Gilead Sciences (GILD) 10-Q 6 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 30, 2019
Cover page.
Entity Interactive Data Current	Yes
Entity Address, Address Line One	333 Lakeside Drive
Title of 12(b) Security	Common Stock, par value, $0.001 per share
Entity Incorporation, State or Country Code	DE
Document Transition Report	false
Document Quarterly Report	true
Entity Registrant Name	GILEAD SCIENCES, INC.
Entity Central Index Key	0000882095
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Jun. 30, 2019
Entity File Number	0-19731
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Amendment Flag	false
Entity Emerging Growth Company	false
Entity Small Business Company	false
Entity Common Stock, Shares Outstanding		1,266,455,481
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Tax Identification Number	94-3047598
Trading Symbol	GILD
Security Exchange Name	NASDAQ
Entity Address, City or Town	Foster City,
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94404
City Area Code	650
Local Phone Number	574-3000

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 11,240	$ 17,940
Short-term marketable securities	15,943	12,149
Accounts receivable, net of allowances of $610 and $583, respectively	3,396	3,327
Inventories	884	814
Prepaid and other current assets	2,264	1,606
Total current assets	33,727	35,836
Property, plant and equipment, net	4,249	4,006
Long-term marketable securities	3,051	1,423
Intangible assets, net	15,152	15,738
Goodwill	4,117	4,117
Other long-term assets	2,914	2,555
Total assets	63,210	63,675
Current liabilities:
Accounts payable	617	790
Accrued government and other rebates	3,585	3,928
Other accrued liabilities	2,760	3,139
Current portion of long-term debt and other obligations, net	1,999	2,748
Total current liabilities	8,961	10,605
Long-term debt, net	24,084	24,574
Long-term income taxes payable	5,837	5,922
Other long-term obligations	1,577	1,040
Commitments and contingencies
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; 5,600 shares authorized; 1,267 and 1,282 shares issued and outstanding, respectively	1	1
Additional paid-in capital	2,684	2,282
Accumulated other comprehensive income	102	80
Retained earnings	19,829	19,024
Total Gilead stockholders’ equity	22,616	21,387
Noncontrolling interest	135	147
Total stockholders’ equity	22,751	21,534
Total liabilities and stockholders’ equity	$ 63,210	$ 63,675

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for accounts receivable and chargebacks	$ 610	$ 583
Preferred Stock, Par Value (usd per share)	$ 0.001	$ 0.001
Preferred Stock, Authorized (in shares)	5,000,000	5,000,000
Preferred Stock Outstanding (in shares)	0	0
Common Stock Par Value (usd per share)	$ 0.001	$ 0.001
Common Stock Authorized (in shares)	5,600,000,000	5,600,000,000
Common Stock Issued (in shares)	1,267,000,000	1,282,000,000
Common Stock Outstanding (in shares)	1,267,000,000	1,282,000,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues:
Revenues	$ 5,685	$ 5,648	$ 10,966	$ 10,736
Costs and expenses:
Cost of goods sold	1,000	1,196	1,957	2,197
Research and development expenses	1,160	1,192	2,217	2,129
Selling, general and administrative expenses	1,095	980	2,125	1,977
Total costs and expenses	3,255	3,368	6,299	6,303
Income from operations	2,430	2,280	4,667	4,433
Interest expense	(248)	(266)	(502)	(556)
Other income (expense), net	228	72	595	242
Income before provision for income taxes	2,410	2,086	4,760	4,119
Provision for income taxes	535	267	917	761
Net income	1,875	1,819	3,843	3,358
Net income (loss) attributable to noncontrolling interest	(5)	2	(12)	3
Net income attributable to Gilead	$ 1,880	$ 1,817	$ 3,855	$ 3,355
Net income per share attributable to Gilead common stockholders - basic (usd per share)	$ 1.48	$ 1.40	$ 3.03	$ 2.58
Shares used in per share calculation - basic (in shares)	1,270	1,298	1,273	1,302
Net income per share attributable to Gilead common stockholders - diluted (usd per share)	$ 1.47	$ 1.39	$ 3.01	$ 2.55
Shares used in per share calculation - diluted (in shares)	1,277	1,308	1,280	1,314
Product sales
Revenues:
Revenues	$ 5,607	$ 5,540	$ 10,807	$ 10,541
Royalty, contract and other revenues
Revenues:
Revenues	$ 78	$ 108	$ 159	$ 195

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 1,875	$ 1,819	$ 3,843	$ 3,358
Other comprehensive income (loss):
Net foreign currency translation gain (loss), net of tax	(13)	(25)	8	(18)
Available-for-sale debt securities:
Net unrealized gain (loss), net of tax	19	30	49	(6)
Reclassifications to net income, net of tax	0	4	0	4
Net change	19	34	49	(2)
Cash flow hedges:
Net unrealized gain, net of tax	1	118	29	57
Reclassifications to net income, net of tax	(35)	45	(64)	93
Net change	(34)	163	(35)	150
Other comprehensive income (loss)	(28)	172	22	130
Comprehensive income	1,847	1,991	3,865	3,488
Comprehensive income (loss) attributable to noncontrolling interest	(5)	2	(12)	3
Comprehensive income attributable to Gilead	$ 1,852	$ 1,989	$ 3,877	$ 3,485

Condensed Statements of Stockho

Condensed Statements of Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent	Retained Earnings [Member]	Noncontrolling Interest [Member]
Beginning period (in shares) at Dec. 31, 2017		1,308
Beginning Balance at Dec. 31, 2017	$ 20,501	$ 1	$ 1,264	$ 165	$ 19,012	$ 59
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,358				3,355	3
Other comprehensive income, net of tax	130			130
Issuances under employee stock purchase plan, Shares		1
Issuances under employee stock purchase plan	48		48
Issuance under equity incentive plans, Shares		8
Issuances under equity incentive plans	109		109
Stock-based compensation	477		477
Repurchases of common stock, shares		(21)
Repurchases of common stock	(1,580)		(54)		(1,526)
Dividends declared	(1,499)				(1,499)
Ending period (in shares) at Jun. 30, 2018		1,296
Ending Balance at Jun. 30, 2018	21,734	$ 1	1,844	2	19,825	62
Beginning period (in shares) at Mar. 31, 2018		1,300
Beginning Balance at Mar. 31, 2018	20,651	$ 1	1,564	(170)	19,196	60
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,819				1,817	2
Other comprehensive income, net of tax	172			172
Issuance under equity incentive plans, Shares		3
Issuances under equity incentive plans	45		45
Stock-based compensation	253		253
Repurchases of common stock, shares		(7)
Repurchases of common stock	(459)		(18)		(441)
Dividends declared	(747)				(747)
Ending period (in shares) at Jun. 30, 2018		1,296
Ending Balance at Jun. 30, 2018	$ 21,734	$ 1	1,844	2	19,825	62
Beginning period (in shares) at Dec. 31, 2018	1,282	1,282
Beginning Balance at Dec. 31, 2018	$ 21,534	$ 1	2,282	80	19,024	147
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	3,843				3,855	(12)
Other comprehensive income, net of tax	22			22
Issuances under employee stock purchase plan, Shares		1
Issuances under employee stock purchase plan	63		63
Issuance under equity incentive plans, Shares		6
Issuances under equity incentive plans	82		82
Stock-based compensation	319		319
Repurchases of common stock, shares		(22)
Repurchases of common stock	(1,496)		(62)		(1,434)
Dividends declared	$ (1,624)				(1,624)
Ending period (in shares) at Jun. 30, 2019	1,267	1,267
Ending Balance at Jun. 30, 2019	$ 22,751	$ 1	2,684	102	19,829	135
Beginning period (in shares) at Mar. 31, 2019		1,274
Beginning Balance at Mar. 31, 2019	22,091	$ 1	2,494	130	19,326	140
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,875				1,880	(5)
Other comprehensive income, net of tax	(28)			(28)
Issuance under equity incentive plans, Shares		2
Issuances under equity incentive plans	41		41
Stock-based compensation	175		175
Repurchases of common stock, shares		(9)
Repurchases of common stock	(593)		(26)		(567)
Dividends declared	$ (810)				(810)
Ending period (in shares) at Jun. 30, 2019	1,267	1,267
Ending Balance at Jun. 30, 2019	$ 22,751	$ 1	$ 2,684	$ 102	$ 19,829	$ 135

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Stockholders' Equity [Abstract]
Common Stock, Dividends, Per Share, Declared	$ 0.63	$ 0.57	$ 1.26	$ 1.14

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating Activities:
Net income	$ 3,843	$ 3,358
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	120	112
Amortization expense	587	601
Stock-based compensation expense	317	472
Deferred income taxes	28	(2)
Net unrealized (gains) losses from equity securities	(254)	19
Other	66	130
Changes in operating assets and liabilities:
Accounts receivable, net	(68)	277
Inventories	(12)	(34)
Prepaid expenses and other	(34)	622
Accounts payable	(166)	(193)
Income taxes payable	(274)	(1,838)
Accrued liabilities and other	(488)	319
Net cash provided by operating activities	3,665	3,843
Investing Activities:
Purchases of marketable debt securities	(17,022)	(2,009)
Proceeds from sales of marketable debt securities	1,564	676
Proceeds from maturities of marketable debt securities	10,029	11,539
Capital expenditures	(422)	(509)
Other	302	102
Net cash provided by (used in) investing activities	(6,153)	9,595
Financing Activities:
Proceeds from issuances of common stock	141	159
Repurchases of common stock	(1,422)	(1,489)
Repayments of debt and other obligations	(1,250)	(4,500)
Payments of dividends	(1,617)	(1,493)
Other	(75)	(424)
Net cash used in financing activities	(4,223)	(7,747)
Effect of exchange rate changes on cash and cash equivalents	11	(45)
Net change in cash and cash equivalents	(6,700)	5,646
Cash and cash equivalents at beginning of period	17,940	7,588
Cash and cash equivalents at end of period	$ 11,240	$ 13,234

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
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, our 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 June 30, 2019 , we did not have any material VIEs. 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, 2018 , 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 equivalents and marketable securities. Under our investment policy, we limit amounts invested in such securities by credit rating, maturity, industry group, investment type and issuer, except for securities issued by the U.S. government. We are not exposed to any significant concentrations of credit risk from these financial instruments. The goals of our investment policy, in order of priority, are as follows: safety and preservation of principal and diversification of risk; liquidity of investments sufficient to meet cash flow requirements; and a competitive after-tax rate of return. We are also subject to credit risk from our accounts receivable related to our product sales. The majority of our trade accounts receivable arises from product sales in the United States and Europe. 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 as of June 30, 2019 . Recently Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2016-02 “Leases” (ASU 2016-02) and subsequently issued supplemental adoption guidance and clarification (collectively, Topic 842). Topic 842 amends a number of aspects of lease accounting, including requiring lessees to recognize right-of-use assets and lease liabilities for operating leases with a lease term greater than one year. Topic 842 supersedes Topic 840 “Leases.” On January 1, 2019, we adopted Topic 842 using the modified retrospective approach. Results for reporting periods beginning after January 1, 2019 are presented under Topic 842, while prior period amounts are not adjusted and continue to be reported in accordance with our historical accounting under Topic 840. We elected the package of practical expedients permitted under the transition guidance within Topic 842, which allowed us to carry forward the historical lease classification, retain the initial direct costs for any leases that existed prior to the adoption of the standard and not reassess whether any contracts entered into prior to the adoption are leases. We also elected to account for lease and nonlease components in our lease agreements as a single lease component in determining lease assets and liabilities. In addition, we elected not to recognize the right-of-use assets and liabilities for leases with lease terms of one year or less. Upon adoption of Topic 842, we recorded $441 million of right-of-use assets within Other long-term assets and $ 490 million of operating lease liabilities, classified primarily within Other long-term obligations on our Condensed Consolidated Balance Sheet, as of January 1, 2019. The adoption did not have a material impact on our Condensed Consolidated Statements of Income or Condensed Consolidated Statements of Cash Flows. See Note 10 . Leases for additional information. Recently Issued Accounting Standards Not Yet Adopted In June 2016, the FASB issued Accounting Standards Update No. 2016-13 “Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments” (ASU 2016-13). ASU 2016-13 requires measurement and recognition of expected credit losses for financial assets. In April 2019, the FASB issued clarification to ASU 2016-13 within ASU 2019-04 “Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments.” The guidance will become effective for us beginning in the first quarter of 2020 and must be adopted using a modified retrospective approach, with certain exceptions. We are evaluating the impact of the adoption of these standards, but we currently do not expect a material impact on our Condensed Consolidated Financial Statements. In November 2018, the FASB issued Accounting Standards Update No. 2018-18 “Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606” (ASU 2018-18). ASU 2018-18 clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC 606 when the counterparty is a customer. In addition, the update precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue if the counterparty is not a customer for that transaction. This guidance will become effective for us beginning in the first quarter of 2020 and will be applied retrospectively to January 1, 2018 when we initially adopted Topic 606. Early adoption is permitted. We are evaluating the impact of the adoption of this standard, but we currently do not expect a material impact on our Condensed Consolidated Financial Statements.

Revenues

Revenues	6 Months Ended
	Jun. 30, 2019
Revenue from Contract with Customer [Abstract]
Revenues	REVENUES Disaggregation of Revenues The following table disaggregates our product sales by product and geographic region and disaggregates our royalty, contract and other revenues by geographic region (in millions): Three Months Ended June 30, 2019 Three Months Ended June 30, 2018 U.S. Europe Other International Total U.S. Europe Other International Total Product sales: Atripla $ 122 $ 26 $ 4 $ 152 $ 274 $ 39 $ 36 $ 349 Biktarvy 1,023 73 20 1,116 183 2 — 185 Complera/Eviplera 42 72 9 123 82 103 14 199 Descovy 246 69 43 358 311 78 14 403 Genvoya 733 177 70 980 904 207 49 1,160 Odefsey 266 111 10 387 303 77 5 385 Stribild 78 24 6 108 144 34 9 187 Truvada 657 41 20 718 649 86 30 765 Other HIV (1) 9 1 5 15 11 3 5 19 Revenue share – Symtuza (2) 55 29 — 84 — 13 — 13 AmBisome 10 60 35 105 14 55 34 103 Ledipasvir/Sofosbuvir (3) 86 22 85 193 230 22 79 331 Letairis 204 — — 204 244 — — 244 Ranexa 19 — — 19 208 — — 208 Sofosbuvir/Velpatasvir (4) 219 156 118 493 239 168 93 500 Vemlidy 71 5 40 116 59 3 14 76 Viread 9 28 38 75 16 32 34 82 Vosevi 53 15 7 75 86 20 3 109 Yescarta 99 21 — 120 68 — — 68 Zydelig 12 14 — 26 17 22 — 39 Other (5) 41 97 2 140 27 41 47 115 Total product sales 4,054 1,041 512 5,607 4,069 1,005 466 5,540 Royalty, contract and other revenues 19 58 1 78 14 79 15 108 Total revenues $ 4,073 $ 1,099 $ 513 $ 5,685 $ 4,083 $ 1,084 $ 481 $ 5,648 Six Months Ended June 30, 2019 Six Months Ended June 30, 2018 U.S. Europe Other International Total U.S. Europe Other International Total Product sales: Atripla $ 255 $ 42 $ 26 $ 323 $ 502 $ 90 $ 71 $ 663 Biktarvy 1,762 121 26 1,909 218 2 — 220 Complera/Eviplera 86 134 18 238 149 212 28 389 Descovy 479 137 84 700 585 153 26 764 Genvoya 1,461 370 164 1,995 1,757 393 92 2,242 Odefsey 548 217 19 784 582 135 10 727 Stribild 145 42 17 204 277 63 21 361 Truvada 1,208 74 42 1,324 1,156 183 78 1,417 Other HIV (1) 20 2 10 32 20 4 8 32 Revenue share – Symtuza (2) 97 53 — 150 — 20 — 20 AmBisome 18 117 63 198 31 111 68 210 Ledipasvir/Sofosbuvir (3) 203 49 166 418 464 78 137 679 Letairis 401 — — 401 448 — — 448 Ranexa 174 — — 174 403 — — 403 Sofosbuvir/Velpatasvir (4) 449 310 225 984 508 366 162 1,036 Vemlidy 136 9 72 217 106 6 22 134 Viread 21 42 84 147 23 62 94 179 Vosevi 98 31 9 138 172 36 8 216 Yescarta 189 27 — 216 108 — — 108 Zydelig 23 29 1 53 31 40 1 72 Other (5) 77 117 8 202 56 56 109 221 Total product sales 7,850 1,923 1,034 10,807 7,596 2,010 935 10,541 Royalty, contract and other revenues 41 114 4 159 34 131 30 195 Total revenues $ 7,891 $ 2,037 $ 1,038 $ 10,966 $ 7,630 $ 2,141 $ 965 $ 10,736 ____________________ Notes: (1) Includes Emtriva and Tybost (2) Represents our revenue from cobicistat (C), emtricitabine (FTC) and tenofovir alafenamide (TAF) in Symtuza (darunavir/C/FTC/TAF), a fixed dose combination product commercialized by Janssen Sciences Ireland UC (Janssen) (3) Amounts consist of sales of Harvoni and the authorized generic version of Harvoni sold by our separate subsidiary, Asegua Therapeutics LLC (4) Amounts consist of sales of Epclusa and the authorized generic version of Epclusa sold by our separate subsidiary, Asegua Therapeutics LLC (5) Includes Cayston, Hepsera and Sovaldi Revenues Recognized from Performance Obligations Satisfied in Prior Periods Revenues recognized from performance obligations satisfied in prior years related to royalties for licenses of our intellectual property were $171 million and $326 million for the three and six months ended June 30, 2019 , respectively, and $131 million and $228 million for the three and six months ended June 30, 2018 , respectively. Changes in estimates for variable consideration related to sales made in prior years resulted in a $193 million and $300 million increase in revenues for the three and six months ended June 30, 2019 , respectively, and a $91 million and $4 million increase for the three and six months ended June 30, 2018 , respectively. Contract Balances Our contract assets, which consist of unbilled amounts primarily from arrangements where the licensing of intellectual property is the only or predominant performance obligation, totaled $149 million and $125 million as of June 30, 2019 and December 31, 2018 , respectively. Contract liabilities were not material as of June 30, 2019 and December 31, 2018 .

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [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 include quoted prices in active markets for identical assets or liabilities; • Level 2 inputs 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 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 assets and 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 debt securities, accounts receivable, foreign currency exchange contracts, equity securities, accounts payable and short-term and long-term debt. Cash and cash equivalents, marketable debt securities, certain equity securities and foreign currency exchange contracts are reported at their respective fair values on our Condensed Consolidated Balance Sheets. Equity securities without readily determinable fair values are recorded using the measurement alternative of cost less impairment, if any, adjusted for observable price changes in orderly transactions for identical or similar investments of the same issuer. Short-term and long-term debt are reported at their amortized costs on 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): June 30, 2019 December 31, 2018 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Available-for-sale debt securities: U.S. treasury securities $ 3,916 $ — $ — $ 3,916 $ 3,969 $ — $ — $ 3,969 Certificates of deposit — 5,385 — 5,385 — 4,361 — 4,361 U.S. government agencies securities — 1,531 — 1,531 — 938 — 938 Non-U.S. government securities — 420 — 420 — 305 — 305 Corporate debt securities — 13,271 — 13,271 — 13,067 — 13,067 Residential mortgage and asset-backed securities — 536 — 536 — 1,524 — 1,524 Equity securities: Money market funds 3,007 — — 3,007 5,305 — — 5,305 Publicly traded equity securities 1,172 16 — 1,188 881 — — 881 Deferred compensation plan 156 — — 156 124 — — 124 Foreign currency derivative contracts — 48 — 48 — 78 — 78 Total $ 8,251 $ 21,207 $ — $ 29,458 $ 10,279 $ 20,273 $ — $ 30,552 Liabilities: Deferred compensation plan $ 156 $ — $ — $ 156 $ 124 $ — $ — $ 124 Foreign currency derivative contracts — 6 — 6 — 1 — 1 Total $ 156 $ 6 $ — $ 162 $ 124 $ 1 $ — $ 125 Changes in the fair value of equity securities resulted in net unrealized gains of $57 million and $254 million for the three and six months ended June 30, 2019 , respectively, and net unrealized losses of $64 million and $19 million for the three and six months ended June 30, 2018 , respectively, which were included in Other income (expense), net on our Condensed Consolidated Statements of Income. Investments in equity securities without readily determinable fair values were not material for the periods presented. The following table summarizes the classification of our equity securities in our Condensed Consolidated Balance Sheets (in millions): June 30, 2019 December 31, 2018 Cash and cash equivalents $ 3,007 $ 5,305 Prepaid and other current assets 1,178 863 Other long-term assets 166 142 Total $ 4,351 $ 6,310 Our available-for-sale debt securities are classified as cash equivalents, short-term marketable securities and long-term marketable securities on our Condensed Consolidated Balance Sheets. See Note 4 . Available-for-Sale Debt Securities for additional 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-based and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate the 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-month time horizon and all are with counterparties that have a minimum credit rating of A- or equivalent by S&P Global Ratings, Moody’s Investors Service, Inc. or Fitch Ratings, Inc. We estimate the fair values of these contracts by taking into consideration the 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 exchange rates, London Interbank Offered Rates (LIBOR) and swap rates. These inputs, where applicable, are observable at commonly quoted intervals. The total estimated fair values of our short-term and long-term debt, determined using Level 2 inputs based on their quoted market values, were approximately $28.0 billion and $27.1 billion as of June 30, 2019 and December 31, 2018 , respectively, and the carrying values were $26.1 billion and $27.3 billion as of June 30, 2019 and December 31, 2018 , respectively.

Available-for-Sale Debt Securit

Available-for-Sale Debt Securities	6 Months Ended
	Jun. 30, 2019
Debt Securities, Available-for-sale [Abstract]
Available-for-Sale Debt Securities	AVAILABLE-FOR-SALE DEBT SECURITIES The following table summarizes our available-for-sale debt securities (in millions): June 30, 2019 December 31, 2018 Amortized Gross Gross Estimated Amortized Gross Gross Estimated U.S. treasury securities $ 3,917 $ 1 $ (2 ) $ 3,916 $ 3,978 $ — $ (9 ) $ 3,969 Certificates of deposit 5,385 — — 5,385 4,361 — — 4,361 U.S. government agencies securities 1,531 — — 1,531 943 — (5 ) 938 Non-U.S. government securities 420 — — 420 307 — (2 ) 305 Corporate debt securities 13,272 3 (4 ) 13,271 13,095 1 (29 ) 13,067 Residential mortgage and asset-backed securities 537 — (1 ) 536 1,532 — (8 ) 1,524 Total $ 25,062 $ 4 $ (7 ) $ 25,059 $ 24,216 $ 1 $ (53 ) $ 24,164 The following table summarizes the classification of our available-for-sale debt securities in our Condensed Consolidated Balance Sheets (in millions): June 30, 2019 December 31, 2018 Cash and cash equivalents $ 6,065 $ 10,592 Short-term marketable securities 15,943 12,149 Long-term marketable securities 3,051 1,423 Total $ 25,059 $ 24,164 The following table summarizes our available-for-sale debt securities by contractual maturity (in millions): June 30, 2019 Amortized Cost Fair Value Within one year $ 22,010 $ 22,008 After one year through five years 3,016 3,015 After five years through ten years 19 19 After ten years 17 17 Total $ 25,062 $ 25,059 The following table summarizes our available-for-sale debt securities that were in a continuous unrealized loss position, but were not deemed to be other-than-temporarily impaired (in millions): Less Than 12 Months 12 Months or Greater Total Gross Estimated Gross Estimated Gross Estimated June 30, 2019 U.S. treasury securities $ (1 ) $ 1,401 $ (1 ) $ 470 $ (2 ) $ 1,871 Certificates of deposit — 8 — — — 8 U.S. government agencies securities — 391 — 393 — 784 Non-U.S. government securities — 11 — 161 — 172 Corporate debt securities (1 ) 922 (3 ) 1,988 (4 ) 2,910 Residential mortgage and asset-backed securities — 26 (1 ) 437 (1 ) 463 Total $ (2 ) $ 2,759 $ (5 ) $ 3,449 $ (7 ) $ 6,208 December 31, 2018 U.S. treasury securities $ — $ 896 $ (9 ) $ 1,383 $ (9 ) $ 2,279 U.S. government agencies securities — 30 (5 ) 553 (5 ) 583 Non-U.S. government securities — 86 (2 ) 192 (2 ) 278 Corporate debt securities (1 ) 1,600 (28 ) 4,204 (29 ) 5,804 Residential mortgage and asset-backed securities — 192 (8 ) 1,186 (8 ) 1,378 Total $ (1 ) $ 2,804 $ (52 ) $ 7,518 $ (53 ) $ 10,322 We held a total of 593 and 1,348 positions, which were in an unrealized loss position, as of June 30, 2019 and December 31, 2018 , respectively. Based on our review of these securities, we believe we had no other-than-temporary impairments as of June 30, 2019 and December 31, 2018 , 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 not material for the three and six months ended June 30, 2019 and 2018

Derivative Financial Instrument

Derivative Financial Instruments	6 Months Ended
	Jun. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	DERIVATIVE FINANCIAL INSTRUMENTS 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, primarily the Euro. 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 unrealized 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 on our Condensed Consolidated Statements of Income. We hedge our exposure to foreign currency exchange rate fluctuations for forecasted product sales that are denominated in a non-functional currency. The derivative instruments we use to hedge this exposure are designated as cash flow hedges and have maturities of 18 months or less. Upon executing a hedging contract and quarterly thereafter, we assess hedge effectiveness using regression analysis. The unrealized gains or losses in Accumulated other comprehensive income ( AOCI) are reclassified into product sales when the respective hedged transactions affect earnings. The majority of gains and losses related to the hedged forecasted transactions reported in AOCI as of June 30, 2019 are expected to be reclassified to product sales within 12 months . The cash flow effects of our derivative contracts for the six months ended June 30, 2019 and 2018 were included within Net cash provided by operating activities on our Condensed Consolidated Statements of Cash Flows. We had notional amounts on foreign currency exchange contracts outstanding of $2.9 billion and $2.2 billion as of June 30, 2019 and December 31, 2018 , respectively. While all our derivative contracts allow us the right to offset assets and liabilities, we have presented amounts on a gross basis. The following table summarizes the classification and fair values of derivative instruments in our Condensed Consolidated Balance Sheets (in millions): June 30, 2019 Asset Derivatives Liability Derivatives Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Other current assets $ 47 Other accrued liabilities $ (4 ) Foreign currency exchange contracts Other long-term assets 1 Other long-term obligations (2 ) Total derivatives designated as hedges 48 (6 ) Derivatives not designated as hedges: Foreign currency exchange contracts Other current assets — Other accrued liabilities — Total derivatives not designated as hedges — — Total derivatives $ 48 $ (6 ) December 31, 2018 Asset Derivatives Liability Derivatives Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Other current assets $ 73 Other accrued liabilities $ (1 ) Foreign currency exchange contracts Other long-term assets 5 Other long-term obligations — Total derivatives designated as hedges 78 (1 ) Derivatives not designated as hedges: Foreign currency exchange contracts Other current assets — Other accrued liabilities — Total derivatives not designated as hedges — — Total derivatives $ 78 $ (1 ) The following table summarizes the effect of our foreign currency exchange contracts on our Condensed Consolidated Financial Statements (in millions): Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 Derivatives designated as hedges: Gains recognized in AOCI $ 1 $ 119 $ 29 $ 58 Gains (losses) reclassified from AOCI into product sales 36 (45 ) 65 (93 ) Derivatives not designated as hedges: Gains (losses) recognized in Other income (expense), net $ (5 ) $ 10 $ (11 ) $ (4 ) The following table summarizes the potential effect of offsetting our foreign currency exchange contracts on our Condensed Consolidated Balance Sheets (in millions): Gross Amounts Not Offset on our Condensed Consolidated Balance Sheets Description Gross Amounts of Recognized Assets/Liabilities Gross Amounts Offset on our Condensed Consolidated Balance Sheets Amounts of Assets/Liabilities Presented on our Condensed Consolidated Balance Sheets Derivative Financial Instruments Cash Collateral Received/ Pledged Net Amount (Legal Offset) As of June 30, 2019 Derivative assets $ 48 $ — $ 48 $ (6 ) $ — $ 42 Derivative liabilities (6 ) — (6 ) 6 — — As of December 31, 2018 Derivative assets $ 78 $ — $ 78 $ (1 ) $ — $ 77 Derivative liabilities (1 ) — (1 ) 1 — — From time to time, we may discontinue cash flow hedges and, as a result, record related amounts in Other income (expense), net on our Condensed Consolidated Statements of Income. There was no discontinuance of cash flow hedges for the three and six months ended June 30, 2019 and 2018

Collaborative And Other Arrange

Collaborative And Other Arrangements	6 Months Ended
	Jun. 30, 2019
Collaborative and Other Arrangements [Abstract]
Collaborative and Other Arrangements [Text Block]	COLLABORATIVE AND OTHER ARRANGEMENTS We enter into collaborations and other similar arrangements with third parties for the development and commercialization of certain products and product candidates. These arrangements may include non-refundable up-front payments, payments by us for options to acquire certain rights, contingent obligations by us for potential development and regulatory milestone payments and/or sales-based milestone payments, royalty payments, revenue or profit sharing arrangements, cost sharing arrangements and equity investments. During the three and six months ended June 30, 2019 and 2018 , we entered into several collaborative and other similar arrangements, including equity investments and licensing arrangements, that we do not consider to be individually material. Cash outflows and accrued up-front payments related to these arrangements totaled $206 million and $393 million for the three and six months ended June 30, 2019 , respectively, and $284 million and $304 million for the three and six months ended June 30, 2018 , respectively. We recorded up-front collaboration and licensing expenses related to these arrangements of $165 million and $291 million for the three and six months ended June 30, 2019 , respectively, and $160 million for both the three and six months ended June 30, 2018 within Research and development expenses on our Condensed Consolidated Statements of Income and the remaining amounts were recorded in Prepaid and other current assets and Other long-term assets on our Condensed Consolidated Balance Sheets. Under the financial terms of these arrangements, we may be required to make payments upon achievement of various developmental, regulatory and commercial milestones, which could be significant. Future milestone payments, if any, will be reflected on our Condensed Consolidated Statements of Income when the corresponding events become probable. In addition, we may be required to pay significant royalties on future sales if products related to these arrangements are commercialized. The payment of these amounts, however, is contingent upon the occurrence of various future events, which have a high degree of uncertainty of occurrence.

Other Financial Information

Other Financial Information	6 Months Ended
	Jun. 30, 2019
Other Financial Information [Abstract]
Other Financial Information	OTHER FINANCIAL INFORMATION Inventories The following table summarizes our inventories (in millions): June 30, 2019 December 31, 2018 Raw materials $ 1,832 $ 1,888 Work in process 265 235 Finished goods 498 507 Total $ 2,595 $ 2,630 Reported as: Inventories $ 884 $ 814 Other long-term assets 1,711 1,816 Total $ 2,595 $ 2,630 Amounts reported as other long-term assets primarily consisted of raw materials as of June 30, 2019 and December 31, 2018 . Other Accrued Liabilities The following table summarizes the components of other accrued liabilities (in millions): June 30, 2019 December 31, 2018 Compensation and employee benefits $ 433 $ 555 Accrued payment for marketing-related rights acquired from Japan Tobacco Inc. 175 365 Other accrued expenses 2,152 2,219 Total $ 2,760 $ 3,139

Intangible Assets

Intangible Assets	6 Months Ended
	Jun. 30, 2019
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Intangible Assets	INTANGIBLE ASSETS The following table summarizes our intangible assets, net (in millions): June 30, 2019 December 31, 2018 Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Adjustment Net Carrying Amount Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Adjustment Net Carrying Amount Finite-lived assets: Intangible asset - sofosbuvir $ 10,720 $ (3,903 ) $ — $ 6,817 $ 10,720 $ (3,554 ) $ — $ 7,166 Intangible asset - axicabtagene ciloleucel (DLBCL) 6,200 (588 ) — 5,612 6,200 (416 ) — 5,784 Intangible asset - Ranexa 688 (688 ) — — 688 (678 ) — 10 Other 1,098 (415 ) (3 ) 680 1,096 (359 ) (3 ) 734 Total finite-lived assets 18,706 (5,594 ) (3 ) 13,109 18,704 (5,007 ) (3 ) 13,694 Indefinite-lived assets - In Process Research & Development 2,047 — (4 ) 2,043 2,047 — (3 ) 2,044 Total intangible assets $ 20,753 $ (5,594 ) $ (7 ) $ 15,152 $ 20,751 $ (5,007 ) $ (6 ) $ 15,738 Aggregate amortization expense related to finite-lived intangible assets was $288 million and $587 million for the three and six months ended June 30, 2019 , respectively, and $300 million and $601 million for the three and six months ended June 30, 2018 , respectively, and was primarily included in Cost of goods sold on our Condensed Consolidated Statements of Income. The following table summarizes the estimated future amortization expense associated with our finite-lived intangible assets as of June 30, 2019 (in millions): Fiscal Year Amount 2019 (remaining six months) $ 563 2020 1,125 2021 1,125 2022 1,125 2023 1,125 Thereafter 8,046 Total $ 13,109

Debt and Credit Facilities

Debt and Credit Facilities	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Debt and Credit Facilities	DEBT AND CREDIT FACILITIES The following table summarizes our borrowings under various financing arrangements (in millions): Carrying Amount Type of Borrowing Issue Date Due Date Interest Rate June 30, 2019 December 31, 2018 Senior Unsecured September 2017 March 2019 3-month LIBOR + 0.22% $ — $ 750 Senior Unsecured March 2014 April 2019 2.05% — 500 Senior Unsecured September 2017 September 2019 1.85% 999 999 Senior Unsecured September 2017 September 2019 3-month LIBOR + 0.25% 500 499 Senior Unsecured November 2014 February 2020 2.35% 500 499 Senior Unsecured September 2015 September 2020 2.55% 1,997 1,996 Senior Unsecured March 2011 April 2021 4.50% 998 997 Senior Unsecured December 2011 December 2021 4.40% 1,248 1,247 Senior Unsecured September 2016 March 2022 1.95% 498 498 Senior Unsecured September 2015 September 2022 3.25% 997 997 Senior Unsecured September 2016 September 2023 2.50% 746 746 Senior Unsecured March 2014 April 2024 3.70% 1,744 1,744 Senior Unsecured November 2014 February 2025 3.50% 1,745 1,745 Senior Unsecured September 2015 March 2026 3.65% 2,733 2,731 Senior Unsecured September 2016 March 2027 2.95% 1,245 1,245 Senior Unsecured September 2015 September 2035 4.60% 990 990 Senior Unsecured September 2016 September 2036 4.00% 741 740 Senior Unsecured December 2011 December 2041 5.65% 995 995 Senior Unsecured March 2014 April 2044 4.80% 1,734 1,734 Senior Unsecured November 2014 February 2045 4.50% 1,731 1,730 Senior Unsecured September 2015 March 2046 4.75% 2,217 2,216 Senior Unsecured September 2016 March 2047 4.15% 1,725 1,724 Total debt, net 26,083 27,322 Less current portion 1,999 2,748 Total long-term debt, net $ 24,084 $ 24,574 In March 2019 , we repaid $750 million of our senior unsecured notes upon maturity that were issued in September 2017 , and in April 2019 , we repaid $500 million of our senior unsecured notes upon maturity that were issued in March 2014 . We are required to comply with certain covenants under our credit agreement and note indentures governing our senior notes. As of June 30, 2019 , we were not in violation of any covenants. Additionally, as of June 30, 2019 and December 31, 2018 , there were no amounts outstanding under our $2.5 billion five -year revolving credit facility agreement maturing in May 2021.

Leases

Leases	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Leases	LEASES We lease facilities and equipment primarily related to administrative, research and development and sales and marketing activities under various non-cancelable operating leases in the United States and markets outside the United States. We determine if an arrangement contains a lease at inception. Right-of-use assets and lease liabilities are recognized at the commencement date based on the present value of the lease payments over the lease term, which is the non-cancelable period stated in the contract adjusted for any options to extend or terminate when it is reasonably certain that we will exercise that option. Some of our leases include options to extend the terms for up to 15 years and some include options to terminate the lease within one year after the lease commencement date. Right-of-use assets include any prepaid lease payments and exclude lease incentives and initial direct costs incurred. As of June 30, 2019, we do not have material finance leases. As most of our operating leases do not provide an implicit interest rate, we use a portfolio approach to determine a collateralized incremental borrowing rate based on the information available at the commencement date to determine the lease liability. Operating lease expense for the minimum lease payments is recognized on a straight-line basis over the lease term. Operating lease expenses including variable costs and short-term leases were $38 million and $74 million for the three and six months ended June 30, 2019 , respectively. The following table summarizes balance sheet and other information related to our operating leases as of June 30, 2019 (in millions, except weighted average data): Classification Amount Right-of-use assets, net Other long-term assets $ 504 Lease liabilities - current Other accrued liabilities $ 73 Lease liabilities - noncurrent Other long-term obligations $ 481 Weighted average remaining lease term 9.5 years Weighted average discount rate 3.60 % The following table summarizes other supplemental information related to our operating leases (in millions): Three Months Ended Six Months Ended June 30, 2019 June 30, 2019 Cash paid for amounts included in the measurement of lease liabilities $ 18 $ 36 Right-of-use assets obtained in exchange for lease liabilities $ 70 $ 100 The following table summarizes a maturity analysis of our operating lease liabilities showing the aggregate lease payments as of June 30, 2019 (in millions): Fiscal Year Amount 2019 (remaining six months) $ 47 2020 87 2021 83 2022 75 2023 66 Thereafter 305 Total undiscounted lease payments 663 Less: imputed interest (109 ) Total discounted lease payments $ 554 The following table summarizes the aggregate undiscounted non-cancelable future minimum lease payments for operating leases under the prior leases standard as of December 31, 2018 (in millions): Fiscal Year Amount 2019 $ 89 2020 78 2021 66 2022 60 2023 52 Thereafter 229 Total minimum lease payments $ 574

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
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. We recognize accruals for such actions to the extent that we conclude that a loss is both probable and reasonably estimable. We accrue for the best estimate of a loss within a range; however, if no estimate in the range is better than any other, then we accrue the minimum amount in the range. If we determine that a loss is reasonably possible and the loss or range of loss can be estimated, we disclose the possible loss. Unless otherwise noted, 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. We did no t recognize any accruals for the actions described below in our Condensed Consolidated Balance Sheets as of June 30, 2019 and December 31, 2018 , as we did not believe losses were probable. Litigation Related to Sofosbuvir In 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 2013, we received approval from U.S. Food and Drug Administration (FDA) for sofosbuvir, now known commercially as Sovaldi. Sofosbuvir is also included in all of our marketed HCV products. We have received a number of litigation 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 are aware of patents and patent applications owned by third parties that have been or may in the future be alleged by such parties to cover the use of our HCV products. If third parties obtain valid and enforceable patents, and successfully prove infringement of those patents by our HCV products, we could be required to pay significant monetary damages. We cannot predict the ultimate outcome of intellectual property claims related to our HCV products. We have spent, and will continue to spend, significant resources defending against these claims. Litigation with Idenix Pharmaceuticals, Inc. (Idenix), Universita Degli Studi di Cagliari (UDSG), Centre National de la Recherche Scientifique and L’Universite Montpellier II In 2013, Idenix, 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 infringes U.S. Patent No. 7,608,600 (the ‘600 patent). Also in 2013, Idenix and UDSG sued us in the U.S. District Court for the District of Massachusetts alleging that the commercialization of sofosbuvir infringes U.S. Patent Nos. 6,914,054 (the ‘054 patent) and 7,608,597 (the ‘597 patent). In 2014, the court transferred the Massachusetts litigation to the U.S. District Court for the District of Delaware. Prior to trial in 2016, Idenix committed to give us a covenant not to sue with respect to any claims arising out of the ‘054 patent related to sofosbuvir and withdrew that patent from the trial. A jury trial was held in 2016 on the ‘597 patent, and the jury found that we willfully infringed the asserted claims of the ‘597 patent and awarded Idenix $2.54 billion in past damages. In 2018, the judge invalidated Idenix’s ‘597 patent and vacated the jury’s award of $2.54 billion in past damages. Idenix appealed this decision to the U.S. Court of Appeals for the Federal Circuit (CAFC), and oral argument took place in July 2019. No decision has been handed down yet. We believe the Delaware court’s decision correctly found that, as a matter of law, the ‘597 patent is invalid, and we remain confident in the merits of our case on appeal. We believe that the possibility of a material adverse outcome on this matter is remote. In 2014, the European Patent Office (EPO) granted Idenix’s 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 2016, and the EPO ruled in our favor and revoked the ‘489 patent. Idenix has appealed. In 2014, Idenix also initiated infringement proceedings against us in Germany and France alleging that the commercialization of Sovaldi would infringe the German and French counterparts of the ‘489 patent. In 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 2016. Idenix has not appealed this decision of the German court staying the proceedings. Upon Idenix’s request, the French proceedings have been stayed. Litigation with the University of Minnesota The University of Minnesota (the University) has obtained Patent No. 8,815,830 (the ‘830 patent), which purports to broadly cover nucleosides with antiviral and anticancer activity. In 2016, the University filed a lawsuit against us in the U.S. District Court for the District of Minnesota, alleging that the commercialization of sofosbuvir-containing products infringes the ‘830 patent. We believe the ‘830 patent is invalid and will not be infringed by the continued commercialization of sofosbuvir. In 2017, the court granted our motion to transfer the case to California. We have also filed four petitions for inter partes review with the USPTO Patent Trial and Appeal Board (PTAB) alleging that all asserted claims are invalid for anticipation and obviousness. In 2018, the District Court stayed the litigation until after the PTAB rules on our petitions for inter partes review. Litigation Related to Axicabtagene Ciloleucel We own patents and patent applications that claim axicabtagene ciloleucel chimeric DNA segments. Third parties may have, or may obtain rights to, patents that allegedly could be used to prevent or attempt to prevent us from commercializing axicabtagene ciloleucel or to require us to obtain a license in order to commercialize axicabtagene ciloleucel. For example, we are aware that Juno Therapeutics, Inc. (Juno) has exclusively licensed Patent No. 7,446,190 (the ‘190 patent), which was issued to Sloan Kettering Cancer Center. In September 2017, Juno and Sloan Kettering Cancer Center filed a lawsuit against us in the U.S. District Court for the Central District of California, alleging that the commercialization of axicabtagene ciloleucel infringes the ‘190 patent. In October 2017, following FDA approval for Yescarta, Juno filed a second complaint alleging that axicabtagene ciloleucel infringes the ‘190 patent. Juno subsequently moved to dismiss the September 2017 complaint and has maintained the October 2017 complaint. The court has set a trial date of December 2019 for this lawsuit. We cannot predict the ultimate outcome of intellectual property claims related to axicabtagene ciloleucel. If Juno’s patent is upheld as valid and Juno successfully proves infringement of that patent by axicabtagene ciloleucel, we could be required to pay significant monetary damages or we could be prevented from selling Yescarta unless we were able to obtain a license to this patent. Such a license may not be available on commercially reasonable terms or at all. Litigation Related to Bictegravir In 2018, ViiV Healthcare Company (ViiV) filed a lawsuit against us in the U.S. District Court of Delaware, alleging that the commercialization of bictegravir, sold commercially in combination with tenofovir alafenamide and emtricitabine as Biktarvy, infringes ViiV’s U.S. Patent No. 8,129,385 (the ‘385 patent), which was issued to Shionogi & Co. Ltd. and GlaxoSmithKline LLC. The ‘385 patent is the compound patent covering ViiV’s dolutegravir. Bictegravir is structurally different from dolutegravir, and we believe that bictegravir does not infringe the claims of the ‘385 patent. To the extent that ViiV’s patent claims are interpreted to cover bictegravir, we believe those claims are invalid. The U.S. Patent and Trademark Office (USPTO) has granted us patents covering bictegravir. The court has set a trial date of September 2020 for this lawsuit. In 2018, ViiV also filed a lawsuit against us in the Federal Court of Canada, alleging that our activities relating to our bictegravir compound have infringed ViiV’s Canadian Patent No. 2,606,282 (the ‘282 patent), which was issued to Shionogi & Co. Ltd. and ViiV. The ‘282 patent is the compound patent covering ViiV’s dolutegravir. We believe that bictegravir does not infringe the claims of the ‘282 patent. To the extent that ViiV’s patent claims are interpreted to cover bictegravir, we believe those claims are invalid. We cannot predict the ultimate outcome of intellectual property claims related to bictegravir. If ViiV’s patents are upheld as valid and ViiV successfully proves infringement of those patents by bictegravir, we could be required to pay significant monetary damages. 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. To seek approval for a generic version of a product having NCE status, a generic company may submit its ANDA to FDA four years after the branded product’s approval. Current legal proceedings of significance with generic manufacturers include: HIV Products In 2018, we received notice that Zydus Pharmaceuticals (USA) Inc. (Zydus) submitted an ANDA to FDA requesting permission to manufacture and market generic versions of Truvada at various dosage strengths. In the notice, Zydus alleges that two patents associated with emtricitabine and four patents associated with the emtricitabine and tenofovir disoproxil fumarate fixed-dose combination are invalid, unenforceable and/or will not be infringed by Zydus’ manufacture, use or sale of generic versions of Truvada at various dosage strengths. In response, we filed a lawsuit against Zydus in the U.S. District Court for the District of New Jersey for infringement of our patents. In 2018, we received notice that Mylan Pharmaceuticals Inc. (Mylan) submitted an ANDA to FDA requesting permission to manufacture and market a generic version of Stribild. In the notice, Mylan alleges that one patent owned by Japan Tobacco Inc. (JT) and associated with elvitegravir is invalid, unenforceable and/or will not be infringed by Mylan’s manufacture, use or sale of a generic version of Stribild. In 2019, JT filed a lawsuit against Mylan in the U.S. District Court for the Northern District of West Virginia for infringement of its patent. In 2019, JT reached an agreement with Mylan to resolve the lawsuit, which has been dismissed. HCV Products In 2018, we received notices from Natco Pharma Limited (Natco) and Teva Pharmaceuticals (Teva) that they have each submitted an ANDA to FDA requesting permission to manufacture and market a generic version of Sovaldi. In Teva’s notice, it alleges that nine patents associated with sofosbuvir are invalid, unenforceable and/or will not be infringed by Teva’s manufacture, use or sale of generic versions of Sovaldi. In response, we filed lawsuits against Teva in the U.S. District Court for the District of New Jersey and the U.S. District Court for the District of Delaware for infringement of these patents. In Natco’s notice, it alleges that two patents associated with sofosbuvir are invalid, unenforceable and/or will not be infringed by Natco’s manufacture, use or sale of generic versions of Sovaldi. We also filed lawsuits against Natco in the U.S. District Court for the District of New Jersey and the U.S. District Court for the District of Delaware for infringement of these patents. In 2018, we reached an agreement with Teva to resolve the lawsuit, which has been dismissed. The settlement agreement has been filed with the Federal Trade Commission and Department of Justice as required by law. In 2019, we reached an agreement with Natco to resolve the lawsuit, which has been dismissed. The settlement agreement has been filed with the Federal Trade Commission and Department of Justice as required by law. European Patent Claims In 2015, several parties filed oppositions in the EPO requesting revocation of one of our granted European patents covering sofosbuvir that expires in 2028. In 2016, the EPO upheld the validity of certain claims of our sofosbuvir patent. We have appealed this decision, seeking to restore all of the original claims, and several of the original opposing parties have also appealed, requesting full revocation. The appeal process may take several years. In 2017, several parties filed oppositions in the EPO requesting revocation of our granted European patent relating to sofosbuvir that expires in 2024. The EPO conducted an oral hearing for this opposition in 2018 and upheld the claims. Two of the original opposing parties have appealed, requesting full revocation. The appeal process may take several years. In 2016, several parties filed oppositions in the EPO requesting revocation of our granted European patent covering TAF that expires in 2021. In 2017, the EPO upheld the validity of the claims of our TAF patent. Three parties have appealed this decision. The appeal process may take several years. In 2017, several parties filed oppositions in the EPO requesting revocation of our granted European patent relating to TAF hemifumarate that expires in 2032. We responded to these oppositions, and a hearing was held in February 2019. The patent was upheld at this hearing. Three parties have appealed this decision. The appeal process may take several years. In 2016, three parties filed oppositions in the EPO requesting revocation of our granted European patent covering cobicistat that expires in 2027. In 2017, the EPO upheld the validity of the claims of our cobicistat patent. One of the original opposing parties has appealed this decision. The appeal process may take several years. 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, TAF hemifumarate and cobicistat in the European Union 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. If we lose patent protection for any of these compounds, our revenues and results of operations 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. Government Investigations and Related Litigation In 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 2014, the U.S. Department of Justice informed us that, following an investigation, it declined to intervene in a False Claims Act lawsuit filed by two former employees. Also in 2014, the former employees served a First Amended Complaint, and the U.S. District Court for the Northern District of California issued an order granting in its entirety, without prejudice, our motion to dismiss the First Amended Complaint. In 2015, the plaintiffs filed a Second Amended Complaint, and the District Court issued an order granting our motion to dismiss the Second Amended Complaint. The plaintiffs then filed a notice of appeal in the U.S. Court of Appeals for the Ninth Circuit. In 2017, the Ninth Circuit granted our motion to stay the case pending an appeal to the U.S. Supreme Court, and we filed a Petition for a Writ of Certiorari to the U.S. Supreme Court. In 2018, the Solicitor General submitted a brief for the United States to the U.S. Supreme Court stating its intention to file a motion to dismiss under the federal False Claims Act. In January 2019, the U.S. Supreme Court denied the petition and the case has been remanded to the District Court. In March 2019, the Department of Justice filed a motion to dismiss the Second Amended Complaint, which the District Court is expected to rule upon later this year. In 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 documents concerning our provision of financial assistance to patients for our HCV products. We are cooperating with this inquiry. In 2017, we received a subpoena from the U.S. Attorney’s Office for the District of Massachusetts requesting documents related to our copay coupon program and Medicaid price reporting methodology. We are cooperating with this inquiry. In 2017, we received a voluntary request for information from the U.S. Attorney’s Office for the Eastern District of Pennsylvania requesting information related to our reimbursement support offerings, clinical education programs and interactions with specialty pharmacies for Sovaldi and Harvoni. In 2018, we received another voluntary request for information related to our speaker programs and advisory boards for our HCV and hepatitis B virus products. We are cooperating with these voluntary requests. In 2017, we received a subpoena from the California Department of Insurance and the Alameda County District Attorney’s Office requesting documents related to our marketing activities, reimbursement support offerings, clinical education programs and interactions with specialty pharmacies for Harvoni and Sovaldi. We are cooperating with this inquiry. In 2017, we also received a subpoena from the U.S. Attorney’s Office for the Southern District of New York requesting documents related to our promotional speaker programs for HIV. We are cooperating with this inquiry. Product Liability We have been named as a defendant in one class action lawsuit and various product liability lawsuits related to Viread, Truvada, Atripla, Complera and Stribild. Plaintiffs allege that Viread, Truvada, Atripla, Complera and/or Stribild caused them to suffer kidney and/or bone injuries. The lawsuits, all of which are pending in state or federal court in California, involve hundreds of plaintiffs. Plaintiffs in these cases seek damages and other relief on various grounds for alleged personal injury and economic loss. We intend to vigorously defend ourselves in these actions. While we believe these cases are without merit, we cannot predict the ultimate outcome. If plaintiffs are successful in their claims, we could be required to pay significant monetary damages. Antitrust and Consumer Protection We (along with JT, Bristol-Myers Squibb Company and Johnson & Johnson, Inc.) have been named as defendants in a class action lawsuit filed in 2019 related to various drugs used to treat HIV, including drugs used in combination antiretroviral therapy. Plaintiffs allege that we (and the other defendants) engaged in various conduct to restrain competition in violation of federal and state antitrust laws and state consumer protection laws. The lawsuit, a consolidated action pending in the United States District Court for the Northern District of California, seeks to bring claims on behalf of a nationwide class of end-payor purchasers. Plaintiffs seek damages, permanent injunctive relief, and other relief. We intend to vigorously defend ourselves in this action. While we believe this action is without merit, we cannot predict the ultimate outcome. If plaintiffs are successful in their claims, we could be required to pay significant monetary damages or could be subject to permanent injunctive relief. 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	6 Months Ended
	Jun. 30, 2019
Equity [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY Stock Repurchase Program In the first quarter of 2016, our Board of Directors authorized a $12.0 billion stock repurchase program ( 2016 Program ) under which repurchases may be made in the open market or in privately negotiated transactions. We started repurchases under the 2016 Program in April 2016. During the three and six months ended June 30, 2019 , we repurchased and retired 9 million and 21 million shares of our common stock for $588 million and $1.4 billion , respectively, through open market transactions under the 2016 Program . During the three and six months ended June 30, 2018 , we repurchased and retired 7 million and 20 million shares of our common stock for $450 million and $1.5 billion , respectively, through open market transactions under the 2016 Program. As of June 30, 2019 , the remaining authorized repurchase amount under the 2016 Program was $3.7 billion . Accumulated Other Comprehensive Income (Loss) The following table summarizes the changes in AOCI by component, net of tax during the six months ended June 30, 2019 and 2018 (in millions): Foreign Currency Translation Unrealized Gains and Losses on Available-for-Sale Debt Securities Unrealized Gains and Losses on Cash Flow Hedges Total Balance at December 31, 2018 $ 47 $ (52 ) $ 85 $ 80 Net unrealized gain 8 49 29 86 Reclassifications to net income — — (64 ) (64 ) Net current period other comprehensive income (loss) 8 49 (35 ) 22 Balance at June 30, 2019 $ 55 $ (3 ) $ 50 $ 102 Foreign Currency Translation Unrealized Gains and Losses on Available-for-Sale Debt Securities Unrealized Gains and Losses on Cash Flow Hedges Total Balance at December 31, 2017 $ 85 $ 194 $ (114 ) $ 165 Reclassifications to retained earnings as a result of the adoption of new accounting standards — (293 ) — (293 ) Balance at January 1, 2018 85 (99 ) (114 ) (128 ) Net unrealized gain (loss) (18 ) (6 ) 57 33 Reclassifications to net income — 4 93 97 Net current period other comprehensive income (loss) (18 ) (2 ) 150 130 Balance at June 30, 2018 $ 67 $ (101 ) $ 36 $ 2 The amounts reclassified to net income for gains and losses on cash flow hedges are recorded as part of Product sales on our Condensed Consolidated Statements of Income. See Note 5 . Derivative Financial Instruments for additional information. The amounts reclassified to net income for gains and losses on available-for-sale debt securities are recorded as part of Other income (expense), net on our Condensed Consolidated Statements of Income. The income tax impact allocated to each component of other comprehensive income was not material for the periods presented.

Net Income Per Share Attributab

Net Income Per Share Attributable to Gilead Common Stockholders	6 Months Ended
	Jun. 30, 2019
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 and other dilutive securities outstanding during the period. The potentially dilutive shares of our common stock resulting from the assumed exercise of outstanding stock options and equivalents were determined under the treasury stock method. Potential shares of common stock excluded from the computation of diluted net income per share attributable to Gilead common shareholders because their effect would have been antidilutive were 17 million and 14 million for the three and six months ended June 30, 2019 , respectively, and 21 million and 16 million for the three and six months ended June 30, 2018 , respectively. The following table summarizes the calculation of basic and diluted net income per share attributable to Gilead common stockholders (in millions, except per share amounts): Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 Net income attributable to Gilead $ 1,880 $ 1,817 $ 3,855 $ 3,355 Shares used in per share calculation - basic 1,270 1,298 1,273 1,302 Dilutive effect of stock options and equivalents 7 10 7 12 Shares used in per share calculation - diluted 1,277 1,308 1,280 1,314 Net income per share attributable to Gilead common stockholders - basic $ 1.48 $ 1.40 $ 3.03 $ 2.58 Net income per share attributable to Gilead common stockholders - diluted $ 1.47 $ 1.39 $ 3.01 $ 2.55

Segment Information

Segment Information	6 Months Ended
	Jun. 30, 2019
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, who is our chief executive officer. See Note 2 . Revenues for a summary of disaggregated revenues by product and geographic region. 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 Six Months Ended June 30, June 30, 2019 2018 2019 2018 AmerisourceBergen Corp. 20 % 20 % 20 % 20 % Cardinal Health, Inc. 21 % 20 % 21 % 20 % McKesson Corp. 20 % 21 % 20 % 21 %

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Our effective income tax rate of 22.2% for the three months ended June 30, 2019 differed from the U.S. federal statutory rate of 21% primarily due to the tax on Global Intangible Low-Taxed Income, state taxes and our portion of the non-tax deductible Branded Prescription Drug (BPD) fee, partially offset by earnings from non-U.S. subsidiaries that operate in jurisdictions with lower tax rates than the United States. Our effective income tax rate of 19.3% for the six months ended June 30, 2019 differed from the U.S. federal statutory rate of 21% primarily due to a $119 million tax benefit related to settlements with taxing authorities and earnings from non-U.S. subsidiaries that operate in jurisdictions with lower tax rates than the United States, partially offset by the Global Intangible Low-Taxed Income, state taxes and our portion of the non-tax deductible BPD fee. Our effective income tax rates of 12.8% and 18.5% for the three and six months ended June 30, 2018 , respectively, differed from the U.S. federal statutory rate of 21% primarily due to tax benefits of $202 million and $153 million , respectively, related to settlements of tax examinations and earnings from non-U.S. subsidiaries that operate in jurisdictions with lower tax rates than the United States, partially offset by the Global Intangible Low-Taxed Income and state taxes. We file federal, state and foreign income tax returns in the United States and in many foreign jurisdictions. For federal and California income tax purposes, the statute of limitations is open for 2013 and 2010 onwards, respectively. Our income tax returns are subject to audit by federal, state and foreign tax authorities. We are currently under examination by the IRS for the tax years from 2013 to 2015 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 regularly 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. Our unrecognized tax benefits decreased by $119 million during the six months ended June 30, 2019 due to settlements with taxing authorities. As of June 30, 2019 , we believe that it is reasonably possible that our unrecognized tax benefits may materially change in the next 12 months due to potential resolutions with a taxing authority. An estimate of the range of the reasonably possible change cannot be determined at this time. In June 2019, the U.S. Court of Appeals for the Ninth Circuit (Ninth Circuit) issued an opinion in Altera Corp. v. Commissioner reversing the prior decision of the United States Tax Court and requiring related parties in an intercompany cost-sharing arrangement to share expenses related to stock-based compensation. It is possible that there will be further judicial review of this issue; and as such, we believe the law to be unsettled and continue to recognize tax benefits for the exclusion of stock-based compensation from our cost-sharing arrangement. We will continue to monitor this issue and will reassess our evaluation of the financial reporting impact when more information becomes available.

Subsequent Event (Notes)

Subsequent Event (Notes)	6 Months Ended
	Jun. 30, 2019
Subsequent Events [Abstract]
Subsequent Events [Text Block]	SUBSEQUENT EVENT In July 2019, we entered into an Option, License and Collaboration Agreement (the Collaboration Agreement) with Galapagos NV (Galapagos), pursuant to which the parties entered into a global collaboration that covers Galapagos’ current and future product portfolio (other than filgotinib, an investigational, selective JAK1 inhibitor for inflammatory disease indications, which is already subject to the parties’ existing collaborative arrangement). Upon the closing of the Collaboration Agreement, we will make an up-front license and option fee payment of $3.95 billion and an equity investment in Galapagos of approximately $1.1 billion . Collaboration Agreement Under the Collaboration Agreement, we will acquire rights to participate in the development and commercialization of GLPG-1690, Galapagos’ Phase 3 candidate for idiopathic pulmonary fibrosis, and receive option rights to participate in the development and commercialization of GLPG-1972, a Phase 2b candidate for osteoarthritis, and Galapagos’ other current and future clinical programs that have entered clinical development during the first ten years of the collaboration. We may exercise our option to acquire a license to a program after the receipt of a data package from a completed, qualifying Phase 2 study for such program (or, in certain circumstances, the first Phase 3 study). If GLPG-1690 receives marketing approval in the United States, we will pay Galapagos $325 million as well as tiered royalties. If we exercise our option to acquire a license to the GLPG-1972 program after the completion of Galapagos’ ongoing Phase 2 trial, we will pay a $250 million option exercise fee. In addition, following opt-in, Galapagos would be eligible to receive up to $750 million in development, regulatory and commercial milestones on GLPG-1972 as well as tiered royalties. With respect to all other products in Galapagos’ current and future pipeline, if we exercise our option to acquire a license to a program, we will pay a $150 million option exercise fee per program. In addition, Galapagos will receive tiered royalties ranging from 20% to 24% on net sales of all Galapagos products optioned by us as part of the Collaboration Agreement (including GLPG-1690 and GLPG-1972), subject to customary royalty terms and adjustments. If we exercise our option rights for a program, we will share development costs and mutually agreed commercialization costs equally with Galapagos, subject to the ability of either party to conduct certain independent research or development activities and independent commercial activities in their respective territories. Galapagos will retain exclusive rights to commercialize products included in the optioned program in the European Union, Iceland, Norway, Lichtenstein and Switzerland, and we will have exclusive commercialization rights for such products for all other countries globally, except for GLPG-1972 where we will only acquire the U.S. rights as they are the only rights not subject to a license agreement between Galapagos and a third party. For each program we opt-in to, we are required to use commercially reasonable efforts to obtain marketing approval in the United States and Japan and to market, promote, sell or distribute one product for one indication in the United States and Japan. We may terminate the collaboration in its entirety or on a program-by-program and country-by-country basis with advance notice as well as following other customary termination events. Subscription Agreement In July 2019, we entered into a Subscription Agreement (the Subscription Agreement) with Galapagos pursuant to which we agreed to purchase, subject to certain conditions, the number of ordinary shares of Galapagos, no par value (the Subscription Shares), sufficient to bring our aggregate ownership percentage in Galapagos at the closing of the Subscription Agreement to 20.1% on a fully diluted basis. The price per subscription share is equal to €140.59 . In addition, subject to and upon Galapagos’ shareholders’ approval, we will be issued and will subscribe to warrants that confer the right to subscribe for a number of new shares to be issued by Galapagos sufficient to bring the number of shares owned by us to 29.9% of the issued and outstanding shares. We are subject to a 10 -year standstill restricting our ability to acquire voting securities of Galapagos exceeding more than 29.9% of the then issued and outstanding voting securities of Galapagos. We agreed not to, without the prior consent of Galapagos, dispose of any equity securities of Galapagos prior to the earlier of the second anniversary of the closing of the Subscription Agreement and the termination of the Subscription Agreement (if the closing does not occur). During the period running from the date that is two years following the closing of the Subscription Agreement until the date that is five years following the closing of the Subscription Agreement, we shall not, without the prior consent of Galapagos, dispose of any equity securities of Galapagos if after such disposal we would own less than 20.1% of the then issued and outstanding voting securities of Galapagos. We will have the right to have two designees appointed to Galapagos’ board of directors (the Galapagos Board) following the closing of the Subscription Agreement and the approval of Galapagos’ shareholders. In the event that our designees are not approved by Galapagos’ shareholders, our designees will be invited to the Galapagos Board as observers.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2019
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, our 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 June 30, 2019 , we did not have any material VIEs. 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, 2018 , 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 equivalents and marketable securities. Under our investment policy, we limit amounts invested in such securities by credit rating, maturity, industry group, investment type and issuer, except for securities issued by the U.S. government. We are not exposed to any significant concentrations of credit risk from these financial instruments. The goals of our investment policy, in order of priority, are as follows: safety and preservation of principal and diversification of risk; liquidity of investments sufficient to meet cash flow requirements; and a competitive after-tax rate of return. We are also subject to credit risk from our accounts receivable related to our product sales. The majority of our trade accounts receivable arises from product sales in the United States and Europe. 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 as of June 30, 2019
Recently Issued Accounting Standards	Recently Adopted Accounting Standards In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2016-02 “Leases” (ASU 2016-02) and subsequently issued supplemental adoption guidance and clarification (collectively, Topic 842). Topic 842 amends a number of aspects of lease accounting, including requiring lessees to recognize right-of-use assets and lease liabilities for operating leases with a lease term greater than one year. Topic 842 supersedes Topic 840 “Leases.” On January 1, 2019, we adopted Topic 842 using the modified retrospective approach. Results for reporting periods beginning after January 1, 2019 are presented under Topic 842, while prior period amounts are not adjusted and continue to be reported in accordance with our historical accounting under Topic 840. We elected the package of practical expedients permitted under the transition guidance within Topic 842, which allowed us to carry forward the historical lease classification, retain the initial direct costs for any leases that existed prior to the adoption of the standard and not reassess whether any contracts entered into prior to the adoption are leases. We also elected to account for lease and nonlease components in our lease agreements as a single lease component in determining lease assets and liabilities. In addition, we elected not to recognize the right-of-use assets and liabilities for leases with lease terms of one year or less. Upon adoption of Topic 842, we recorded $441 million of right-of-use assets within Other long-term assets and $ 490 million of operating lease liabilities, classified primarily within Other long-term obligations on our Condensed Consolidated Balance Sheet, as of January 1, 2019. The adoption did not have a material impact on our Condensed Consolidated Statements of Income or Condensed Consolidated Statements of Cash Flows. See Note 10 . Leases for additional information. Recently Issued Accounting Standards Not Yet Adopted In June 2016, the FASB issued Accounting Standards Update No. 2016-13 “Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments” (ASU 2016-13). ASU 2016-13 requires measurement and recognition of expected credit losses for financial assets. In April 2019, the FASB issued clarification to ASU 2016-13 within ASU 2019-04 “Codification Improvements to Topic 326, Financial Instruments-Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments.” The guidance will become effective for us beginning in the first quarter of 2020 and must be adopted using a modified retrospective approach, with certain exceptions. We are evaluating the impact of the adoption of these standards, but we currently do not expect a material impact on our Condensed Consolidated Financial Statements. In November 2018, the FASB issued Accounting Standards Update No. 2018-18 “Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606” (ASU 2018-18). ASU 2018-18 clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC 606 when the counterparty is a customer. In addition, the update precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue if the counterparty is not a customer for that transaction. This guidance will become effective for us beginning in the first quarter of 2020 and will be applied retrospectively to January 1, 2018 when we initially adopted Topic 606. Early adoption is permitted. We are evaluating the impact of the adoption of this standard, but we currently do not expect a material impact on our Condensed Consolidated Financial Statements.

Revenues Disaggregation of Reve

Revenues Disaggregation of Revenues (Tables)	6 Months Ended
	Jun. 30, 2019
Disaggregation of Revenue [Abstract]
Disaggregation of Revenues	The following table disaggregates our product sales by product and geographic region and disaggregates our royalty, contract and other revenues by geographic region (in millions): Three Months Ended June 30, 2019 Three Months Ended June 30, 2018 U.S. Europe Other International Total U.S. Europe Other International Total Product sales: Atripla $ 122 $ 26 $ 4 $ 152 $ 274 $ 39 $ 36 $ 349 Biktarvy 1,023 73 20 1,116 183 2 — 185 Complera/Eviplera 42 72 9 123 82 103 14 199 Descovy 246 69 43 358 311 78 14 403 Genvoya 733 177 70 980 904 207 49 1,160 Odefsey 266 111 10 387 303 77 5 385 Stribild 78 24 6 108 144 34 9 187 Truvada 657 41 20 718 649 86 30 765 Other HIV (1) 9 1 5 15 11 3 5 19 Revenue share – Symtuza (2) 55 29 — 84 — 13 — 13 AmBisome 10 60 35 105 14 55 34 103 Ledipasvir/Sofosbuvir (3) 86 22 85 193 230 22 79 331 Letairis 204 — — 204 244 — — 244 Ranexa 19 — — 19 208 — — 208 Sofosbuvir/Velpatasvir (4) 219 156 118 493 239 168 93 500 Vemlidy 71 5 40 116 59 3 14 76 Viread 9 28 38 75 16 32 34 82 Vosevi 53 15 7 75 86 20 3 109 Yescarta 99 21 — 120 68 — — 68 Zydelig 12 14 — 26 17 22 — 39 Other (5) 41 97 2 140 27 41 47 115 Total product sales 4,054 1,041 512 5,607 4,069 1,005 466 5,540 Royalty, contract and other revenues 19 58 1 78 14 79 15 108 Total revenues $ 4,073 $ 1,099 $ 513 $ 5,685 $ 4,083 $ 1,084 $ 481 $ 5,648 Six Months Ended June 30, 2019 Six Months Ended June 30, 2018 U.S. Europe Other International Total U.S. Europe Other International Total Product sales: Atripla $ 255 $ 42 $ 26 $ 323 $ 502 $ 90 $ 71 $ 663 Biktarvy 1,762 121 26 1,909 218 2 — 220 Complera/Eviplera 86 134 18 238 149 212 28 389 Descovy 479 137 84 700 585 153 26 764 Genvoya 1,461 370 164 1,995 1,757 393 92 2,242 Odefsey 548 217 19 784 582 135 10 727 Stribild 145 42 17 204 277 63 21 361 Truvada 1,208 74 42 1,324 1,156 183 78 1,417 Other HIV (1) 20 2 10 32 20 4 8 32 Revenue share – Symtuza (2) 97 53 — 150 — 20 — 20 AmBisome 18 117 63 198 31 111 68 210 Ledipasvir/Sofosbuvir (3) 203 49 166 418 464 78 137 679 Letairis 401 — — 401 448 — — 448 Ranexa 174 — — 174 403 — — 403 Sofosbuvir/Velpatasvir (4) 449 310 225 984 508 366 162 1,036 Vemlidy 136 9 72 217 106 6 22 134 Viread 21 42 84 147 23 62 94 179 Vosevi 98 31 9 138 172 36 8 216 Yescarta 189 27 — 216 108 — — 108 Zydelig 23 29 1 53 31 40 1 72 Other (5) 77 117 8 202 56 56 109 221 Total product sales 7,850 1,923 1,034 10,807 7,596 2,010 935 10,541 Royalty, contract and other revenues 41 114 4 159 34 131 30 195 Total revenues $ 7,891 $ 2,037 $ 1,038 $ 10,966 $ 7,630 $ 2,141 $ 965 $ 10,736 ____________________ Notes: (1) Includes Emtriva and Tybost (2) Represents our revenue from cobicistat (C), emtricitabine (FTC) and tenofovir alafenamide (TAF) in Symtuza (darunavir/C/FTC/TAF), a fixed dose combination product commercialized by Janssen Sciences Ireland UC (Janssen) (3) Amounts consist of sales of Harvoni and the authorized generic version of Harvoni sold by our separate subsidiary, Asegua Therapeutics LLC (4) Amounts consist of sales of Epclusa and the authorized generic version of Epclusa sold by our separate subsidiary, Asegua Therapeutics LLC (5) Includes Cayston, Hepsera and Sovaldi

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Summary of assets and liabilities measured at fair value	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): June 30, 2019 December 31, 2018 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Available-for-sale debt securities: U.S. treasury securities $ 3,916 $ — $ — $ 3,916 $ 3,969 $ — $ — $ 3,969 Certificates of deposit — 5,385 — 5,385 — 4,361 — 4,361 U.S. government agencies securities — 1,531 — 1,531 — 938 — 938 Non-U.S. government securities — 420 — 420 — 305 — 305 Corporate debt securities — 13,271 — 13,271 — 13,067 — 13,067 Residential mortgage and asset-backed securities — 536 — 536 — 1,524 — 1,524 Equity securities: Money market funds 3,007 — — 3,007 5,305 — — 5,305 Publicly traded equity securities 1,172 16 — 1,188 881 — — 881 Deferred compensation plan 156 — — 156 124 — — 124 Foreign currency derivative contracts — 48 — 48 — 78 — 78 Total $ 8,251 $ 21,207 $ — $ 29,458 $ 10,279 $ 20,273 $ — $ 30,552 Liabilities: Deferred compensation plan $ 156 $ — $ — $ 156 $ 124 $ — $ — $ 124 Foreign currency derivative contracts — 6 — 6 — 1 — 1 Total $ 156 $ 6 $ — $ 162 $ 124 $ 1 $ — $ 125
Summary of Classification of Equity Securities	The following table summarizes the classification of our equity securities in our Condensed Consolidated Balance Sheets (in millions): June 30, 2019 December 31, 2018 Cash and cash equivalents $ 3,007 $ 5,305 Prepaid and other current assets 1,178 863 Other long-term assets 166 142 Total $ 4,351 $ 6,310

Available-for-Sale Debt Secur_2

Available-for-Sale Debt Securities (Tables)	6 Months Ended
	Jun. 30, 2019
Debt Securities, Available-for-sale [Abstract]
Reconciliation of Available-for-Sale Debt Securities from Cost Basis to Fair Value	The following table summarizes our available-for-sale debt securities (in millions): June 30, 2019 December 31, 2018 Amortized Gross Gross Estimated Amortized Gross Gross Estimated U.S. treasury securities $ 3,917 $ 1 $ (2 ) $ 3,916 $ 3,978 $ — $ (9 ) $ 3,969 Certificates of deposit 5,385 — — 5,385 4,361 — — 4,361 U.S. government agencies securities 1,531 — — 1,531 943 — (5 ) 938 Non-U.S. government securities 420 — — 420 307 — (2 ) 305 Corporate debt securities 13,272 3 (4 ) 13,271 13,095 1 (29 ) 13,067 Residential mortgage and asset-backed securities 537 — (1 ) 536 1,532 — (8 ) 1,524 Total $ 25,062 $ 4 $ (7 ) $ 25,059 $ 24,216 $ 1 $ (53 ) $ 24,164
Summary of Classification of Available-for-Sale Debt Securities	The following table summarizes the classification of our available-for-sale debt securities in our Condensed Consolidated Balance Sheets (in millions): June 30, 2019 December 31, 2018 Cash and cash equivalents $ 6,065 $ 10,592 Short-term marketable securities 15,943 12,149 Long-term marketable securities 3,051 1,423 Total $ 25,059 $ 24,164
Summary of Available-for-Sale Debt Securities by Contractual Maturity	The following table summarizes our available-for-sale debt securities by contractual maturity (in millions): June 30, 2019 Amortized Cost Fair Value Within one year $ 22,010 $ 22,008 After one year through five years 3,016 3,015 After five years through ten years 19 19 After ten years 17 17 Total $ 25,062 $ 25,059
Summary of Available-for-Sale Debt Securities in a Continuous Loss Position Deemed not to be Other-than-Temporarily Impaired	The following table summarizes our available-for-sale debt securities that were in a continuous unrealized loss position, but were not deemed to be other-than-temporarily impaired (in millions): Less Than 12 Months 12 Months or Greater Total Gross Estimated Gross Estimated Gross Estimated June 30, 2019 U.S. treasury securities $ (1 ) $ 1,401 $ (1 ) $ 470 $ (2 ) $ 1,871 Certificates of deposit — 8 — — — 8 U.S. government agencies securities — 391 — 393 — 784 Non-U.S. government securities — 11 — 161 — 172 Corporate debt securities (1 ) 922 (3 ) 1,988 (4 ) 2,910 Residential mortgage and asset-backed securities — 26 (1 ) 437 (1 ) 463 Total $ (2 ) $ 2,759 $ (5 ) $ 3,449 $ (7 ) $ 6,208 December 31, 2018 U.S. treasury securities $ — $ 896 $ (9 ) $ 1,383 $ (9 ) $ 2,279 U.S. government agencies securities — 30 (5 ) 553 (5 ) 583 Non-U.S. government securities — 86 (2 ) 192 (2 ) 278 Corporate debt securities (1 ) 1,600 (28 ) 4,204 (29 ) 5,804 Residential mortgage and asset-backed securities — 192 (8 ) 1,186 (8 ) 1,378 Total $ (1 ) $ 2,804 $ (52 ) $ 7,518 $ (53 ) $ 10,322

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of classification and fair value of derivative instruments	The following table summarizes the classification and fair values of derivative instruments in our Condensed Consolidated Balance Sheets (in millions): June 30, 2019 Asset Derivatives Liability Derivatives Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Other current assets $ 47 Other accrued liabilities $ (4 ) Foreign currency exchange contracts Other long-term assets 1 Other long-term obligations (2 ) Total derivatives designated as hedges 48 (6 ) Derivatives not designated as hedges: Foreign currency exchange contracts Other current assets — Other accrued liabilities — Total derivatives not designated as hedges — — Total derivatives $ 48 $ (6 ) December 31, 2018 Asset Derivatives Liability Derivatives Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Other current assets $ 73 Other accrued liabilities $ (1 ) Foreign currency exchange contracts Other long-term assets 5 Other long-term obligations — Total derivatives designated as hedges 78 (1 ) Derivatives not designated as hedges: Foreign currency exchange contracts Other current assets — Other accrued liabilities — Total derivatives not designated as hedges — — Total derivatives $ 78 $ (1 )
Summary of effect of foreign currency exchange contracts	The following table summarizes the effect of our foreign currency exchange contracts on our Condensed Consolidated Financial Statements (in millions): Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 Derivatives designated as hedges: Gains recognized in AOCI $ 1 $ 119 $ 29 $ 58 Gains (losses) reclassified from AOCI into product sales 36 (45 ) 65 (93 ) Derivatives not designated as hedges: Gains (losses) recognized in Other income (expense), net $ (5 ) $ 10 $ (11 ) $ (4 )
Summary of potential effect of offsetting derivatives	The following table summarizes the potential effect of offsetting our foreign currency exchange contracts on our Condensed Consolidated Balance Sheets (in millions): Gross Amounts Not Offset on our Condensed Consolidated Balance Sheets Description Gross Amounts of Recognized Assets/Liabilities Gross Amounts Offset on our Condensed Consolidated Balance Sheets Amounts of Assets/Liabilities Presented on our Condensed Consolidated Balance Sheets Derivative Financial Instruments Cash Collateral Received/ Pledged Net Amount (Legal Offset) As of June 30, 2019 Derivative assets $ 48 $ — $ 48 $ (6 ) $ — $ 42 Derivative liabilities (6 ) — (6 ) 6 — — As of December 31, 2018 Derivative assets $ 78 $ — $ 78 $ (1 ) $ — $ 77 Derivative liabilities (1 ) — (1 ) 1 — —

Other Financial Information (Ta

Other Financial Information (Tables)	6 Months Ended
	Jun. 30, 2019
Other Financial Information [Abstract]
Schedule of Inventories	The following table summarizes our inventories (in millions): June 30, 2019 December 31, 2018 Raw materials $ 1,832 $ 1,888 Work in process 265 235 Finished goods 498 507 Total $ 2,595 $ 2,630 Reported as: Inventories $ 884 $ 814 Other long-term assets 1,711 1,816 Total $ 2,595 $ 2,630
Schedule of Other Accrued Liabilities	The following table summarizes the components of other accrued liabilities (in millions): June 30, 2019 December 31, 2018 Compensation and employee benefits $ 433 $ 555 Accrued payment for marketing-related rights acquired from Japan Tobacco Inc. 175 365 Other accrued expenses 2,152 2,219 Total $ 2,760 $ 3,139

Intangible Assets (Tables)

Intangible Assets (Tables)	6 Months Ended
	Jun. 30, 2019
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Schedule of Finite-Lived Intangible Assets	The following table summarizes our intangible assets, net (in millions): June 30, 2019 December 31, 2018 Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Adjustment Net Carrying Amount Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Adjustment Net Carrying Amount Finite-lived assets: Intangible asset - sofosbuvir $ 10,720 $ (3,903 ) $ — $ 6,817 $ 10,720 $ (3,554 ) $ — $ 7,166 Intangible asset - axicabtagene ciloleucel (DLBCL) 6,200 (588 ) — 5,612 6,200 (416 ) — 5,784 Intangible asset - Ranexa 688 (688 ) — — 688 (678 ) — 10 Other 1,098 (415 ) (3 ) 680 1,096 (359 ) (3 ) 734 Total finite-lived assets 18,706 (5,594 ) (3 ) 13,109 18,704 (5,007 ) (3 ) 13,694 Indefinite-lived assets - In Process Research & Development 2,047 — (4 ) 2,043 2,047 — (3 ) 2,044 Total intangible assets $ 20,753 $ (5,594 ) $ (7 ) $ 15,152 $ 20,751 $ (5,007 ) $ (6 ) $ 15,738
Schedule of Indefinite-Lived Intangible Assets	The following table summarizes our intangible assets, net (in millions): June 30, 2019 December 31, 2018 Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Adjustment Net Carrying Amount Gross Carrying Amount Accumulated Amortization Foreign Currency Translation Adjustment Net Carrying Amount Finite-lived assets: Intangible asset - sofosbuvir $ 10,720 $ (3,903 ) $ — $ 6,817 $ 10,720 $ (3,554 ) $ — $ 7,166 Intangible asset - axicabtagene ciloleucel (DLBCL) 6,200 (588 ) — 5,612 6,200 (416 ) — 5,784 Intangible asset - Ranexa 688 (688 ) — — 688 (678 ) — 10 Other 1,098 (415 ) (3 ) 680 1,096 (359 ) (3 ) 734 Total finite-lived assets 18,706 (5,594 ) (3 ) 13,109 18,704 (5,007 ) (3 ) 13,694 Indefinite-lived assets - In Process Research & Development 2,047 — (4 ) 2,043 2,047 — (3 ) 2,044 Total intangible assets $ 20,753 $ (5,594 ) $ (7 ) $ 15,152 $ 20,751 $ (5,007 ) $ (6 ) $ 15,738
Schedule of Estimated Future Amortization Expense	The following table summarizes the estimated future amortization expense associated with our finite-lived intangible assets as of June 30, 2019 (in millions): Fiscal Year Amount 2019 (remaining six months) $ 563 2020 1,125 2021 1,125 2022 1,125 2023 1,125 Thereafter 8,046 Total $ 13,109

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	6 Months Ended
	Jun. 30, 2019
Debt Disclosure [Abstract]
Summary of Debt Carrying Amount	The following table summarizes our borrowings under various financing arrangements (in millions): Carrying Amount Type of Borrowing Issue Date Due Date Interest Rate June 30, 2019 December 31, 2018 Senior Unsecured September 2017 March 2019 3-month LIBOR + 0.22% $ — $ 750 Senior Unsecured March 2014 April 2019 2.05% — 500 Senior Unsecured September 2017 September 2019 1.85% 999 999 Senior Unsecured September 2017 September 2019 3-month LIBOR + 0.25% 500 499 Senior Unsecured November 2014 February 2020 2.35% 500 499 Senior Unsecured September 2015 September 2020 2.55% 1,997 1,996 Senior Unsecured March 2011 April 2021 4.50% 998 997 Senior Unsecured December 2011 December 2021 4.40% 1,248 1,247 Senior Unsecured September 2016 March 2022 1.95% 498 498 Senior Unsecured September 2015 September 2022 3.25% 997 997 Senior Unsecured September 2016 September 2023 2.50% 746 746 Senior Unsecured March 2014 April 2024 3.70% 1,744 1,744 Senior Unsecured November 2014 February 2025 3.50% 1,745 1,745 Senior Unsecured September 2015 March 2026 3.65% 2,733 2,731 Senior Unsecured September 2016 March 2027 2.95% 1,245 1,245 Senior Unsecured September 2015 September 2035 4.60% 990 990 Senior Unsecured September 2016 September 2036 4.00% 741 740 Senior Unsecured December 2011 December 2041 5.65% 995 995 Senior Unsecured March 2014 April 2044 4.80% 1,734 1,734 Senior Unsecured November 2014 February 2045 4.50% 1,731 1,730 Senior Unsecured September 2015 March 2046 4.75% 2,217 2,216 Senior Unsecured September 2016 March 2047 4.15% 1,725 1,724 Total debt, net 26,083 27,322 Less current portion 1,999 2,748 Total long-term debt, net $ 24,084 $ 24,574

Leases (Tables)

Leases (Tables)	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Balance Sheet and Other Information Related to Operating Leases	The following table summarizes balance sheet and other information related to our operating leases as of June 30, 2019 (in millions, except weighted average data): Classification Amount Right-of-use assets, net Other long-term assets $ 504 Lease liabilities - current Other accrued liabilities $ 73 Lease liabilities - noncurrent Other long-term obligations $ 481 Weighted average remaining lease term 9.5 years Weighted average discount rate 3.60 %
Supplemental Information Related to Operating Leases	The following table summarizes other supplemental information related to our operating leases (in millions): Three Months Ended Six Months Ended June 30, 2019 June 30, 2019 Cash paid for amounts included in the measurement of lease liabilities $ 18 $ 36 Right-of-use assets obtained in exchange for lease liabilities $ 70 $ 100
Operating Lease Aggregate Future Lease Payments	The following table summarizes a maturity analysis of our operating lease liabilities showing the aggregate lease payments as of June 30, 2019 (in millions): Fiscal Year Amount 2019 (remaining six months) $ 47 2020 87 2021 83 2022 75 2023 66 Thereafter 305 Total undiscounted lease payments 663 Less: imputed interest (109 ) Total discounted lease payments $ 554 The following table summarizes the aggregate undiscounted non-cancelable future minimum lease payments for operating leases under the prior leases standard as of December 31, 2018 (in millions): Fiscal Year Amount 2019 $ 89 2020 78 2021 66 2022 60 2023 52 Thereafter 229 Total minimum lease payments $ 574

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2019
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss) The following table summarizes the changes in AOCI by component, net of tax during the six months ended June 30, 2019 and 2018 (in millions): Foreign Currency Translation Unrealized Gains and Losses on Available-for-Sale Debt Securities Unrealized Gains and Losses on Cash Flow Hedges Total Balance at December 31, 2018 $ 47 $ (52 ) $ 85 $ 80 Net unrealized gain 8 49 29 86 Reclassifications to net income — — (64 ) (64 ) Net current period other comprehensive income (loss) 8 49 (35 ) 22 Balance at June 30, 2019 $ 55 $ (3 ) $ 50 $ 102 Foreign Currency Translation Unrealized Gains and Losses on Available-for-Sale Debt Securities Unrealized Gains and Losses on Cash Flow Hedges Total Balance at December 31, 2017 $ 85 $ 194 $ (114 ) $ 165 Reclassifications to retained earnings as a result of the adoption of new accounting standards — (293 ) — (293 ) Balance at January 1, 2018 85 (99 ) (114 ) (128 ) Net unrealized gain (loss) (18 ) (6 ) 57 33 Reclassifications to net income — 4 93 97 Net current period other comprehensive income (loss) (18 ) (2 ) 150 130 Balance at June 30, 2018 $ 67 $ (101 ) $ 36 $ 2

Net Income Per Share Attribut_2

Net Income Per Share Attributable to Gilead Common Stockholders (Tables)	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Schedule of the Calculation of Basic and Diluted Earnings Per Share	The following table summarizes the calculation of basic and diluted net income per share attributable to Gilead common stockholders (in millions, except per share amounts): Three Months Ended Six Months Ended June 30, June 30, 2019 2018 2019 2018 Net income attributable to Gilead $ 1,880 $ 1,817 $ 3,855 $ 3,355 Shares used in per share calculation - basic 1,270 1,298 1,273 1,302 Dilutive effect of stock options and equivalents 7 10 7 12 Shares used in per share calculation - diluted 1,277 1,308 1,280 1,314 Net income per share attributable to Gilead common stockholders - basic $ 1.48 $ 1.40 $ 3.03 $ 2.58 Net income per share attributable to Gilead common stockholders - diluted $ 1.47 $ 1.39 $ 3.01 $ 2.55

Segment Information (Tables)

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2019
Segment Reporting [Abstract]
Summary 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 Six Months Ended June 30, June 30, 2019 2018 2019 2018 AmerisourceBergen Corp. 20 % 20 % 20 % 20 % Cardinal Health, Inc. 21 % 20 % 21 % 20 % McKesson Corp. 20 % 21 % 20 % 21 %

Summary of Significant Accoun_3

Summary of Significant Accounting Policies Accounting Standards Adoption 2016-02 (Details) - USD ($) $ in Millions	Jun. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets, net	$ 504
Operating Lease, Liability	$ 554
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets, net		$ 441
Operating Lease, Liability		$ 490

Revenues (Details)

Revenues (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 5,685	$ 5,648	$ 10,966	$ 10,736
Revenues	5,685	5,648	10,966	10,736
U.S.
Disaggregation of Revenue [Line Items]
Revenues	4,073	4,083	7,891	7,630
Europe
Disaggregation of Revenue [Line Items]
Revenues	1,099	1,084	2,037	2,141
Other International
Disaggregation of Revenue [Line Items]
Revenues	513	481	1,038	965
Atripla
Disaggregation of Revenue [Line Items]
Revenues	152	349	323	663
Atripla | U.S.
Disaggregation of Revenue [Line Items]
Revenues	122	274	255	502
Atripla | Europe
Disaggregation of Revenue [Line Items]
Revenues	26	39	42	90
Atripla | Other International
Disaggregation of Revenue [Line Items]
Revenues	4	36	26	71
Biktarvy
Disaggregation of Revenue [Line Items]
Revenues	1,116	185	1,909	220
Biktarvy | U.S.
Disaggregation of Revenue [Line Items]
Revenues	1,023	183	1,762	218
Biktarvy | Europe
Disaggregation of Revenue [Line Items]
Revenues	73	2	121	2
Biktarvy | Other International
Disaggregation of Revenue [Line Items]
Revenues	20	0	26	0
Complera/Eviplera
Disaggregation of Revenue [Line Items]
Revenues	123	199	238	389
Complera/Eviplera | U.S.
Disaggregation of Revenue [Line Items]
Revenues	42	82	86	149
Complera/Eviplera | Europe
Disaggregation of Revenue [Line Items]
Revenues	72	103	134	212
Complera/Eviplera | Other International
Disaggregation of Revenue [Line Items]
Revenues	9	14	18	28
Descovy
Disaggregation of Revenue [Line Items]
Revenues	358	403	700	764
Descovy | U.S.
Disaggregation of Revenue [Line Items]
Revenues	246	311	479	585
Descovy | Europe
Disaggregation of Revenue [Line Items]
Revenues	69	78	137	153
Descovy | Other International
Disaggregation of Revenue [Line Items]
Revenues	43	14	84	26
Genvoya
Disaggregation of Revenue [Line Items]
Revenues	980	1,160	1,995	2,242
Genvoya | U.S.
Disaggregation of Revenue [Line Items]
Revenues	733	904	1,461	1,757
Genvoya | Europe
Disaggregation of Revenue [Line Items]
Revenues	177	207	370	393
Genvoya | Other International
Disaggregation of Revenue [Line Items]
Revenues	70	49	164	92
Odefsey
Disaggregation of Revenue [Line Items]
Revenues	387	385	784	727
Odefsey | U.S.
Disaggregation of Revenue [Line Items]
Revenues	266	303	548	582
Odefsey | Europe
Disaggregation of Revenue [Line Items]
Revenues	111	77	217	135
Odefsey | Other International
Disaggregation of Revenue [Line Items]
Revenues	10	5	19	10
Stribild
Disaggregation of Revenue [Line Items]
Revenues	108	187	204	361
Stribild | U.S.
Disaggregation of Revenue [Line Items]
Revenues	78	144	145	277
Stribild | Europe
Disaggregation of Revenue [Line Items]
Revenues	24	34	42	63
Stribild | Other International
Disaggregation of Revenue [Line Items]
Revenues	6	9	17	21
Truvada
Disaggregation of Revenue [Line Items]
Revenues	718	765	1,324	1,417
Truvada | U.S.
Disaggregation of Revenue [Line Items]
Revenues	657	649	1,208	1,156
Truvada | Europe
Disaggregation of Revenue [Line Items]
Revenues	41	86	74	183
Truvada | Other International
Disaggregation of Revenue [Line Items]
Revenues	20	30	42	78
Other HIV
Disaggregation of Revenue [Line Items]
Revenues	15	19	32	32
Other HIV | U.S.
Disaggregation of Revenue [Line Items]
Revenues	9	11	20	20
Other HIV | Europe
Disaggregation of Revenue [Line Items]
Revenues	1	3	2	4
Other HIV | Other International
Disaggregation of Revenue [Line Items]
Revenues	5	5	10	8
Revenue share - Symtuza
Disaggregation of Revenue [Line Items]
Revenues	84	13	150	20
Revenue share - Symtuza | U.S.
Disaggregation of Revenue [Line Items]
Revenues	55	0	97	0
Revenue share - Symtuza | Europe
Disaggregation of Revenue [Line Items]
Revenues	29	13	53	20
Revenue share - Symtuza | Other International
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
AmBisome
Disaggregation of Revenue [Line Items]
Revenues	105	103	198	210
AmBisome | U.S.
Disaggregation of Revenue [Line Items]
Revenues	10	14	18	31
AmBisome | Europe
Disaggregation of Revenue [Line Items]
Revenues	60	55	117	111
AmBisome | Other International
Disaggregation of Revenue [Line Items]
Revenues	35	34	63	68
Ledipasvir/Sofosbuvir
Disaggregation of Revenue [Line Items]
Revenues	193	331	418	679
Ledipasvir/Sofosbuvir | U.S.
Disaggregation of Revenue [Line Items]
Revenues	86	230	203	464
Ledipasvir/Sofosbuvir | Europe
Disaggregation of Revenue [Line Items]
Revenues	22	22	49	78
Ledipasvir/Sofosbuvir | Other International
Disaggregation of Revenue [Line Items]
Revenues	85	79	166	137
Letairis
Disaggregation of Revenue [Line Items]
Revenues	204	244	401	448
Letairis | U.S.
Disaggregation of Revenue [Line Items]
Revenues	204	244	401	448
Letairis | Europe
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Letairis | Other International
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Ranexa
Disaggregation of Revenue [Line Items]
Revenues	19	208	174	403
Ranexa | U.S.
Disaggregation of Revenue [Line Items]
Revenues	19	208	174	403
Ranexa | Europe
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Ranexa | Other International
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Sofosbuvir/Velpatasvir
Disaggregation of Revenue [Line Items]
Revenues	493	500	984	1,036
Sofosbuvir/Velpatasvir | U.S.
Disaggregation of Revenue [Line Items]
Revenues	219	239	449	508
Sofosbuvir/Velpatasvir | Europe
Disaggregation of Revenue [Line Items]
Revenues	156	168	310	366
Sofosbuvir/Velpatasvir | Other International
Disaggregation of Revenue [Line Items]
Revenues	118	93	225	162
Vemlidy
Disaggregation of Revenue [Line Items]
Revenues	116	76	217	134
Vemlidy | U.S.
Disaggregation of Revenue [Line Items]
Revenues	71	59	136	106
Vemlidy | Europe
Disaggregation of Revenue [Line Items]
Revenues	5	3	9	6
Vemlidy | Other International
Disaggregation of Revenue [Line Items]
Revenues	40	14	72	22
Viread
Disaggregation of Revenue [Line Items]
Revenues	75	82	147	179
Viread | U.S.
Disaggregation of Revenue [Line Items]
Revenues	9	16	21	23
Viread | Europe
Disaggregation of Revenue [Line Items]
Revenues	28	32	42	62
Viread | Other International
Disaggregation of Revenue [Line Items]
Revenues	38	34	84	94
Vosevi
Disaggregation of Revenue [Line Items]
Revenues	75	109	138	216
Vosevi | U.S.
Disaggregation of Revenue [Line Items]
Revenues	53	86	98	172
Vosevi | Europe
Disaggregation of Revenue [Line Items]
Revenues	15	20	31	36
Vosevi | Other International
Disaggregation of Revenue [Line Items]
Revenues	7	3	9	8
Yescarta
Disaggregation of Revenue [Line Items]
Revenues	120	68	216	108
Yescarta | U.S.
Disaggregation of Revenue [Line Items]
Revenues	99	68	189	108
Yescarta | Europe
Disaggregation of Revenue [Line Items]
Revenues	21	0	27	0
Yescarta | Other International
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Zydelig
Disaggregation of Revenue [Line Items]
Revenues	26	39	53	72
Zydelig | U.S.
Disaggregation of Revenue [Line Items]
Revenues	12	17	23	31
Zydelig | Europe
Disaggregation of Revenue [Line Items]
Revenues	14	22	29	40
Zydelig | Other International
Disaggregation of Revenue [Line Items]
Revenues	0	0	1	1
Other(3)
Disaggregation of Revenue [Line Items]
Revenues	140	115	202	221
Other(3) | U.S.
Disaggregation of Revenue [Line Items]
Revenues	41	27	77	56
Other(3) | Europe
Disaggregation of Revenue [Line Items]
Revenues	97	41	117	56
Other(3) | Other International
Disaggregation of Revenue [Line Items]
Revenues	2	47	8	109
Product sales
Disaggregation of Revenue [Line Items]
Revenues	5,607	5,540	10,807	10,541
Product sales | U.S.
Disaggregation of Revenue [Line Items]
Revenues	4,054	4,069	7,850	7,596
Product sales | Europe
Disaggregation of Revenue [Line Items]
Revenues	1,041	1,005	1,923	2,010
Product sales | Other International
Disaggregation of Revenue [Line Items]
Revenues	512	466	1,034	935
Royalty, contract and other revenues
Disaggregation of Revenue [Line Items]
Revenues	78	108	159	195
Revenues	78	108	159	195
Royalty, contract and other revenues | U.S.
Disaggregation of Revenue [Line Items]
Revenues	19	14	41	34
Royalty, contract and other revenues | Europe
Disaggregation of Revenue [Line Items]
Revenues	58	79	114	131
Royalty, contract and other revenues | Other International
Disaggregation of Revenue [Line Items]
Revenues	$ 1	$ 15	$ 4	$ 30

Revenues Revenues Recognized fr

Revenues Revenues Recognized from Performance Obligations Satisfied in Prior Periods (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Contract with Customer, Performance Obligation Satisfied in Previous Period [Line Items]
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 171	$ 131	$ 326	$ 228
Change in estimate variable consideration [Member]
Contract with Customer, Performance Obligation Satisfied in Previous Period [Line Items]
Contract with Customer, Performance Obligation Satisfied in Previous Period	$ 193	$ 91	$ 300	$ 4

Revenues Contract Assets (Detai

Revenues Contract Assets (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Contract Assets [Abstract]
Contract assets	$ 149	$ 125

Fair Value Measurements Summary

Fair Value Measurements Summary of assets and liabilities measured at fair value (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Assets:
Available-for-sale debt securities	$ 25,059	$ 24,164
Total	4,351	6,310
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement
Assets:
Total	29,458	30,552
Liabilities:
Total	162	125
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | U.S. treasury securities
Assets:
Available-for-sale debt securities	3,916	3,969
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Certificates of deposit
Assets:
Available-for-sale debt securities	5,385	4,361
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | U.S. government agencies securities
Assets:
Available-for-sale debt securities	1,531	938
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Non-U.S. government securities
Assets:
Available-for-sale debt securities	420	305
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Corporate debt securities
Assets:
Available-for-sale debt securities	13,271	13,067
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Residential mortgage and asset-backed securities
Assets:
Available-for-sale debt securities	536	1,524
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Money market funds
Assets:
Equity securities	3,007	5,305
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Publicly traded equity securities
Assets:
Equity securities	1,188	881
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Deferred compensation plan
Assets:
Equity securities	156	124
Liabilities:
Deferred compensation plan	156	124
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Foreign currency derivative contracts
Assets:
Foreign currency derivative contracts	48	78
Liabilities:
Foreign currency derivative contracts	6	1
Fair Value, Measurements, Recurring | Level 1
Assets:
Total	8,251	10,279
Liabilities:
Total	156	124
Fair Value, Measurements, Recurring | Level 1 | U.S. treasury securities
Assets:
Available-for-sale debt securities	3,916	3,969
Fair Value, Measurements, Recurring | Level 1 | Certificates of deposit
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 1 | U.S. government agencies securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Non-U.S. government securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Corporate debt securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Residential mortgage and asset-backed securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Money market funds
Assets:
Equity securities	3,007	5,305
Fair Value, Measurements, Recurring | Level 1 | Publicly traded equity securities
Assets:
Equity securities	1,172	881
Fair Value, Measurements, Recurring | Level 1 | Deferred compensation plan
Assets:
Equity securities	156	124
Liabilities:
Deferred compensation plan	156	124
Fair Value, Measurements, Recurring | Level 1 | Foreign currency derivative contracts
Assets:
Foreign currency derivative contracts	0	0
Liabilities:
Foreign currency derivative contracts	0	0
Fair Value, Measurements, Recurring | Level 2
Assets:
Total	21,207	20,273
Liabilities:
Total	6	1
Fair Value, Measurements, Recurring | Level 2 | U.S. treasury securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 2 | Certificates of deposit
Assets:
Available-for-sale debt securities	5,385	4,361
Fair Value, Measurements, Recurring | Level 2 | U.S. government agencies securities
Assets:
Available-for-sale debt securities	1,531	938
Fair Value, Measurements, Recurring | Level 2 | Non-U.S. government securities
Assets:
Available-for-sale debt securities	420	305
Fair Value, Measurements, Recurring | Level 2 | Corporate debt securities
Assets:
Available-for-sale debt securities	13,271	13,067
Fair Value, Measurements, Recurring | Level 2 | Residential mortgage and asset-backed securities
Assets:
Available-for-sale debt securities	536	1,524
Fair Value, Measurements, Recurring | Level 2 | Money market funds
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring | Level 2 | Publicly traded equity securities
Assets:
Equity securities	16	0
Fair Value, Measurements, Recurring | Level 2 | Deferred compensation plan
Assets:
Equity securities	0	0
Liabilities:
Deferred compensation plan	0	0
Fair Value, Measurements, Recurring | Level 2 | Foreign currency derivative contracts
Assets:
Foreign currency derivative contracts	48	78
Liabilities:
Foreign currency derivative contracts	6	1
Fair Value, Measurements, Recurring | Level 3
Assets:
Total	0	0
Liabilities:
Total	0	0
Fair Value, Measurements, Recurring | Level 3 | U.S. treasury securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Certificates of deposit
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 3 | U.S. government agencies securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Non-U.S. government securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Residential mortgage and asset-backed securities
Assets:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Money market funds
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Publicly traded equity securities
Assets:
Equity securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Deferred compensation plan
Assets:
Equity securities	0	0
Liabilities:
Deferred compensation plan	0	0
Fair Value, Measurements, Recurring | Level 3 | Foreign currency derivative contracts
Assets:
Foreign currency derivative contracts	0	0
Liabilities:
Foreign currency derivative contracts	$ 0	$ 0

Fair Value Measurements Summa_2

Fair Value Measurements Summary of Classification on Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	$ 4,351	$ 6,310
Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	3,007	5,305
Prepaid and other current assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	1,178	863
Other long-term assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 166	$ 142

Fair Value Measurements Additio

Fair Value Measurements Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gain on investment of equity securities	$ 57		$ 254
Unrealized loss on investment of equity securities		$ 64		$ 19
Short-term and long-term debt	26,083		26,083		$ 27,322
Market value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term and long-term debt	28,000		28,000		27,100
Carrying value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term and long-term debt	$ 26,100		$ 26,100		$ 27,300

Available-for-Sale Debt Secur_3

Available-for-Sale Debt Securities - Summary of Available-for-Sale Debt Securities at Estimated Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Available-for-Sale Debt Securities
Amortized Cost	$ 25,062	$ 24,216
Gross Unrealized Gains	4	1
Gross Unrealized Losses	(7)	(53)
Available-for-sale debt securities	25,059	24,164
U.S. treasury securities
Available-for-Sale Debt Securities
Amortized Cost	3,917	3,978
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(2)	(9)
Available-for-sale debt securities	3,916	3,969
Certificates of deposit
Available-for-Sale Debt Securities
Amortized Cost	5,385	4,361
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Available-for-sale debt securities	5,385	4,361
U.S. government agencies securities
Available-for-Sale Debt Securities
Amortized Cost	1,531	943
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(5)
Available-for-sale debt securities	1,531	938
Non-U.S. government securities
Available-for-Sale Debt Securities
Amortized Cost	420	307
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(2)
Available-for-sale debt securities	420	305
Corporate debt securities
Available-for-Sale Debt Securities
Amortized Cost	13,272	13,095
Gross Unrealized Gains	3	1
Gross Unrealized Losses	(4)	(29)
Available-for-sale debt securities	13,271	13,067
Residential mortgage and asset-backed securities
Available-for-Sale Debt Securities
Amortized Cost	537	1,532
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(8)
Available-for-sale debt securities	$ 536	$ 1,524

Available-for-Sale Debt Secur_4

Available-for-Sale Debt Securities - Summary of the Balance Sheet Classification of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Available-for-Sale Debt Securities
Available-for-sale debt securities	$ 25,059	$ 24,164
Cash and cash equivalents
Available-for-Sale Debt Securities
Available-for-sale debt securities	6,065	10,592
Short-term marketable securities
Available-for-Sale Debt Securities
Available-for-sale debt securities	15,943	12,149
Long-term marketable securities
Available-for-Sale Debt Securities
Available-for-sale debt securities	$ 3,051	$ 1,423

Available-for-Sale Debt Secur_5

Available-for-Sale Debt Securities - Summary of Available-for-Sale Debt Securities by Contractual Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Amortized Cost
Within one year	$ 22,010
After one year through five years	3,016
After five years through ten years	19
After ten years	17
Amortized Cost	25,062	$ 24,216
Fair Value
Within one year	22,008
After one year through five years	3,015
After five years through ten years	19
After ten years	17
Available-for-sale debt securities	$ 25,059	$ 24,164

Available-for-Sale Debt Secur_6

Available-for-Sale Debt Securities - Summary of Available-for-Sale Debt Securities in a Continuous Unrealized Loss Position Deemed not to be Other-than-Temporarily Impaired (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Available-for-Sale Debt Securities
Less than 12 Months, Unrealized Losses	$ (2)	$ (1)
Less than 12 Months, Fair Value	2,759	2,804
12 Months or Greater, Unrealized Losses	(5)	(52)
12 Months or Greater, Fair Value	3,449	7,518
Gross Unrealized Losses	(7)	(53)
Total Estimated Fair Value	6,208	10,322
U.S. treasury securities
Available-for-Sale Debt Securities
Less than 12 Months, Unrealized Losses	(1)	0
Less than 12 Months, Fair Value	1,401	896
12 Months or Greater, Unrealized Losses	(1)	(9)
12 Months or Greater, Fair Value	470	1,383
Gross Unrealized Losses	(2)	(9)
Total Estimated Fair Value	1,871	2,279
Certificates of deposit
Available-for-Sale Debt Securities
Less than 12 Months, Unrealized Losses	0
Less than 12 Months, Fair Value	8
12 Months or Greater, Unrealized Losses	0
12 Months or Greater, Fair Value	0
Gross Unrealized Losses	0
Total Estimated Fair Value	8
U.S. government agencies securities
Available-for-Sale Debt Securities
Less than 12 Months, Unrealized Losses	0	0
Less than 12 Months, Fair Value	391	30
12 Months or Greater, Unrealized Losses	0	(5)
12 Months or Greater, Fair Value	393	553
Gross Unrealized Losses	0	(5)
Total Estimated Fair Value	784	583
Non-U.S. government securities
Available-for-Sale Debt Securities
Less than 12 Months, Unrealized Losses	0	0
Less than 12 Months, Fair Value	11	86
12 Months or Greater, Unrealized Losses	0	(2)
12 Months or Greater, Fair Value	161	192
Gross Unrealized Losses	0	(2)
Total Estimated Fair Value	172	278
Corporate debt securities
Available-for-Sale Debt Securities
Less than 12 Months, Unrealized Losses	(1)	(1)
Less than 12 Months, Fair Value	922	1,600
12 Months or Greater, Unrealized Losses	(3)	(28)
12 Months or Greater, Fair Value	1,988	4,204
Gross Unrealized Losses	(4)	(29)
Total Estimated Fair Value	2,910	5,804
Residential mortgage and asset-backed securities
Available-for-Sale Debt Securities
Less than 12 Months, Unrealized Losses	0	0
Less than 12 Months, Fair Value	26	192
12 Months or Greater, Unrealized Losses	(1)	(8)
12 Months or Greater, Fair Value	437	1,186
Gross Unrealized Losses	(1)	(8)
Total Estimated Fair Value	$ 463	$ 1,378

Available-for-Sale Debt Secur_7

Available-for-Sale Debt Securities - Additional Information (Details) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2019USD ($)position	Dec. 31, 2018USD ($)position
Debt Securities, Available-for-sale [Abstract]
Securities in unrealized loss positions, number of positions (securities) | position	593	1,348
Other-than-temporary Impairment Loss, Debt Securities, Available-for-sale | $	$ 0	$ 0

Derivative Financial Instrume_3

Derivative Financial Instruments - Summary of Classification and Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	$ 48	$ 78
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	6	1
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	48	78
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	6	1
Designated as Hedging Instrument | Other current assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	47	73
Designated as Hedging Instrument | Other accrued liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	4	1
Designated as Hedging Instrument | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	1	5
Designated as Hedging Instrument | Other long-term obligations
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	2	0
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	0	0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	0	0
Not Designated as Hedging Instrument | Other current assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement	0	0
Not Designated as Hedging Instrument | Other accrued liabilities
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ 0	$ 0

Derivative Financial Instrume_4

Derivative Financial Instruments - Summary of Effect of Foreign Currency Exchange Contracts (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gains recognized in AOCI	$ 1	$ 119	$ 29	$ 58
Gains (losses) reclassified from AOCI into product sales	36	(45)	65	(93)
Gains (losses) recognized in Other income (expense), net	$ (5)	$ 10	$ (11)	$ (4)

Derivative Financial Instrume_5

Derivative Financial Instruments - Summary of Potential Effect of Offsetting Derivatives (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Derivative Asset [Abstract]
Gross Amounts of Recognized Assets/Liabilities	$ 48	$ 78
Gross Amounts Offset on our Condensed Consolidated Balance Sheets	0	0
Amounts of Assets/Liabilities Presented on our Condensed Consolidated Balance Sheets	48	78
Derivative Financial Instruments	(6)	(1)
Cash Collateral Received/ Pledged	0	0
Net Amount (Legal Offset)	42	77
Derivative Liability [Abstract]
Gross Amounts of Recognized Assets/Liabilities	(6)	(1)
Gross Amounts Offset on our Condensed Consolidated Balance Sheets	0	0
Amounts of Assets/Liabilities Presented on our Condensed Consolidated Balance Sheets	(6)	(1)
Derivative Financial Instruments	6	1
Cash Collateral Received/ Pledged	0	0
Net Amount (Legal Offset)	$ 0	$ 0

Derivative Financial Instrume_6

Derivative Financial Instruments - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivative [Line Items]
Notional amounts on foreign currency exchange contracts	$ 2,900		$ 2,900		$ 2,200
Gain (Loss) on Discontinuation of Cash Flow Hedges	$ 0	$ 0	$ 0	$ 0
Maximum
Derivative [Line Items]
Maturity on derivative instruments	18 years
Estimate of time to transfer	12 years

Collaborative And Other Arran_2

Collaborative And Other Arrangements Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Collaborative and Other Arrangements [Abstract]
Cash Outflows and Accrued Up-front Payments Related to Collaborative and Other Similar Arrangements	$ 206	$ 284	$ 393	$ 304
Up-front Collaboration and Licensing Expenses Related to Collaborative and Similar Arrangements	$ 165	$ 160	$ 291	$ 160

Other Financial Information Inv

Other Financial Information Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Other Financial Information [Abstract]
Raw materials	$ 1,832	$ 1,888
Work in process	265	235
Finished goods	498	507
Total	2,595	2,630
Inventories	884	814
Other long-term assets	1,711	1,816
Total	$ 2,595	$ 2,630

Other Financial Information Oth

Other Financial Information Other Accrued Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Other Financial Information [Abstract]
Compensation and employee benefits	$ 433	$ 555
Accrued Liabilities and Other Liabilities	175	365
Other accrued expenses	2,152	2,219
Total	$ 2,760	$ 3,139

Intangible Assets - Summary of

Intangible Assets - Summary of Intangible Assets (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Gross Carrying Amount	$ 20,753	$ 20,751
Foreign Currency Translation Adjustment	(7)	(6)
Intangible assets, net	15,152	15,738
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	18,706	18,704
Accumulated Amortization	5,594	5,007
Foreign Currency Translation Adjustment	(3)	(3)
Net Carrying Amount	13,109	13,694
Indefinite-lived assets - In Process Research & Development
Indefinite-lived Intangible Assets [Line Items]
Gross Carrying Amount	2,047	2,047
Net Carrying Amount	2,043	2,044
In Process Research and Development [Member]
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived Intangible Assets, Foreign Currency Translation Gain (Loss)	(4)	(3)
Intangible asset - sofosbuvir
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	10,720	10,720
Accumulated Amortization	3,903	3,554
Foreign Currency Translation Adjustment	0	0
Net Carrying Amount	6,817	7,166
Intangible asset - axicabtagene ciloleucel (DLBCL)
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	6,200	6,200
Accumulated Amortization	588	416
Foreign Currency Translation Adjustment	0	0
Net Carrying Amount	5,612	5,784
Intangible asset - Ranexa
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	688	688
Accumulated Amortization	688	678
Foreign Currency Translation Adjustment	0	0
Net Carrying Amount	0	10
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,098	1,096
Accumulated Amortization	415	359
Foreign Currency Translation Adjustment	(3)	(3)
Net Carrying Amount	$ 680	$ 734

Intangible Assets - Schedule of

Intangible Assets - Schedule of Estimated Future Amortization Expense (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Intangible Assets, Net (Excluding Goodwill) [Abstract]
2019 (remaining six months)	$ 563
2020	1,125
2021	1,125
2022	1,125
2023	1,125
Thereafter	8,046
Total	$ 13,109	$ 13,694

Intangible Assets - Additional

Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Amortization of Intangible Assets	$ 288	$ 300	$ 587	$ 601

Debt and Credit Facilities Summ

Debt and Credit Facilities Summary of Debt Carrying Amount (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Short-term and long-term debt	$ 26,083	$ 27,322
Long-term Debt, Current Maturities	1,999	2,748
Total long-term debt, net	24,084	24,574
Unsecured Debt | 2017 Senior Unsecured Notes Due in March 2019
Debt Instrument [Line Items]
Long-term debt	$ 0	750
Unsecured Debt | Senior Unsecured Notes Due in April 2019
Debt Instrument [Line Items]
Interest Rate	2.05%
Long-term debt	$ 0	500
Unsecured Debt | 2017 Senior Unsecured Notes Due in September 2019 with Fixed Rate
Debt Instrument [Line Items]
Interest Rate	1.85%
Long-term debt	$ 999	999
Unsecured Debt | 2017 Senior Unsecured Notes Due in September 2019 with Floating Rate
Debt Instrument [Line Items]
Long-term debt	$ 500	499
Unsecured Debt | Senior Unsecured Notes Due In February 2020
Debt Instrument [Line Items]
Interest Rate	2.35%
Long-term debt	$ 500	499
Unsecured Debt | Senior Unsecured Notes Due in September 2020
Debt Instrument [Line Items]
Interest Rate	2.55%
Long-term debt	$ 1,997	1,996
Unsecured Debt | Senior Unsecured Notes Due in April 2021
Debt Instrument [Line Items]
Interest Rate	4.50%
Long-term debt	$ 998	997
Unsecured Debt | Senior Unsecured Notes Due In December 2021
Debt Instrument [Line Items]
Interest Rate	4.40%
Long-term debt	$ 1,248	1,247
Unsecured Debt | Senior Unsecured Notes Due in March 2022
Debt Instrument [Line Items]
Interest Rate	1.95%
Long-term debt	$ 498	498
Unsecured Debt | Senior Unsecured Notes Due in September 2022
Debt Instrument [Line Items]
Interest Rate	3.25%
Long-term debt	$ 997	997
Unsecured Debt | Senior Unsecured Notes Due in September 2023
Debt Instrument [Line Items]
Interest Rate	2.50%
Long-term debt	$ 746	746
Unsecured Debt | Senior Unsecured Notes Due in April 2024
Debt Instrument [Line Items]
Interest Rate	3.70%
Long-term debt	$ 1,744	1,744
Unsecured Debt | Senior Unsecured Notes Due in February 2025
Debt Instrument [Line Items]
Interest Rate	3.50%
Long-term debt	$ 1,745	1,745
Unsecured Debt | Senior Unsecured Notes Due in March 2026
Debt Instrument [Line Items]
Interest Rate	3.65%
Long-term debt	$ 2,733	2,731
Unsecured Debt | Senior Unsecured Notes Due in March 2027
Debt Instrument [Line Items]
Interest Rate	2.95%
Long-term debt	$ 1,245	1,245
Unsecured Debt | Senior Unsecured Notes Due in September 2035
Debt Instrument [Line Items]
Interest Rate	4.60%
Long-term debt	$ 990	990
Unsecured Debt | Senior Unsecured Notes Due in September 2036
Debt Instrument [Line Items]
Interest Rate	4.00%
Long-term debt	$ 741	740
Unsecured Debt | Senior Unsecured Notes Due in December 2041
Debt Instrument [Line Items]
Interest Rate	5.65%
Long-term debt	$ 995	995
Unsecured Debt | Senior Unsecured Notes Due in April 2044
Debt Instrument [Line Items]
Interest Rate	4.80%
Long-term debt	$ 1,734	1,734
Unsecured Debt | Senior Unsecured Notes Due in February 2045
Debt Instrument [Line Items]
Interest Rate	4.50%
Long-term debt	$ 1,731	1,730
Unsecured Debt | Senior Unsecured Notes Due in March 2046
Debt Instrument [Line Items]
Interest Rate	4.75%
Long-term debt	$ 2,217	2,216
Unsecured Debt | Senior Unsecured Notes Due in March 2047
Debt Instrument [Line Items]
Interest Rate	4.15%
Long-term debt	$ 1,725	$ 1,724
London Interbank Offered Rate (LIBOR) | 2017 Senior Unsecured Notes Due in September 2019 with Floating Rate
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.25%
London Interbank Offered Rate (LIBOR) | 2017 Senior Unsecured Notes Due in March 2019
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.22%

Debt and Credit Facilities Addi

Debt and Credit Facilities Additional Information (Details) - USD ($) $ in Millions	1 Months Ended
	Apr. 30, 2019	Mar. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Term Loan Facilities
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 2,500
Amount outstanding			$ 0	$ 0
Senior Unsecured Note Issued September 2017 [Member] | Unsecured Debt
Debt Instrument [Line Items]
Repayments of Unsecured Debt		$ 750
Senior Unsecured Note Issued September 2014 [Member] | Unsecured Debt
Debt Instrument [Line Items]
Repayments of Unsecured Debt	$ 500

Leases Narrative (Details)

Leases Narrative (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019USD ($)	Jun. 30, 2019USD ($)
Leases [Abstract]
Lease term extension	15 years	15 years
Termination period		one year
Operating lease expense	$ 38	$ 74

Leases Balance Sheet Location D

Leases Balance Sheet Location Detail (Details) $ in Millions	Jun. 30, 2019USD ($)
Leases [Abstract]
Right-of-use assets, net	$ 504
Lease liabilities - current	73
Lease liabilities - noncurrent	$ 481
Weighted average remaining lease term	9 years 6 months
Weighted average discount rate	3.60%

Leases Supplemental Information

Leases Supplemental Information Related to Leases (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Leases [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	$ 18	$ 36
Right-of-use assets obtained in exchange for lease liabilities	$ 70	$ 100

Leases Summary of Operating Lea

Leases Summary of Operating Lease Liabilities Maturity (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Operating Leases, Summary of Aggregate Future Lease Payments After Adoption of 842
2019 (remaining six months)	$ 47
2020	87
2021	83
2022	75
2023	66
Thereafter	305
Total undiscounted lease payments	663
Less: imputed interest	(109)
Total discounted lease payments	$ 554
Operating Leases, Summary of Aggregate Future Lease Payments Before Adoption of 842
2019		$ 89
2020		78
2021		66
2022		60
2023		52
Thereafter		229
Total minimum lease payments		$ 574

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Dec. 31, 2016	Jun. 30, 2018	Jun. 30, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Litigation accrual			$ 0	$ 0
Indenix [Member]
Loss Contingencies [Line Items]
Damages awarded	$ 2,540
Motion invalidated past damages, amount		$ 2,540

Stockholders' Equity Summary of

Stockholders' Equity Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 22,091	$ 20,651	$ 21,534	$ 20,501
Net current period other comprehensive income (loss)	(28)	172	22	130
Ending Balance	22,751	21,734	22,751	21,734
Foreign Currency Translation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			47	85
Reclassifications to retained earnings as a result of the adoption of new accounting standards					$ 0
Balance at January 1, 2018					85
Net unrealized gain (loss)	8	(18)
Reclassifications to net income	0	0
Net current period other comprehensive income (loss)	8	(18)
Ending Balance	55	67	55	67
Unrealized Gains and Losses on Available-for-Sale Securities
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			(52)	194
Balance at January 1, 2018					(99)
Net unrealized gain (loss)	49	(6)
Reclassifications to net income	0	4
Net current period other comprehensive income (loss)	49	(2)
Ending Balance	(3)	(101)	(3)	(101)
Unrealized Gains and Losses on Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			85	(114)
Reclassifications to retained earnings as a result of the adoption of new accounting standards					0
Balance at January 1, 2018					(114)
Net unrealized gain (loss)	29	57
Reclassifications to net income	(64)	93
Net current period other comprehensive income (loss)	(35)	150
Ending Balance	50	36	50	36
AOCI Attributable to Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	130	(170)	80	165
Reclassifications to retained earnings as a result of the adoption of new accounting standards					(293)
Balance at January 1, 2018					$ (128)
Net unrealized gain (loss)	86	33
Reclassifications to net income	(64)	97
Net current period other comprehensive income (loss)	(28)	172	22	130
Ending Balance	$ 102	$ 2	$ 102	$ 2

Stockholders' Equity Stock Repu

Stockholders' Equity Stock Repurchase Program (Details) - 2016 Stock Repurchase Program - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 28, 2016
Equity, Class of Treasury Stock [Line Items]
Authorized amount					$ 12,000
Repurchases of common stock (in shares)	9	7	21	20
Repurchases of common stock, amount	$ 588	$ 450	$ 1,400	$ 1,500
Remaining authorized repurchase amount	$ 3,700		$ 3,700

Net Income Per Share Attribut_3

Net Income Per Share Attributable to Gilead Common Stockholders - Additional Information (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Additional Information [Abstract]
Antidilutive securities excluded from earnings per share computation	17	21	14	16

Net Income Per Share Attribut_4

Net Income Per Share Attributable to Gilead Common Stockholders - Schedule of the Calculation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income attributable to Gilead	$ 1,880	$ 1,817	$ 3,855	$ 3,355
Shares used in per share calculation - basic (in shares)	1,270	1,298	1,273	1,302
Dilutive effect of stock options and equivalents (in shares)	7	10	7	12
Shares used in per share calculation - diluted (in shares)	1,277	1,308	1,280	1,314
Net income per share attributable to Gilead common stockholders - basic (usd per share)	$ 1.48	$ 1.40	$ 3.03	$ 2.58
Net income per share attributable to Gilead common stockholders - diluted (usd per share)	$ 1.47	$ 1.39	$ 3.01	$ 2.55

Segment Information - Summary o

Segment Information - Summary of Revenue by Major Customers (Details) - segment	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting [Abstract]
Number of operating segments	1
Customer Concentration Risk | Sales Revenue, Net | AmerisourceBergen Corp.
Revenue, Major Customer [Line Items]
Percentage of total revenues	20.00%	20.00%	20.00%	20.00%
Customer Concentration Risk | Sales Revenue, Net | Cardinal Health, Inc.
Revenue, Major Customer [Line Items]
Percentage of total revenues	21.00%	20.00%	21.00%	20.00%
Customer Concentration Risk | Sales Revenue, Net | McKesson Corp.
Revenue, Major Customer [Line Items]
Percentage of total revenues	20.00%	21.00%	20.00%	21.00%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Effective income tax rate	22.20%	12.80%	19.30%	18.50%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	21.00%	21.00%	21.00%
Tax Adjustments, Settlements, and Unusual Provisions		$ (202)	$ (119)	$ (153)
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities			$ 119

Subsequent Event (Details)

Subsequent Event (Details) - 1 months ended Jul. 31, 2019 - Subsequent Event [Member] $ in Millions	USD ($)	EUR (€)
Galapagos Collaboration Agreement [Member]
Subsequent Event [Line Items]
Up-front license and option fee payment upon closing of collaboration agreement	$ 3,950
Estimated equity investment upon closing of the subscription agreement	1,100
Potential Milestone Payment Upon Marketing Approval of GLPG-1972	325
Potential Option Exercise Fee for GLPG-1972	250
Potential Milestone for GLPG-1972 after Option Exercise	750
Potential Option Exercise Fee Per Program	$ 150
Galapagos Collaboration Agreement [Member] | Minimum [Member]
Subsequent Event [Line Items]
Potential Sales Based Tiered Royalties	20.00%	20.00%
Galapagos Collaboration Agreement [Member] | Maximum [Member]
Subsequent Event [Line Items]
Potential Sales Based Tiered Royalties	24.00%	24.00%
Galapagos Subscription Agreement [Member]
Subsequent Event [Line Items]
Potential Ownership Percentage in Galapagos Upon Closing of the Subscription Agreement	20.10%	20.10%
Potential Subscription Price | €		€ 140.59
Potential Ownership Percentage in Galapagos Upon Warrant Exercises	29.90%	29.90%
Standstill Restricting Term	10 years	10 years
Maximum Ownership Percentage in Galapagos Based on the Terms of the Subscription Agreement	29.90%	29.90%
Minimum Ownership Percentage in Galapagos Based on the Terms of the Subscription Agreement	20.10%	20.10%

Uncategorized Items - q219form1

Label	Element	Value
Accounting Standards Update 2016-02 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 8,000,000
Accounting Standards Update 2016-02 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	8,000,000
Accounting Standards Update 2016-01 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	190,000,000
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	483,000,000
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (293,000,000)