 4.40% 1,244 1,244 Senior Unsecured September 2015 September 2022 3.25% 995 995 Senior Unsecured March 2014 April 2024 3.70% 1,740 1,740 Senior Unsecured November 2014 February 2025 3.50% 1,742 1,742 Senior Unsecured September 2015 March 2026 3.65% 2,724 2,724 Senior Unsecured September 2015 September 2035 4.60% 988 988 Senior Unsecured December 2011 December 2041 5.65% 995 995 Senior Unsecured March 2014 April 2044 4.80% 1,732 1,732 Senior Unsecured November 2014 February 2045 4.50% 1,728 1,728 Senior Unsecured September 2015 March 2046 4.75% 2,213 2,212 Total debt, net 22,030 22,055 Less current portion 953 982 Total long-term debt, net $ 21,077 $ 21,073 _____________________________

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2016
Equity [Abstract]
Schedule of Stockholders Equity	The following table summarizes the changes in stockholders’ equity (in millions): Gilead Stockholders’ Equity Noncontrolling Interest Total Common Stock Additional Paid-In Capital Accumulated Other Comprehensive Income (Loss) Retained Earnings Shares Amount Balance at December 31, 2015 1,422 $ 1 $ 444 $ 88 $ 18,001 $ 579 $ 19,113 Net income — — — — 3,566 1 3,567 Other comprehensive loss, net of tax — — — (252 ) — — (252 ) Change in noncontrolling interest — — — — — 41 41 Issuances under employee stock purchase plan 1 — 48 — — — 48 Issuances under equity incentive plans 6 — 40 — — — 40 Stock-based compensation — — 88 — — — 88 Tax benefits from employee stock plans — — 87 — — — 87 Repurchases of common stock (81 ) — (193 ) — (7,935 ) — (8,128 ) Convertible senior notes settlement — — (95 ) — — — (95 ) Convertible notes hedge settlement — — 95 — — — 95 Dividends declared — — — — (587 ) — (587 ) Reclassification of conversion spread of senior convertible notes — — (733 ) — — — (733 ) Reclassification of convertible notes hedges — — 733 — — — 733 Reclassification to equity component of currently redeemable convertible senior notes — — 2 — — — 2 Balance at March 31, 2016 1,348 $ 1 $ 516 $ (164 ) $ 13,045 $ 621 $ 14,019
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table summarizes the changes in AOCI by component, net of tax (in millions): 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, 2015 $ (45 ) $ (16 ) $ 149 $ 88 Other comprehensive income (loss) before reclassifications 2 (24 ) (150 ) (172 ) Amounts reclassified from AOCI — — (80 ) (80 ) Net current period other comprehensive income (loss) 2 (24 ) (230 ) (252 ) Balance at March 31, 2016 $ (43 ) $ (40 ) $ (81 ) $ (164 )

Net Income Per Share Attribut30

Net Income Per Share Attributable to Gilead Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Schedule of Numerator and Denominator Used in the Calculation of Basic and Diluted Earnings Per Share	The following table is a reconciliation of the denominator used in the calculation of basic and diluted net income per share attributable to Gilead common stockholders (in millions): Three Months Ended March 31, 2016 2015 Net income attributable to Gilead $ 3,566 $ 4,333 Shares used in per share calculation - basic 1,383 1,488 Effect of dilutive securities: Stock options and equivalents 16 26 Conversion spread related to the May 2016 Notes 7 16 Warrants related to the May 2016 Notes 6 39 Shares used in per share calculation - diluted 1,412 1,569 Net income per share attributable to Gilead common stockholders - basic $ 2.58 $ 2.91 Net income per share attributable to Gilead common stockholders - diluted $ 2.53 $ 2.76

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2016
Segment Reporting [Abstract]
Product Sales by Product	Total product sales on an individual product basis are summarized in the following table (in millions): Three Months Ended March 31, 2016 2015 Antiviral products: Harvoni $ 3,017 $ 3,579 Sovaldi 1,277 972 Truvada 898 771 Atripla 675 734 Stribild 477 356 Complera/Eviplera 381 320 Viread 272 234 Genvoya 158 — Other antiviral 28 22 Total antiviral products 7,183 6,988 Other products: Letairis 175 151 Ranexa 144 117 AmBisome 86 85 Zydelig 49 26 Other 44 38 Total product sales $ 7,681 $ 7,405
Schedule of Revenue by Major Customers	The following table summarizes revenues from each of our customers who individually accounted for 10% or more of our total revenues (as a percentage of total revenues): Three Months Ended March 31, 2016 2015 McKesson Corp. 21 % 25 % AmerisourceBergen Corp. 17 % 21 % Cardinal Health, Inc. 16 % 17 %

Summary of Significant Accoun32

Summary of Significant Accounting Policies Concentrations of Risk (Details)	3 Months Ended
	Mar. 31, 2016
Cash and cash equivalents concentration risk
Concentration Risk [Line Items]
Concentration Risk, Percentage	15.00%

Southern European Receivables (

Southern European Receivables (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Accounts Receivable
Accounts Receivable	$ 6,163	$ 5,854
Southern Europe [Member]
Accounts Receivable
Accounts Receivable	819
Southern Europe [Member] | Greater than 120 Days
Accounts Receivable
Accounts Receivable	237
Southern Europe [Member] | Greater Than 12 Months
Accounts Receivable
Accounts Receivable	$ 32

Fair Value Measurements (Summar

Fair Value Measurements (Summary of assets and liabilities recorded at fair value) (Details) - USD ($) $ in Millions		Mar. 31, 2016		Mar. 04, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		$ 17,463			$ 23,520
Equity securities		280
Convertible Note Hedge, Fair Value		792	[1]	$ 733
Conversion spread of convertible senior notes	[1]	792
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Note Hedge, Fair Value	[1]	792
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities		280
Deferred compensation plan		74			66
Fair value, Assets, Total		6,469			14,616
Deferred compensation plan		74			66
Fair value, Liabilities, Total		74			66
Fair Value, Measurements, Recurring | Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		2,128			10,161
Fair Value, Measurements, Recurring | Level 1 | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		3,987			4,389
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative contracts		74			210
Fair value, Assets, Total		11,934			9,180
Conversion spread of convertible senior notes	[1]	792
Foreign currency derivative contracts		140			41
Fair value, Liabilities, Total		932			41
Fair Value, Measurements, Recurring | Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		7,284			5,773
Fair Value, Measurements, Recurring | Level 2 | Residential mortgage and asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		2,233			1,695
Fair Value, Measurements, Recurring | Level 2 | U.S. government agencies securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		775			707
Fair Value, Measurements, Recurring | Level 2 | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		364			448
Fair Value, Measurements, Recurring | Level 2 | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		378			313
Fair Value, Measurements, Recurring | Level 2 | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		34			34
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration		33			59
Fair value, Liabilities, Total		33			59
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency derivative contracts		74			210
Deferred compensation plan		74			66
Fair value, Assets, Total		18,403			23,796
Contingent consideration		33			59
Deferred compensation plan		74			66
Foreign currency derivative contracts		140			41
Fair value, Liabilities, Total		1,039			166
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement [Member] | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		2,128			10,161
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement [Member] | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		7,284			5,773
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement [Member] | U.S. treasury securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		3,987			4,389
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement [Member] | Residential mortgage and asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		2,233			1,695
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement [Member] | U.S. government agencies securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		775			707
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement [Member] | Certificates of deposit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		364			448
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement [Member] | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		378			313
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement [Member] | Municipal debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Estimated Fair Value		$ 34			$ 34
[1]	See Note 4, Derivative Financial Instruments for further information.

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Fair Value and Carrying Value of Debt [Line Items]
Derivative, Average Remaining Maturity	18 months
Debt, Long-term and Short-term, Combined Amount	$ 22,030	$ 22,055	[1]
Debt Instrument, Fair Value Disclosure	$ 24,700	$ 23,700
[1]	In connection with our adoption of the ASU relating to the presentation of debt issuance costs during the first quarter of 2016, debt balances at December 31, 2015 have been retrospectively adjusted by $123 million to include unamortized debt issuance costs. Prior to our adoption of the ASU, these unamortized debt issuance costs were included in prepaid and other current assets and other long-term assets in our Condensed Consolidated Balance Sheets.

Available-for-Sale Securities S

Available-for-Sale Securities Summary of Available-for-Sale Securities at Estimated Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Available-for-Sale Securities
Amortized Cost	$ 17,505	$ 23,570
Gross Unrealized Gains	42	1
Gross Unrealized Losses	(84)	(51)
Estimated Fair Value	17,463	23,520
Money market funds
Available-for-Sale Securities
Amortized Cost	2,128	10,161
Estimated Fair Value	2,128	10,161
Corporate debt securities
Available-for-Sale Securities
Amortized Cost	7,261	5,795
Gross Unrealized Gains	28	1
Gross Unrealized Losses	(5)	(23)
Estimated Fair Value	7,284	5,773
U.S. treasury securities
Available-for-Sale Securities
Amortized Cost	3,980	4,407
Gross Unrealized Gains	8
Gross Unrealized Losses	(1)	(18)
Estimated Fair Value	3,987	4,389
Residential mortgage and asset-backed securities
Available-for-Sale Securities
Amortized Cost	2,229	1,701
Gross Unrealized Gains	5
Gross Unrealized Losses	(1)	(6)
Estimated Fair Value	2,233	1,695
U.S. government agencies securities
Available-for-Sale Securities
Amortized Cost	774	709
Gross Unrealized Gains	1
Gross Unrealized Losses		(2)
Estimated Fair Value	775	707
Certificates of deposit
Available-for-Sale Securities
Amortized Cost	364	448
Estimated Fair Value	364	448
Non-U.S. government securities
Available-for-Sale Securities
Amortized Cost	378	315
Gross Unrealized Losses		(2)
Estimated Fair Value	378	313
Municipal debt securities
Available-for-Sale Securities
Amortized Cost	34	34
Estimated Fair Value	34	$ 34
Equity Securities [Member]
Available-for-Sale Securities
Amortized Cost	357
Gross Unrealized Losses	(77)
Estimated Fair Value	$ 280

Available-for-Sale Securities37

Available-for-Sale Securities Summary of the Classification of Available-for-Sale Securities (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Short-term marketable securities	$ 2,004	$ 1,756
Long-term marketable securities	13,003	11,601
Other long-term assets	280	0
Total	17,463	23,520
Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 2,176	$ 10,163

Available-for-Sale Securities38

Available-for-Sale Securities Summary of Available-for-Sale Securities by Contractual Maturity (Details) $ in Millions	Mar. 31, 2016USD ($)
Amortized Cost
Less than one year	$ 4,180
Greater than one year but less than five years	12,750
Greater than five years but less than ten years	185
Greater than ten years	33
Amortized Cost	17,148
Fair Value
Less than one year	4,180
Greater than one year but less than five years	12,785
Greater than five years but less than ten years	185
Greater than ten years	33
Available-for-sale Securities, Debt Securities	$ 17,183

Summary of Available-for-Sale S

Summary of Available-for-Sale Securities in a Continuous Unrealized Loss Position Deemed not to be Other-than-Temporarily Impaired (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ (84)	$ (51)
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	4,193	11,900
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	74	63
Available for Sale Securities - Gross Unrealized Losses	(84)	(51)
Continuous Unrealized Loss Position, Estimated Fair Value	4,267	11,963
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(5)	(23)
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	1,834	4,891
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	50	43
Available for Sale Securities - Gross Unrealized Losses	(5)	(23)
Continuous Unrealized Loss Position, Estimated Fair Value	1,884	4,934
U.S. treasury securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1)	(18)
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	1,075	4,342
Available for Sale Securities - Gross Unrealized Losses	(1)	(18)
Continuous Unrealized Loss Position, Estimated Fair Value	1,075	4,342
Residential mortgage and asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(1)	(6)
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	667	1,626
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	24	20
Available for Sale Securities - Gross Unrealized Losses	(1)	(6)
Continuous Unrealized Loss Position, Estimated Fair Value	691	1,646
U.S. government agencies securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	(2)
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	116	707
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value	0
Available for Sale Securities - Gross Unrealized Losses	0	(2)
Continuous Unrealized Loss Position, Estimated Fair Value	116	707
Non-U.S. government securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		(2)
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	221	313
Continuous Unrealized Loss Position, 12 Months or Greater, Estimated Fair Value		0
Available for Sale Securities - Gross Unrealized Losses		(2)
Continuous Unrealized Loss Position, Estimated Fair Value	221	313
Municipal debt securities
Schedule of Available-for-sale Securities [Line Items]
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value		21
Continuous Unrealized Loss Position, Estimated Fair Value		$ 21
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	(77)
Continuous Unrealized Loss Position, Less than 12 Months, Estimated Fair Value	280
Available for Sale Securities - Gross Unrealized Losses	(77)
Continuous Unrealized Loss Position, Estimated Fair Value	$ 280

Available-for-Sale Securities N

Available-for-Sale Securities Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016USD ($)position	Dec. 31, 2015USD ($)position
Investments, Debt and Equity Securities [Abstract]
Cash excluded from available-for-sale debt securities table	$ 4,100	$ 2,700
Securities in unrealized loss positions, number of positions (securities) | position	1,073	2,742
Other than temporary impairment losses, investments	$ 0	$ 0

Derivative Financial Instrume41

Derivative Financial Instruments Summary of Information about the Fair Values of Derivative Instruments on Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivative Asset Fair Value	$ 74	$ 210
Derivative Liability, Fair Value	140	41
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset Fair Value	73	209
Derivative Liability, Fair Value	139	40
Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset Fair Value	71	200
Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value	121	32
Designated as Hedging Instrument | Other Long-Term Assets
Derivatives, Fair Value [Line Items]
Derivative Asset Fair Value	2	9
Designated as Hedging Instrument | Other Long-Term Obligations
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value	18	8
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset Fair Value	1	1
Derivative Liability, Fair Value	1	1
Not Designated as Hedging Instrument | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset Fair Value	1	1
Not Designated as Hedging Instrument | Other Current Liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value	$ 1	$ 1

Derivative Financial Instrume42

Derivative Financial Instruments Summary of the effect of foreign currency exchange contracts on condensed consolidated statements of income (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gains (losses) recognized in AOCI (effective portion)	$ (160)	$ 389
Gains reclassified from AOCI into product sales (effective portion)	86	145
Gains recognized in Other income (expense), net (ineffective portion and amounts excluded from effectiveness testing)	14	1
Gains (losses) recognized in Other income (expense), net	$ (151)	$ 108

Derivative Financial Instrume43

Derivative Financial Instruments Table of Offsetting Derivative Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Derivative Asset [Abstract]
Gross Amounts of Recognized Assets	$ 74	$ 210
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Amount of Assets Presented in the Condensed Consolidated Balance Sheet	74	210
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheet - Derivative Financial Instruments	(66)	(38)
Gross Amounts Not Offset in the Condensed Consolidated Balance Sheet - Cash Collateral Received/Pledged	0	0
Net Amount (Legal Offset)	8	172
Derivative Liability [Abstract]
Gross Amount of Recognized Liabilities	(140)	(41)
Gross Amounts Offset in the Condensed Consolidated Balance Sheet	0	0
Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheet	(140)	(41)
Gross Amount Not Offset in the Condensed Consolidated Balance Sheet - Derivative Financial Instruments	66	38
Gross Amount Not Offset in the Condensed Consolidated Balance Sheet - Cash Collateral Received/Pledged	0	0
Net Amount (Legal Offset)	$ (74)	$ (3)

Derivative Financial Instrume44

Derivative Financial Instruments Narrative (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016		Mar. 04, 2016	Dec. 31, 2015
Derivative [Line Items]
Derivative, Notional Amount		$ 9,900			$ 9,100
Equity Component of Conversion Spread, Fair Value				$ 733
Convertible Note Hedge, Fair Value	[1]	792
Convertible Note Hedge, Fair Value		792	[1]	$ 733
Loss on Conversion Spread		(59)
Gain on Convertible Note Hedges		$ 59
Maximum [Member]
Derivative [Line Items]
Derivative, Average Remaining Maturity		18 months
[1]	See Note 4, Derivative Financial Instruments for further information.

Other Financial Information Inv

Other Financial Information Inventory (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Schedule of Inventory [Line Items]
Raw materials	$ 1,239	$ 1,332
Work in process	761	542
Finished goods	731	852
Total	2,731	2,726
Inventories	1,880	1,955
Other long-term assets	$ 851	$ 771

Other Financial Information (Na

Other Financial Information (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Inventory [Line Items]
Inventories	$ 1,880	$ 1,955
Efavirenz [Member] | BMS & Gilead Sciences, LLC Joint Venture
Inventory [Line Items]
Inventories	$ 1,300	$ 1,300

Other Financial Information Pre

Other Financial Information Prepaid and other current assets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Schedule of Prepaid and Other Current Assets [Line Items]
Prepaid taxes	$ 705	$ 773
Other prepaid expenses	319	240
Convertible note hedges	792	0
Other current assets	259	505
Total prepaid and other current assets	$ 2,075	$ 1,518

Other Financial Information Oth

Other Financial Information Other Accrued Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Accrued Liabilities, Current [Abstract]
Accrued royalties	$ 190	$ 237
Branded Prescription Drug fee	513	649
Compensation and employee benefits	235	380
Income taxes payable	51	65
Other accrued expenses	1,936	1,841
Total other accrued liabilities	$ 2,925	$ 3,172

Intangible Assets Schedule of C

Intangible Assets Schedule of Carrying Amount of Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Finite-lived intangible assets	$ 9,605	$ 9,815
Indefinite-lived intangible assets	318	432
Total intangible assets	$ 9,923	$ 10,247

Intangible Assets Schedule of F

Intangible Assets Schedule of Finite Lived Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 11,863	$ 11,863
Accumulated Amortization	2,258	2,048
Intangible asset - sofosbuvir
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	10,720	10,720
Accumulated Amortization	1,631	1,456
Intangible asset - Ranexa
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	688	688
Accumulated Amortization	388	363
Other
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	455	455
Accumulated Amortization	$ 239	$ 229

Intangible Assets Schedule of51

Intangible Assets Schedule of Future Amortization Expense (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Intangible Assets, Net (Excluding Goodwill) [Abstract]
2016 (remaining nine months)	$ 629
2,017	844
2,018	849
2,019	741
2,020	713
2021 and thereafter	5,829
Total	$ 9,605	$ 9,815

Intangible Assets Schedule of I

Intangible Assets Schedule of Indefinite Lived Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets	$ 318	$ 432
Other
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets	117	117
Indefinite-lived intangible asset - momelotinib
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets	$ 201	$ 315

Intangible Assets and Goodwill

Intangible Assets and Goodwill (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Acquired Indefinite-lived Intangible Assets [Line Items]
In-process research and development impairment	$ 114	$ 0
Cost of goods sold
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization of Finite-Lived Intangible Assets	210	$ 206
YM Biosciences [Member]
Acquired Indefinite-lived Intangible Assets [Line Items]
In-process research and development impairment	$ 114

Collaborative Arrangements Narr

Collaborative Arrangements Narrative (Details) - BMS & Gilead Sciences, LLC Joint Venture - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Total assets
Variable Interest Entity [Line Items]
Variable interest entity, assets	$ 2,441	$ 2,464
Cash and cash equivalents
Variable Interest Entity [Line Items]
Variable interest entity, assets	132	166
Accounts receivable, net
Variable Interest Entity [Line Items]
Variable interest entity, assets	251	269
Inventories
Variable Interest Entity [Line Items]
Variable interest entity, assets	2,056	2,027
Total liabilities
Variable Interest Entity [Line Items]
Variable interest entity, liabilities	929	1,055
Accounts payable
Variable Interest Entity [Line Items]
Variable interest entity, liabilities	544	606
Other accrued liabilities
Variable Interest Entity [Line Items]
Variable interest entity, liabilities	$ 385	$ 449

Collaborative Arrangements Coll

Collaborative Arrangements Collaborative Arrangement with Galapagos (Details) shares in Millions, $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2016USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2015USD ($)	Jan. 31, 2016€ / shares	Jan. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Available-for-sale Securities, Equity Securities, Noncurrent		$ 280				$ 0
Collaboration Arrangement Investment in Counterparty Ownership Percentage					14.75%
Research and development expenses		$ 1,265	$ 696
Percentage of Costs Responsible		80.00%
Galapagos [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License Fee Payment	$ 300
Available-for-sale Securities, Equity Securities, Noncurrent					$ 425
Share Price | € / shares				€ 58
Investment Owned, Balance, Shares | shares					6.8
Research and development expenses	68
Percentage of Costs Responsible		20.00%
Development And Regulatory Milestones-Based [Member] | Galapagos [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential Future Milestone Payment	755
Sales-Based Milestones [Member] | Galapagos [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential Future Milestone Payment	$ 600
Other Long-Term Assets | Galapagos [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Available-for-sale Securities, Amortized Cost Basis					$ 357

Debt and Credit Facility Schedu

Debt and Credit Facility Schedule of Carrying Amounts of Senior Notes (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Unamortized Debt Issuance Expense		$ 123
Debt, Long-term and Short-term, Combined Amount	$ 22,030	22,055	[1]
Less Current Portion	953	982	[1]
Total Long-Term Debt, Net	$ 21,077	21,073	[1]
Senior Unsecured Notes Due In December 2016
Debt Instrument [Line Items]
Stated interest rate	3.05%
Senior Unsecured Notes	$ 699	699	[1]
Senior Unsecured Notes Due in September 2018
Debt Instrument [Line Items]
Stated interest rate	1.85%
Senior Unsecured Notes	$ 997	997	[1]
Senior Unsecured Notes Due in April 2019
Debt Instrument [Line Items]
Stated interest rate	2.05%
Senior Unsecured Notes	$ 498	498	[1]
Senior Unsecured Notes Due In February 2020
Debt Instrument [Line Items]
Stated interest rate	2.35%
Senior Unsecured Notes	$ 498	497	[1]
Senior Unsecured Notes Due in September 2020
Debt Instrument [Line Items]
Stated interest rate	2.55%
Senior Unsecured Notes	$ 1,990	1,989	[1]
Senior Unsecured Notes Due April 2021 Member
Debt Instrument [Line Items]
Stated interest rate	4.50%
Senior Unsecured Notes	$ 993	992	[1]
Senior Unsecured Notes Due In December 2021
Debt Instrument [Line Items]
Stated interest rate	4.40%
Senior Unsecured Notes	$ 1,244	1,244	[1]
Senior Unsecured Notes Due in September 2022
Debt Instrument [Line Items]
Stated interest rate	3.25%
Senior Unsecured Notes	$ 995	995	[1]
Senior Unsecured Notes Due in April 2024
Debt Instrument [Line Items]
Stated interest rate	3.70%
Senior Unsecured Notes	$ 1,740	1,740	[1]
Senior Unsecured Notes Due in February 2025
Debt Instrument [Line Items]
Stated interest rate	3.50%
Senior Unsecured Notes	$ 1,742	1,742	[1]
Senior Unsecured Notes Due in March 2026
Debt Instrument [Line Items]
Stated interest rate	3.65%
Senior Unsecured Notes	$ 2,724	2,724	[1]
Senior Unsecured Notes Due in September 2035
Debt Instrument [Line Items]
Stated interest rate	4.60%
Senior Unsecured Notes	$ 988	988	[1]
Senior Unsecured Notes Due December 2041
Debt Instrument [Line Items]
Stated interest rate	5.65%
Senior Unsecured Notes	$ 995	995	[1]
Senior Unsecured Notes Due in April 2044
Debt Instrument [Line Items]
Stated interest rate	4.80%
Senior Unsecured Notes	$ 1,732	1,732	[1]
Senior Unsecured Notes Due in February 2045
Debt Instrument [Line Items]
Stated interest rate	4.50%
Senior Unsecured Notes	$ 1,728	1,728	[1]
Senior Unsecured Notes Due in March 2046
Debt Instrument [Line Items]
Stated interest rate	4.75%
Senior Unsecured Notes	$ 2,213	2,212	[1]
Convertible Senior Notes Due In May 2016
Debt Instrument [Line Items]
Stated interest rate	1.625%
Convertible Senior Notes	$ 254	$ 283	[1]
[1]	In connection with our adoption of the ASU relating to the presentation of debt issuance costs during the first quarter of 2016, debt balances at December 31, 2015 have been retrospectively adjusted by $123 million to include unamortized debt issuance costs. Prior to our adoption of the ASU, these unamortized debt issuance costs were included in prepaid and other current assets and other long-term assets in our Condensed Consolidated Balance Sheets.

Debt and Credit Facility (Narra

Debt and Credit Facility (Narrative) (Details) $ / shares in Units, shares in Millions	Jul. 31, 2010USD ($)$ / shares	Mar. 31, 2016USD ($)$ / sharesshares	Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Proceeds from convertible note hedges		$ 95,000,000	$ 154,000,000
Equity component of currently redeemable convertible notes		0		$ 2,000,000
Convertible Senior Notes Due May 2016
Debt Instrument [Line Items]
Debt principal repayment, conversion		31,000,000
Debt Instrument, Convertible, Beneficial Conversion Feature		$ 95,000,000
Debt Instrument, Convertible, Conversion Ratio	44.0428	44.7828
Debt Instrument, Face Amount	$ 1,000
Exercise price of warrants or rights (usd per share) | $ / shares	$ 22.71	$ 22.33
2016 Warrants
Debt Instrument [Line Items]
Exercise price of warrants or rights (usd per share) | $ / shares	$ 30.05	$ 28.33
Class of Warrant or Right, Outstanding | shares		9
Credit Facility Due January 2017
Debt Instrument [Line Items]
Long-term line of credit		$ 0

Commitment and Contingencies Na

Commitment and Contingencies Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
Jury awarded damages	$ 200

Stockholders' Equity Schedule o

Stockholders' Equity Schedule of Stockholders Equity (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)	1,422
Balance at December 31, 2015	$ 19,113
Net income	3,567	$ 4,332
Other comprehensive loss, net of tax	(252)	$ 238
Change in noncontrolling interest	41
Issuances under employee stock purchase plan	48
Issuances under equity incentive plans	40
Stock-based compensation	88
Tax benefits from employee stock plans	87
Repurchases of common stock	(8,128)
Convertible senior notes settlement	(95)
Convertible notes hedge settlement	95
Dividends declared	(587)
Reclassification of conversion spread of senior convertible notes	(733)
Reclassification of convertible notes hedges	733
Reclassification to equity component of currently redeemable convertible senior notes	$ 2
Ending Balance (in shares)	1,348
Balance at March 31, 2016	$ 14,019
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)	1,422
Balance at December 31, 2015	$ 1
Issuances under employee stock purchase plan (in shares)	1
Issuances under equity incentive plans (in shares)	6
Repurchases of common stock (in shares)	(81)
Ending Balance (in shares)	1,348
Balance at March 31, 2016	$ 1
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2015	444
Issuances under employee stock purchase plan	48
Issuances under equity incentive plans	40
Stock-based compensation	88
Tax benefits from employee stock plans	87
Repurchases of common stock	(193)
Convertible senior notes settlement	(95)
Convertible notes hedge settlement	95
Reclassification of conversion spread of senior convertible notes	(733)
Reclassification of convertible notes hedges	733
Reclassification to equity component of currently redeemable convertible senior notes	2
Balance at March 31, 2016	516
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2015	88
Other comprehensive loss, net of tax	(252)
Balance at March 31, 2016	(164)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2015	18,001
Net income	3,566
Repurchases of common stock	(7,935)
Dividends declared	(587)
Balance at March 31, 2016	13,045
Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2015	579
Net income	1
Change in noncontrolling interest	41
Balance at March 31, 2016	$ 621

Stockholders' Equity Schedule60

Stockholders' Equity Schedule of Accumulated Comprehensive Income (loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2014	$ 88
Other comprehensive income (loss) before reclassifications	(172)
Amounts reclassified from accumulated other comprehensive income (loss)	(80)
Net current period other comprehensive income (loss)	(252)	$ 238
Balance at March 31, 2015	(164)
Foreign Currency Items
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2014	(45)
Other comprehensive income (loss) before reclassifications	2
Amounts reclassified from accumulated other comprehensive income (loss)	0
Net current period other comprehensive income (loss)	2
Balance at March 31, 2015	(43)
Unrealized Gains and Losses on Available-for-Sale Securities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2014	(16)
Other comprehensive income (loss) before reclassifications	(24)
Amounts reclassified from accumulated other comprehensive income (loss)	0
Net current period other comprehensive income (loss)	(24)
Balance at March 31, 2015	(40)
Unrealized Gains and Losses on Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at December 31, 2014	149
Other comprehensive income (loss) before reclassifications	(150)
Amounts reclassified from accumulated other comprehensive income (loss)	(80)
Net current period other comprehensive income (loss)	(230)
Balance at March 31, 2015	$ (81)

Stockholders' Equity Narrative

Stockholders' Equity Narrative (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended		3 Months Ended
	Apr. 30, 2016	Feb. 29, 2016	Mar. 31, 2016	Jan. 31, 2016
Stock Repurchased
Stock Repurchased and Retired During Period, Value			$ 8,128
2015 Stock Repurchase Program
Stock Repurchased
Authorized amount				$ 15,000
Stock repurchased and retired during period (shares)			34
Stock Repurchased and Retired During Period, Value			$ 3,000
2016 Stock Repurchase Program [Member]
Stock Repurchased
Authorized amount		$ 12,000
Accelerated Share Repurchases, Date [Domain]
Stock Repurchased
Accelerated Share Repurchases, Payment		$ (5,000)
Stock repurchased and retired during period (shares)		46
Accelerated Share Repurchases, Initial Price Paid Per Share		$ 86.68
Subsequent Event [Member] | Accelerated Share Repurchases, Date [Domain]
Stock Repurchased
Stock repurchased and retired during period (shares)	8
Accelerated Share Repurchases, Final Price Paid Per Share	$ 92.09

Net Income Per Share Attribut62

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 ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Debt Instrument [Line Items]
Net income attributable to Gilead	$ 3,566	$ 4,333
Shares used in per share calculation - basic (in shares)	1,383	1,488
Stock options and equivalents (shares)	16	26
Conversion spread related to notes (shares)	7	16
Warrants related to the May Notes (shares)	6	39
Shares used in per share calculation - diluted (in shares)	1,412	1,569
Earnings Per Share, Basic	$ 2.58	$ 2.91
Earnings Per Share, Diluted	$ 2.53	$ 2.76

Net Income Per Share Attribut63

Net Income Per Share Attributable to Gilead Common Stockholders (Narrative) (Details) - shares shares in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Debt Instrument, Redemption [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4	1

Segment Information Segment rep

Segment Information Segment reporting information, revenue for reportable segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenue from External Customer [Line Items]
Product sales	$ 7,681	$ 7,405
Total antiviral products
Revenue from External Customer [Line Items]
Product sales	7,183	6,988
Harvoni
Revenue from External Customer [Line Items]
Product sales	3,017	3,579
Sovaldi
Revenue from External Customer [Line Items]
Product sales	1,277	972
Truvada
Revenue from External Customer [Line Items]
Product sales	898	771
Atripla
Revenue from External Customer [Line Items]
Product sales	675	734
Stribild
Revenue from External Customer [Line Items]
Product sales	477	356
Complera/Eviplera
Revenue from External Customer [Line Items]
Product sales	381	320
Viread
Revenue from External Customer [Line Items]
Product sales	272	234
Genvoya [Member]
Revenue from External Customer [Line Items]
Product sales	158	0
Other antiviral
Revenue from External Customer [Line Items]
Product sales	28	22
Letairis
Revenue from External Customer [Line Items]
Product sales	175	151
Ranexa
Revenue from External Customer [Line Items]
Product sales	144	117
AmBisome
Revenue from External Customer [Line Items]
Product sales	86	85
Zydelig
Revenue from External Customer [Line Items]
Product sales	49	26
Other
Revenue from External Customer [Line Items]
Product sales	$ 44	$ 38

Segment Information Schedule of

Segment Information Schedule of revenue by major customers (Details)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
McKesson Corp.
Revenue, Major Customer [Line Items]
Percentage of Revenues	21.00%	25.00%
AmerisourceBergen Corp.
Revenue, Major Customer [Line Items]
Percentage of Revenues	17.00%	21.00%
Cardinal Health, Inc.
Revenue, Major Customer [Line Items]
Percentage of Revenues	16.00%	17.00%
Minimum [Member]
Revenue, Major Customer [Line Items]
Percentage of Revenues	10.00%

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details)	3 Months Ended
	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Effective income tax rate from continuing operations	20.80%
Federal statutory income tax rate	35.00%