Gilead Sciences (GILD) 10-Q 6 May 21 2021 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	0-19731
Entity Registrant Name	GILEAD SCIENCES, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	94-3047598
Entity Address, Address Line One	333 Lakeside Drive
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
Title of each class	Common Stock, par value, $0.001 per share
Trading Symbol(s)	GILD
Name of each exchange on which registered	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		1,254,178,166
Entity Central Index Key	0000882095
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 4,065	$ 5,997
Short-term marketable securities	1,601	1,411
Accounts receivable, net	3,925	4,892
Inventories	1,779	1,683
Prepaid and other current assets	1,908	2,013
Total current assets	13,278	15,996
Property, plant and equipment, net	4,990	4,967
Long-term marketable securities	579	502
Intangible assets, net	34,781	33,126
Goodwill	8,334	8,108
Other long-term assets	5,530	5,708
Total assets	67,492	68,407
Current liabilities:
Accounts payable	570	844
Accrued government and other rebates	3,369	3,460
Accrued and other current liabilities	3,507	4,336
Current portion of long-term debt and other obligations, net	2,259	2,757
Total current liabilities	9,705	11,397
Long-term debt, net	27,907	28,645
Long-term income taxes payable	5,022	5,016
Deferred tax liability	4,464	3,914
Other long-term obligations	1,430	1,214
Commitments and contingencies (Note 11)
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; 1,254 shares issued and outstanding	1	1
Additional paid-in capital	4,092	3,880
Accumulated other comprehensive income (loss)	38	(60)
Retained earnings	14,821	14,381
Total Gilead stockholders’ equity	18,952	18,202
Noncontrolling interest	12	19
Total stockholders’ equity	18,964	18,221
Total liabilities and stockholders’ equity	$ 67,492	$ 68,407

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Stockholders’ equity:
Preferred stock, par value (in dollars 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 (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	5,600,000,000	5,600,000,000
Common stock, issued (in shares)	1,254,000,000	1,254,000,000
Common stock, outstanding (in shares)	1,254,000,000	1,254,000,000

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Revenues:
Total revenues	$ 6,423	$ 5,548
Costs and expenses:
Cost of goods sold	1,361	969
Research and development expenses	1,055	1,004
Acquired in-process research and development expenses	62	97
Selling, general and administrative expenses	1,055	1,076
Total costs and expenses	3,533	3,146
Income from operations	2,890	2,402
Interest expense	(257)	(241)
Other income (expense), net	(369)	(158)
Income before income taxes	2,264	2,003
Income tax expense	542	465
Net income	1,722	1,538
Net loss attributable to noncontrolling interest	(7)	(13)
Net income attributable to Gilead	$ 1,729	$ 1,551
Net income per share attributable to Gilead common stockholders - basic (in dollars per share)	$ 1.38	$ 1.23
Shares used in per share calculation - basic (in shares)	1,256	1,262
Net income per share attributable to Gilead common stockholders - diluted (in dollars per share)	$ 1.37	$ 1.22
Shares used in per share calculation - diluted (in shares)	1,262	1,270
Product sales
Revenues:
Total revenues	$ 6,340	$ 5,467
Royalty, contract and other revenues
Revenues:
Total revenues	$ 83	$ 81

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 1,722	$ 1,538
Other comprehensive income (loss):
Net foreign currency translation gain (loss), net of tax	10	(39)
Available-for-sale debt securities:
Net unrealized loss, net of tax	(2)	(23)
Reclassifications to net income, net of tax	0	(11)
Net change	(2)	(34)
Cash flow hedges:
Net unrealized gain, net of tax	68	57
Reclassifications to net income, net of tax	22	(23)
Net change	90	34
Other comprehensive income (loss)	98	(39)
Comprehensive income	1,820	1,499
Comprehensive loss attributable to noncontrolling interest	(7)	(13)
Comprehensive income attributable to Gilead	$ 1,827	$ 1,512

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Millions	Total	Cumulative effect from the adoption of new accounting standard	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Retained EarningsCumulative effect from the adoption of new accounting standard	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2019			1,266,000,000
Beginning balance at Dec. 31, 2019	$ 22,650	$ (7)	$ 1	$ 3,051	$ 85	$ 19,388	$ (7)	$ 125
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,538					1,551		(13)
Other comprehensive income (loss), net of tax	(39)				(39)
Issuances under employee stock purchase plan (in shares)			1,000,000
Issuances under employee stock purchase plan	66			66
Issuance under equity incentive plans (in shares)			7,000,000
Issuances under equity incentive plans	111			111
Stock-based compensation	141			141
Repurchases of common stock (in shares)			(20,000,000)
Repurchases of common stock	(1,414)			(58)		(1,356)
Dividends declared	(867)					(867)
Ending balance (in shares) at Mar. 31, 2020			1,254,000,000
Ending balance at Mar. 31, 2020	$ 22,179		$ 1	3,311	46	18,709		112
Beginning balance (in shares) at Dec. 31, 2020	1,254,000,000		1,254,000,000
Beginning balance at Dec. 31, 2020	$ 18,221		$ 1	3,880	(60)	14,381		19
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,722					1,729		(7)
Other comprehensive income (loss), net of tax	98				98
Issuances under employee stock purchase plan (in shares)			1,000,000
Issuances under employee stock purchase plan	76			76
Issuance under equity incentive plans (in shares)			5,000,000
Issuances under equity incentive plans	12			12
Stock-based compensation	140			140
Repurchases of common stock (in shares)			(6,000,000)
Repurchases of common stock	(399)			(16)		(383)
Dividends declared	$ (906)					(906)
Ending balance (in shares) at Mar. 31, 2021	1,254,000,000		1,254,000,000
Ending balance at Mar. 31, 2021	$ 18,964		$ 1	$ 4,092	$ 38	$ 14,821		$ 12

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Stockholders' Equity [Abstract]
Common stock, dividends declared (in dollars per share)	$ 0.71	$ 0.68

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities:
Net income	$ 1,722	$ 1,538
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation expense	78	68
Amortization expense	395	281
Stock-based compensation expense	139	141
Acquired in-process research and development expenses	62	97
Deferred income taxes	71	56
Net losses from equity securities	351	283
Other	201	73
Changes in operating assets and liabilities:
Accounts receivable, net	975	(376)
Inventories	(69)	15
Prepaid expenses and other	(8)	46
Accounts payable	(253)	(109)
Income taxes payable	(316)	(127)
Accrued and other liabilities	(738)	(550)
Net cash provided by operating activities	2,610	1,436
Investing Activities:
Purchases of marketable debt securities	(931)	(13,158)
Proceeds from sales of marketable debt securities	60	9,656
Proceeds from maturities of marketable debt securities	619	3,449
Acquisitions, including in-process research and development, net of cash acquired	(1,255)	(63)
Purchases of equity securities	(279)	(8)
Capital expenditures	(165)	(171)
Other	(91)	(49)
Net cash used in investing activities	(2,042)	(344)
Financing Activities:
Proceeds from issuances of common stock	88	177
Repurchases of common stock	(309)	(1,328)
Repayments of debt and other obligations	(1,250)	(500)
Payments of dividends	(917)	(874)
Other	(89)	(86)
Net cash used in financing activities	(2,477)	(2,611)
Effect of exchange rate changes on cash and cash equivalents	(23)	(61)
Net change in cash and cash equivalents	(1,932)	(1,580)
Cash and cash equivalents at beginning of period	5,997	11,631
Cash and cash equivalents at end of period	$ 4,065	$ 10,051

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2021
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 a variable interest entity (“VIE”) 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 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. 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, 2020, included in our Annual Report on Form 10-K filed with the U.S. Securities and Exchange Commission. Segment Information We have one operating segment, which focuses on the discovery, development and commercialization of innovative medicines in areas of unmet medical need. Our Chief Executive Officer, as the chief operating decision-maker (“CODM”), manages and allocates resources to the operations of the company on an entity-wide basis. Managing and allocating resources on an entity-wide basis enables our CODM to assess the overall level of resources available and how to best deploy these resources across functions and research and development (“R&D”) projects based on unmet medical need and, as necessary, reallocate resources among our internal R&D portfolio and external opportunities to best support the long-term growth of our business. See Note 2. Revenues for a summary of disaggregated revenues by product and geographic region. Significant Accounting Policies, Estimates and Judgments The preparation of these Condensed Consolidated Financial Statements in accordance with U.S. generally accepted accounting principles requires management 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, such as the economic considerations related to the impact that the coronavirus disease (“COVID-19”) could have on our significant accounting estimates. Actual results may differ significantly from these estimates. Reclassification Certain amounts for the three months ended March 31, 2020 were reclassified to conform to the current period presentation. Beginning in the second quarter of 2020, acquired in-process research and development (“IPR&D”) expenses are reported separately from Research and development expenses on our Condensed Consolidated Statements of Income. Our Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2020, has also been conformed to separately present acquired IPR&D expenses. 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. Trade accounts receivable are recorded net of allowances for wholesaler chargebacks related to government and other programs, cash discounts for prompt payment and credit losses. Estimates of our allowance for credit losses consider a number of factors including existing contractual payment terms, individual customer circumstances, historical payment patterns of our customers, a review of the local economic environment and its potential impact on expected future customer payment patterns and government funding and reimbursement practices. The majority of our trade accounts receivable arises from product sales in the United States, Europe and Japan. There were no material write-offs charged against the allowance for the three months ended March 31, 2021 and 2020. Certain of the raw materials and components that we utilize in our operations are obtained through single suppliers. Certain of the raw materials that we utilize in our operations are made at only one facility. Since the suppliers of key components and raw materials must be named in a new drug application filed with U.S. Food and Drug Administration (“FDA”) for a product, significant delays can occur if the qualification of a new supplier is required. If delivery of material from our suppliers is interrupted for any reason, we may be unable to ship our commercial products or to supply our product candidates for clinical trials.

REVENUES

REVENUES	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
REVENUES	REVENUES Disaggregation of Revenues Revenues were as follows: Three Months Ended March 31, 2021 Three Months Ended March 31, 2020 (in millions) U.S. Europe Other International Total U.S. Europe Other International Total Product Sales: HIV Atripla $ 23 $ 4 $ 4 $ 31 $ 81 $ 7 $ 7 $ 95 Biktarvy 1,465 216 143 1,824 1,412 181 100 1,693 Complera/Eviplera 25 34 4 63 24 47 5 76 Descovy 282 42 35 359 363 61 34 458 Genvoya 506 106 61 673 612 151 61 824 Odefsey 240 113 14 367 269 127 13 409 Stribild 31 11 4 46 34 17 2 53 Truvada 119 7 9 135 383 8 15 406 Other HIV (1) 6 1 10 17 3 2 3 8 Revenue share - Symtuza (2) 89 44 2 135 72 38 2 112 Total HIV 2,786 578 286 3,650 3,253 639 242 4,134 Hepatitis C virus (“HCV”) Ledipasvir/Sofosbuvir (3) 19 16 21 56 53 11 48 112 Sofosbuvir/Velpatasvir (4) 214 75 92 381 311 122 131 564 Other HCV (5) 25 44 4 73 34 15 4 53 Total HCV 258 135 117 510 398 148 183 729 Hepatitis B virus (“HBV”) / Hepatitis Delta virus (“HDV”) Vemlidy 77 8 96 181 73 7 56 136 Viread 4 7 20 31 4 11 25 40 Other HBV/HDV (6) — 8 — 8 8 2 — 10 Total HBV/HDV 81 23 116 220 85 20 81 186 Veklury 820 388 248 1,456 — — — — Cell Therapy Tecartus 27 4 — 31 — — — — Yescarta 92 61 7 160 103 37 — 140 Total Cell Therapy 119 65 7 191 103 37 — 140 Trodelvy 72 — — 72 — — — — Other AmBisome 12 66 43 121 18 59 42 119 Letairis 54 — — 54 83 — — 83 Ranexa 3 — — 3 8 — — 8 Zydelig 8 7 — 15 8 12 — 20 Other (7) 27 13 8 48 33 12 3 48 Total Other 104 86 51 241 150 83 45 278 Total product sales 4,240 1,275 825 6,340 3,989 927 551 5,467 Royalty, contract and other revenues 20 61 2 83 17 48 16 81 Total revenues $ 4,260 $ 1,336 $ 827 $ 6,423 $ 4,006 $ 975 $ 567 $ 5,548 _______________________________ (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 Unlimited Company. (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 Vosevi and Sovaldi. (6) Includes Hepcludex and Hepsera. (7) Includes Cayston and Jyseleca. Revenues from Major Customers The following table summarizes revenues from each of our customers who individually accounted for 10% or more of our total revenues: Three Months Ended March 31, (as a percentage of total revenues) 2021 2020 AmerisourceBergen Corporation 27 % 22 % Cardinal Health, Inc. 18 % 22 % McKesson Corporation 17 % 21 % 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 $226 million and $188 million for the three months ended March 31, 2021 and 2020, respectively. Variable consideration is included in the net sales price only to the extent a significant reversal in the amount of cumulative revenue recognized is not probable of occurring when the uncertainty associated with the variable consideration is subsequently resolved. Estimates are assessed each period and updated to reflect current information. Changes in estimates for variable consideration related to sales made in prior years resulted in a $332 million and $38 million increase in revenues for the three months ended March 31, 2021 and 2020, 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 $185 million and $198 million as of March 31, 2021 and December 31, 2020, respectively. Contract liabilities, which generally result from receipt of advance payment before our performance under the contract, were $91 million and $97 million as of March 31, 2021 and December 31, 2020, respectively. During the three months ended March 31, 2021 and 2020, revenue recognized that was included in the contract liability balance as of the beginning of the respective years was not material. Revenue expected to be recognized in the future from contract liabilities as the related performance obligations are satisfied is not expected to be material in any one year.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2021
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 on our Condensed Consolidated Balance Sheets at amounts that approximate current fair values. 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: March 31, 2021 December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Available-for-sale debt securities: U.S. treasury securities $ 464 $ — $ — $ 464 $ 309 $ — $ — $ 309 Certificates of deposit — 358 — 358 — 216 — 216 Non-U.S. government securities — 62 — 62 — 43 — 43 Corporate debt securities — 1,247 — 1,247 — 1,142 — 1,142 Residential mortgage and asset-backed securities — 347 — 347 — 316 — 316 Equity securities: Money market funds 2,216 — — 2,216 4,361 — — 4,361 Equity investment in Galapagos 1,302 — — 1,302 1,648 — — 1,648 Other publicly traded equity securities 968 — — 968 743 — — 743 Deferred compensation plan 235 — — 235 218 — — 218 Foreign currency derivative contracts — 32 — 32 — 12 — 12 Total $ 5,185 $ 2,046 $ — $ 7,231 $ 7,279 $ 1,729 $ — $ 9,008 Liabilities: Liability for MYR contingent consideration $ — $ — $ 341 $ 341 $ — $ — $ — $ — Deferred compensation plan 235 — — 235 218 — — 218 Foreign currency derivative contracts — 41 — 41 — 121 — 121 Total $ 235 $ 41 $ 341 $ 617 $ 218 $ 121 $ — $ 339 Equity Securities The following table summarizes the classification of our equity securities measured at fair value on a recurring basis on our Condensed Consolidated Balance Sheets: (in millions) March 31, 2021 December 31, 2020 Cash and cash equivalents $ 2,216 $ 4,361 Prepaid and other current assets (1) 797 853 Other long-term assets (1) 1,708 1,756 Total $ 4,721 $ 6,970 ________________________________ (1) Includes equity investment in Galapagos NV (“Galapagos”) Equity investments not measured at fair value and excluded from the above tables were limited partnerships and other equity method investments of $69 million and $58 million at March 31, 2021 and December 31, 2020, respectively, and other equity investments without readily determinable fair values of $225 million and $204 million at March 31, 2021 and December 31, 2020, respectively. These amounts were included in Other long-term assets on our Condensed Consolidated Balance Sheets. Changes in the fair value of equity securities resulted in net unrealized losses of $351 million and $283 million for the three months ended March 31, 2021 and 2020, respectively, which were included in Other income (expense), net on our Condensed Consolidated Statements of Income. Our available-for-sale debt securities are classified as cash equivalents, short-term marketable securities and long-term marketable securities in our Condensed Consolidated Balance Sheets. See Note 4. Available-For-Sale Debt Securities for additional information. Equity Investment in Galapagos The following table summarizes the classification of our equity investment in Galapagos in our Condensed Consolidated Balance Sheets: (in millions) March 31, 2021 December 31, 2020 Prepaid and other current assets $ 276 $ 351 Other long-term assets 1,026 1,297 Total $ 1,302 $ 1,648 We elected and applied the fair value option to account for our equity investment in Galapagos whereby the investment is marked to market through earnings each reporting period based on the market price of Galapagos shares. We believe the fair value option best reflects the underlying economics of the investment. The portion of the investment subject to long-term contractual lock-up provisions is classified within Other long-term assets and the remainder is classified as Prepaid and other current assets on our Condensed Consolidated Balance Sheets. Subsequent to the first quarter of 2021, we amended the Galapagos subscription agreement to extend the initial lock-up provision for certain Galapagos shares from August 2021 to August 2024. As a result, all of our equity investment in Galapagos became subject to long-term contractual lock-up provisions and will be classified as Other long-term assets commencing in the second quarter of 2021. Level 2 Inputs We estimate the fair values of Level 2 financial 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 and swap rates. These inputs, where applicable, are observable at commonly quoted intervals. The total estimated fair values of our aggregate short-term and long-term debt, determined using Level 2 inputs based on their quoted market values, were approximately $31.6 billion and $34.6 billion as of March 31, 2021 and December 31, 2020, respectively, and the carrying values were $29.1 billion and $30.3 billion as of March 31, 2021 and December 31, 2020, respectively. Level 3 Inputs During the three months ended March 31, 2021, we measured assets acquired and liabilities assumed at fair value on a nonrecurring basis, in connection with our acquisition of MYR GmbH (“MYR”). Total consideration for the MYR acquisition included a liability for contingent consideration of $341 million as of the acquisition date. This contingent liability was measured at fair value using probability-weighted scenarios for FDA approval. See Note 6. Acquisitions for additional information. As of March 31, 2021 and December 31, 2020, the carrying value of the liability related to future royalties assumed from the fourth quarter 2020 Immunomedics, Inc. (“Immunomedics”) acquisition approximated fair value, determined using Level 3 inputs. See Note 10. Debt and Credit Facilities for additional information.

AVAILABLE-FOR-SALE DEBT SECURIT

AVAILABLE-FOR-SALE DEBT SECURITIES	3 Months Ended
	Mar. 31, 2021
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: March 31, 2021 December 31, 2020 (in millions) Amortized Gross Gross Estimated Amortized Gross Gross Estimated U.S. treasury securities $ 464 $ — $ — $ 464 $ 308 $ 1 $ — $ 309 Certificates of deposit 358 — — 358 216 — — 216 Non-U.S. government securities 62 — — 62 43 — — 43 Corporate debt securities 1,247 1 (1) 1,247 1,140 2 — 1,142 Residential mortgage and asset-backed securities 347 — — 347 316 — — 316 Total $ 2,478 $ 1 $ (1) $ 2,478 $ 2,023 $ 3 $ — $ 2,026 The following table summarizes the classification of our available-for-sale debt securities in our Condensed Consolidated Balance Sheets: (in millions) March 31, 2021 December 31, 2020 Cash and cash equivalents $ 298 $ 113 Short-term marketable securities 1,601 1,411 Long-term marketable securities 579 502 Total $ 2,478 $ 2,026 Accrued interest receivable excluded from both the fair value and amortized cost basis of the available-for-sale debt securities was $9 million as of March 31, 2021 and December 31, 2020 and is recorded in Prepaid and other current assets on our Condensed Consolidated Balance Sheets. There were no write-offs of accrued interest receivable during the three months ended March 31, 2021 and 2020. The following table summarizes our available-for-sale debt securities by contractual maturity: March 31, 2021 (in millions) Amortized Cost Fair Value Within one year $ 1,898 $ 1,899 After one year through five years 563 562 After five years 17 17 Total $ 2,478 $ 2,478

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	DERIVATIVE FINANCIAL INSTRUMENTSOur 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 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 March 31, 2021 are expected to be reclassified to product sales within 12 months. The cash flow effects of our derivative contracts for the three months ended March 31, 2021 and 2020 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 $3.0 billion and $2.4 billion as of March 31, 2021 and December 31, 2020, 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 on our Condensed Consolidated Balance Sheets: March 31, 2021 Asset Derivatives Liability Derivatives (in millions) Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Prepaid and other current assets $ 25 Other accrued liabilities $ (41) Foreign currency exchange contracts Other long-term assets 7 Other long-term obligations — Total derivatives designated as hedges 32 (41) Derivatives not designated as hedges: Foreign currency exchange contracts Prepaid and other current assets — Other accrued liabilities — Total derivatives not designated as hedges — — Total derivatives $ 32 $ (41) December 31, 2020 Asset Derivatives Liability Derivatives (in millions) Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Prepaid and other current assets $ — Other accrued liabilities $ (113) Foreign currency exchange contracts Other long-term assets — Other long-term obligations (7) Total derivatives designated as hedges — (120) Derivatives not designated as hedges: Foreign currency exchange contracts Prepaid and other current assets 12 Other accrued liabilities (1) Total derivatives not designated as hedges 12 (1) Total derivatives $ 12 $ (121) The following table summarizes the effect of our foreign currency exchange contracts on our Condensed Consolidated Financial Statements: Three Months Ended March 31, (in millions) 2021 2020 Derivatives designated as hedges: Gains recognized in AOCI $ 78 $ 66 Gains (losses) reclassified from AOCI into product sales $ (25) $ 27 Derivatives not designated as hedges: Gains recognized in Other income (expense), net $ 34 $ 24 From time to time, we may discontinue cash flow hedges and, as a result, record related amounts in Other income (expense), net on our Condensed Consolidated Statements of Income. There were no discontinuances of cash flow hedges for the three months ended March 31, 2021 and 2020. As of March 31, 2021 and December 31, 2020, we only held foreign currency exchange contracts. The following table summarizes the potential effect of offsetting our foreign currency exchange contracts on our Condensed Consolidated Balance Sheets: Gross Amounts Not Offset (in millions) Gross Amounts Gross Amounts Amounts of Assets/Liabilities Presented Derivative Cash Collateral Net Amount As of March 31, 2021 Derivative assets $ 32 $ — $ 32 $ (22) $ — $ 10 Derivative liabilities $ (41) $ — $ (41) $ 22 $ — $ (19) As of December 31, 2020 Derivative assets $ 12 $ — $ 12 $ (12) $ — $ — Derivative liabilities $ (121) $ — $ (121) $ 12 $ — $ (109)

ACQUISITIONS

ACQUISITIONS	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS We account for business combinations using the acquisition method of accounting, which generally requires that assets acquired and liabilities assumed be recorded at their fair values as of the acquisition date. Any excess of consideration over the fair value of net assets acquired is recorded as goodwill. Transaction costs associated with business combinations are expensed as they are incurred. The first quarter 2021 acquisition of MYR and the fourth quarter 2020 acquisition of Immunomedics were accounted for as business combinations. MYR On March 4, 2021, we completed the acquisition of MYR, a German biotechnology company. MYR focuses on the development and commercialization of therapeutics for the treatment of HDV. The acquisition provides Gilead with Hepcludex, which was conditionally approved by the European Medicines Agency (“EMA”) in July 2020 for the treatment of chronic HDV infection in adults with compensated liver disease. Upon closing, MYR became a wholly-owned subsidiary of Gilead. The financial results of MYR were included in our Condensed Consolidated Financial Statements from the date of the acquisition. MYR contributed an immaterial net loss from the date of acquisition through March 31, 2021. We recorded other acquisition-related expenses of $11 million, primarily representing closing costs and related fees, in Selling, general and administrative expenses on our Condensed Consolidated Statements of Income for the three months ended March 31, 2021. The aggregate consideration for this acquisition of approximately €1.3 billion (or $1.6 billion) primarily consists of €1.0 billion (or approximately $1.2 billion) paid upon closing and contingent consideration of up to €300 million, subject to customary adjustments, representing a potential future milestone payment upon FDA approval of Hepcludex. The estimated fair value of this contingent liability was $341 million as of the acquisition date and recorded in Other long-term obligations on our Condensed Consolidated Balance Sheets. The contingent consideration was estimated using probability-weighted scenarios for FDA approval. The fair value estimates for the assets acquired and liabilities assumed were based upon valuations using information known and knowable as of the date of this filing. Changes to these assumptions and estimates could cause an impact to the valuation of assets acquired, including intangible assets, goodwill and the related tax impacts of the acquisition, as well as legal and other contingencies. The amounts recognized will be finalized as the information necessary to complete the analysis is obtained, but no later than one year after the acquisition date. The following table summarizes estimated fair values of assets acquired and liabilities assumed as of the acquisition date: (in millions) Amount Intangible assets Finite-lived intangible asset $ 845 Acquired IPR&D 1,190 Deferred income taxes, net (513) Other assets (and liabilities), net (187) Total identifiable net assets 1,335 Goodwill 226 Total consideration $ 1,561 Intangible Assets The finite-lived intangible asset of $845 million represents the estimated fair value of Hepcludex for HDV in Europe as of the acquisition date. The fair value was determined by applying the income approach using unobservable inputs to estimate probability-weighted net cash flows attributable to Hepcludex for HDV in Europe and a discount rate of 12%. The discount rate used represents the estimated rate that market participants would use to value this intangible asset. This intangible asset is being amortized over an estimated useful life of 10 years. Acquired intangible assets related to IPR&D consist of Hepcludex for HDV in all other regions without regulatory approval, including the U.S. The estimated aggregate fair value of $1.2 billion as of the acquisition date was determined by applying the income approach using unobservable inputs to estimate probability-weighted net cash flows attributable to this asset and a discount rate of 12%. The discount rate used represents the estimated rate that market participants would use to value this intangible asset. Some of the more significant assumptions inherent in the development of intangible asset fair values include: estimates of projected future cash flows including revenues and operating profits; probability of success; the discount rate selected; the life of the potential commercialized products and the risks related to the viability of and potential alternative treatments in any future target markets, among other factors. Intangible assets related to IPR&D projects are considered to be indefinite-lived assets until the completion or abandonment of the associated R&D efforts. The inputs used for valuing these identifiable intangibles are unobservable and considered Level 3 under the fair value measurement and disclosure guidance. Deferred Income Taxes The net deferred tax liability was based upon the difference between the estimated book basis and tax basis of net assets acquired and an estimate for the final pre-acquisition net operating losses of MYR. Goodwill The excess of the consideration transferred over the fair values of assets acquired and liabilities assumed of $226 million was recorded as goodwill, which primarily reflects the future economic benefits arising from other assets acquired that could not be individually identified and separately recognized. Goodwill recognized for MYR is not expected to be deductible for income tax purposes. Immunomedics In the fourth quarter of 2020, we completed the acquisition of Immunomedics for cash consideration of $20.6 billion. Immunomedics is a wholly-owned subsidiary of Gilead. The acquisition was financed with the majority of the proceeds from the September 2020 senior unsecured notes offering, an additional $1.0 billion borrowing under a new senior unsecured term loan facility and cash on hand. The following table summarizes estimated fair values of assets acquired and liabilities assumed as of the acquisition date: (in millions) Amount Cash and cash equivalents $ 726 Inventories 946 Intangible assets Finite-lived intangible asset 4,600 Acquired IPR&D 15,760 Outlicense contract 175 Deferred income taxes (4,565) Liability related to future royalties (1,100) Other assets (and liabilities), net 64 Total identifiable net assets 16,606 Goodwill 3,991 Total consideration transferred $ 20,597 There were no measurement period adjustments recorded to the fair values of assets acquired and liabilities assumed during the three months ended March 31, 2021.

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND INTANGIBLE ASSETS	GOODWILL AND INTANGIBLE ASSETS Goodwill The following table summarizes the changes in the carrying amount of goodwill: (in millions) Amount Balance at December 31, 2020 $ 8,108 Goodwill resulting from the acquisition of MYR 226 Balance at March 31, 2021 $ 8,334 Intangible Assets The following table summarizes our Intangible assets, net: March 31, 2021 December 31, 2020 (in millions) Gross Accumulated Foreign Currency Translation Adjustment Net Carrying Amount Gross Accumulated Foreign Currency Translation Adjustment Net Carrying Amount Finite-lived assets: Intangible asset - sofosbuvir $ 10,720 $ (5,127) $ — $ 5,593 $ 10,720 $ (4,952) $ — $ 5,768 Intangible asset - axicabtagene ciloleucel (1) 7,110 (1,196) — 5,914 6,200 (1,105) — 5,095 Intangible asset - Trodelvy (2) 4,600 (158) — 4,442 4,600 (63) — 4,537 Intangible asset - Hepcludex for HDV 845 (7) — 838 — — — — Other 1,391 (567) — 824 1,377 (540) (1) 836 Total finite-lived assets 24,666 (7,055) — 17,611 22,897 (6,660) (1) 16,236 Indefinite-lived assets - IPR&D (3)(4) 17,170 — — 17,170 16,890 — — 16,890 Total intangible assets $ 41,836 $ (7,055) $ — $ 34,781 $ 39,787 $ (6,660) $ (1) $ 33,126 _______________________________ (1) Gross carrying amount as of March 31, 2021 includes $910 million reclassified from indefinite-lived assets - IPR&D following the March 2021 FDA approval of Yescarta for the treatment of adult patients with relapsed or refractory follicular lymphoma. (2) Amounts represent Trodelvy for metastatic triple-negative breast cancer. (3) Gross carrying amount as of March 31, 2021 includes $1.2 billion recognized from the first quarter 2021 MYR acquisition. See Note 6. Acquisitions for additional information. (4) In April 2021, FDA granted accelerated approval of Trodelvy for use in adult patients with locally advanced or metastatic urothelial cancer, a new indication. Accordingly, the related amount of $1.0 billion will be reclassified to finite-lived assets in the second quarter of 2021. Aggregate amortization expense related to finite-lived intangible assets was $395 million and $281 million for the three months ended March 31, 2021 and 2020, 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 March 31, 2021: (in millions) Amount 2021 (remaining nine months) $ 1,256 2022 1,675 2023 1,675 2024 1,675 2025 1,669 Thereafter 9,661 Total $ 17,611

OTHER FINANCIAL INFORMATION

OTHER FINANCIAL INFORMATION	3 Months Ended
	Mar. 31, 2021
Other Financial Information [Abstract]
OTHER FINANCIAL INFORMATION	OTHER FINANCIAL INFORMATION Accounts receivable, net The following table summarizes our Accounts receivable, net: (in millions) March 31, 2021 December 31, 2020 Accounts receivable $ 4,647 $ 5,560 Less: chargebacks 607 552 Less: cash discounts and other 64 72 Less: allowances for credit losses 51 44 Accounts receivable, net $ 3,925 $ 4,892 Inventories The following table summarizes our Inventories: (in millions) March 31, 2021 December 31, 2020 Raw materials $ 1,023 $ 1,080 Work in process 856 976 Finished goods 1,117 958 Total $ 2,996 $ 3,014 Reported as: Inventories $ 1,779 $ 1,683 Other long-term assets (1) 1,217 1,331 Total $ 2,996 $ 3,014 ________________________________ (1) Amounts primarily consist of raw materials. Accrued and other current liabilities The following table summarizes the components of Accrued and other current liabilities: (in millions) March 31, 2021 December 31, 2020 Compensation and employee benefits $ 494 $ 864 Income taxes payable 215 598 Allowance for sales returns 524 587 Accrued and other current liabilities 2,274 2,287 Total $ 3,507 $ 4,336

COLLABORATIONS AND OTHER ARRANG

COLLABORATIONS AND OTHER ARRANGEMENTS	3 Months Ended
	Mar. 31, 2021
Collaborative and Other Arrangements [Abstract]
COLLABORATIONS AND OTHER ARRANGEMENTS	COLLABORATIONS AND OTHER ARRANGEMENTS We continue to pursue licensing and strategic collaborations and other similar arrangements with third parties for the development and commercialization of certain products and product candidates. These arrangements may involve two or more parties who are active participants in the operating activities of the collaboration and are exposed to significant risks and rewards depending on the commercial success of the activities. These arrangements may include non-refundable upfront payments, expense reimbursements or 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 and cost-sharing arrangements. We also continue to pursue equity investments in third parties focused on the development and commercialization of products and product candidates. Merck Sharp & Dohme Corp. (“Merck”) On March 13, 2021, we entered into a license and collaboration agreement with Merck, a subsidiary of Merck & Co., Inc. to jointly develop and commercialize long-acting investigational treatments in HIV that combine Gilead’s investigational capsid inhibitor, lenacapavir, and Merck’s investigational nucleoside reverse transcriptase translocation inhibitor, islatravir. The collaboration will initially focus on long-acting oral and injectable formulations. Under the terms of the agreement, Gilead and Merck will share global development and commercialization costs at 60% and 40%, respectively, across the oral and injectable formulation programs. For long-acting oral products, Gilead will lead commercialization in the U.S. and Merck will lead commercialization in the European Union (“EU”) and rest of the world. For long-acting injectable products, Merck will lead commercialization in the U.S. and Gilead will lead commercialization in the EU and rest of the world. Gilead and Merck will jointly promote the combination products in the U.S. and certain other major markets. We will share global product revenues with Merck equally until product revenues surpass certain pre-determined per formulation revenue tiers. Upon passing $2.0 billion in net product sales for the oral combination in a given calendar year, our share of revenue will increase to 65% for any revenues above the threshold for such calendar year. Upon passing $3.5 billion in net product sales for the injectable combination in a given calendar year, our share of revenue will increase to 65% for any revenues above the threshold for such calendar year. There was no material impact from the agreement on our Condensed Consolidated Financial Statements for the three months ended March 31, 2021. We will also have the option to license certain of Merck’s investigational oral integrase inhibitors to develop in combination with lenacapavir. Reciprocally, Merck will have the option to license certain of Gilead’s investigational oral integrase inhibitors to develop in combination with islatravir. Each company may exercise its option for such investigational oral integrase inhibitor of the other company within the first five years after execution of the agreement, following completion of the first Phase 1 clinical trial of that integrase inhibitor. Upon exercise of an option, the companies will split development cost and revenues, unless the non-exercising company decides to opt-out, in which case the non-exercising company will be paid a royalty. Arcus Biosciences, Inc. (“Arcus”) On May 27, 2020, we entered into a transaction with Arcus, which included entry into an option, license and collaboration agreement (the “Collaboration Agreement”) and a common stock purchase agreement and an investor rights agreement (together, and as subsequently amended the “Stock Purchase Agreements”). In 2020, pursuant to the Stock Purchase Agreements and a separate secondary equity offering, we acquired approximately 8.2 million shares of Arcus common stock for approximately $261 million. In the first quarter of 2021, we amended and restated the common stock purchase agreement and acquired approximately 5.7 million additional shares of Arcus common stock for $220 million. As a result, we currently own a total of 13.8 million shares of Arcus, which represented approximately 19.5% of the issued and outstanding voting stock of Arcus immediately following the closing of the transaction. We recorded our equity investments in Arcus in Other long-term assets on our Condensed Consolidated Balance Sheets as the investments are subject to contractual lock-up provisions, subject to certain conditions. We account for our equity investments in Arcus at fair value with changes in fair value recognized in Other income (expense), net on our Condensed Consolidated Statements of Income for each reporting period. Under the Stock Purchase Agreements, we have the right to purchase additional shares of Arcus from Arcus over the five year period beginning on the closing of the Stock Purchase Agreements, up to a maximum of 35% of the outstanding voting stock. We are subject to a three year standstill, which period began on the date the parties entered into the Stock Purchase Agreements, restricting our ability to acquire voting stock of Arcus exceeding more than 35% of the then issued and outstanding voting stock of Arcus, subject to certain exceptions. Additionally, we agreed not to dispose of any equity securities of Arcus prior to the second anniversary of the closing of the Stock Purchase Agreements without the prior consent of Arcus, subject to certain exceptions. The amendment and restatement of the common stock purchase agreement in the first quarter of 2021 did not modify any of these terms. Other Arrangements During the three months ended March 31, 2021 and 2020, we entered into several collaborations, equity investments and licensing arrangements as well as other similar arrangements that we do not consider to be individually material. We recorded upfront collaboration expenses related to these arrangements of $62 million and $97 million for the three months ended March 31, 2021 and 2020, respectively, within Acquired in-process research and development expenses on our Condensed Consolidated Statements of Income. Cash payments made related to our equity investments were $59 million and $8 million for the three months ended March 31, 2021 and 2020, respectively, which were primarily recorded in 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 developmental, regulatory and commercial milestones, which could be significant. Future milestone payments, if any, will be reflected in 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.

DEBT AND CREDIT FACILITIES

DEBT AND CREDIT FACILITIES	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
DEBT AND CREDIT FACILITIES	DEBT AND CREDIT FACILITIES The following table summarizes the carrying amount of our borrowings under various financing arrangements: (in millions) Carrying Amount Type of Borrowing Issue Date Maturity Date Interest Rate March 31, 2021 December 31, 2020 Senior Unsecured March 2011 April 2021 4.50% $ — $ 1,000 Senior Unsecured September 2020 September 2021 3-month LIBOR + 0.15% 500 499 Senior Unsecured December 2011 December 2021 4.40% 1,249 1,249 Senior Unsecured September 2016 March 2022 1.95% 499 499 Senior Unsecured September 2015 September 2022 3.25% 999 998 Senior Unsecured September 2016 September 2023 2.50% 748 748 Senior Unsecured September 2020 September 2023 3-month LIBOR + 0.52% 498 498 Senior Unsecured September 2020 September 2023 0.75% 1,993 1,992 Term Loan October 2020 October 2023 variable 748 998 Senior Unsecured March 2014 April 2024 3.70% 1,746 1,746 Senior Unsecured November 2014 February 2025 3.50% 1,747 1,746 Senior Unsecured September 2015 March 2026 3.65% 2,737 2,737 Senior Unsecured September 2016 March 2027 2.95% 1,246 1,246 Senior Unsecured September 2020 October 2027 1.20% 746 745 Senior Unsecured September 2020 October 2030 1.65% 992 992 Senior Unsecured September 2015 September 2035 4.60% 992 991 Senior Unsecured September 2016 September 2036 4.00% 742 741 Senior Unsecured September 2020 October 2040 2.60% 986 986 Senior Unsecured December 2011 December 2041 5.65% 996 996 Senior Unsecured March 2014 April 2044 4.80% 1,735 1,735 Senior Unsecured November 2014 February 2045 4.50% 1,732 1,732 Senior Unsecured September 2015 March 2046 4.75% 2,219 2,219 Senior Unsecured September 2016 March 2047 4.15% 1,726 1,726 Senior Unsecured September 2020 October 2050 2.80% 1,476 1,476 Total senior unsecured notes and term loan facility 29,052 30,295 Liability related to future royalties 1,114 1,107 Total debt, net 30,166 31,402 Less: current portion of long-term debt and other obligations, net 2,259 2,757 Total long-term debt, net $ 27,907 $ 28,645 Debt During the three months ended March 31, 2021, we repaid $1.25 billion of debt. In January 2021, we repaid $1.0 billion of senior unsecured notes prior to the April 2021 maturity, by exercising a 3-month par call. In March 2021, we repaid $250 million principal amount under our three-year $1.0 billion senior unsecured term loan facility, leaving $750 million principal amount outstanding as of March 31, 2021. No new debt was issued during the three months ended March 31, 2021. We are required to comply with certain covenants under our note indentures governing our senior unsecured notes. As of March 31, 2021, we were in compliance with all covenants. Credit Facility As of March 31, 2021 and December 31, 2020, there were no amounts outstanding under our $2.5 billion revolving credit facility maturing in June 2025, and we were in compliance with all covenants.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Legal Proceedings 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 material 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 or the outcome (including in excess of any accrual) is not expected to be material, and we cannot reasonably estimate the maximum potential exposure or the range of possible loss. We did not have any material accruals for the matters described below on our Condensed Consolidated Balance Sheets as of March 31, 2021 and December 31, 2020. Litigation Related to Sofosbuvir In 2012, we acquired Pharmasset, Inc. Through the acquisition, we acquired sofosbuvir, a nucleotide analog that acts to inhibit the replication of the HCV. In 2013, we received approval from 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’Université Montpellier II 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. We prevailed at all phases of litigation concerning the ’597 patent, and in January 2021, the U.S. Supreme Court denied Idenix’s petition for review, making the judgment against Idenix final. Litigation with the University of Minnesota The University of Minnesota (the “University”) has obtained U.S. 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 petitions for inter partes review with the U.S. Patent and Trademark Office Patent Trial and Appeal Board (“PTAB”) alleging that all asserted claims are invalid for anticipation and obviousness. The PTAB instituted one of these petitions and a merits hearing was held in February 2021. In 2018, the U.S. District Court for the Northern District of California stayed the litigation until after the PTAB concludes the inter partes review that it has initiated, which we expect will occur in 2021. Litigation with NuCana plc. (“NuCana”) NuCana has obtained European Patent No. 2,955,190 (the “EP ’190 patent”) that allegedly covers sofosbuvir. In Opposition proceedings before the European Patent Office (“EPO”) held in February 2021, the EPO Opposition Division upheld the validity of the EP ’190 patent in amended form. We believe that the amended EP ’190 patent claims are invalid. Subsequently, we initiated proceedings to invalidate the UK counterpart of the EP ’190 patent in the High Court of England & Wales. In March 2021, NuCana filed a counterclaim against us in the High Court of England & Wales alleging patent infringement of the UK counterpart and seeking damages and other relief. In April 2021, NuCana also filed a lawsuit against us in Germany at the Landgericht Düsseldorf alleging patent infringement of the German counterpart of the EP ’190 patent and seeking damages and relief. Litigation Related to Axicabtagene Ciloleucel In October 2017, Juno Therapeutics, Inc. and Sloan Kettering Cancer Center (collectively, “Juno”) filed a lawsuit against us in the U.S. District Court for the Central District of California, alleging that the commercialization of axicabtagene ciloleucel, sold commercially as Yescarta, infringes on U.S. Patent No. 7,446,190 (the “’190 patent”). A jury trial was held on the ’190 patent, and in December 2019, the jury found that the asserted claims of the ’190 patent were valid, and that we willfully infringed the asserted claims of the ’190 patent. The jury also awarded Juno damages in amounts of $585 million in an up-front payment and a 27.6% running royalty from October 2017 through the date of the jury’s verdict. The parties filed post-trial motions in the first quarter of 2020, and the trial judge entered a judgment in April 2020. The trial judge affirmed the jury’s verdict, enhanced the past damages by 50% and maintained the royalties on future Yescarta sales at 27.6%. In April 2020, we filed an appeal seeking to reverse the judgment or obtain a new trial due to errors made by the trial judge. In assessing whether we should accrue a liability for this litigation in our Condensed Consolidated Financial Statements, we considered various factors, including the legal and factual circumstances of the case, the jury’s verdict, the district court’s pre- and post-trial orders, the current status of the proceedings, applicable law, the views of legal counsel and the likelihood that the judgment will be upheld on appeal. As a result of this review, we have determined, in accordance with applicable accounting standards, that it is not probable that we will incur a material loss as a result of this litigation. If the judgment is reversed on appeal, the loss is expected to be zero. If the judgment is upheld in its entirety on appeal, we estimate a loss through the first quarter of 2021 to be approximately $1.4 billion, which consists primarily of (i) approximately $811 million, which represents damages on Yescarta revenues through December 12, 2019, and prejudgment interest thereon, (ii) approximately $389 million, which represents a 50% enhancement of past damages and (iii) approximately $225 million for royalties on Yescarta revenues from December 13, 2019 to March 31, 2021. The estimated loss does not include post-judgment interest on the foregoing, which is not estimated to be material as of March 31, 2021. Although we cannot predict with certainty the ultimate outcome of this litigation on appeal, we believe the jury’s verdict and the judgment to be in error. 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”) covering ViiV’s dolutegravir. Bictegravir is structurally different from dolutegravir, and we believe that bictegravir does not infringe the claims of the ’385 patent. The court has set a trial date of January 2022 for this lawsuit. ViiV is seeking billions of dollars for alleged damages comprised of ViiV’s lost profits and a royalty on sales of bictegravir from launch through the trial. ViiV calculates these damages based on the cumulative U.S. revenues from Biktarvy since launch, which have totaled $12.9 billion through March 31, 2021. In addition, should a court find that we are liable for infringement, we expect ViiV will seek a royalty on sales after the trial. Although we cannot predict with certainty the ultimate outcome of this litigation, an adverse judgment could result in substantial monetary damages, including ViiV’s lost profits and royalties through trial, and a going-forward royalty stream on future sales. 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. In January 2020, the court held a summary trial to assess ViiV’s infringement allegations. In April 2020, the court determined that bictegravir does not infringe the claims of the ’282 patent and dismissed the case. ViiV has appealed this decision. Argument on the appeal took place in April 2021, and a decision is expected in the second half of 2021. In November and December 2019, ViiV filed lawsuits in France, Germany, Ireland and the UK asserting the relevant national designations of European Patent No. 3 045 206 (“EP ’206”); in Australia asserting Australian Patent No. 2006239177; in Japan asserting Japanese Patent No. 4295353; and in Korea asserting Korean Patent Nos. 1848819 (“KR ’819”) and 1363875. These patents all relate to molecules which ViiV claims would act as integrase inhibitors. We believe that bictegravir does not infringe the claims of any of ViiV’s patents. In 2019, we filed an opposition in the EPO requesting revocation of EP ’206. The EPO hearing took place in January 2021, and the patent claims, which do not cover bictegravir, were maintained in amended form. Additionally, in 2020, we filed a petition in the Korean Intellectual Property Office requesting invalidation of KR ’819. Following a trial, a tribunal of the Korean Intellectual Property Trial and Appeal Board found KR ’819 to be invalid. In March 2021, ViiV appealed this decision. The court in Germany held a hearing on the issue of infringement in April 2021. In all jurisdictions, to the extent that the claims of ViiV’s patents are interpreted to cover bictegravir, we believe that those claims are invalid. We cannot predict the ultimate outcome of intellectual property claims related to bictegravir. Litigation Relating to Pre-Exposure Prophylaxis In August 2019, we filed petitions requesting inter partes review of U.S. Patent Nos. 9,044,509, 9,579,333, 9,937,191 and 10,335,423 (collectively, “HHS Patents”) by PTAB. The HHS Patents are assigned to the U.S. Department of Health and Human Services (“HHS”) and purport to claim a process of protecting a primate host from infection by an immunodeficiency retrovirus by administering a combination of emtricitabine and tenofovir or TDF prior to exposure of the host to the immunodeficiency retrovirus, a process commonly known as pre-exposure prophylaxis (“PrEP”). In November 2019, the U.S. Department of Justice filed a lawsuit against us in the U.S. District Court of Delaware, alleging that the sale of Truvada and Descovy for use as PrEP infringes the HHS Patents. In February 2020, PTAB declined to institute our petitions for inter partes review of the HHS Patents. In April 2020, we filed a breach of contract lawsuit against the U.S. federal government in the Court of Federal Claims, alleging violations of four material transfer agreements (“MTAs”) related to the research underlying the HHS Patents and a clinical trial agreement (“CTA”) by the U.S. Centers for Disease Control and Prevention related to PrEP research. Although we cannot predict with certainty the ultimate outcome of these litigation matters, we believe that the U.S. federal government breached the MTAs and CTA, that Truvada and Descovy do not infringe the HHS Patents and that the HHS Patents are invalid over prior art descriptions of Truvada’s use for PrEP and post-exposure prophylaxis as well because physicians and patients were using the claimed methods years before HHS filed the applications for the patents. A trial date for the lawsuit in the Court of Federal Claims has been set for June 2022, and a trial date for the lawsuit in the District Court of Delaware has been set for May 2023. 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. Starting in December 2019, we received letters from Lupin Ltd., Apotex Inc., Shilpa Medicare Ltd., Sunshine Lake Pharma Co. Ltd., Laurus Labs, Natco Pharma Ltd., Macleods Pharma Ltd., Hetero Labs Ltd. and Cipla Ltd. (collectively, “generic manufacturers”) indicating that they have submitted ANDAs to FDA requesting permission to market and manufacture generic versions of certain of our tenofovir alafenamide (“TAF”)-containing products. Between them, these generic manufacturers seek to market generic versions of Odefsey, Descovy and Vemlidy. Some generic manufacturers have challenged the validity of four patents listed on the Orange Book and associated with TAF, while others have challenged the validity of two of our Orange Book-listed patents associated with TAF. We filed lawsuits against the generic manufacturers, and we intend to enforce and defend our intellectual property. 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 hearing is scheduled for July 2021. 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. In 2016, several parties filed oppositions in the EPO requesting revocation of our granted European patent covering TAF that expires in 2026. In 2017, the EPO upheld the validity of the claims of our TAF patent. Three parties have appealed this decision. The appeal hearing was held in March 2021, and the validity of all claims were upheld. In 2017, several parties filed oppositions in the EPO requesting revocation of our granted European patent relating to TAF hemifumarate that expires in 2032. In 2019, the EPO upheld the validity of the claims of our TAF hemifumarate patent. Three parties have appealed this decision. 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. Two parties have appealed this decision. The appeal process may take several years for all EPO opposition proceedings. 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 EMA. 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. Antitrust and Consumer Protection We (along with Japan Tobacco, Inc. (“Japan Tobacco”), Bristol-Myers Squibb Company (“BMS”) and Johnson & Johnson, Inc.)) have been named as defendants in class action lawsuits filed in 2019 and 2020 related to various drugs used to treat HIV, including drugs used in combination antiretroviral therapy. Japan Tobacco was dismissed from the lawsuit after a favorable court ruling on the defendants’ motion to dismiss. Plaintiffs allege that we (and the other remaining defendants) engaged in various conduct to restrain competition in violation of federal and state antitrust laws and state consumer protection laws. The lawsuits, which have been or may be consolidated, are all pending in the U.S. District Court for the Northern District of California. The lawsuits seek to bring claims on behalf of two nationwide classes - one of direct purchasers consisting largely of wholesales, and another of end-payor purchasers, including health insurers and individual patients. Plaintiffs seek damages, permanent injunctive relief and other relief. In September 2020, we along with generic manufacturers Cipla Ltd. and Cipla USA Inc. (“Cipla”) were named as defendants in a class action lawsuit filed in the U.S. District Court for the Northern District of California by Jacksonville Police Officers and Fire Fighters Health Insurance Trust (“Jacksonville Trust”) on behalf of end-payor purchasers. Jacksonville Trust claims that the 2014 settlement agreement between us and Cipla, which settled a patent dispute relating to patents covering our Emtriva, Truvada, and Atripla products and permitted generic entry prior to patent expiry, violates certain federal and state antitrust and consumer protection laws. Plaintiffs seek damages, permanent injunctive relief and other relief. In February 2021, we along with BMS and generic manufacturer Teva Pharmaceuticals USA were named as defendants in a lawsuit filed in the First Judicial District Court for the State of New Mexico, county of Santa Fe by the New Mexico Attorney General. The New Mexico Attorney General alleges that we (and the other defendants) restrained competition in violation of New Mexico state antitrust and consumer protection laws. In March 2021, we removed the case to the U.S. District Court for the District of New Mexico. The New Mexico Attorney General seeks damages and other relief. 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 or could be subject to permanent injunctive relief awarded in favor of plaintiffs. Product Liability We have been named as a defendant in two class action lawsuits 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 experience kidney, bone and/or tooth injuries. The lawsuits, which are pending in state or federal court in California, Delaware, Florida, New Jersey and Missouri, involve more than 21,000 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. Government Investigation In 2017, we 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. Qui Tam Litigation Two former sales employees filed a qui tam lawsuit against Gilead in August 2017 in the U.S. District Court for the Eastern District of Pennsylvania. Following the government’s decision not to intervene in the suit, the relators served us with a Second Amended Complaint in November 2019. The lawsuit alleges that Gilead’s HBV speaker programs and advisory boards violated the federal False Claims Act and various state false claims acts. The relators seek all available relief under these statutes. Another former sales employee also filed a qui tam lawsuit against Gilead in March 2017 in U.S. District Court for the Eastern District of Pennsylvania. Following the government’s decision not to intervene in the suit, the relator served us with a Second Amended Complaint in January 2021. The lawsuit alleges that Gilead’s HCV patient access programs, clinical educator programs, speaker programs, and other sales and marketing programs violated the federal False Claims Act and various state false claims acts. The relator seeks all available relief under these statutes. Two former employees filed a qui tam lawsuit against Gilead in April 2020 in California state court. These same former employees had previously filed a qui tam lawsuit in federal court in California and the U.S. Department of Justice declined intervention and moved to dismiss relators’ federal False Claims Act claims. Relators subsequently voluntarily dismissed their federal lawsuit and refiled their lawsuit in California state court. Following the California Attorney General’s Office’s decision not to intervene, relators served Gilead with their complaint in August 2020. The complaint alleges violations of the California False Claims Act (”CFCA”) and employment law claims. Relators seek all available relief under the CFCA. Health Choice Advocates, LLC (“Health Choice”) filed a qui tam lawsuit against Gilead in April 2020 in New Jersey state court. Following the New Jersey Attorney General’s Office’s decision not to intervene in the suit, Health Choice served us with their original complaint in August 2020. The lawsuit alleges that Gilead violated the New Jersey False Claims Act through our clinical educator programs for Sovaldi and Harvoni and our HCV and HIV patient access programs. The lawsuit seeks all available relief under the New Jersey False Claims Act. In April 2021, the trial court granted our motion to dismiss with prejudice. Health Choice filed another qui tam lawsuit against Gilead in May 2020 making similar allegations in Texas state court. Following the Texas Attorney General’s Office’s decision not to intervene in the suit, Health Choice served us with their original complaint in October 2020. The lawsuit alleges that Gilead violated the Texas Medicare Fraud Prevention Act (“TMFPA”) through our clinical educator programs for Sovaldi and Harvoni and our HCV and HIV patient access programs. The lawsuit seeks all available relief under the TMFPA. We intend to vigorously defend ourselves in these actions. While we believe these cases are without merit, we cannot predict the ultimate outcomes. If any of these plaintiffs are successful in their claims, we could be required to pay significant monetary damages. Securities Litigation Immunomedics and several of its former officers and directors have been named as defendants in putative class actions filed in 2018 and 2019. The lawsuits were consolidated in September 2019, and plaintiffs filed a consolidated complaint in November 2019. Plaintiffs allege that Immunomedics and the individual defendants violated the federal securities laws in connection with Immunomedics’ Biologics License Application for Trodelvy, and seek certification of a class of shareholders, damages and other relief. The consolidated lawsuit is pending in the United States District Court for the District of New Jersey. While we believe this case 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. Other Matters We are a party to various legal actions that arose in the ordinary course of our business. We do not believe that these other legal actions will have a material adverse impact on our consolidated business, financial position or results of operations.

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS’ EQUITY Stock Repurchase Programs 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. In the first quarter of 2020, our Board of Directors authorized a new $5.0 billion stock repurchase program (“2020 Program”), which will commence upon the completion of the 2016 Program. Purchases under the 2020 Program may be made in the open market or in privately negotiated transactions. During the three months ended March 31, 2021 and 2020, we repurchased and retired 4.8 million and 18.7 million shares of our common stock for $309 million and $1.3 billion, respectively, through open market transactions under the 2016 Program. As of March 31, 2021, the remaining authorized repurchase amount under both programs was $6.5 billion. Accumulated Other Comprehensive Income The following table summarizes the changes in AOCI by component, net of tax: (in millions) Foreign Currency Translation, Net of Tax Unrealized Gains and Losses on Available-for-Sale Debt Securities, Net of Tax Unrealized Gains and Losses on Cash Flow Hedges, Net of Tax Total Balance at December 31, 2020 $ 51 $ 2 $ (113) $ (60) Net unrealized gain (loss) 10 (2) 68 76 Reclassifications to net income — — 22 22 Net current period other comprehensive income (loss) 10 (2) 90 98 Balance at March 31, 2021 $ 61 $ — $ (23) $ 38 (in millions) Foreign Currency Translation, Net of Tax Unrealized Gains and Losses on Available-for-Sale Debt Securities, Net of Tax Unrealized Gains and Losses on Cash Flow Hedges, Net of Tax Total Balance at December 31, 2019 $ 53 $ 1 $ 31 $ 85 Net unrealized gain (loss) (39) (23) 57 (5) Reclassifications to net income — (11) (23) (34) Net current period other comprehensive income (loss) (39) (34) 34 (39) Balance at March 31, 2020 $ 14 $ (33) $ 65 $ 46 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. Gross realized gains and losses on available-for-sale debt securities were not material for the three months ended March 31, 2021 and 2020. The income tax impact allocated to each component of other comprehensive income (loss) was not material for the periods presented.

NET INCOME PER SHARE ATTRIBUTAB

NET INCOME PER SHARE ATTRIBUTABLE TO GILEAD COMMON STOCKHOLDERS	3 Months Ended
	Mar. 31, 2021
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 metho d. Potential shares of common stock excluded from the computation of diluted net income per share attributable to Gilead common stockholders because their effect would have been antidilutive were 15 million and 14 million, for the three months ended March 31, 2021 and 2020, respectively. The following table summarizes the calculation of basic and diluted net income per share attributable to Gilead common stockholders: Three Months Ended March 31, (in millions, except per share amounts) 2021 2020 Net income attributable to Gilead $ 1,729 $ 1,551 Shares used in per share calculation - basic 1,256 1,262 Dilutive effect of stock options and equivalents 6 8 Shares used in per share calculation - diluted 1,262 1,270 Net income per share attributable to Gilead common stockholders - basic $ 1.38 $ 1.23 Net income per share attributable to Gilead common stockholders - diluted $ 1.37 $ 1.22

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The following table summarizes our income tax expense: Three Months Ended March 31, (in millions, except percentages) 2021 2020 Income before income taxes $ 2,264 $ 2,003 Income tax expense $ 542 $ 465 Effective tax rate 23.9 % 23.2 % Our effective income tax rate of 23.9% for the three months ended March 31, 2021 differed from the U.S. federal statutory rate of 21% primarily due to unfavorable changes in the fair value of our equity investment in Galapagos that are non-deductible for income tax purposes, partially offset by net discrete tax benefits related to settlements with taxing authorities. Our effective income tax rate of 23.2% for the three months ended March 31, 2020 differed from the U.S. federal statutory rate of 21% primarily due to the Global Intangible Low-Taxed Income tax, state taxes and our portion of the non-deductible branded prescription drug fee. We are currently under examination by the U.S. Internal Revenue Service for the tax years from 2016 to 2018 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 to determine our assessment of unrecognized tax benefits in accordance with the income tax guidance which clarifies the accounting for uncertainty in income taxes.

SUBSEQUENT EVENT

SUBSEQUENT EVENT	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
SUBSEQUENT EVENT	SUBSEQUENT EVENTIn April 2021, Gilead donated equity securities at fair value to the Gilead Foundation, a California nonprofit public benefit corporation (“Foundation”). The Foundation is a related party as certain officers of the Company also serve as directors of the Foundation. The donation expense of $206 million will be recorded within Selling, general and administrative expenses on our Condensed Consolidated Statements of Income in the second quarter of 2021.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
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 a variable interest entity (“VIE”) 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 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.
Segment Information	We have one operating segment, which focuses on the discovery, development and commercialization of innovative medicines in areas of unmet medical need. Our Chief Executive Officer, as the chief operating decision-maker (“CODM”), manages and allocates resources to the operations of the company on an entity-wide basis. Managing and allocating resources on an entity-wide basis enables our CODM to assess the overall level of resources available and how to best deploy these resources across functions and research and development (“R&D”) projects based on unmet medical need and, as necessary, reallocate resources among our internal R&D portfolio and external opportunities to best support the long-term growth of our business.
Significant Accounting Policies, Estimates and Judgments	The preparation of these Condensed Consolidated Financial Statements in accordance with U.S. generally accepted accounting principles requires management 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, such as the economic considerations related to the impact that the coronavirus disease (“COVID-19”) could have on our significant accounting estimates. Actual results may differ significantly from these estimates.
Reclassification	Certain amounts for the three months ended March 31, 2020 were reclassified to conform to the current period presentation. Beginning in the second quarter of 2020, acquired in-process research and development (“IPR&D”) expenses are reported separately from Research and development expenses on our Condensed Consolidated Statements of Income. Our Condensed Consolidated Statements of Cash Flows for the three months ended March 31, 2020, has also been conformed to separately present acquired IPR&D expenses.
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. Trade accounts receivable are recorded net of allowances for wholesaler chargebacks related to government and other programs, cash discounts for prompt payment and credit losses. Estimates of our allowance for credit losses consider a number of factors including existing contractual payment terms, individual customer circumstances, historical payment patterns of our customers, a review of the local economic environment and its potential impact on expected future customer payment patterns and government funding and reimbursement practices. The majority of our trade accounts receivable arises from product sales in the United States, Europe and Japan. There were no material write-offs charged against the allowance for the three months ended March 31, 2021 and 2020. Certain of the raw materials and components that we utilize in our operations are obtained through single suppliers. Certain of the raw materials that we utilize in our operations are made at only one facility. Since the suppliers of key components and raw materials must be named in a new drug application filed with U.S. Food and Drug Administration (“FDA”) for a product, significant delays can occur if the qualification of a new supplier is required. If delivery of material from our suppliers is interrupted for any reason, we may be unable to ship our commercial products or to supply our product candidates for clinical trials.
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. We elected and applied the fair value option to account for our equity investment in Galapagos whereby the investment is marked to market through earnings each reporting period based on the market price of Galapagos shares. We believe the fair value option best reflects the underlying economics of the investment. The portion of the investment subject to long-term contractual lock-up provisions is classified within Other long-term assets and the remainder is classified as Prepaid and other current assets on our Condensed Consolidated Balance Sheets. Subsequent to the first quarter of 2021, we amended the Galapagos subscription agreement to extend the initial lock-up provision for certain Galapagos shares from August 2021 to August 2024. As a result, all of our equity investment in Galapagos became subject to long-term contractual lock-up provisions and will be classified as Other long-term assets commencing in the second quarter of 2021. Level 2 Inputs We estimate the fair values of Level 2 financial 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 and swap rates. These inputs, where applicable, are observable at commonly quoted intervals.

REVENUES (Tables)

REVENUES (Tables)	3 Months Ended
	Mar. 31, 2021
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenues	Revenues were as follows: Three Months Ended March 31, 2021 Three Months Ended March 31, 2020 (in millions) U.S. Europe Other International Total U.S. Europe Other International Total Product Sales: HIV Atripla $ 23 $ 4 $ 4 $ 31 $ 81 $ 7 $ 7 $ 95 Biktarvy 1,465 216 143 1,824 1,412 181 100 1,693 Complera/Eviplera 25 34 4 63 24 47 5 76 Descovy 282 42 35 359 363 61 34 458 Genvoya 506 106 61 673 612 151 61 824 Odefsey 240 113 14 367 269 127 13 409 Stribild 31 11 4 46 34 17 2 53 Truvada 119 7 9 135 383 8 15 406 Other HIV (1) 6 1 10 17 3 2 3 8 Revenue share - Symtuza (2) 89 44 2 135 72 38 2 112 Total HIV 2,786 578 286 3,650 3,253 639 242 4,134 Hepatitis C virus (“HCV”) Ledipasvir/Sofosbuvir (3) 19 16 21 56 53 11 48 112 Sofosbuvir/Velpatasvir (4) 214 75 92 381 311 122 131 564 Other HCV (5) 25 44 4 73 34 15 4 53 Total HCV 258 135 117 510 398 148 183 729 Hepatitis B virus (“HBV”) / Hepatitis Delta virus (“HDV”) Vemlidy 77 8 96 181 73 7 56 136 Viread 4 7 20 31 4 11 25 40 Other HBV/HDV (6) — 8 — 8 8 2 — 10 Total HBV/HDV 81 23 116 220 85 20 81 186 Veklury 820 388 248 1,456 — — — — Cell Therapy Tecartus 27 4 — 31 — — — — Yescarta 92 61 7 160 103 37 — 140 Total Cell Therapy 119 65 7 191 103 37 — 140 Trodelvy 72 — — 72 — — — — Other AmBisome 12 66 43 121 18 59 42 119 Letairis 54 — — 54 83 — — 83 Ranexa 3 — — 3 8 — — 8 Zydelig 8 7 — 15 8 12 — 20 Other (7) 27 13 8 48 33 12 3 48 Total Other 104 86 51 241 150 83 45 278 Total product sales 4,240 1,275 825 6,340 3,989 927 551 5,467 Royalty, contract and other revenues 20 61 2 83 17 48 16 81 Total revenues $ 4,260 $ 1,336 $ 827 $ 6,423 $ 4,006 $ 975 $ 567 $ 5,548 _______________________________ (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 Unlimited Company. (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 Vosevi and Sovaldi. (6) Includes Hepcludex and Hepsera. (7) Includes Cayston and Jyseleca.
Revenues from Major Customers	The following table summarizes revenues from each of our customers who individually accounted for 10% or more of our total revenues: Three Months Ended March 31, (as a percentage of total revenues) 2021 2020 AmerisourceBergen Corporation 27 % 22 % Cardinal Health, Inc. 18 % 22 % McKesson Corporation 17 % 21 %

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2021
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: March 31, 2021 December 31, 2020 (in millions) Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total Assets: Available-for-sale debt securities: U.S. treasury securities $ 464 $ — $ — $ 464 $ 309 $ — $ — $ 309 Certificates of deposit — 358 — 358 — 216 — 216 Non-U.S. government securities — 62 — 62 — 43 — 43 Corporate debt securities — 1,247 — 1,247 — 1,142 — 1,142 Residential mortgage and asset-backed securities — 347 — 347 — 316 — 316 Equity securities: Money market funds 2,216 — — 2,216 4,361 — — 4,361 Equity investment in Galapagos 1,302 — — 1,302 1,648 — — 1,648 Other publicly traded equity securities 968 — — 968 743 — — 743 Deferred compensation plan 235 — — 235 218 — — 218 Foreign currency derivative contracts — 32 — 32 — 12 — 12 Total $ 5,185 $ 2,046 $ — $ 7,231 $ 7,279 $ 1,729 $ — $ 9,008 Liabilities: Liability for MYR contingent consideration $ — $ — $ 341 $ 341 $ — $ — $ — $ — Deferred compensation plan 235 — — 235 218 — — 218 Foreign currency derivative contracts — 41 — 41 — 121 — 121 Total $ 235 $ 41 $ 341 $ 617 $ 218 $ 121 $ — $ 339
Summary of Classification of Equity Securities	The following table summarizes the classification of our equity securities measured at fair value on a recurring basis on our Condensed Consolidated Balance Sheets: (in millions) March 31, 2021 December 31, 2020 Cash and cash equivalents $ 2,216 $ 4,361 Prepaid and other current assets (1) 797 853 Other long-term assets (1) 1,708 1,756 Total $ 4,721 $ 6,970 ________________________________ (1) Includes equity investment in Galapagos NV (“Galapagos”)
Equity Method Investments	The following table summarizes the classification of our equity investment in Galapagos in our Condensed Consolidated Balance Sheets: (in millions) March 31, 2021 December 31, 2020 Prepaid and other current assets $ 276 $ 351 Other long-term assets 1,026 1,297 Total $ 1,302 $ 1,648

AVAILABLE-FOR-SALE DEBT SECUR_2

AVAILABLE-FOR-SALE DEBT SECURITIES (Tables)	3 Months Ended
	Mar. 31, 2021
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: March 31, 2021 December 31, 2020 (in millions) Amortized Gross Gross Estimated Amortized Gross Gross Estimated U.S. treasury securities $ 464 $ — $ — $ 464 $ 308 $ 1 $ — $ 309 Certificates of deposit 358 — — 358 216 — — 216 Non-U.S. government securities 62 — — 62 43 — — 43 Corporate debt securities 1,247 1 (1) 1,247 1,140 2 — 1,142 Residential mortgage and asset-backed securities 347 — — 347 316 — — 316 Total $ 2,478 $ 1 $ (1) $ 2,478 $ 2,023 $ 3 $ — $ 2,026
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) March 31, 2021 December 31, 2020 Cash and cash equivalents $ 298 $ 113 Short-term marketable securities 1,601 1,411 Long-term marketable securities 579 502 Total $ 2,478 $ 2,026
Summary of Available-for-Sale Debt Securities by Contractual Maturity	The following table summarizes our available-for-sale debt securities by contractual maturity: March 31, 2021 (in millions) Amortized Cost Fair Value Within one year $ 1,898 $ 1,899 After one year through five years 563 562 After five years 17 17 Total $ 2,478 $ 2,478

DERIVATIVE FINANCIAL INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2021
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 on our Condensed Consolidated Balance Sheets: March 31, 2021 Asset Derivatives Liability Derivatives (in millions) Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Prepaid and other current assets $ 25 Other accrued liabilities $ (41) Foreign currency exchange contracts Other long-term assets 7 Other long-term obligations — Total derivatives designated as hedges 32 (41) Derivatives not designated as hedges: Foreign currency exchange contracts Prepaid and other current assets — Other accrued liabilities — Total derivatives not designated as hedges — — Total derivatives $ 32 $ (41) December 31, 2020 Asset Derivatives Liability Derivatives (in millions) Classification Fair Value Classification Fair Value Derivatives designated as hedges: Foreign currency exchange contracts Prepaid and other current assets $ — Other accrued liabilities $ (113) Foreign currency exchange contracts Other long-term assets — Other long-term obligations (7) Total derivatives designated as hedges — (120) Derivatives not designated as hedges: Foreign currency exchange contracts Prepaid and other current assets 12 Other accrued liabilities (1) Total derivatives not designated as hedges 12 (1) Total derivatives $ 12 $ (121)
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: Three Months Ended March 31, (in millions) 2021 2020 Derivatives designated as hedges: Gains recognized in AOCI $ 78 $ 66 Gains (losses) reclassified from AOCI into product sales $ (25) $ 27 Derivatives not designated as hedges: Gains recognized in Other income (expense), net $ 34 $ 24
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: Gross Amounts Not Offset (in millions) Gross Amounts Gross Amounts Amounts of Assets/Liabilities Presented Derivative Cash Collateral Net Amount As of March 31, 2021 Derivative assets $ 32 $ — $ 32 $ (22) $ — $ 10 Derivative liabilities $ (41) $ — $ (41) $ 22 $ — $ (19) As of December 31, 2020 Derivative assets $ 12 $ — $ 12 $ (12) $ — $ — Derivative liabilities $ (121) $ — $ (121) $ 12 $ — $ (109)

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	3 Months Ended
	Mar. 31, 2021
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes estimated fair values of assets acquired and liabilities assumed as of the acquisition date: (in millions) Amount Intangible assets Finite-lived intangible asset $ 845 Acquired IPR&D 1,190 Deferred income taxes, net (513) Other assets (and liabilities), net (187) Total identifiable net assets 1,335 Goodwill 226 Total consideration $ 1,561 The following table summarizes estimated fair values of assets acquired and liabilities assumed as of the acquisition date: (in millions) Amount Cash and cash equivalents $ 726 Inventories 946 Intangible assets Finite-lived intangible asset 4,600 Acquired IPR&D 15,760 Outlicense contract 175 Deferred income taxes (4,565) Liability related to future royalties (1,100) Other assets (and liabilities), net 64 Total identifiable net assets 16,606 Goodwill 3,991 Total consideration transferred $ 20,597

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following table summarizes the changes in the carrying amount of goodwill: (in millions) Amount Balance at December 31, 2020 $ 8,108 Goodwill resulting from the acquisition of MYR 226 Balance at March 31, 2021 $ 8,334
Schedule of Finite-Lived Intangible Assets	The following table summarizes our Intangible assets, net: March 31, 2021 December 31, 2020 (in millions) Gross Accumulated Foreign Currency Translation Adjustment Net Carrying Amount Gross Accumulated Foreign Currency Translation Adjustment Net Carrying Amount Finite-lived assets: Intangible asset - sofosbuvir $ 10,720 $ (5,127) $ — $ 5,593 $ 10,720 $ (4,952) $ — $ 5,768 Intangible asset - axicabtagene ciloleucel (1) 7,110 (1,196) — 5,914 6,200 (1,105) — 5,095 Intangible asset - Trodelvy (2) 4,600 (158) — 4,442 4,600 (63) — 4,537 Intangible asset - Hepcludex for HDV 845 (7) — 838 — — — — Other 1,391 (567) — 824 1,377 (540) (1) 836 Total finite-lived assets 24,666 (7,055) — 17,611 22,897 (6,660) (1) 16,236 Indefinite-lived assets - IPR&D (3)(4) 17,170 — — 17,170 16,890 — — 16,890 Total intangible assets $ 41,836 $ (7,055) $ — $ 34,781 $ 39,787 $ (6,660) $ (1) $ 33,126 _______________________________ (1) Gross carrying amount as of March 31, 2021 includes $910 million reclassified from indefinite-lived assets - IPR&D following the March 2021 FDA approval of Yescarta for the treatment of adult patients with relapsed or refractory follicular lymphoma. (2) Amounts represent Trodelvy for metastatic triple-negative breast cancer. (3) Gross carrying amount as of March 31, 2021 includes $1.2 billion recognized from the first quarter 2021 MYR acquisition. See Note 6. Acquisitions for additional information. (4) In April 2021, FDA granted accelerated approval of Trodelvy for use in adult patients with locally advanced or metastatic urothelial cancer, a new indication. Accordingly, the related amount of $1.0 billion will be reclassified to finite-lived assets in the second quarter of 2021.
Schedule of Indefinite-Lived Intangible Assets	The following table summarizes our Intangible assets, net: March 31, 2021 December 31, 2020 (in millions) Gross Accumulated Foreign Currency Translation Adjustment Net Carrying Amount Gross Accumulated Foreign Currency Translation Adjustment Net Carrying Amount Finite-lived assets: Intangible asset - sofosbuvir $ 10,720 $ (5,127) $ — $ 5,593 $ 10,720 $ (4,952) $ — $ 5,768 Intangible asset - axicabtagene ciloleucel (1) 7,110 (1,196) — 5,914 6,200 (1,105) — 5,095 Intangible asset - Trodelvy (2) 4,600 (158) — 4,442 4,600 (63) — 4,537 Intangible asset - Hepcludex for HDV 845 (7) — 838 — — — — Other 1,391 (567) — 824 1,377 (540) (1) 836 Total finite-lived assets 24,666 (7,055) — 17,611 22,897 (6,660) (1) 16,236 Indefinite-lived assets - IPR&D (3)(4) 17,170 — — 17,170 16,890 — — 16,890 Total intangible assets $ 41,836 $ (7,055) $ — $ 34,781 $ 39,787 $ (6,660) $ (1) $ 33,126 _______________________________ (1) Gross carrying amount as of March 31, 2021 includes $910 million reclassified from indefinite-lived assets - IPR&D following the March 2021 FDA approval of Yescarta for the treatment of adult patients with relapsed or refractory follicular lymphoma. (2) Amounts represent Trodelvy for metastatic triple-negative breast cancer. (3) Gross carrying amount as of March 31, 2021 includes $1.2 billion recognized from the first quarter 2021 MYR acquisition. See Note 6. Acquisitions for additional information. (4) In April 2021, FDA granted accelerated approval of Trodelvy for use in adult patients with locally advanced or metastatic urothelial cancer, a new indication. Accordingly, the related amount of $1.0 billion will be reclassified to finite-lived assets in the second quarter of 2021.
Schedule of Estimated Future Amortization Expense	The following table summarizes the estimated future amortization expense associated with our finite-lived intangible assets as of March 31, 2021: (in millions) Amount 2021 (remaining nine months) $ 1,256 2022 1,675 2023 1,675 2024 1,675 2025 1,669 Thereafter 9,661 Total $ 17,611

OTHER FINANCIAL INFORMATION (Ta

OTHER FINANCIAL INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2021
Other Financial Information [Abstract]
Schedule of Accounts Receivable	The following table summarizes our Accounts receivable, net: (in millions) March 31, 2021 December 31, 2020 Accounts receivable $ 4,647 $ 5,560 Less: chargebacks 607 552 Less: cash discounts and other 64 72 Less: allowances for credit losses 51 44 Accounts receivable, net $ 3,925 $ 4,892
Schedule of Inventories	The following table summarizes our Inventories: (in millions) March 31, 2021 December 31, 2020 Raw materials $ 1,023 $ 1,080 Work in process 856 976 Finished goods 1,117 958 Total $ 2,996 $ 3,014 Reported as: Inventories $ 1,779 $ 1,683 Other long-term assets (1) 1,217 1,331 Total $ 2,996 $ 3,014 ________________________________ (1) Amounts primarily consist of raw materials.
Schedule of Other Accrued Liabilities	The following table summarizes the components of Accrued and other current liabilities: (in millions) March 31, 2021 December 31, 2020 Compensation and employee benefits $ 494 $ 864 Income taxes payable 215 598 Allowance for sales returns 524 587 Accrued and other current liabilities 2,274 2,287 Total $ 3,507 $ 4,336

DEBT AND CREDIT FACILITIES (Tab

DEBT AND CREDIT FACILITIES (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Summary of Debt Carrying Amount	The following table summarizes the carrying amount of our borrowings under various financing arrangements: (in millions) Carrying Amount Type of Borrowing Issue Date Maturity Date Interest Rate March 31, 2021 December 31, 2020 Senior Unsecured March 2011 April 2021 4.50% $ — $ 1,000 Senior Unsecured September 2020 September 2021 3-month LIBOR + 0.15% 500 499 Senior Unsecured December 2011 December 2021 4.40% 1,249 1,249 Senior Unsecured September 2016 March 2022 1.95% 499 499 Senior Unsecured September 2015 September 2022 3.25% 999 998 Senior Unsecured September 2016 September 2023 2.50% 748 748 Senior Unsecured September 2020 September 2023 3-month LIBOR + 0.52% 498 498 Senior Unsecured September 2020 September 2023 0.75% 1,993 1,992 Term Loan October 2020 October 2023 variable 748 998 Senior Unsecured March 2014 April 2024 3.70% 1,746 1,746 Senior Unsecured November 2014 February 2025 3.50% 1,747 1,746 Senior Unsecured September 2015 March 2026 3.65% 2,737 2,737 Senior Unsecured September 2016 March 2027 2.95% 1,246 1,246 Senior Unsecured September 2020 October 2027 1.20% 746 745 Senior Unsecured September 2020 October 2030 1.65% 992 992 Senior Unsecured September 2015 September 2035 4.60% 992 991 Senior Unsecured September 2016 September 2036 4.00% 742 741 Senior Unsecured September 2020 October 2040 2.60% 986 986 Senior Unsecured December 2011 December 2041 5.65% 996 996 Senior Unsecured March 2014 April 2044 4.80% 1,735 1,735 Senior Unsecured November 2014 February 2045 4.50% 1,732 1,732 Senior Unsecured September 2015 March 2046 4.75% 2,219 2,219 Senior Unsecured September 2016 March 2047 4.15% 1,726 1,726 Senior Unsecured September 2020 October 2050 2.80% 1,476 1,476 Total senior unsecured notes and term loan facility 29,052 30,295 Liability related to future royalties 1,114 1,107 Total debt, net 30,166 31,402 Less: current portion of long-term debt and other obligations, net 2,259 2,757 Total long-term debt, net $ 27,907 $ 28,645

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Summary of Changes in Accumulated Other Comprehensive Income (Loss)	The following table summarizes the changes in AOCI by component, net of tax: (in millions) Foreign Currency Translation, Net of Tax Unrealized Gains and Losses on Available-for-Sale Debt Securities, Net of Tax Unrealized Gains and Losses on Cash Flow Hedges, Net of Tax Total Balance at December 31, 2020 $ 51 $ 2 $ (113) $ (60) Net unrealized gain (loss) 10 (2) 68 76 Reclassifications to net income — — 22 22 Net current period other comprehensive income (loss) 10 (2) 90 98 Balance at March 31, 2021 $ 61 $ — $ (23) $ 38 (in millions) Foreign Currency Translation, Net of Tax Unrealized Gains and Losses on Available-for-Sale Debt Securities, Net of Tax Unrealized Gains and Losses on Cash Flow Hedges, Net of Tax Total Balance at December 31, 2019 $ 53 $ 1 $ 31 $ 85 Net unrealized gain (loss) (39) (23) 57 (5) Reclassifications to net income — (11) (23) (34) Net current period other comprehensive income (loss) (39) (34) 34 (39) Balance at March 31, 2020 $ 14 $ (33) $ 65 $ 46

NET INCOME PER SHARE ATTRIBUT_2

NET INCOME PER SHARE ATTRIBUTABLE TO GILEAD COMMON STOCKHOLDERS (Tables)	3 Months Ended
	Mar. 31, 2021
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: Three Months Ended March 31, (in millions, except per share amounts) 2021 2020 Net income attributable to Gilead $ 1,729 $ 1,551 Shares used in per share calculation - basic 1,256 1,262 Dilutive effect of stock options and equivalents 6 8 Shares used in per share calculation - diluted 1,262 1,270 Net income per share attributable to Gilead common stockholders - basic $ 1.38 $ 1.23 Net income per share attributable to Gilead common stockholders - diluted $ 1.37 $ 1.22

INCOME TAXES (Tables)

INCOME TAXES (Tables)	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Summary of the Provision for Income Taxes	The following table summarizes our income tax expense: Three Months Ended March 31, (in millions, except percentages) 2021 2020 Income before income taxes $ 2,264 $ 2,003 Income tax expense $ 542 $ 465 Effective tax rate 23.9 % 23.2 %

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	3 Months Ended
	Mar. 31, 2021USD ($)segment	Mar. 31, 2020USD ($)
Accounting Policies [Abstract]
Number of operating segments | segment	1
Write-offs charged against allowance | $	$ 0	$ 0

REVENUES - Disaggregation of Re

REVENUES - Disaggregation of Revenues (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenues	$ 6,423	$ 5,548
U.S.
Disaggregation of Revenue [Line Items]
Total revenues	4,260	4,006
Europe
Disaggregation of Revenue [Line Items]
Total revenues	1,336	975
Other International
Disaggregation of Revenue [Line Items]
Total revenues	827	567
Total product sales
Disaggregation of Revenue [Line Items]
Total revenues	6,340	5,467
Total product sales | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	4,240	3,989
Total product sales | Europe
Disaggregation of Revenue [Line Items]
Total revenues	1,275	927
Total product sales | Other International
Disaggregation of Revenue [Line Items]
Total revenues	825	551
Total HIV
Disaggregation of Revenue [Line Items]
Total revenues	3,650	4,134
Total HIV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	2,786	3,253
Total HIV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	578	639
Total HIV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	286	242
Atripla
Disaggregation of Revenue [Line Items]
Total revenues	31	95
Atripla | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	23	81
Atripla | Europe
Disaggregation of Revenue [Line Items]
Total revenues	4	7
Atripla | Other International
Disaggregation of Revenue [Line Items]
Total revenues	4	7
Biktarvy
Disaggregation of Revenue [Line Items]
Total revenues	1,824	1,693
Biktarvy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	1,465	1,412
Biktarvy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	216	181
Biktarvy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	143	100
Complera/Eviplera
Disaggregation of Revenue [Line Items]
Total revenues	63	76
Complera/Eviplera | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	25	24
Complera/Eviplera | Europe
Disaggregation of Revenue [Line Items]
Total revenues	34	47
Complera/Eviplera | Other International
Disaggregation of Revenue [Line Items]
Total revenues	4	5
Descovy
Disaggregation of Revenue [Line Items]
Total revenues	359	458
Descovy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	282	363
Descovy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	42	61
Descovy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	35	34
Genvoya
Disaggregation of Revenue [Line Items]
Total revenues	673	824
Genvoya | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	506	612
Genvoya | Europe
Disaggregation of Revenue [Line Items]
Total revenues	106	151
Genvoya | Other International
Disaggregation of Revenue [Line Items]
Total revenues	61	61
Odefsey
Disaggregation of Revenue [Line Items]
Total revenues	367	409
Odefsey | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	240	269
Odefsey | Europe
Disaggregation of Revenue [Line Items]
Total revenues	113	127
Odefsey | Other International
Disaggregation of Revenue [Line Items]
Total revenues	14	13
Stribild
Disaggregation of Revenue [Line Items]
Total revenues	46	53
Stribild | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	31	34
Stribild | Europe
Disaggregation of Revenue [Line Items]
Total revenues	11	17
Stribild | Other International
Disaggregation of Revenue [Line Items]
Total revenues	4	2
Truvada
Disaggregation of Revenue [Line Items]
Total revenues	135	406
Truvada | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	119	383
Truvada | Europe
Disaggregation of Revenue [Line Items]
Total revenues	7	8
Truvada | Other International
Disaggregation of Revenue [Line Items]
Total revenues	9	15
Other HIV
Disaggregation of Revenue [Line Items]
Total revenues	17	8
Other HIV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	6	3
Other HIV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	1	2
Other HIV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	10	3
Revenue share - Symtuza
Disaggregation of Revenue [Line Items]
Total revenues	135	112
Revenue share - Symtuza | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	89	72
Revenue share - Symtuza | Europe
Disaggregation of Revenue [Line Items]
Total revenues	44	38
Revenue share - Symtuza | Other International
Disaggregation of Revenue [Line Items]
Total revenues	2	2
Total HCV
Disaggregation of Revenue [Line Items]
Total revenues	510	729
Total HCV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	258	398
Total HCV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	135	148
Total HCV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	117	183
Ledipasvir/Sofosbuvir
Disaggregation of Revenue [Line Items]
Total revenues	56	112
Ledipasvir/Sofosbuvir | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	19	53
Ledipasvir/Sofosbuvir | Europe
Disaggregation of Revenue [Line Items]
Total revenues	16	11
Ledipasvir/Sofosbuvir | Other International
Disaggregation of Revenue [Line Items]
Total revenues	21	48
Sofosbuvir/Velpatasvir
Disaggregation of Revenue [Line Items]
Total revenues	381	564
Sofosbuvir/Velpatasvir | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	214	311
Sofosbuvir/Velpatasvir | Europe
Disaggregation of Revenue [Line Items]
Total revenues	75	122
Sofosbuvir/Velpatasvir | Other International
Disaggregation of Revenue [Line Items]
Total revenues	92	131
Other HCV
Disaggregation of Revenue [Line Items]
Total revenues	73	53
Other HCV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	25	34
Other HCV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	44	15
Other HCV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	4	4
Total HBV/HDV
Disaggregation of Revenue [Line Items]
Total revenues	220	186
Total HBV/HDV | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	81	85
Total HBV/HDV | Europe
Disaggregation of Revenue [Line Items]
Total revenues	23	20
Total HBV/HDV | Other International
Disaggregation of Revenue [Line Items]
Total revenues	116	81
Vemlidy
Disaggregation of Revenue [Line Items]
Total revenues	181	136
Vemlidy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	77	73
Vemlidy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	8	7
Vemlidy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	96	56
Viread
Disaggregation of Revenue [Line Items]
Total revenues	31	40
Viread | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	4	4
Viread | Europe
Disaggregation of Revenue [Line Items]
Total revenues	7	11
Viread | Other International
Disaggregation of Revenue [Line Items]
Total revenues	20	25
Other HBV/HBD
Disaggregation of Revenue [Line Items]
Total revenues	8	10
Other HBV/HBD | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	0	8
Other HBV/HBD | Europe
Disaggregation of Revenue [Line Items]
Total revenues	8	2
Other HBV/HBD | Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Veklury
Disaggregation of Revenue [Line Items]
Total revenues	1,456	0
Veklury | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	820	0
Veklury | Europe
Disaggregation of Revenue [Line Items]
Total revenues	388	0
Veklury | Other International
Disaggregation of Revenue [Line Items]
Total revenues	248	0
Total Cell Therapy
Disaggregation of Revenue [Line Items]
Total revenues	191	140
Total Cell Therapy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	119	103
Total Cell Therapy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	65	37
Total Cell Therapy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	7	0
Tecartus
Disaggregation of Revenue [Line Items]
Total revenues	31	0
Tecartus | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	27	0
Tecartus | Europe
Disaggregation of Revenue [Line Items]
Total revenues	4	0
Tecartus | Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Yescarta
Disaggregation of Revenue [Line Items]
Total revenues	160	140
Yescarta | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	92	103
Yescarta | Europe
Disaggregation of Revenue [Line Items]
Total revenues	61	37
Yescarta | Other International
Disaggregation of Revenue [Line Items]
Total revenues	7	0
Trodelvy
Disaggregation of Revenue [Line Items]
Total revenues	72	0
Trodelvy | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	72	0
Trodelvy | Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Trodelvy | Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Total Other
Disaggregation of Revenue [Line Items]
Total revenues	241	278
Total Other | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	104	150
Total Other | Europe
Disaggregation of Revenue [Line Items]
Total revenues	86	83
Total Other | Other International
Disaggregation of Revenue [Line Items]
Total revenues	51	45
AmBisome
Disaggregation of Revenue [Line Items]
Total revenues	121	119
AmBisome | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	12	18
AmBisome | Europe
Disaggregation of Revenue [Line Items]
Total revenues	66	59
AmBisome | Other International
Disaggregation of Revenue [Line Items]
Total revenues	43	42
Letairis
Disaggregation of Revenue [Line Items]
Total revenues	54	83
Letairis | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	54	83
Letairis | Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Letairis | Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Ranexa
Disaggregation of Revenue [Line Items]
Total revenues	3	8
Ranexa | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	3	8
Ranexa | Europe
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Ranexa | Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Zydelig
Disaggregation of Revenue [Line Items]
Total revenues	15	20
Zydelig | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	8	8
Zydelig | Europe
Disaggregation of Revenue [Line Items]
Total revenues	7	12
Zydelig | Other International
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Other
Disaggregation of Revenue [Line Items]
Total revenues	48	48
Other | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	27	33
Other | Europe
Disaggregation of Revenue [Line Items]
Total revenues	13	12
Other | Other International
Disaggregation of Revenue [Line Items]
Total revenues	8	3
Royalty, contract and other revenues
Disaggregation of Revenue [Line Items]
Total revenues	83	81
Royalty, contract and other revenues | U.S.
Disaggregation of Revenue [Line Items]
Total revenues	20	17
Royalty, contract and other revenues | Europe
Disaggregation of Revenue [Line Items]
Total revenues	61	48
Royalty, contract and other revenues | Other International
Disaggregation of Revenue [Line Items]
Total revenues	$ 2	$ 16

REVENUES - Revenues from Major

REVENUES - Revenues from Major Customers (Details) - Revenue from Contract with Customer Benchmark - Customer Concentration Risk	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AmerisourceBergen Corporation
Revenue, Major Customer [Line Items]
Percentage of revenues	27.00%	22.00%
Cardinal Health, Inc.
Revenue, Major Customer [Line Items]
Percentage of revenues	18.00%	22.00%
McKesson Corporation
Revenue, Major Customer [Line Items]
Percentage of revenues	17.00%	21.00%

REVENUES - Additional Informati

REVENUES - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Contract assets	$ 185		$ 198
Contract liabilities	91		$ 97
Change in estimate of variable consideration	332	$ 38
Royalty
Disaggregation of Revenue [Line Items]
Contract with customer, performance obligation satisfied in previous period	$ 226	$ 188

FAIR VALUE MEASUREMENTS - Summa

FAIR VALUE MEASUREMENTS - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Assets:
Total	$ 2,478	$ 2,026
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement
Assets:
Total	7,231	9,008
Liabilities:
Total	617	339
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | MYR GmbH
Liabilities:
Liability for MYR contingent consideration	341	0
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | U.S. treasury securities
Assets:
Total	464	309
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Certificates of deposit
Assets:
Total	358	216
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Non-U.S. government securities
Assets:
Total	62	43
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Corporate debt securities
Assets:
Total	1,247	1,142
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Residential mortgage and asset-backed securities
Assets:
Total	347	316
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Money market funds
Assets:
Marketable equity securities	2,216	4,361
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Equity investment in Galapagos
Assets:
Marketable equity securities	1,302	1,648
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Other publicly traded equity securities
Assets:
Marketable equity securities	968	743
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Deferred compensation plan
Assets:
Marketable equity securities	235	218
Liabilities:
Deferred compensation plan	235	218
Fair Value, Measurements, Recurring | Estimate of Fair Value Measurement | Foreign currency derivative contracts
Assets:
Foreign currency derivative contracts	32	12
Liabilities:
Foreign currency derivative contracts	41	121
Fair Value, Measurements, Recurring | Level 1
Assets:
Total	5,185	7,279
Liabilities:
Total	235	218
Fair Value, Measurements, Recurring | Level 1 | MYR GmbH
Liabilities:
Liability for MYR contingent consideration	0	0
Fair Value, Measurements, Recurring | Level 1 | U.S. treasury securities
Assets:
Total	464	309
Fair Value, Measurements, Recurring | Level 1 | Certificates of deposit
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 1 | Non-U.S. government securities
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 1 | Corporate debt securities
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 1 | Residential mortgage and asset-backed securities
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 1 | Money market funds
Assets:
Marketable equity securities	2,216	4,361
Fair Value, Measurements, Recurring | Level 1 | Equity investment in Galapagos
Assets:
Marketable equity securities	1,302	1,648
Fair Value, Measurements, Recurring | Level 1 | Other publicly traded equity securities
Assets:
Marketable equity securities	968	743
Fair Value, Measurements, Recurring | Level 1 | Deferred compensation plan
Assets:
Marketable equity securities	235	218
Liabilities:
Deferred compensation plan	235	218
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	2,046	1,729
Liabilities:
Total	41	121
Fair Value, Measurements, Recurring | Level 2 | MYR GmbH
Liabilities:
Liability for MYR contingent consideration	0	0
Fair Value, Measurements, Recurring | Level 2 | U.S. treasury securities
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 2 | Certificates of deposit
Assets:
Total	358	216
Fair Value, Measurements, Recurring | Level 2 | Non-U.S. government securities
Assets:
Total	62	43
Fair Value, Measurements, Recurring | Level 2 | Corporate debt securities
Assets:
Total	1,247	1,142
Fair Value, Measurements, Recurring | Level 2 | Residential mortgage and asset-backed securities
Assets:
Total	347	316
Fair Value, Measurements, Recurring | Level 2 | Money market funds
Assets:
Marketable equity securities	0	0
Fair Value, Measurements, Recurring | Level 2 | Equity investment in Galapagos
Assets:
Marketable equity securities	0	0
Fair Value, Measurements, Recurring | Level 2 | Other publicly traded equity securities
Assets:
Marketable equity securities	0	0
Fair Value, Measurements, Recurring | Level 2 | Deferred compensation plan
Assets:
Marketable 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	32	12
Liabilities:
Foreign currency derivative contracts	41	121
Fair Value, Measurements, Recurring | Level 3
Assets:
Total	0	0
Liabilities:
Total	341	0
Fair Value, Measurements, Recurring | Level 3 | MYR GmbH
Liabilities:
Liability for MYR contingent consideration	341	0
Fair Value, Measurements, Recurring | Level 3 | U.S. treasury securities
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 3 | Certificates of deposit
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 3 | Non-U.S. government securities
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 3 | Corporate debt securities
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 3 | Residential mortgage and asset-backed securities
Assets:
Total	0	0
Fair Value, Measurements, Recurring | Level 3 | Money market funds
Assets:
Marketable equity securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Equity investment in Galapagos
Assets:
Marketable equity securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Other publicly traded equity securities
Assets:
Marketable equity securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Deferred compensation plan
Assets:
Marketable 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 - Sum_2

FAIR VALUE MEASUREMENTS - Summary of Classification of Equity Securities (Details) - Other Equity Securities - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total	$ 4,721	$ 6,970
Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable equity securities	2,216	4,361
Prepaid and other current assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable equity securities	797	853
Other long-term assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable equity securities	$ 1,708	$ 1,756

FAIR VALUE MEASUREMENTS - Addit

FAIR VALUE MEASUREMENTS - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity investments not measured at fair value	$ 69		$ 58
Equity investments without readily determinable fair values	225		204
Net losses from equity securities	(351)	$ (283)
Level 2 | MYR GmbH | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liability for MYR contingent consideration	0		0
Level 3 | MYR GmbH | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liability for MYR contingent consideration	341		0
Market value | MYR GmbH | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Liability for MYR contingent consideration	341		0
Market value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term and long-term debt	31,600		34,600
Carrying value | Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Short-term and long-term debt, carrying values	$ 29,100		$ 30,300

FAIR VALUE MEASUREMENTS - Equit

FAIR VALUE MEASUREMENTS - Equity Investment In Galapagos (Details) - Galapagos NV - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity investment	$ 1,302	$ 1,648
Prepaid and other current assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity investment	276	351
Other long-term assets
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Equity investment	$ 1,026	$ 1,297

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	Mar. 31, 2021	Dec. 31, 2020
Available-for-Sale Debt Securities
Amortized Cost	$ 2,478	$ 2,023
Gross Unrealized Gains	1	3
Gross Unrealized Losses	(1)	0
Estimated Fair Value	2,478	2,026
U.S. treasury securities
Available-for-Sale Debt Securities
Amortized Cost	464	308
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Estimated Fair Value	464	309
Certificates of deposit
Available-for-Sale Debt Securities
Amortized Cost	358	216
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	358	216
Non-U.S. government securities
Available-for-Sale Debt Securities
Amortized Cost	62	43
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	62	43
Corporate debt securities
Available-for-Sale Debt Securities
Amortized Cost	1,247	1,140
Gross Unrealized Gains	1	2
Gross Unrealized Losses	(1)	0
Estimated Fair Value	1,247	1,142
Residential mortgage and asset-backed securities
Available-for-Sale Debt Securities
Amortized Cost	347	316
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 347	$ 316

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	Mar. 31, 2021	Dec. 31, 2020
Available-for-Sale Debt Securities
Total	$ 2,478	$ 2,026
Cash and cash equivalents
Available-for-Sale Debt Securities
Total	298	113
Short-term marketable securities
Available-for-Sale Debt Securities
Total	1,601	1,411
Long-term marketable securities
Available-for-Sale Debt Securities
Total	$ 579	$ 502

AVAILABLE-FOR-SALE DEBT SECUR_5

AVAILABLE-FOR-SALE DEBT SECURITIES - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021USD ($)position	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Debt Securities, Available-for-sale [Abstract]
Accrued interest receivable	$ 9,000,000		$ 9,000,000
Write-offs of accrued interest receivable	$ 0	$ 0
Number of positions held in an unrealized loss position | position	203
Impairment recognized	$ 0

AVAILABLE-FOR-SALE DEBT SECUR_6

AVAILABLE-FOR-SALE DEBT SECURITIES - Summary of Available-for-Sale Debt Securities by Contractual Maturity (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Amortized Cost
Within one year	$ 1,898
After one year through five years	563
After five years	17
Amortized Cost	2,478	$ 2,023
Fair Value
Within one year	1,899
After one year through five years	562
After five years	17
Total	$ 2,478	$ 2,026

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivative [Line Items]
Derivative, notional amount	$ 3,000,000,000		$ 2,400,000,000
Discontinuances of cash flow hedges	$ 0	$ 0
Maximum
Derivative [Line Items]
Maturities of derivative instruments	18 months
Time estimate for gains (losses) to be reclassified from AOCI to product sales	12 months

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Classification and Fair Value of Derivative Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	$ 32	$ 12
Derivative liability, fair value	(41)	(121)
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	32	0
Derivative liability, fair value	(41)	(120)
Designated as Hedging Instrument | Prepaid and other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	25	0
Designated as Hedging Instrument | Other accrued liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	(41)	(113)
Designated as Hedging Instrument | Other long-term assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	7	0
Designated as Hedging Instrument | Other long-term obligations
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	0	(7)
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	12
Derivative liability, fair value	0	(1)
Not Designated as Hedging Instrument | Prepaid and other current assets
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	12
Not Designated as Hedging Instrument | Other accrued liabilities
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	$ 0	$ (1)

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Effect of Foreign Currency Exchange Contracts (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gains recognized in AOCI	$ 78	$ 66
Gains (losses) reclassified from AOCI into product sales	(25)	27
Gains recognized in Other income (expense), net	$ 34	$ 24

DERIVATIVE FINANCIAL INSTRUME_6

DERIVATIVE FINANCIAL INSTRUMENTS - Summary of Potential Effect of Offsetting Derivatives (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Derivative assets
Gross Amounts of Recognized Assets/Liabilities	$ 32	$ 12
Gross Amounts Offset on our Condensed Consolidated Balance Sheets	0	0
Amounts of Assets/Liabilities Presented on our Condensed Consolidated Balance Sheets	32	12
Derivative Financial Instruments	(22)	(12)
Cash Collateral Received/ Pledged	0	0
Net Amount (Legal Offset)	10	0
Derivative liabilities
Gross Amounts of Recognized Assets/Liabilities	(41)	(121)
Gross Amounts Offset on our Condensed Consolidated Balance Sheets	0	0
Amounts of Assets/Liabilities Presented on our Condensed Consolidated Balance Sheets	(41)	(121)
Derivative Financial Instruments	22	12
Cash Collateral Received/ Pledged	0	0
Net Amount (Legal Offset)	$ (19)	$ (109)

ACQUISITIONS - Narrative (Detai

ACQUISITIONS - Narrative (Details) € in Millions	Mar. 04, 2021USD ($)	Mar. 04, 2021EUR (€)	Oct. 23, 2020USD ($)	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Mar. 04, 2021EUR (€)
Three-Year Senior Term Loan Facility | Medium-term Notes
Business Combination, Separately Recognized Transactions [Line Items]
Borrowing from senior unsecured term loan facility					$ 1,000,000,000
MYR GmbH
Business Combination, Separately Recognized Transactions [Line Items]
Acquisition-related expenses				$ 11,000,000
Acquisition consideration transferred	$ 1,600,000,000	€ 1,300
Cash paid for acquisition	1,200,000,000	€ 1,000
Fair value of contingent liability	341,000,000
Finite-lived intangible assets	845,000,000
Goodwill	226,000,000
Expected tax deductible goodwill				$ 0
MYR GmbH | Maximum
Business Combination, Separately Recognized Transactions [Line Items]
Liability for MYR contingent consideration | €						€ 300
MYR GmbH | Hepcludex For HDV
Business Combination, Separately Recognized Transactions [Line Items]
Finite-lived intangible assets	$ 845,000,000
Weighted average useful life	10 years	10 years
MYR GmbH | Hepcludex For HDV | Discount Rate
Business Combination, Separately Recognized Transactions [Line Items]
Measurement input	0.12					0.12
MYR GmbH | Acquired IPR&D
Business Combination, Separately Recognized Transactions [Line Items]
Acquired IPR&D	$ 1,190,000,000
MYR GmbH | Acquired IPR&D | Discount Rate
Business Combination, Separately Recognized Transactions [Line Items]
Measurement input	0.12					0.12
Immunomedics
Business Combination, Separately Recognized Transactions [Line Items]
Acquisition consideration transferred			$ 20,600,000,000
Goodwill			3,991,000,000
Immunomedics | Acquired IPR&D
Business Combination, Separately Recognized Transactions [Line Items]
Acquired IPR&D			$ 15,760,000,000

ACQUISITIONS - Schedule of Fair

ACQUISITIONS - Schedule of Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Mar. 04, 2021	Oct. 23, 2020
MYR GmbH
Business Combination, Separately Recognized Transactions [Line Items]
Finite-lived intangible assets	$ 845
Deferred income taxes	(513)
Other assets (and liabilities), net	(187)
Total identifiable net assets	1,335
Goodwill	226
Total consideration transferred	1,561
MYR GmbH | Acquired IPR&D
Business Combination, Separately Recognized Transactions [Line Items]
Acquired IPR&D	$ 1,190
Immunomedics
Business Combination, Separately Recognized Transactions [Line Items]
Cash and cash equivalents		$ 726
Inventories		946
Deferred income taxes		(4,565)
Liability related to future royalties		(1,100)
Other assets (and liabilities), net		64
Total identifiable net assets		16,606
Goodwill		3,991
Total consideration transferred		20,597
Immunomedics | Acquired IPR&D
Business Combination, Separately Recognized Transactions [Line Items]
Acquired IPR&D		15,760
Immunomedics | Trodelvy for mTNBC
Business Combination, Separately Recognized Transactions [Line Items]
Finite-lived intangible assets		4,600
Immunomedics | Outlicense contract
Business Combination, Separately Recognized Transactions [Line Items]
Finite-lived intangible assets		$ 175

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS - Goodwill (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 8,108
Goodwill resulting from the acquisition of MYR	226
Ending balance	$ 8,334

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS - Summary of Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount		$ 24,666	$ 22,897
Accumulated Amortization		(7,055)	(6,660)
Foreign Currency Translation Adjustment		0	(1)
Net Carrying Amount		17,611	16,236
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Gross  Carrying Amount		41,836	39,787
Accumulated Amortization		(7,055)	(6,660)
Foreign Currency Translation Adjustment		0	(1)
Net Carrying Amount		34,781	33,126
Acquired IPR&D
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Gross  Carrying Amount		17,170	16,890
Foreign Currency Translation Adjustment		0	0
Net Carrying Amount		17,170	16,890
Intangible assets reclassified from indefinite-lived assets		(910)
Forecast | Subsequent Event | Acquired IPR&D
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Reclassified amounts	$ 1,000
Intangible asset - sofosbuvir
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount		10,720	10,720
Accumulated Amortization		(5,127)	(4,952)
Foreign Currency Translation Adjustment		0	0
Net Carrying Amount		5,593	5,768
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Accumulated Amortization		(5,127)	(4,952)
Intangible asset - axicabtagene ciloleucel
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount		7,110	6,200
Accumulated Amortization		(1,196)	(1,105)
Foreign Currency Translation Adjustment		0	0
Net Carrying Amount		5,914	5,095
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Intangible assets reclassified from indefinite-lived assets		910
Accumulated Amortization		(1,196)	(1,105)
Intangible asset - Trodelvy for mTNBC
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount		4,600	4,600
Accumulated Amortization		(158)	(63)
Foreign Currency Translation Adjustment		0	0
Net Carrying Amount		4,442	4,537
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Accumulated Amortization		(158)	(63)
Intangible asset - Hepcludex for HDV
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount		845	0
Accumulated Amortization		(7)	0
Foreign Currency Translation Adjustment		0	0
Net Carrying Amount		838	0
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Accumulated Amortization		(7)	0
Other
Finite-Lived Intangible Assets [Line Items]
Gross  Carrying Amount		1,391	1,377
Accumulated Amortization		(567)	(540)
Foreign Currency Translation Adjustment		0	(1)
Net Carrying Amount		824	836
Indefinite-lived Intangible Assets (Excluding Goodwill) [Abstract]
Accumulated Amortization		$ (567)	$ (540)

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Aggregate amortization expense related to finite-lived intangible assets	$ 395	$ 281

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS - Schedule of Estimated Future Amortization Expense (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
2021 (remaining nine months)	$ 1,256
2022	1,675
2023	1,675
2024	1,675
2025	1,669
Thereafter	9,661
Net Carrying Amount	$ 17,611	$ 16,236

OTHER FINANCIAL INFORMATION - A

OTHER FINANCIAL INFORMATION - Accounts Receivable, Net (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Other Financial Information [Abstract]
Accounts receivable	$ 4,647	$ 5,560
Less: chargebacks	607	552
Less: cash discounts and other	64	72
Less: allowances for credit losses	51	44
Accounts receivable, net	$ 3,925	$ 4,892

OTHER FINANCIAL INFORMATION - I

OTHER FINANCIAL INFORMATION - Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Other Financial Information [Abstract]
Raw materials	$ 1,023	$ 1,080
Work in process	856	976
Finished goods	1,117	958
Total	2,996	3,014
Inventories	1,779	1,683
Other long-term assets	$ 1,217	$ 1,331

OTHER FINANCIAL INFORMATION - O

OTHER FINANCIAL INFORMATION - Other Accrued Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Other Financial Information [Abstract]
Compensation and employee benefits	$ 494	$ 864
Income taxes payable	215	598
Allowance for sales returns	524	587
Accrued and other current liabilities	2,274	2,287
Total	$ 3,507	$ 4,336

COLLABORATIONS AND OTHER ARRA_2

COLLABORATIONS AND OTHER ARRANGEMENTS (Details) - USD ($) shares in Millions	Mar. 13, 2021	May 27, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Merck Sharp & Dohme Corp agreement
Collaborative Arrangements
Percent of global development and commercialization costs	60.00%
Option period to license	5 years
Merck Sharp & Dohme Corp agreement | Merck
Collaborative Arrangements
Percent of global development and commercialization costs	40.00%
Merck Sharp & Dohme Corp agreement | Oral Formulation Product
Collaborative Arrangements
Net product sales threshold	$ 2,000,000,000
Percent of global product revenues	65.00%
Merck Sharp & Dohme Corp agreement | Injectable Formulation Product
Collaborative Arrangements
Net product sales threshold	$ 3,500,000,000
Percent of global product revenues	65.00%
Arcus stock purchase agreement | Arcus
Collaborative Arrangements
Ownership percentage by noncontrolling owners			19.50%
Other collaboration arrangements
Collaborative Arrangements
Upfront collaboration expenses related to other collaborative arrangements			$ 62,000,000	$ 97,000,000
Cash payments made related to equity investments			$ 59,000,000	$ 8,000,000
Arcus | Arcus stock purchase agreement
Collaborative Arrangements
Equity securities acquired (in shares)			5.7		8.2
Payments to acquire equity securities			$ 220,000,000		$ 261,000,000
Equity securities (in shares)			13.8
Purchase period		5 years
Restriction period		3 years
Arcus | the “Stock Purchase Agreements”
Collaborative Arrangements
Maximum percentage of outstanding stock allowed to be purchased		35.00%

DEBT AND CREDIT FACILITIES - Su

DEBT AND CREDIT FACILITIES - Summary of Debt Carrying Amount (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total debt, net	$ 30,166	$ 31,402
Less: current portion of long-term debt and other obligations, net	2,259	2,757
Total long-term debt, net	27,907	28,645
Senior Notes and Medium-Term Notes
Debt Instrument [Line Items]
Total debt, net	$ 29,052	30,295
Senior Notes | 4.50% Senior Unsecured Notes Due April 2021
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
Total debt, net	$ 0	1,000
Senior Notes | 0.15% LIBOR Senior Unsecured Notes Due September 2021
Debt Instrument [Line Items]
Total debt, net	$ 500	499
Senior Notes | 0.15% LIBOR Senior Unsecured Notes Due September 2021 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	0.15%
Senior Notes | 4.40% Senior Unsecured Notes Due December 2021
Debt Instrument [Line Items]
Interest rate, stated percentage	4.40%
Total debt, net	$ 1,249	1,249
Senior Notes | 1.95% Senior Unsecured Notes Due March 2022
Debt Instrument [Line Items]
Interest rate, stated percentage	1.95%
Total debt, net	$ 499	499
Senior Notes | 3.25% Senior Unsecured Notes Due September 2022
Debt Instrument [Line Items]
Interest rate, stated percentage	3.25%
Total debt, net	$ 999	998
Senior Notes | 2.50% Senior Unsecured Notes Due September 2023
Debt Instrument [Line Items]
Interest rate, stated percentage	2.50%
Total debt, net	$ 748	748
Senior Notes | 0.52% LIBOR Senior Unsecured Notes Due September 2023
Debt Instrument [Line Items]
Total debt, net	$ 498	498
Senior Notes | 0.52% LIBOR Senior Unsecured Notes Due September 2023 | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate	0.52%
Senior Notes | 0.75% Senior Unsecured Notes Due September 2023
Debt Instrument [Line Items]
Interest rate, stated percentage	0.75%
Total debt, net	$ 1,993	1,992
Senior Notes | 3.70% Senior Unsecured Notes Due April 2024
Debt Instrument [Line Items]
Interest rate, stated percentage	3.70%
Total debt, net	$ 1,746	1,746
Senior Notes | 3.50% Senior Unsecured Notes Due February 2025
Debt Instrument [Line Items]
Interest rate, stated percentage	3.50%
Total debt, net	$ 1,747	1,746
Senior Notes | 3.65% Senior Unsecured Notes Due March 2026
Debt Instrument [Line Items]
Interest rate, stated percentage	3.65%
Total debt, net	$ 2,737	2,737
Senior Notes | 2.95% Senior Unsecured Notes Due March 2027
Debt Instrument [Line Items]
Interest rate, stated percentage	2.95%
Total debt, net	$ 1,246	1,246
Senior Notes | 1.20% Senior Unsecured Notes Due October 2027
Debt Instrument [Line Items]
Interest rate, stated percentage	1.20%
Total debt, net	$ 746	745
Senior Notes | 1.65% Senior Unsecured Notes Due October 2030
Debt Instrument [Line Items]
Interest rate, stated percentage	1.65%
Total debt, net	$ 992	992
Senior Notes | 4.60% Senior Unsecured Notes Due September 2035
Debt Instrument [Line Items]
Interest rate, stated percentage	4.60%
Total debt, net	$ 992	991
Senior Notes | 4.00% Senior Unsecured Notes Due September 2036
Debt Instrument [Line Items]
Interest rate, stated percentage	4.00%
Total debt, net	$ 742	741
Senior Notes | 2.60% Senior Unsecured Notes Due October 2040
Debt Instrument [Line Items]
Interest rate, stated percentage	2.60%
Total debt, net	$ 986	986
Senior Notes | 5.65% Senior Unsecured Notes Due December 204
Debt Instrument [Line Items]
Interest rate, stated percentage	5.65%
Total debt, net	$ 996	996
Senior Notes | 4.80% Senior Unsecured Notes Due April 2044
Debt Instrument [Line Items]
Interest rate, stated percentage	4.80%
Total debt, net	$ 1,735	1,735
Senior Notes | 4.50% Senior Unsecured Notes Due February 2045
Debt Instrument [Line Items]
Interest rate, stated percentage	4.50%
Total debt, net	$ 1,732	1,732
Senior Notes | 4.75% Senior Unsecured Notes Due March 2046
Debt Instrument [Line Items]
Interest rate, stated percentage	4.75%
Total debt, net	$ 2,219	2,219
Senior Notes | 4.15% Senior Unsecured Notes Due March 2047
Debt Instrument [Line Items]
Interest rate, stated percentage	4.15%
Total debt, net	$ 1,726	1,726
Senior Notes | 2.80% Senior Unsecured Notes Due October 2050
Debt Instrument [Line Items]
Interest rate, stated percentage	2.80%
Total debt, net	$ 1,476	1,476
Medium-term Notes | Variable Term Loan Note Due October 2023
Debt Instrument [Line Items]
Total debt, net	748	998
Notes Payable, Other Payables
Debt Instrument [Line Items]
Total debt, net	$ 1,114	$ 1,107

DEBT AND CREDIT FACILITIES - Ad

DEBT AND CREDIT FACILITIES - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended
	Mar. 31, 2021	Jan. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Repayments of long-term debt			$ 1,250,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Amounts outstanding under revolving credit facilities	$ 0		0	$ 0
Revolving Credit Facility | the "2020 Revolving Credit Facility"
Debt Instrument [Line Items]
Maximum borrowing capacity	2,500,000,000		2,500,000,000
Senior Notes | the "2014 Senior Notes"
Debt Instrument [Line Items]
Repayments of senior unsecured notes		$ 1,000,000,000
Medium-term Notes | Three-Year Senior Term Loan Facility
Debt Instrument [Line Items]
Repayments of senior unsecured notes	$ 250,000,000
Contractual term	3 years
Maximum borrowing capacity	$ 1,000,000,000		1,000,000,000
Remaining outstanding	$ 750,000,000		$ 750,000,000

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details)	1 Months Ended			3 Months Ended	12 Months Ended	38 Months Ended
	Apr. 30, 2020plaintiffagreement	Dec. 31, 2019USD ($)patentopposingParty	Aug. 31, 2017plaintiff	Mar. 31, 2021USD ($)plaintiffopposingPartylawsuit	Dec. 31, 2016party	Mar. 31, 2021USD ($)opposingParty	Dec. 31, 2018opposingParty	Dec. 31, 2017opposingParty
Loss Contingencies [Line Items]
Number of patents challenged, scenario one | patent		4
Number of patents challenged, scenario two | patent		2
Juno Therapeutics, Inc. and Sloan Kettering Cancer Center
Loss Contingencies [Line Items]
Damages awarded		$ 585,000,000
Running royalty rate from October 2017		27.60%
Enhancement rate on past damages	50.00%
Running royalty rate on future sales	27.60%
Estimate of possible loss representing past sales				$ 811,000,000		$ 811,000,000
Estimate of possible loss representing enhancement of past damages				389,000,000		389,000,000
Estimate of possible loss representing royalties and prejudgment interest				225,000,000		225,000,000
Juno Therapeutics, Inc. and Sloan Kettering Cancer Center | Minimum
Loss Contingencies [Line Items]
Estimate of possible loss				0		0
Juno Therapeutics, Inc. and Sloan Kettering Cancer Center | Maximum
Loss Contingencies [Line Items]
Estimate of possible loss				$ 1,400,000,000		1,400,000,000
ViiV Healthcare Company | Pending Litigation
Loss Contingencies [Line Items]
Damages amount						$ 12,900,000,000
Pre-Exposure Prophylaxis
Loss Contingencies [Line Items]
Number of material transfer agreements | agreement	4
European Patent Claims
Loss Contingencies [Line Items]
Number of parties appealed | opposingParty		3		2		2	2	3
Number of parties filing opposition | party					3
Product Liability
Loss Contingencies [Line Items]
Number of class action lawsuits | lawsuit				2
Number of plaintiffs involved | plaintiff				21,000
Qui Tam
Loss Contingencies [Line Items]
Number of plaintiffs involved | plaintiff	2		2

STOCKHOLDERS' EQUITY - Addition

STOCKHOLDERS' EQUITY - Additional Information (Details) - USD ($) shares in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2016
Class of Stock [Line Items]
Shares repurchased and retired (in shares)	4.8	18.7
Value of shares repurchased and retired	$ 309,000,000	$ 1,300,000,000
Remaining authorized repurchase amount under stock repurchase programs	$ 6,500,000,000
2016 Stock Repurchase Program
Class of Stock [Line Items]
Authorized amount under stock repurchase program			$ 12,000,000,000
2020 Stock Repurchase Program
Class of Stock [Line Items]
Authorized amount under stock repurchase program		$ 5,000,000,000

STOCKHOLDERS' EQUITY - Summary

STOCKHOLDERS' EQUITY - Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 18,221	$ 22,650
Other comprehensive income (loss)	98	(39)
Ending balance	18,964	22,179
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(60)	85
Net unrealized gain (loss)	76	(5)
Reclassifications to net income	22	(34)
Other comprehensive income (loss)	98	(39)
Ending balance	38	46
Foreign Currency Translation, Net of Tax
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	51	53
Net unrealized gain (loss)	10	(39)
Reclassifications to net income	0	0
Other comprehensive income (loss)	10	(39)
Ending balance	61	14
Unrealized Gains and Losses on Available-for-Sale Debt Securities, Net of Tax
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	2	1
Net unrealized gain (loss)	(2)	(23)
Reclassifications to net income	0	(11)
Other comprehensive income (loss)	(2)	(34)
Ending balance	0	(33)
Unrealized Gains and Losses on Cash Flow Hedges, Net of Tax
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(113)	31
Net unrealized gain (loss)	68	57
Reclassifications to net income	22	(23)
Other comprehensive income (loss)	90	34
Ending balance	$ (23)	$ 65

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
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Antidilutive securities excluded from earnings per share computation (in shares)	15	14

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
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net income attributable to Gilead	$ 1,729	$ 1,551
Shares used in per share calculation - basic (in shares)	1,256	1,262
Dilutive effect of stock options and equivalents (in shares)	6	8
Shares used in per share calculation - diluted (in shares)	1,262	1,270
Net income per share attributable to Gilead common stockholders - basic (in dollars per share)	$ 1.38	$ 1.23
Net income per share attributable to Gilead common stockholders - diluted (in dollars per share)	$ 1.37	$ 1.22

INCOME TAXES - Summary of the P

INCOME TAXES - Summary of the Provision for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income before income taxes	$ 2,264	$ 2,003
Income tax expense	$ 542	$ 465
Effective tax rate	23.90%	23.20%

INCOME TAXES - Additional Infor

INCOME TAXES - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Effective tax rate	23.90%	23.20%

SUBSEQUENT EVENT (Details)

SUBSEQUENT EVENT (Details) $ in Millions	3 Months Ended
	Jun. 30, 2021USD ($)
Gilead Foundation | Subsequent Event | Equity Securities Donation | Forecast
Related Party Transaction [Line Items]
Donation expense	$ 206