Merck & Co. (MRK) 10-Q 5 Aug 20 2020 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Jul. 31, 2020
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	1-6571
Entity Registrant Name	Merck & Co., Inc.
Entity Incorporation, State or Country Code	NJ
Entity Tax Identification Number	22-1918501
Entity Address, Address Line One	2000 Galloping Hill Road
Entity Address, City or Town	Kenilworth
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	07033
City Area Code	(908)
Local Phone Number	740-4000
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		2,529,241,070
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Entity Central Index Key	0000310158
Current Fiscal Year End Date	--12-31
Common Stock
Entity Information [Line Items]
Title of 12(b) Security	Common Stock ($0.50 par value)
Trading Symbol	MRK
Security Exchange Name	NYSE
1.125% Notes due 2021
Entity Information [Line Items]
Title of 12(b) Security	1.125% Notes due 2021
Trading Symbol	MRK/21
Security Exchange Name	NYSE
0.500% Notes due 2024
Entity Information [Line Items]
Title of 12(b) Security	0.500% Notes due 2024
Trading Symbol	MRK 24
Security Exchange Name	NYSE
1.875% Notes due 2026
Entity Information [Line Items]
Title of 12(b) Security	1.875% Notes due 2026
Trading Symbol	MRK/26
Security Exchange Name	NYSE
2.500% Notes due 2034
Entity Information [Line Items]
Title of 12(b) Security	2.500% Notes due 2034
Trading Symbol	MRK/34
Security Exchange Name	NYSE
1.375% Notes due 2036
Entity Information [Line Items]
Title of 12(b) Security	1.375% Notes due 2036
Trading Symbol	MRK 36A
Security Exchange Name	NYSE

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENT OF INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Sales	$ 10,872	$ 11,760	$ 22,929	$ 22,575
Costs, Expenses and Other
Cost of sales	3,159	3,401	6,471	6,453
Selling, general and administrative	2,378	2,712	4,933	5,138
Research and development	2,123	2,189	4,331	4,119
Restructuring costs	83	59	155	212
Other (income) expense, net	(390)	140	(318)	327
Total Costs, Expenses and Other	7,353	8,501	15,572	16,249
Income Before Taxes	3,519	3,259	7,357	6,326
Taxes on Income	509	615	1,128	820
Net Income	3,010	2,644	6,229	5,506
Less: Net Income (Loss) Attributable to Noncontrolling Interests	8	(26)	8	(79)
Net Income Attributable to Merck & Co., Inc.	$ 3,002	$ 2,670	$ 6,221	$ 5,585
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.19	$ 1.04	$ 2.46	$ 2.17
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.18	$ 1.03	$ 2.45	$ 2.15

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 3,002	$ 2,670	$ 6,221	$ 5,585
Other Comprehensive (Loss) Income Net of Taxes:
Net unrealized loss on derivatives, net of reclassifications	(120)	(52)	(16)	(100)
Net unrealized gain (loss) on investments, net of reclassifications	0	44	(18)	126
Benefit plan net gain and prior service credit, net of amortization	39	11	99	26
Cumulative translation adjustment	79	(19)	(265)	131
Other comprehensive income (loss), net of taxes	(2)	(16)	(200)	183
Comprehensive Income Attributable to Merck & Co., Inc.	$ 3,000	$ 2,654	$ 6,021	$ 5,768

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEET - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Current Assets
Cash and cash equivalents	$ 11,103	$ 9,676
Short-term investments	0	774
Accounts receivable (net of allowance for doubtful accounts of $90 in 2020 and $86 in 2019)	7,577	6,778
Inventories (excludes inventories of $1,921 in 2020 and $1,480 in 2019 classified in Other assets - see Note 6)	6,056	5,978
Other current assets	4,607	4,277
Total current assets	29,343	27,483
Investments	1,251	1,469
Property, Plant and Equipment, at cost, net of accumulated depreciation of $18,182 in 2020 and $17,686 in 2019	15,789	15,053
Goodwill	20,067	19,425
Other Intangibles, Net	16,566	14,196
Other Assets	7,599	6,771
Total Assets	90,615	84,397
Current Liabilities
Loans payable and current portion of long-term debt	4,718	3,610
Trade accounts payable	3,448	3,738
Accrued and other current liabilities	11,182	12,549
Income taxes payable	1,266	736
Dividends payable	1,564	1,587
Total current liabilities	22,178	22,220
Long-Term Debt	26,156	22,736
Deferred Income Taxes	2,091	1,470
Other Noncurrent Liabilities	12,446	11,970
Merck & Co., Inc. Stockholders’ Equity
Common stock, $0.50 par value Authorized - 6,500,000,000 shares Issued - 3,577,103,522 shares in 2020 and 2019	1,788	1,788
Other paid-in capital	39,373	39,660
Retained earnings	49,724	46,602
Accumulated other comprehensive loss	(6,393)	(6,193)
Stockholders' equity before deduction for treasury stock	84,492	81,857
Less treasury stock, at cost: 1,047,935,095 shares in 2020 and 1,038,087,496 shares in 2019	56,850	55,950
Total Merck & Co., Inc. stockholders’ equity	27,642	25,907
Noncontrolling Interests	102	94
Total equity	27,744	26,001
Liabilities and Equity	$ 90,615	$ 84,397

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEET (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 90	$ 86
Inventories classified in Other assets	1,921	1,480
Accumulated depreciation	$ 18,182	$ 17,686
Common stock, par value (in dollars per share)	$ 0.50	$ 0.50
Common stock, shares authorized (shares)	6,500,000,000	6,500,000,000
Common stock, shares issued (in shares)	3,577,103,522	3,577,103,522
Treasury stock, shares (shares)	1,047,935,095	1,038,087,496

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash Flows from Operating Activities
Net income	$ 6,229	$ 5,506
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	1,869	1,871
Intangible asset impairment charges	20	252
Deferred income taxes	122	(149)
Share-based compensation	229	204
Other	(202)	114
Net changes in assets and liabilities	(4,193)	(3,378)
Net Cash Provided by Operating Activities	4,074	4,420
Cash Flows from Investing Activities
Capital expenditures	(1,654)	(1,377)
Purchases of securities and other investments	(77)	(1,810)
Proceeds from sales of securities and other investments	1,892	4,935
Acquisition of ArQule, Inc., net of cash acquired	(2,545)	0
Acquisition of Antelliq Corporation, net of cash acquired	0	(3,620)
Other acquisitions, net of cash acquired	(321)	(270)
Other	195	85
Net Cash Used in Investing Activities	(2,510)	(2,057)
Cash Flows from Financing Activities
Net change in short-term borrowings	1,967	(3,532)
Payments on debt	(1,952)	0
Proceeds from issuance of debt	4,445	4,958
Purchases of treasury stock	(1,281)	(2,325)
Dividends paid to stockholders	(3,128)	(2,896)
Proceeds from exercise of stock options	40	304
Other	(444)	(207)
Net Cash Used in Financing Activities	(353)	(3,698)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	2	28
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	1,213	(1,307)
Cash, Cash Equivalents and Restricted Cash at Beginning of Year (includes restricted cash of $258 million at January 1, 2020 included in Other Assets)	9,934	7,967
Cash, Cash Equivalents and Restricted Cash at End of Period (includes restricted cash of $44 million at June 30, 2020 included in Other Assets)	$ 11,147	$ 6,660

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Statement of Cash Flows [Abstract]
Restricted cash	$ 44	$ 258

Basis of Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of Merck & Co., Inc. (Merck or the Company) have been prepared pursuant to the rules and regulations for reporting on Form 10-Q. Accordingly, certain information and disclosures required by accounting principles generally accepted in the United States (GAAP) for complete consolidated financial statements are not included herein. These interim statements should be read in conjunction with the audited financial statements and notes thereto included in Merck’s Form 10-K filed on February 26, 2020. The results of operations of any interim period are not necessarily indicative of the results of operations for the full year. In the Company’s opinion, all adjustments necessary for a fair statement of these interim statements have been included and are of a normal and recurring nature. Planned Spin-Off of Women’s Health, Legacy Brands and Biosimilars into New Company In February 2020, Merck announced its intention to spin-off products from its women’s health, legacy brands and biosimilars businesses into a new, independent, publicly traded company named Organon & Co. (Organon) through a distribution of Organon’s publicly traded stock to Company shareholders. The distribution is expected to qualify as tax-free to the Company and its shareholders for U.S. federal income tax purposes. The legacy brands included in the transaction consist of dermatology, non-opioid pain, respiratory, and select cardiovascular products including Zetia (ezetimibe) and Vytorin (ezetimibe and simvastatin), as well as the rest of Merck’s diversified brands franchise. Merck’s existing research pipeline programs will continue to be owned and developed within Merck as planned. Organon will have development capabilities initially focused on late-stage development and life-cycle management and is expected over time to develop research capabilities in selected therapeutic areas. The spin-off is expected to be completed in the first half of 2021, subject to market and certain other conditions. Subsequent to the spin-off, the historical results of the women’s health, legacy brands and biosimilars businesses will be reflected as discontinued operations in the Company’s consolidated financial statements. Recently Adopted Accounting Standards In June 2016, the Financial Accounting Standards Board (FASB) issued new guidance on the accounting for credit losses on financial instruments. The new guidance introduces an expected loss model for estimating credit losses, replacing the incurred loss model. The new guidance also changes the impairment model for available-for-sale debt securities, requiring the use of an allowance to record estimated credit losses (and subsequent recoveries). The Company adopted the new guidance effective January 1, 2020. There was no impact to the Company’s consolidated financial statements upon adoption. In November 2018, the FASB issued new guidance for collaborative arrangements intended to reduce diversity in practice by clarifying whether certain transactions between collaborative arrangement participants should be accounted for under revenue recognition guidance (ASC 606). The Company adopted the new guidance effective January 1, 2020, which resulted in minor changes to the presentation of information related to the Company’s collaborative arrangements. Recently Issued Accounting Standards Not Yet Adopted In December 2019, the FASB issued amended guidance on the accounting and reporting of income taxes. The guidance is intended to simplify the accounting for income taxes by removing exceptions related to certain intraperiod tax allocations and deferred tax liabilities; clarifying guidance primarily related to evaluating the step-up tax basis for goodwill in a business combination; and reflecting enacted changes in tax laws or rates in the annual effective tax rate. The amended guidance is effective for interim and annual periods in 2021. Early adoption is permitted. The amendments in the new guidance are to be applied on a retrospective basis, on a modified retrospective basis through a cumulative-effect adjustment to retained earnings or prospectively, depending on the amendment. The Company is currently evaluating the impact of adoption on its consolidated financial statements. In January 2020, the FASB issued new guidance intended to clarify certain interactions between accounting standards related to equity securities, equity method investments and certain derivatives. The guidance addresses accounting for the transition into and out of the equity method of accounting and measuring certain purchased options and forward contracts to acquire investments. The new guidance is effective for interim and annual periods in 2021 and is to be applied prospectively. Early adoption is permitted. The Company is currently evaluating the impact of adoption on its consolidated financial statements. In March 2020, the FASB issued optional guidance to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. The guidance provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform. The optional guidance is effective upon issuance and can be applied on a prospective basis at any time between January 1, 2020 through December 31, 2022. The Company is currently evaluating the impact of adoption on its consolidated financial statements.

Acquisitions, Research Collabor

Acquisitions, Research Collaborations and License Agreements	6 Months Ended
	Jun. 30, 2020
Business Combinations [Abstract]
Acquisitions, Research Collaborations and License Agreements	Acquisitions, Research Collaborations and License Agreements The Company continues to pursue acquisitions and the establishment of external alliances such as research collaborations and licensing agreements to complement its internal research capabilities. These arrangements often include upfront payments, as well as expense reimbursements or payments to the third party, and milestone, royalty or profit share arrangements, contingent upon the occurrence of certain future events linked to the success of the asset in development. The Company also reviews its marketed products and pipeline to examine candidates which may provide more value through out-licensing and, as part of its portfolio assessment process, may also divest certain assets. Pro forma financial information for acquired businesses is not presented if the historical financial results of the acquired entity are not significant when compared with the Company’s financial results. In July 2020, Merck acquired the U.S. rights to Sentinel Flavor Tabs and Sentinel Spectrum Chews from Virbac Corporation for approximately $400 million . Sentinel products provide protection against common parasites in dogs. The transaction will be accounted for as an acquisition of an asset. There are no future contingent payments associated with the acquisition. Also, in July 2020, Merck and Ridgeback Biotherapeutics LP (Ridgeback Bio), a closely held biotechnology company, closed a collaboration agreement to develop MK-4482 (formerly known as EIDD-2801), an orally available antiviral candidate currently in clinical development for the treatment of patients with COVID-19. Merck gained exclusive worldwide rights to develop and commercialize MK-4482 and related molecules. Under the terms of the agreement, Ridgeback Bio received an upfront payment and also is eligible to receive future contingent payments dependent upon the achievement of certain developmental and regulatory approval milestones, as well as a share of the net profits of MK-4482 and related molecules, if approved. Merck and Ridgeback are committed to ensure that any medicines developed for SARS-CoV-2 (the causative agent of COVID-19) will be accessible and affordable globally. In June 2020, Merck acquired privately held Themis Bioscience GmbH (Themis), a company focused on vaccines and immune-modulation therapies for infectious diseases and cancer for $366 million in cash. Merck may make additional contingent payments of up to $740 million , including up to $80 million for development milestones, up to $260 million for regulatory approval milestones, and up to $400 million for commercial milestones. Themis has a broad pipeline of vaccine candidates and immune-modulatory therapies developed using its innovative measles virus vector platform based on a vector originally developed by scientists at the Institut Pasteur and licensed exclusively to Themis for select viral indications. The acquisition builds upon an ongoing collaboration between the two companies to develop vaccine candidates using the measles virus vector platform and is expected to accelerate the development of Themis’ COVID-19 vaccine candidate (V591). V591 is in preclinical development and clinical studies are planned to start in the third quarter of 2020. The transaction was accounted for as an acquisition of a business. The Company determined the fair value of the contingent consideration was $97 million at the acquisition date utilizing a probability-weighted estimated cash flow stream using an appropriate discount rate dependent on the nature and timing of the milestone payment. Merck recognized intangible assets for in-process research and development (IPR&D) of $136 million , cash of $62 million , deferred tax assets of $72 million and other net liabilities of $22 million . The excess of the consideration transferred over the fair value of net assets acquired of $215 million was recorded as goodwill that was allocated to the Pharmaceutical segment and is not deductible for tax purposes. The fair values of the identifiable intangible assets related to IPR&D were determined using an income approach. Actual cash flows are likely to be different than those assumed. In connection with the transaction, Merck has entered into a memorandum of understanding that reflects the parties’ commitments to address the COVID-19 pandemic by developing, manufacturing and distributing the vaccine on a global basis and with pricing that makes the vaccine both available around the world and accessible to those who need it. In May 2020, Merck and the International AIDS Vaccine Initiative, Inc. (IAVI), a nonprofit scientific research organization dedicated to addressing urgent, unmet global health challenges, announced a new collaboration to develop V590, an investigational vaccine against SARS-CoV-2 being studied for the prevention of COVID-19. This vaccine candidate will use the recombinant vesicular stomatitis virus (rVSV) technology that is the basis for Merck’s approved Ebola Zaire virus vaccine, Ervebo (Ebola Zaire Vaccine, Live), which was the first rVSV vaccine approved for use in humans. Under the terms of the agreement, Merck made an upfront payment of $6.5 million and may make additional contingent payments of up to $100 million for sales-based milestones, as well as royalty payments. Merck has also signed an agreement with the Biomedical Advanced Research and Development Authority (BARDA), part of the office of the Assistant Secretary for Preparedness and Response within an agency of the United States Department of Health and Human Services, to provide initial funding support for this effort. Under the agreement, IAVI and Merck will work together to advance the development and global clinical evaluation of a SARS-CoV-2 vaccine candidate designed and engineered by IAVI scientists. The vaccine candidate is in preclinical development, and clinical studies are planned to start later in 2020. Merck will lead regulatory filings globally. Both organizations will work together to develop the vaccine and make it accessible and affordable globally, if approved. In January 2020, Merck acquired ArQule, Inc. (ArQule), a publicly traded biopharmaceutical company focused on kinase inhibitor discovery and development for the treatment of patients with cancer and other diseases. Total consideration paid of $2.7 billion included $138 million of share-based compensation payments to settle equity awards attributable to precombination service and cash paid for transaction costs on behalf of ArQule. The Company incurred $95 million of transaction costs directly related to the acquisition of ArQule, consisting almost entirely of share-based compensation payments to settle non-vested equity awards attributable to postcombination service. These costs were included in Selling, general and administrative expenses in the first six months of 2020. ArQule’s lead investigational candidate, MK-1026 (formerly ARQ 531), is a novel, oral Bruton’s tyrosine kinase (BTK) inhibitor currently being evaluated for the treatment of B-cell malignancies. The estimated fair value of assets acquired and liabilities assumed from ArQule is as follows: ($ in millions) January 16, 2020 Cash and cash equivalents $ 145 IPR&D MK-1026 (formerly ARQ 531) (1) 2,280 IPR&D MK-7075 (formerly ARQ 092) (1) 170 Licensing arrangement for ARQ 087 80 Deferred income tax liabilities (434 ) Other assets and liabilities, net 35 Total identifiable net assets 2,276 Goodwill (2) 414 Consideration transferred $ 2,690 (1) The estimated fair values of the identifiable intangible assets related to in-process research and development (IPR&D) were determined using an income approach. The future net cash flows were discounted to present value utilizing a discount rate of 12.5% . Actual cash flows are likely to be different than those assumed. (2) The goodwill was allocated to the Pharmaceutical segment and is not deductible for tax purposes. On April 1, 2019, Merck acquired Antelliq Corporation (Antelliq), a leader in digital animal identification, traceability and monitoring solutions. These solutions help veterinarians, farmers and pet owners gather critical data to improve management, health and well-being of livestock and pets. Merck paid $2.3 billion to acquire all outstanding shares of Antelliq and spent $1.3 billion to repay Antelliq’s debt. The transaction was accounted for as an acquisition of a business. The estimated fair value of assets acquired and liabilities assumed from Antelliq is as follows: ($ in millions) April 1, 2019 Cash and cash equivalents $ 31 Accounts receivable 73 Inventories 93 Property, plant and equipment 60 Identifiable intangible assets (useful lives ranging from 18-24 years) (1) 2,689 Deferred income tax liabilities (589 ) Other assets and liabilities, net (82 ) Total identifiable net assets 2,275 Goodwill (2) 1,376 Consideration transferred $ 3,651 (1) The estimated fair values of identifiable intangible assets relate primarily to trade names and were determined using an income approach. The future net cash flows were discounted to present value utilizing a discount rate of 11.5% . Actual cash flows are likely to be different than those assumed. (2) The goodwill recognized is largely attributable to anticipated synergies expected to arise after the acquisition and was allocated to the Animal Health segment. The goodwill is not deductible for tax purposes. The Company’s results for the second quarter of 2019 include two months of activity for Antelliq. The Company incurred $47 million of transaction costs directly related to the acquisition of Antelliq, consisting largely of advisory fees, which are reflected in Selling, general and administrative expenses in the first six months of 2019. Also in April 2019, Merck acquired Immune Design, a late-stage immunotherapy company employing next-generation in vivo approaches to enable the body’s immune system to fight disease, for $301 million in cash. The transaction was accounted for as an acquisition of a business. Merck recognized intangible assets of $156 million , cash of $83 million and other net assets of $42 million . The excess of the consideration transferred over the fair value of net assets acquired of $20 million was recorded as goodwill that was allocated to the Pharmaceutical segment and is not deductible for tax purposes. The fair values of

Collaborative Arrangements

Collaborative Arrangements	6 Months Ended
	Jun. 30, 2020
Collaborative Arrangements [Abstract]
Collaborative Arrangements	Collaborative Arrangements Merck has entered into collaborative arrangements that provide the Company with varying rights to develop, produce and market products together with its collaborative partners. Both parties in these arrangements are active participants and exposed to significant risks and rewards dependent on the commercial success of the activities of the collaboration. Merck’s more significant collaborative arrangements are discussed below. AstraZeneca In July 2017, Merck and AstraZeneca PLC (AstraZeneca) entered into a global strategic oncology collaboration to co-develop and co-commercialize AstraZeneca’s Lynparza (olaparib) for multiple cancer types. Lynparza is an oral poly (ADP-ribose) polymerase (PARP) inhibitor currently approved for certain types of advanced ovarian, breast, pancreatic and prostate cancers. The companies are jointly developing and commercializing Lynparza, both as monotherapy and in combination trials with other potential medicines. Independently, Merck and AstraZeneca will develop and commercialize Lynparza in combinations with their respective PD-1 and PD-L1 medicines, Keytruda (pembrolizumab) and Imfinzi. The companies will also jointly develop and commercialize AstraZeneca’s Koselugo (selumetinib), an oral, selective inhibitor of MEK, part of the mitogen-activated protein kinase (MAPK) pathway, currently being developed for multiple indications. In April 2020, Koselugo was approved by the U.S. Food and Drug Administration (FDA) for the treatment of pediatric patients two years of age and older with neurofibromatosis type 1 who have symptomatic, inoperable plexiform neurofibromas. Under the terms of the agreement, AstraZeneca and Merck will share the development and commercialization costs for Lynparza and Koselugo monotherapy and non-PD-L1/PD-1 combination therapy opportunities. Profits from Lynparza and Koselugo product sales generated through monotherapies or combination therapies are shared equally. Merck will fund all development and commercialization costs of Keytruda in combination with Lynparza or Koselugo. AstraZeneca will fund all development and commercialization costs of Imfinzi in combination with Lynparza or Koselugo. AstraZeneca is the principal on Lynparza and Koselugo sales transactions. Merck records its share of Lynparza and Koselugo product sales, net of cost of sales and commercialization costs, as alliance revenue and its share of development costs associated with the collaboration as part of Research and development expenses. Reimbursements received from AstraZeneca for research and development expenses are recognized as reductions to Research and development costs. As part of the agreement, Merck made an upfront payment to AstraZeneca of $1.6 billion in 2017 and made payments of $750 million over a multi-year period for certain license options. In addition, the agreement provides for additional contingent payments from Merck to AstraZeneca related to the successful achievement of sales-based and regulatory milestones. In the second quarter of 2020, Merck determined it was probable that sales of Lynparza in the future would trigger $400 million of sales-based milestone payments from Merck to AstraZeneca. Accordingly, Merck recorded a $400 million liability and a corresponding increase to the intangible asset related to Lynparza. Prior to 2020, Merck accrued sales-based milestone payments aggregating $1.0 billion related to Lynparza, of which $200 million and $250 million was paid to AstraZeneca in 2019 and 2018, respectively, and $250 million was paid in the first six months of 2020. Potential future sales-based milestone payments of $2.7 billion have not yet been accrued as they are not deemed by the Company to be probable at this time. In the second quarter of 2020, Lynparza received regulatory approvals triggering capitalized milestone payments of $135 million from Merck to AstraZeneca. In 2019 and 2018, Lynparza received regulatory approvals triggering capitalized milestone payments of $60 million and $140 million , respectively, in the aggregate from Merck to AstraZeneca. Potential future regulatory milestone payments of $1.4 billion remain under the agreement. The intangible asset balance related to Lynparza (which includes capitalized sales-based and regulatory milestone payments) was $1.3 billion at June 30, 2020 and is included in Other Intangibles, Net on the Consolidated Balance Sheet. The amount is being amortized over its estimated useful life through 2028 as supported by projected future cash flows, subject to impairment testing. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Alliance revenue - Lynparza $ 178 $ 111 $ 323 $ 190 Cost of sales (1) 137 73 164 92 Selling, general and administrative 39 33 72 59 Research and development 37 33 73 78 ($ in millions) June 30, 2020 December 31, 2019 Receivables from AstraZeneca included in Other current assets $ 168 $ 128 Payables to AstraZeneca included in Accrued and other current liabilities (2) 324 577 Payables to AstraZeneca included in Other Noncurrent Liabilities (2) 400 — (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone payments. Eisai In March 2018, Merck and Eisai Co., Ltd. (Eisai) announced a strategic collaboration for the worldwide co-development and co-commercialization of Lenvima (lenvatinib), an orally available tyrosine kinase inhibitor discovered by Eisai. Lenvima is currently approved for the treatment of certain types of thyroid cancer, hepatocellular carcinoma, in combination with everolimus for certain patients with renal cell carcinoma, and in combination with Keytruda for the treatment of certain patients with endometrial carcinoma. Under the agreement, Merck and Eisai will develop and commercialize Lenvima jointly, both as monotherapy and in combination with Keytruda . Eisai records Lenvima product sales globally (Eisai is the principal on Lenvima sales transactions), and Merck and Eisai share profits equally. Merck records its share of Lenvima product sales, net of cost of sales and commercialization costs, as alliance revenue. Expenses incurred during co-development, including for studies evaluating Lenvima as monotherapy, are shared equally by the two companies and reflected in Research and development expenses. Under the agreement, Merck made an upfront payment to Eisai of $750 million and agreed to make payments of up to $650 million for certain option rights through 2021 (of which $325 million was paid in March 2019, $200 million was paid in March 2020 and $125 million is expected to be paid in March 2021). In addition, the agreement provides for additional contingent payments from Merck to Eisai related to the successful achievement of sales-based and regulatory milestones. In the second quarter of 2020, Merck determined it was probable that sales of Lenvima in the future would trigger sales-based milestone payments aggregating $370 million from Merck to Eisai. Accordingly, Merck recorded a $370 million liability and a corresponding increase to the intangible asset related to Lenvima. Prior to 2020, Merck accrued sales-based milestone payments aggregating $950 million . Of these amounts, $50 million was paid to Eisai in 2019 and an additional $500 million was paid in the first six months of 2020. Potential future sales-based milestone payments of $2.7 billion have not yet been accrued as they are not deemed by the Company to be probable at this time. In 2018, Lenvima received regulatory approvals triggering capitalized milestone payments of $250 million in the aggregate from Merck to Eisai. Potential future regulatory milestone payments of $135 million remain under the agreement. The intangible asset balance related to Lenvima (which includes capitalized sales-based and regulatory milestone payments) was $1.2 billion at June 30, 2020 and is included in Other Intangibles, Net on the Consolidated Balance Sheet. The amount is being amortized over its estimated useful life through 2026 as supported by projected future cash flows, subject to impairment testing. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Alliance revenue - Lenvima $ 151 $ 97 $ 279 $ 171 Cost of sales (1) 135 23 170 74 Selling, general and administrative 19 19 31 38 Research and development 56 62 120 109 ($ in millions) June 30, 2020 December 31, 2019 Receivables from Eisai included in Other current assets $ 173 $ 150 Payables to Eisai included in Accrued and other current liabilities (2) 325 700 Payables to Eisai included in Other Noncurrent Liabilities (3) 570 525 (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone and future option payments. (3) Includes accrued milestone payments. Bayer AG In 2014, the Company entered into a worldwide clinical development collaboration with Bayer AG (Bayer) to market and develop soluble guanylate cyclase (sGC) modulators including Bayer’s Adempas (riociguat), which is approved to treat pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. The two companies have implemented a joint development and commercialization strategy. The collaboration also includes clinical development of Bayer’s vericiguat, which is in development for the potential treatment of worsening heart failure. Vericiguat is currently under review by the FDA. Under the agreement, Bayer leads commercialization of Adempas in the Americas, while Merck leads commercialization in the rest of the world. For vericiguat, if approved, Bayer will lead commercialization in the rest of world and Merck will lead in the Americas. Both companies share in development costs and profits on sales and have the right to co-promote in territories where they are not the lead. Merck records sales of Adempas in its marketing territories, as well as alliance revenue, which is Merck’s share of profits from the sale of Adempas in Bayer’s marketing territories. In addition, the agreement provides for additional contingent payments from Merck to Bayer related to the successful achievement of sales-based milestones. Prior to 2020, Merck accrued $725 million of sales-based milestone payments for this collaboration, of which $350 million was paid to Bayer in 2018. There is an additional $400 million potential future sales-based milestone payment that has not yet been accrued as it is not deemed by the Company to be probable at this time. The intangible asset balance related to this collaboration (which includes the acquired intangible asset balance, as well as capitalized sales-based milestone payments) was $832 million at June 30, 2020 and is included in Other Intangibles, Net on the Consolidated Balance Sheet. The amount is being amortized over its estimated useful life through 2027 as supported by projected future cash flows, subject to impairment testing. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Alliance revenue - Adempas $ 79 $ 51 $ 133 $ 94 Net sales of Adempas recorded by Merck 57 53 113 100 Total sales $ 136 $ 104 $ 246 $ 194 Cost of sales (1) 28 29 57 58 Selling, general and administrative 17 11 28 20 Research and development 16 32 41 62 ($ in millions) June 30, 2020 December 31, 2019 Receivables from Bayer included in Other current assets $ 62 $ 49 Payables to Bayer included in Other Noncurrent Liabilities (2) 375 375 (1) Includes amortization of intangible assets. (2) Represents accrued milestone payment.

Restructuring

Restructuring	6 Months Ended
	Jun. 30, 2020
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring In early 2019, Merck approved a new global restructuring program (Restructuring Program) as part of a worldwide initiative focused on further optimizing the Company’s manufacturing and supply network, as well as reducing its global real estate footprint. This program is a continuation of the Company’s plant rationalization, builds on prior restructuring programs and does not include any actions associated with the planned spin-off of Organon. As the Company continues to evaluate its global footprint and overall operating model, it subsequently identified additional actions under the Restructuring Program, and could identify further actions over time. The actions currently contemplated under the Restructuring Program are expected to be substantially completed by the end of 2023, with the cumulative pretax costs to be incurred by the Company to implement the program estimated to be approximately $2.5 billion . The Company estimates that approximately 60% of the cumulative pretax costs will result in cash outlays, primarily related to employee separation expense and facility shut-down costs. Approximately 40% of the cumulative pretax costs will be non-cash, relating primarily to the accelerated depreciation of facilities to be closed or divested. The Company expects to record charges of approximately $800 million in 2020 related to the Restructuring Program. Actions under previous global restructuring programs have been substantially completed. The Company recorded total pretax costs of $150 million and $159 million in the second quarter of 2020 and 2019 , respectively, and $318 million and $346 million for the first six months of 2020 and 2019, respectively, related to restructuring program activities. Since inception of the Restructuring Program through June 30, 2020 , Merck has recorded total pretax accumulated costs of approximately $1.2 billion . For segment reporting, restructuring charges are unallocated expenses. The following tables summarize the charges related to restructuring program activities by type of cost: Three Months Ended June 30, 2020 Six Months Ended June 30, 2020 ($ in millions) Separation Costs Accelerated Depreciation Other Total Separation Costs Accelerated Depreciation Other Total Cost of sales $ — $ 31 $ (6 ) $ 25 $ — $ 56 $ 37 $ 93 Selling, general and administrative — 11 — 11 — 22 — 22 Research and development — 31 — 31 — 48 — 48 Restructuring costs 35 — 48 83 82 — 73 155 $ 35 $ 73 $ 42 $ 150 $ 82 $ 126 $ 110 $ 318 Three Months Ended June 30, 2019 Six Months Ended June 30, 2019 ($ in millions) Separation Costs Accelerated Depreciation Other Total Separation Costs Accelerated Depreciation Other Total Cost of sales $ — $ 64 $ 1 $ 65 $ — $ 98 $ 1 $ 99 Selling, general and administrative — 32 — 32 — 32 — 32 Research and development — 2 1 3 — 2 1 3 Restructuring costs 25 — 34 59 153 — 59 212 $ 25 $ 98 $ 36 $ 159 $ 153 $ 132 $ 61 $ 346 Separation costs are associated with actual headcount reductions, as well as those headcount reductions which were probable and could be reasonably estimated. Accelerated depreciation costs primarily relate to manufacturing, research and administrative facilities and equipment to be sold or closed as part of the programs. Accelerated depreciation costs represent the difference between the depreciation expense to be recognized over the revised useful life of the asset, based upon the anticipated date the site will be closed or divested or the equipment disposed of, and depreciation expense as determined utilizing the useful life prior to the restructuring actions. All the sites have and will continue to operate up through the respective closure dates and, since future undiscounted cash flows are sufficient to recover the respective book values, Merck is recording accelerated depreciation over the revised useful life of the site assets. Anticipated site closure dates, particularly related to manufacturing locations, have been and may continue to be adjusted to reflect changes resulting from regulatory or other factors. Other activity in 2020 and 2019 includes asset abandonment, facility shut-down and other related costs, as well as pretax gains and losses resulting from the sales of facilities and related assets. Additionally, other activity includes certain employee-related costs associated with pension and other postretirement benefit plans (see Note 11) and share-based compensation. The following table summarizes the charges and spending relating to restructuring program activities for the six months ended June 30, 2020 : ($ in millions) Separation Costs Accelerated Depreciation Other Total Restructuring reserves January 1, 2020 $ 690 $ — $ 69 $ 759 Expense 82 126 110 318 (Payments) receipts, net (328 ) — (163 ) (491 ) Non-cash activity — (126 ) 34 (92 ) Restructuring reserves June 30, 2020 (1) $ 444 $ — $ 50 $ 494 (1)

Financial Instruments

Financial Instruments	6 Months Ended
	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	Financial Instruments Derivative Instruments and Hedging Activities The Company manages the impact of foreign exchange rate movements and interest rate movements on its earnings, cash flows and fair values of assets and liabilities through operational means and through the use of various financial instruments, including derivative instruments. A significant portion of the Company’s revenues and earnings in foreign affiliates is exposed to changes in foreign exchange rates. The objectives and accounting related to the Company’s foreign currency risk management program, as well as its interest rate risk management activities are discussed below. Foreign Currency Risk Management The Company has established revenue hedging, balance sheet risk management and net investment hedging programs to protect against volatility of future foreign currency cash flows and changes in fair value caused by changes in foreign exchange rates. The objective of the revenue hedging program is to reduce the variability caused by changes in foreign exchange rates that would affect the U.S. dollar value of future cash flows derived from foreign currency denominated sales, primarily the euro, Japanese yen and Chinese renminbi. To achieve this objective, the Company will hedge a portion of its forecasted foreign currency denominated third-party and intercompany distributor entity sales (forecasted sales) that are expected to occur over its planning cycle, typically no more than two years into the future. The Company will layer in hedges over time, increasing the portion of forecasted sales hedged as it gets closer to the expected date of the forecasted sales. The portion of forecasted sales hedged is based on assessments of cost-benefit profiles that consider natural offsetting exposures, revenue and exchange rate volatilities and correlations, and the cost of hedging instruments. The Company manages its anticipated transaction exposure principally with purchased local currency put options, forward contracts and purchased collar options. The fair values of these derivative contracts are recorded as either assets (gain positions) or liabilities (loss positions) in the Condensed Consolidated Balance Sheet. Changes in the fair value of derivative contracts are recorded each period in either current earnings or Other comprehensive income ( OCI ), depending on whether the derivative is designated as part of a hedge transaction and, if so, the type of hedge transaction. For derivatives that are designated as cash flow hedges, the unrealized gains or losses on these contracts are recorded in Accumulated other comprehensive income ( AOCI ) and reclassified into Sales when the hedged anticipated revenue is recognized. For those derivatives which are not designated as cash flow hedges, but serve as economic hedges of forecasted sales, unrealized gains or losses are recorded in Sales each period. The cash flows from both designated and non-designated contracts are reported as operating activities in the Condensed Consolidated Statement of Cash Flows. The Company does not enter into derivatives for trading or speculative purposes. The Company manages operating activities and net asset positions at each local subsidiary in order to mitigate the effects of exchange on monetary assets and liabilities. The Company also uses a balance sheet risk management program to mitigate the exposure of net monetary assets that are denominated in a currency other than a subsidiary’s functional currency from the effects of volatility in foreign exchange. In these instances, Merck principally utilizes forward exchange contracts to offset the effects of exchange on exposures denominated in developed country currencies, primarily the euro and Japanese yen. For exposures in developing country currencies, the Company will enter into forward contracts to partially offset the effects of exchange on exposures when it is deemed economical to do so based on a cost-benefit analysis that considers the magnitude of the exposure, the volatility of the exchange rate and the cost of the hedging instrument. The cash flows from these contracts are reported as operating activities in the Condensed Consolidated Statement of Cash Flows. Monetary assets and liabilities denominated in a currency other than the functional currency of a given subsidiary are remeasured at spot rates in effect on the balance sheet date with the effects of changes in spot rates reported in Other (income) expense, net . The forward contracts are not designated as hedges and are marked to market through Other (income) expense, net . Accordingly, fair value changes in the forward contracts help mitigate the changes in the value of the remeasured assets and liabilities attributable to changes in foreign currency exchange rates, except to the extent of the spot-forward differences. These differences are not significant due to the short-term nature of the contracts, which typically have average maturities at inception of less than one year . The Company also uses forward exchange contracts to hedge a portion of its net investment in foreign operations against movements in exchange rates. The forward contracts are designated as hedges of the net investment in a foreign operation. The unrealized gains or losses on these contracts are recorded in foreign currency translation adjustment within OCI and remain in AOCI until either the sale or complete or substantially complete liquidation of the subsidiary. The Company excludes certain portions of the change in fair value of its derivative instruments from the assessment of hedge effectiveness (excluded components). Changes in fair value of the excluded components are recognized in OCI . The Company recognizes in earnings the initial value of the excluded components on a straight-line basis over the life of the derivative instrument, rather than using the mark-to-market approach. The cash flows from these contracts are reported as investing activities in the Condensed Consolidated Statement of Cash Flows. Foreign exchange risk is also managed through the use of foreign currency debt. The Company’s senior unsecured euro-denominated notes have been designated as, and are effective as, economic hedges of the net investment in a foreign operation. Accordingly, foreign currency transaction gains or losses due to spot rate fluctuations on the euro-denominated debt instruments are included in foreign currency translation adjustment within OCI . The effects of the Company’s net investment hedges on OCI and the Consolidated Statement of Income are shown below: Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income (1) Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing Three Months Ended June 30, Six Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, ($ in millions) 2020 2019 2020 2019 2020 2019 2020 2019 Net Investment Hedging Relationships Foreign exchange contracts $ 8 $ 17 $ 5 $ 7 $ (4 ) $ (8 ) $ (11 ) $ (15 ) Euro-denominated notes 72 28 21 (2 ) — — — — (1) No amounts were reclassified from AOCI into income related to the sale of a subsidiary. Interest Rate Risk Management The Company may use interest rate swap contracts on certain investing and borrowing transactions to manage its net exposure to interest rate changes and to reduce its overall cost of borrowing. The Company does not use leveraged swaps and, in general, does not leverage any of its investment activities that would put principal capital at risk. In February 2020, five interest rate swaps with notional amounts of $250 million each matured. These swaps effectively converted the Company’s $1.25 billion , 1.85% fixed-rate notes due 2020 to variable rate debt. At June 30, 2020 , the Company was a party to 14 pay-floating, receive-fixed interest rate swap contracts designated as fair value hedges of fixed-rate notes in which the notional amounts match the amount of the hedged fixed-rate notes as detailed in the table below. June 30, 2020 ($ in millions) Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 3.875% notes due 2021 $ 1,150 5 $ 1,150 2.40% notes due 2022 1,000 4 1,000 2.35% notes due 2022 1,250 5 1,250 The interest rate swap contracts are designated hedges of the fair value changes in the notes attributable to changes in the benchmark London Interbank Offered Rate (LIBOR) swap rate. The fair value changes in the notes attributable to changes in the LIBOR swap rate are recorded in interest expense along with the offsetting fair value changes in the swap contracts. The cash flows from these contracts are reported as operating activities in the Condensed Consolidated Statement of Cash Flows. The table below presents the location of amounts recorded on the Consolidated Balance Sheet related to cumulative basis adjustments for fair value hedges: Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount ($ in millions) June 30, 2020 December 31, 2019 June 30, 2020 December 31, 2019 Balance Sheet Line Item in which Hedged Item is Included Loans payable and current portion of long-term debt $ 1,160 $ 1,249 $ 10 $ (1 ) Long-Term Debt 2,318 3,409 71 14 Presented in the table below is the fair value of derivatives on a gross basis segregated between those derivatives that are designated as hedging instruments and those that are not designated as hedging instruments: June 30, 2020 December 31, 2019 Fair Value of Derivative U.S. Dollar Notional Fair Value of Derivative U.S. Dollar Notional ($ in millions) Balance Sheet Caption Asset Liability Asset Liability Derivatives Designated as Hedging Instruments Interest rate swap contracts Other current assets $ 10 $ — $ 1,150 $ — $ — $ — Interest rate swap contracts Other Assets 72 — 2,250 15 — 3,400 Interest rate swap contracts Accrued and other current liabilities — — — — 1 1,250 Foreign exchange contracts Other current assets 83 — 4,959 152 — 6,117 Foreign exchange contracts Other Assets 70 — 1,993 55 — 2,160 Foreign exchange contracts Accrued and other current liabilities — 27 1,884 — 22 1,748 Foreign exchange contracts Other Noncurrent Liabilities — 1 11 — 1 53 $ 235 $ 28 $ 12,247 $ 222 $ 24 $ 14,728 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts Other current assets $ 93 $ — $ 5,324 $ 66 $ — $ 7,245 Foreign exchange contracts Accrued and other current liabilities — 103 5,865 — 73 8,693 $ 93 $ 103 $ 11,189 $ 66 $ 73 $ 15,938 $ 328 $ 131 $ 23,436 $ 288 $ 97 $ 30,666 As noted above, the Company records its derivatives on a gross basis in the Condensed Consolidated Balance Sheet. The Company has master netting agreements with several of its financial institution counterparties (see Concentrations of Credit Risk below). The following table provides information on the Company’s derivative positions subject to these master netting arrangements as if they were presented on a net basis, allowing for the right of offset by counterparty and cash collateral exchanged per the master agreements and related credit support annexes: June 30, 2020 December 31, 2019 ($ in millions) Asset Liability Asset Liability Gross amounts recognized in the condensed consolidated balance sheet $ 328 $ 131 $ 288 $ 97 Gross amounts subject to offset in master netting arrangements not offset in the condensed consolidated balance sheet (115 ) (115 ) (84 ) (84 ) Cash collateral received (38 ) — (34 ) — Net amounts $ 175 $ 16 $ 170 $ 13 The table below provides information regarding the location and amount of pretax (gains) losses of derivatives designated in fair value or cash flow hedging relationships: Sales Other (income) expense, net (1) Other comprehensive income (loss) Sales Other (income) expense, net (1) Other comprehensive income (loss) Three Months Ended June 30, Three Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, ($ in millions) 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 Financial Statement Line Items in which Effects of Fair Value or Cash Flow Hedges are Recorded $ 10,872 $ 11,760 $ (390 ) $ 140 $ (2 ) $ (16 ) $ 22,929 $ 22,575 $ (318 ) $ 327 $ (200 ) $ 183 (Gain) loss on fair value hedging relationships Interest rate swap contracts Hedged items — — 1 55 — — — — 68 88 — — Derivatives designated as hedging instruments — — (8 ) (45 ) — — — — (76 ) (68 ) — — Impact of cash flow hedging relationships Foreign exchange contracts Amount of (loss) gain recognized in OCI on derivatives — — — — (109 ) 10 — — — — 69 (2 ) Increase (decrease) in Sales as a result of AOCI reclassifications 42 75 — — (42 ) (75 ) 88 119 — — (88 ) (119 ) Interest rate contracts Amount of gain recognized in Other (income) expense, net on derivatives — — (1 ) (1 ) — — — — (2 ) (2 ) — — Amount of loss recognized in OCI on derivatives — — — — (1 ) (1 ) — — — — (2 ) (5 ) (1) Interest expense is a component of Other (income) expense, net. The table below provides information regarding the income statement effects of derivatives not designated as hedging instruments: Amount of Derivative Pretax (Gain) Loss Recognized in Income Three Months Ended June 30, Six Months Ended June 30, ($ in millions) Income Statement Caption 2020 2019 2020 2019 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts (1) Other (income) expense, net $ 49 $ 2 $ (131 ) $ 120 Foreign exchange contracts (2) Sales 4 (6 ) (3 ) 4 Interest rate contracts (3) Other (income) expense, net 9 — 9 — (1) These derivative contracts mitigate changes in the value of remeasured foreign currency denominated monetary assets and liabilities attributable to changes in foreign currency exchange rates. (2) These derivative contracts serve as economic hedges of forecasted transactions. (3) These derivatives serve as economic hedges against rising treasury rates. At June 30, 2020 , the Company estimates $9 million of pretax net unrealized gains on derivatives maturing within the next 12 months that hedge foreign currency denominated sales over that same period will be reclassified from AOCI to Sales . The amount ultimately reclassified to Sales may differ as foreign exchange rates change. Realized gains and losses are ultimately determined by actual exchange rates at maturity. Investments in Debt and Equity Securities Information on investments in debt and equity securities is as follows: June 30, 2020 December 31, 2019 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Value ($ in millions) Gains Losses Gains Losses U.S. government and agency securities $ 74 $ — $ — $ 74 $ 266 $ 3 $ — $ 269 Foreign government bonds 2 — — 2 — — — — Commercial paper — — — — 668 — — 668 Corporate notes and bonds — — — — 608 13 — 621 Asset-backed securities — — — — 226 1 — 227 Total debt securities $ 76 $ — $ — $ 76 $ 1,768 $ 17 $ — $ 1,785 Publicly traded equity securities (1) 1,307 838 Total debt and publicly traded equity securities $ 1,383 $ 2,623 (1) Unrealized net (gains) losses recognized in Other (income) expense, net on equity securities still held at June 30, 2020 were $(464) million and $(469) million in the second quarter and first six months of 2020 , respectively. Unrealized net losses (gains) recognized in Other (income) expense, net on equity securities still held at June 30, 2019 were $39 million and $(75) million in the second quarter and first six months of 2019 , respectively. At June 30, 2020 and June 30, 2019 , the Company also had $487 million and $465 million , respectively, of equity investments without readily determinable fair values included in Other Assets . The Company recognizes unrealized gains on these equity investments based on favorable observable price changes from transactions involving similar investments of the same investee and recognizes unrealized losses based on unfavorable observable price changes. During the first six months of 2020, the Company recognized unrealized gains of $18 million and unrealized losses of $3 million in Other (income) expense, net related to these equity investments held at June 30, 2020 . During the first six months of 2019 , the Company recognized unrealized gains of $4 million and unrealized losses of $10 million in Other (income) expense, net related to these investments held at June 30, 2019 . Cumulative unrealized gains and cumulative unrealized losses based on observable prices changes for investments in equity investments without readily determinable fair values still held at June 30, 2020 were $127 million and $24 million , respectively. Fair Value Measurements Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The Company uses a fair value hierarchy which maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. There are three levels of inputs used to measure fair value with Level 1 having the highest priority and Level 3 having the lowest: Level 1 - Quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2 - Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; Level 3 - Unobservable inputs that are supported by little or no market activity. Level 3 assets or liabilities are those whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques with significant unobservable inputs, as well as assets or liabilities for which the determination of fair value requires significant judgment or estimation. If the inputs used to measure the financial assets and liabilities fall within more than one level described above, the categorization is based on the lowest level input that is significant to the fair value measurement of the instrument. Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis Financial assets and liabilities measured at fair value on a recurring basis are summarized below: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ($ in millions) June 30, 2020 December 31, 2019 Assets Investments Foreign government bonds $ — $ 2 $ — $ 2 $ — $ — $ — $ — Commercial paper — — — — — 668 — 668 Corporate notes and bonds — — — — — 621 — 621 Asset-backed securities (1) — — — — — 227 — 227 U.S. government and agency securities — — — — — 209 — 209 Publicly traded equity securities 1,249 — — 1,249 518 — — 518 1,249 2 — 1,251 518 1,725 — 2,243 Other assets (2) U.S. government and agency securities 74 — — 74 60 — — 60 Publicly traded equity securities 58 — — 58 320 — — 320 132 — — 132 380 — — 380 Derivative assets (3) Forward exchange contracts — 142 — 142 — 169 — 169 Purchased currency options — 104 — 104 — 104 — 104 Interest rate swaps — 82 — 82 — 15 — 15 — 328 — 328 — 288 — 288 Total assets $ 1,381 $ 330 $ — $ 1,711 $ 898 $ 2,013 $ — $ 2,911 Liabilities Other liabilities Contingent consideration $ — $ — $ 798 $ 798 $ — $ — $ 767 $ 767 Derivative liabilities (3) Forward exchange contracts — 128 — 128 — 95 — 95 Written currency options — 3 — 3 — 1 — 1 Interest rate swaps — — — — — 1 — 1 — 131 — 131 — 97 — 97 Total liabilities $ — $ 131 $ 798 $ 929 $ — $ 97 $ 767 $ 864 (1) Primarily all of the asset-backed securities were highly rated (Standard & Poor’s rating of AAA and Moody’s Investors Service rating of Aaa), secured primarily by auto loan, credit card and student loan receivables, with weighted-average lives of primarily 5 years or less. (2) Investments included in other assets are restricted as to use, including for the payment of benefits under employee benefit plans. (3) The fair value determination of derivatives includes the impact of the credit risk of counterparties to the derivatives and the Company’s own credit risk, the effects of which were not significant. As of June 30, 2020 and December 31, 2019 , Cash and cash equivalents included $10.4 billion and $8.9 billion of cash equivalents, respectively (which would be considered Level 2 in the fair value hierarchy). Contingent Consideration Summarized information about the changes in liabilities for contingent consideration associated with business acquisitions is as follows: Six Months Ended June 30, ($ in millions) 2020 2019 Fair value January 1 $ 767 $ 788 Additions 97 — Changes in estimated fair value (1) 40 50 Payments (106 ) (85 ) Fair value June 30 (2)(3) $ 798 $ 753 (1) Recorded in Cost of sales, Research and development expenses, and Other (income) expense, net . Includes cumulative translation adjustments. (2) Balance at June 30, 2020 includes $138 million recorded as a current liability for amounts expected to be paid within the next 12 months. (3) At June 30, 2020 and December 31, 2019 , $608 million and $625 million , respectively, of the liabilities relate to the termination of the Sanofi-Pasteur MSD joint venture in 2016. As part of the termination, Merck recorded a liability for contingent future royalty payments of 11.5% on net sales of all Merck products that were previously sold by the joint venture through December 31, 2024. The fair value of this liability is determined utilizing the estimated amount and timing of projected cash flows using a risk-adjusted discount rate of 8% to present value the cash flows. The additions to contingent consideration in 2020 relate to the acquisition of Themis (see Note 2). The payments of contingent consideration in both periods relate to liabilities recorded in connection with the termination of the Sanofi-Pasteur MSD joint venture in 2016. Other Fair Value Measurements Some of the Company’s financial instruments, such as cash and cash equivalents, receivables and payables, are reflected in the balance sheet at carrying value, which approximates fair value due to their short-term nature. The estimated fair value of loans payable and long-term debt (including current portion) at June 30, 2020 , was $34.5 billion compared with a carrying value of $30.9 billion and at December 31, 2019 , was $28.8 billion compared with a carrying value of $26.3 billion . Fair value was estimated using recent observable market prices and would be considered Level 2 in the fair value hierarchy. Concentrations of Credit Risk On an ongoing basis, the Company monitors concentrations of credit risk associated with corporate and government issuers of securities and financial institutions with which it conducts business. Credit exposure limits are established to limit a concentration with any single issuer or institution. Cash and investments are placed in instruments that meet high credit quality standards as specified in the Company’s investment policy guidelines. The majority of the Company’s accounts receivable arise from product sales in the United States, Europe and China and are primarily due from drug wholesalers and retailers, hospitals, government agencies, managed health care providers and pharmacy benefit managers. The Company monitors the financial performance and creditworthiness of its customers so that it can properly assess and respond to changes in their credit profile. The Company also continues to monitor global economic conditions, including the volatility associated with international sovereign economies, and associated impacts on the financial markets and its business. The Company has accounts receivable factoring agreements with financial institutions in certain countries to sell accounts receivable. The Company factored $1.9 billion and $2.7 billion of accounts receivable in the second quarter of 2020 and the fourth quarter of 2019 , respectively, under these factoring arrangements, which reduced outstanding accounts receivable. The cash received from the financial institutions is reported within operating activities in the Consolidated Statement of Cash Flows. In certain of these factoring arrangements, for ease of administration, the Company will collect customer payments related to the factored receivables, which it then remits to the financial institutions. The net cash flows relating to these collections are reported as financing activities in the Consolidated Statement of Cash Flows. The cost of factoring such accounts receivable was de minimis . Derivative financial instruments are executed under International Swaps and Derivatives Association master agreements. The master agreements with several of the Company’s financial institution counterparties also include credit support annexes. These annexes contain provisions that require collateral to be exchanged depending on the value of the derivative assets and liabilities, the Company’s credit rating, and the credit rating of the counterparty. Cash collateral received by the Company from various counterparties was $38 million and $34 million at June 30, 2020 and December 31, 2019 , respectively. The obligation to return such collateral is recorded in Accrued and other current liabilities . No cash collateral was advanced by the Company to counterparties as of June 30, 2020 or December 31, 2019 .

Inventories

Inventories	6 Months Ended
	Jun. 30, 2020
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consisted of: ($ in millions) June 30, 2020 December 31, 2019 Finished goods $ 2,032 $ 1,772 Raw materials and work in process 5,874 5,650 Supplies 190 207 Total (approximates current cost) 8,096 7,629 Decrease to LIFO cost (119 ) (171 ) $ 7,977 $ 7,458 Recognized as: Inventories $ 6,056 $ 5,978 Other assets 1,921 1,480 Amounts recognized as Other Assets are comprised almost entirely of raw materials and work in process inventories. At June 30, 2020 and December 31, 2019 , these amounts included $1.7 billion and $1.3 billion , respectively, of inventories not expected to be sold within one year. In addition, these amounts included $266 million and $168 million at June 30, 2020 and December 31, 2019 , respectively, of inventories produced in preparation for product launches.

Long-Term Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt In June 2020, the Company issued $4.5 billion principal amount of senior unsecured notes consisting of $1.0 billion of 0.75% notes due 2026, $1.25 billion of 1.45% notes due 2030, $1.0 billion of 2.35% notes due 2040 and $1.25 billion of 2.45%

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies The Company is involved in various claims and legal proceedings of a nature considered normal to its business, including product liability, intellectual property, and commercial litigation, as well as certain additional matters including governmental and environmental matters. In the opinion of the Company, it is unlikely that the resolution of these matters will be material to the Company’s financial condition, results of operations or cash flows. Given the nature of the litigation discussed below and the complexities involved in these matters, the Company is unable to reasonably estimate a possible loss or range of possible loss for such matters until the Company knows, among other factors, (i) what claims, if any, will survive dispositive motion practice, (ii) the extent of the claims, including the size of any potential class, particularly when damages are not specified or are indeterminate, (iii) how the discovery process will affect the litigation, (iv) the settlement posture of the other parties to the litigation and (v) any other factors that may have a material effect on the litigation. The Company records accruals for contingencies when it is probable that a liability has been incurred and the amount can be reasonably estimated. These accruals are adjusted periodically as assessments change or additional information becomes available. For product liability claims, a portion of the overall accrual is actuarially determined and considers such factors as past experience, number of claims reported and estimates of claims incurred but not yet reported. Individually significant contingent losses are accrued when probable and reasonably estimable. Legal defense costs expected to be incurred in connection with a loss contingency are accrued when probable and reasonably estimable. The Company’s decision to obtain insurance coverage is dependent on market conditions, including cost and availability, existing at the time such decisions are made. The Company has evaluated its risks and has determined that the cost of obtaining product liability insurance outweighs the likely benefits of the coverage that is available and, as such, has no insurance for most product liabilities. Product Liability Litigation Fosamax As previously disclosed, Merck is a defendant in product liability lawsuits in the United States involving Fosamax ( Fosamax Litigation). As of June 30, 2020 , approximately 3,590 cases are pending against Merck in either federal or state court. Plaintiffs in the vast majority of these cases generally allege that they sustained femur fractures and/or other bone injuries (Femur Fractures) in association with the use of Fosamax . All federal cases involving allegations of Femur Fractures have been or will be transferred to a multidistrict litigation in the District of New Jersey (Femur Fracture MDL). In the only bellwether case tried to date in the Femur Fracture MDL, Glynn v. Merck , the jury returned a verdict in Merck’s favor. In addition, in June 2013, the Femur Fracture MDL court granted Merck’s motion for judgment as a matter of law in the Glynn case and held that the plaintiff’s failure to warn claim was preempted by federal law. In August 2013, the Femur Fracture MDL court entered an order requiring plaintiffs in the Femur Fracture MDL to show cause why those cases asserting claims for a femur fracture injury that took place prior to September 14, 2010, should not be dismissed based on the court’s preemption decision in the Glynn case. Pursuant to the show cause order, in March 2014, the Femur Fracture MDL court dismissed with prejudice approximately 650 cases on preemption grounds. Plaintiffs in approximately 515 of those cases appealed that decision to the U.S. Court of Appeals for the Third Circuit (Third Circuit). In March 2017, the Third Circuit issued a decision reversing the Femur Fracture MDL court’s preemption ruling and remanding the appealed cases back to the Femur Fracture MDL court. In May 2019, the U.S. Supreme Court decided that the Third Circuit had incorrectly concluded that the issue of preemption should be resolved by a jury, and accordingly vacated the judgment of the Third Circuit and remanded the proceedings back to the Third Circuit to address the issue in a manner consistent with the Supreme Court’s opinion. In November 2019, the Third Circuit remanded the cases back to the District Court in order to allow that court to determine in the first instance whether the plaintiffs’ state law claims are preempted by federal law under the standards described by the Supreme Court in its opinion. Briefing on the issue is closed, and the parties await the decision of the District Court. Accordingly, as of June 30, 2020 , approximately 970 cases were actively pending in the Femur Fracture MDL. As of June 30, 2020 , approximately 2,345 cases alleging Femur Fractures have been filed in New Jersey state court and are pending before Judge James Hyland in Middlesex County. The parties selected an initial group of cases to be reviewed through fact discovery, and Merck has continued to select additional cases to be reviewed. As of June 30, 2020 , approximately 275 cases alleging Femur Fractures have been filed and are pending in California state court. All of the Femur Fracture cases filed in California state court have been coordinated before a single judge in Orange County, California. Additionally, there are four Femur Fracture cases pending in other state courts. Discovery is presently stayed in the Femur Fracture MDL and in the state court in California. Merck intends to defend against these lawsuits. Januvia/Janumet As previously disclosed, Merck is a defendant in product liability lawsuits in the United States involving Januvia and/or Janumet . As of June 30, 2020 , Merck is aware of approximately 1,440 product users alleging that Januvia and/or Janumet caused the development of pancreatic cancer and other injuries. Most claims have been filed in multidistrict litigation before the U.S. District Court for the Southern District of California (MDL). Outside of the MDL, the majority of claims have been filed in coordinated proceedings before the Superior Court of California, County of Los Angeles (California State Court). In November 2015, the MDL and California State Court–in separate opinions–granted summary judgment to defendants on grounds of federal preemption. Plaintiffs appealed in both forums. In November 2017, the U.S. Court of Appeals for the Ninth Circuit vacated the judgment and remanded for further discovery. In November 2018, the California state appellate court reversed and remanded on similar grounds. In March 2019, the parties in the MDL and the California coordinated proceedings agreed to coordinate and adopt a schedule for completing discovery on general causation and preemption issues and for renewing summary judgment and Daubert motions. Under the stipulated case management schedule, the hearings for Daubert and summary judgment motions are expected to take place in the second half of 2020. As of June 30, 2020 , six product users have claims pending against Merck in state courts other than California, including Illinois. In June 2017, the Illinois trial court denied Merck’s motion for summary judgment based on federal preemption. Merck appealed, and the Illinois appellate court affirmed in December 2018. Merck filed a petition for leave to appeal to the Illinois Supreme Court in February 2019. In April 2019, the Illinois Supreme Court stayed consideration of the pending petition to appeal until the U.S. Supreme Court issued its opinion in Merck Sharp & Dohme Corp. v. Albrecht (relating to the Fosamax matter discussed above). Merck filed the opinion in Albrecht with the Illinois Supreme Court in June 2019. The petition for leave to appeal was decided in September 2019, in which the Illinois Supreme Court directed the intermediate appellate court to reconsider its earlier ruling. The Illinois Appellate Court issued a favorable decision concluding, consistent with Albrecht , that preemption presents a legal question to be resolved by the court. In addition to the claims noted above, the Company has agreed to toll the statute of limitations for approximately 50 additional claims. The Company intends to continue defending against these lawsuits. Vioxx As previously disclosed, Merck is a defendant in a lawsuit brought by the Attorney General of Utah alleging that Merck misrepresented the safety of Vioxx . The lawsuit is pending in Utah state court. Utah seeks damages and penalties under the Utah False Claims Act. A bench trial in this matter has been rescheduled for April 6, 2021. Governmental Proceedings On June 17, 2020, Merck received a Civil Investigative Demand (CID) from the U.S. Department of Justice. The CID requests answers to interrogatories, as well as various documents, regarding temperature excursions at a third-party storage facility containing certain Merck products. Merck is cooperating with the government’s investigation and intends to produce information and/or documents as necessary in response to the CID. As previously disclosed, the Company’s subsidiaries in China have received and may continue to receive inquiries regarding their operations from various Chinese governmental agencies. Some of these inquiries may be related to matters involving other multinational pharmaceutical companies, as well as Chinese entities doing business with such companies. The Company’s policy is to cooperate with these authorities and to provide responses as appropriate. As previously disclosed, from time to time, the Company receives inquiries and is the subject of preliminary investigation activities from competition and other governmental authorities in markets outside the United States. These authorities may include regulators, administrative authorities, and law enforcement and other similar officials, and these preliminary investigation activities may include site visits, formal or informal requests or demands for documents or materials, inquiries or interviews and similar matters. Certain of these preliminary inquiries or activities may lead to the commencement of formal proceedings. Should those proceedings be determined adversely to the Company, monetary fines and/or remedial undertakings may be required. Commercial and Other Litigation Zetia Antitrust Litigation As previously disclosed, Merck, MSD, Schering Corporation and MSP Singapore Company LLC (collectively, the Merck Defendants) are defendants in putative class action and opt-out lawsuits filed in 2018 on behalf of direct and indirect purchasers of Zetia alleging violations of federal and state antitrust laws, as well as other state statutory and common law causes of action. The cases have been consolidated for pretrial purposes in a federal multidistrict litigation before Judge Rebecca Beach Smith in the Eastern District of Virginia. In December 2018, the court denied the Merck Defendants’ motions to dismiss or stay the direct purchaser putative class actions pending bilateral arbitration. In August 2019, the district court adopted in full the report and recommendation of the magistrate judge with respect to the Merck Defendants’ motions to dismiss on non-arbitration issues, thereby granting in part and denying in part Merck Defendants’ motions to dismiss. In addition, in June 2019, the representatives of the putative direct purchaser class filed an amended complaint, and in August 2019, retailer opt-out plaintiffs filed an amended complaint. The Merck Defendants moved to dismiss the new allegations in both complaints. In October 2019, the magistrate judge issued a report and recommendation recommending that the district judge grant the motions in their entirety. In December 2019, the district court adopted this report and recommendation in part. The district court granted the Merck Defendants’ motion to dismiss to the extent the motion sought dismissal of claims for overcharges paid by entities that purchased generic ezetimibe from Par Pharmaceutical, Inc. (Par Pharmaceutical) and dismissed any claims for such overcharges. In November 2019, the direct purchaser plaintiffs and the indirect purchaser plaintiffs filed motions for class certification. On June 18, 2020, the magistrate judge issued a report and recommendation recommending that the district judge grant in part the direct purchasers’ motion for class certification and certify a class of 35 direct purchasers. On July 2, 2020, defendants objected to the report and recommendation. The indirect purchasers’ class certification motion is still pending before the magistrate judge. Trial in this matter has been rescheduled to begin on February 23, 2021. Patent Litigation From time to time, generic manufacturers of pharmaceutical products file abbreviated New Drug Applications (NDAs) with the FDA seeking to market generic forms of the Company’s products prior to the expiration of relevant patents owned by the Company. To protect its patent rights, the Company may file patent infringement lawsuits against such generic companies. Similar lawsuits defending the Company’s patent rights may exist in other countries. The Company intends to vigorously defend its patents, which it believes are valid, against infringement by companies attempting to market products prior to the expiration of such patents. As with any litigation, there can be no assurance of the outcomes, which, if adverse, could result in significantly shortened periods of exclusivity for these products and, with respect to products acquired through acquisitions, potentially significant intangible asset impairment charges. Bridion — Between January and March 2020, the Company received multiple Paragraph IV Certification Letters under the Hatch-Waxman Act notifying the Company that generic drug companies have filed applications to the FDA seeking pre-patent expiry approval to sell generic versions of Bridion (sugammadex) Injection. In March and April 2020, the Company filed patent infringement lawsuits in the U.S. District Courts for the District of New Jersey and the Northern District of West Virginia against those generic companies. These lawsuits, which assert one or more patents covering sugammadex and methods of using sugammadex, automatically stay FDA approval of the generic applications until June 2023 or until adverse court decisions, if any, whichever may occur earlier. No schedule for the cases has been set by the courts. Januvia, Janumet, Janumet XR — In February 2019, Par Pharmaceutical filed suit against the Company in the U.S. District Court for the District of New Jersey, seeking a declaratory judgment of invalidity of a patent owned by the Company covering certain salt and polymorphic forms of sitagliptin that expires in 2026. In response, the Company filed a patent infringement lawsuit in the U.S. District Court for the District of Delaware against Par Pharmaceutical and additional companies that also indicated an intent to market generic versions of Januvia , Janumet , and Janumet XR following expiration of key patent protection in 2022, but prior to the expiration of the later-granted patent owned by the Company covering certain salt and polymorphic forms of sitagliptin that expires in 2026, and a later granted patent owned by the Company covering the Janumet formulation which expires in 2028. Par Pharmaceutical dismissed its case in the U.S. District Court for the District of New Jersey against the Company and will litigate the action in the U.S. District Court for the District of Delaware. The Company filed a patent infringement lawsuit against Mylan Pharmaceuticals Inc. and Mylan Inc. (Mylan) in the Northern District of West Virginia. The Judicial Panel of Multidistrict Litigation entered an order transferring the Company’s lawsuit against Mylan to the U.S. District Court for the District of Delaware for coordinated and consolidated pretrial proceedings with the other cases pending in that district. The U.S. District Court for the District of Delaware has scheduled the lawsuits for a single 3-day trial on invalidity issues in October 2021. The Court will schedule separate 1-day trials on infringement issues if necessary. In the Company’s case against Mylan, the U.S. District Court for the Northern District of West Virginia has conditionally scheduled a three-day trial in December 2021 on all issues. In February 2020, the Company amended its complaint against one defendant, Teva Pharmaceuticals USA, Inc., to add patent infringement claims related to a patent that expires in 2025 and covers certain processes for manufacturing sitagliptin. The Company has settled with five generic companies such that these generic companies can bring their products to the market in November 2026 or earlier under certain circumstances. In October 2019, Mylan filed a petition for Inter Partes Review (IPR) at the United States Patent and Trademark Office (USPTO) seeking invalidity of some, but not all, of the claims of the 2026 patent. The USPTO instituted IPR proceedings in May 2020, finding a reasonable likelihood that the challenged claims are not valid. A trial is scheduled for February 2021 and a final decision is expected in May 2021. After institution, three additional IPR petitions were filed by Teva Pharmaceuticals USA, Inc., Dr. Reddy’s Laboratories, Inc., and Sun Pharmaceutical Industries Ltd., as well as related entities, which requested joinder with Mylan’s IPR proceedings. If the challenges are successful, the unchallenged claims of the 2026 patent will remain valid, subject to the Court proceedings described above. In Germany, a generic company has sought the revocation of the Supplementary Protection Certificate (SPC) for Janumet . If the generic company is successful, Janumet could lose market exclusivity in Germany as early as July 2022. It is possible that challenges to the Janumet SPC could occur in other European countries. Other Litigation There are various other pending legal proceedings involving the Company, principally product liability and intellectual property lawsuits. While it is not feasible to predict the outcome of such proceedings, in the opinion of the Company, either the likelihood of loss is remote or any reasonably possible loss associated with the resolution of such proceedings is not expected to be material to the Company’s financial condition, results of operations or cash flows either individually or in the aggregate. Legal Defense Reserves Legal defense costs expected to be incurred in connection with a loss contingency are accrued when probable and reasonably estimable. Some of the significant factors considered in the review of these legal defense reserves are as follows: the actual costs incurred by the Company; the development of the Company’s legal defense strategy and structure in light of the scope of its litigation; the number of cases being brought against the Company; the costs and outcomes of completed trials and the most current information regarding anticipated timing, progression, and related costs of pre-trial activities and trials in the associated litigation. The amount of legal defense reserves as of June 30, 2020 and December 31, 2019 of approximately $265 million and $240 million , respectively, represents the Company’s best estimate of the minimum amount of defense costs to be incurred in connection with its outstanding litigation; however, events such as additional trials and other events that could arise in the course of its litigation could affect the ultimate amount of legal defense costs to be incurred by the Company. The Company will continue to monitor its legal defense costs and review the adequacy of the associated reserves and may determine to increase the reserves at any time in the future if, based upon the factors set forth, it believes it would be appropriate to do so.

Equity

Equity	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Equity	Equity Three Months Ended June 30, Common Stock Other Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss Treasury Stock Non- controlling Interests Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at April 1, 2019 3,577 $ 1,788 $ 38,768 $ 44,065 $ (5,346 ) 994 $ (51,736 ) $ 131 $ 27,670 Net income attributable to Merck & Co., Inc. — — — 2,670 — — — — 2,670 Other comprehensive loss, net of taxes — — — — (16 ) — — — (16 ) Cash dividends declared on common stock ($0.55 per share) — — — (1,440 ) — — — — (1,440 ) Treasury stock shares purchased — — 1,000 — — 24 (2,235 ) — (1,235 ) Share-based compensation plans and other — — (284 ) — — (8 ) 401 — 117 Net loss attributable to noncontrolling interests — — — — — — — (26 ) (26 ) Other changes in noncontrolling interests — — — — — — — (3 ) (3 ) Balance at June 30, 2019 3,577 $ 1,788 $ 39,484 $ 45,295 $ (5,362 ) 1,010 $ (53,570 ) $ 102 $ 27,737 Balance at April 1, 2020 3,577 $ 1,788 $ 39,697 $ 48,272 $ (6,391 ) 1,053 $ (57,161 ) $ 95 $ 26,300 Net income attributable to Merck & Co., Inc. — — — 3,002 — — — — 3,002 Other comprehensive loss, net of taxes — — — — (2 ) — — — (2 ) Cash dividends declared on common stock ($0.61 per share) — — — (1,550 ) — — — — (1,550 ) Share-based compensation plans and other — — (324 ) — — (5 ) 311 — (13 ) Net income attributable to noncontrolling interests — — — — — — — 8 8 Distributions attributable to noncontrolling interests — — — — — — — (1 ) (1 ) Balance at June 30, 2020 3,577 $ 1,788 $ 39,373 $ 49,724 $ (6,393 ) 1,048 $ (56,850 ) $ 102 $ 27,744 Six Months Ended June 30, Common Stock Other Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss Treasury Stock Non- controlling Interests Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at January 1, 2019 3,577 $ 1,788 $ 38,808 $ 42,579 $ (5,545 ) 985 $ (50,929 ) $ 181 $ 26,882 Net income attributable to Merck & Co., Inc. — — — 5,585 — — — — 5,585 Other comprehensive income, net of taxes — — — — 183 — — — 183 Cash dividends declared on common stock ($1.10 per share) — — — (2,869 ) — — — — (2,869 ) Treasury stock shares purchased — — 1,000 — — 38 (3,325 ) — (2,325 ) Share-based compensation plans and other — — (324 ) — — (13 ) 684 — 360 Net loss attributable to noncontrolling interests — — — — — — — (79 ) (79 ) Balance at June 30, 2019 3,577 $ 1,788 $ 39,484 $ 45,295 $ (5,362 ) 1,010 $ (53,570 ) $ 102 $ 27,737 Balance at January 1, 2020 3,577 $ 1,788 $ 39,660 $ 46,602 $ (6,193 ) 1,038 $ (55,950 ) $ 94 $ 26,001 Net income attributable to Merck & Co., Inc. — — — 6,221 — — — — 6,221 Other comprehensive loss, net of taxes — — — — (200 ) — — — (200 ) Cash dividends declared on common stock ($1.22 per share) — — — (3,099 ) — — — — (3,099 ) Treasury stock shares purchased — — — — — 16 (1,281 ) — (1,281 ) Share-based compensation plans and other — — (287 ) — — (6 ) 381 — 94 Net income attributable to noncontrolling interests — — — — — — — 8 8 Balance at June 30, 2020 3,577 $ 1,788 $ 39,373 $ 49,724 $ (6,393 ) 1,048 $ (56,850 ) $ 102 $ 27,744

Share-Based Compensation Plans

Share-Based Compensation Plans	6 Months Ended
	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Share-Based Compensation Plans	Share-Based Compensation Plans The Company has share-based compensation plans under which the Company grants restricted stock units (RSUs) and performance share units (PSUs) to certain management level employees. In addition, employees and non-employee directors may be granted options to purchase shares of Company common stock at the fair market value at the time of grant. The following table provides the amounts of share-based compensation cost recorded in the Condensed Consolidated Statement of Income: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Pretax share-based compensation expense $ 121 $ 111 $ 229 $ 204 Income tax benefit (16 ) (15 ) (31 ) (28 ) Total share-based compensation expense, net of taxes $ 105 $ 96 $ 198 $ 176 During the first six months of 2020 , the Company granted 6 million RSUs with a weighted-average grant date fair value of $77.74 per RSU and during the first six months of 2019 granted 6 million RSUs with a weighted-average grant date fair value of $76.31 per RSU. During the first six months of 2020 , the Company granted 773 thousand PSUs with a weighted-average grant date fair value of $75.22 per PSU and during the first six months of 2019 granted 609 thousand PSUs with a weighted-average grant date fair value of $90.50 per PSU. During the first six months of 2020, the Company granted 4 million stock options with a weighted-average exercise price of $77.67 per option and during the first six months of 2019 granted 3 million stock options with a weighted-average exercise price of $80.00 per option. The weighted-average fair value of options granted during the first six months of 2020 and 2019 was $9.93 and $10.63 per option, respectively, and was determined using the following assumptions: Six Months Ended 2020 2019 Expected dividend yield 3.1 % 3.2 % Risk-free interest rate 0.4 % 2.4 % Expected volatility 22.1 % 18.7 % Expected life (years) 5.8 5.9 At June 30, 2020 , there was $908 million of total pretax unrecognized compensation expense related to nonvested stock options, RSU and PSU awards which will be recognized over a weighted-average period of 2.2 years . For segment reporting, share-based compensation costs are unallocated expenses.

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Plans	6 Months Ended
	Jun. 30, 2020
Retirement Benefits [Abstract]
Pension and Other Postretirement Benefit Plans	Pension and Other Postretirement Benefit Plans The Company has defined benefit pension plans covering eligible employees in the United States and in certain of its international subsidiaries. The net periodic benefit cost of such plans consisted of the following components: Three Months Ended Six Months Ended 2020 2019 2020 2019 ($ in millions) U.S. International U.S. International U.S. International U.S. International Service cost $ 88 $ 74 $ 74 $ 60 $ 175 $ 148 $ 144 $ 120 Interest cost 109 33 113 44 217 68 228 89 Expected return on plan assets (195 ) (101 ) (205 ) (107 ) (388 ) (205 ) (411 ) (214 ) Amortization of unrecognized prior service credit (12 ) (3 ) (12 ) (3 ) (25 ) (6 ) (25 ) (6 ) Net loss amortization 76 31 35 16 152 62 70 31 Termination benefits 1 — 3 1 4 1 5 1 Curtailments — — — — 2 (1 ) 1 — Settlements 9 2 — — 9 2 — — $ 76 $ 36 $ 8 $ 11 $ 146 $ 69 $ 12 $ 21 The Company now anticipates contributing approximately $220 million to its U.S. pension plans in 2020, of which $170 million was contributed in the first half of the year. The Company provides medical benefits, principally to its eligible U.S. retirees and similar benefits to their dependents, through its other postretirement benefit plans. The net credit of such plans consisted of the following components: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Service cost $ 13 $ 12 $ 26 $ 24 Interest cost 14 18 29 35 Expected return on plan assets (19 ) (18 ) (37 ) (36 ) Amortization of unrecognized prior service credit (22 ) (21 ) (45 ) (43 ) Curtailments — (1 ) (1 ) (1 ) $ (14 ) $ (10 ) $ (28 ) $ (21 ) In connection with restructuring actions (see Note 4), termination charges were recorded on pension plans related to expanded eligibility for certain employees exiting Merck. Also, in connection with these restructuring actions, curtailments were recorded on pension and other postretirement benefit plans and settlements were recorded on certain U.S. and international pension plans as reflected in the tables above. The components of net periodic benefit cost (credit) other than the service cost component are included in Other (income) expense, net (see Note 12), with the exception of certain amounts for termination benefits, curtailments and settlements, which are recorded in Restructuring costs if the event giving rise to the termination benefits, curtailment or settlement is related to restructuring actions as noted above.

Other (Income) Expense, Net

Other (Income) Expense, Net	6 Months Ended
	Jun. 30, 2020
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (Income) Expense, Net Other (income) expense, net, consisted of: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Interest income $ (14 ) $ (75 ) $ (39 ) $ (164 ) Interest expense 209 233 421 442 Exchange losses 24 27 78 128 Income from investments in equity securities, net (1) (551 ) (58 ) (603 ) (32 ) Net periodic defined benefit plan (credit) cost other than service cost (80 ) (140 ) (170 ) (281 ) Other, net 22 153 (5 ) 234 $ (390 ) $ 140 $ (318 ) $ 327 (1) Includes net realized and unrealized gains and losses from investments in equity securities either owned directly or through ownership interests in investment funds. Unrealized gains and losses from investments that are directly owned are determined at the end of the reporting period, while ownership interests in investment funds are accounted for on a one quarter lag. The Company estimates that gains of approximately $300 million will be recognized in the third quarter of 2020 from ownership interests in investment funds. The decline in interest income in the second quarter and first six months of 2020 reflects lower investments and lower interest rates. The lower exchange losses in the first six months of 2020 reflect losses on forward exchange contracts in 2019 related to the acquisition of Antelliq. The increase in income from investments in equity securities, net, in both the second quarter and first six months of 2020 was driven primarily by the recognition of unrealized gains on certain investments, most of which relate to Moderna, Inc., as well as NGM Biopharmaceuticals, Inc. Other, net (as reflected in the table above) in the second quarter and first six months of 2019 includes $78 million and $162 million , respectively, of goodwill impairment charges related to certain businesses in the Healthcare Services segment. Interest paid for the six months ended June 30, 2020 and 2019 was $387 million and $356 million , respectively.

Taxes on Income

Taxes on Income	6 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Taxes on Income	Taxes on Income The effective income tax rates of 14.5% and 18.9% for the second quarter of 2020 and 2019 , respectively, and 15.3% and 13.0% for the first six months of 2020 and 2019, respectively, reflect the impacts of acquisition and divestiture-related costs and restructuring costs, partially offset by the beneficial impact of foreign earnings. In addition, the effective income tax rate for the first six months of 2019 reflects the favorable impact of a $360 million net tax benefit related to the settlement of certain federal income tax matters. In the first quarter of 2019, the Internal Revenue Service (IRS) concluded its examinations of Merck’s 2012-2014 U.S. federal income tax returns. As a result, the Company was required to make a payment of $107 million . The Company’s reserves for unrecognized tax benefits for the years under examination exceeded the adjustments relating to this examination period and therefore the Company recorded a $360 million net tax benefit in the first six months of 2019. This net benefit reflects reductions in reserves for unrecognized tax benefits for tax positions relating to the years that were under examination, partially offset by additional reserves for tax positions not previously reserved for.

Earnings Per Share

Earnings Per Share	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The calculations of earnings per share are as follows: Three Months Ended Six Months Ended ($ and shares in millions except per share amounts) 2020 2019 2020 2019 Net income attributable to Merck & Co., Inc. $ 3,002 $ 2,670 $ 6,221 $ 5,585 Average common shares outstanding 2,527 2,574 2,531 2,579 Common shares issuable (1) 9 14 11 17 Average common shares outstanding assuming dilution 2,536 2,588 2,542 2,596 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders $ 1.19 $ 1.04 $ 2.46 $ 2.17 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders $ 1.18 $ 1.03 $ 2.45 $ 2.15 (1) Issuable primarily under share-based compensation plans. For the second quarter of 2020 and 2019 , 8 million and 3 million , respectively, and for both the first six months of 2020 and 2019, 4 million

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Changes in AOCI by component are as follows: Three Months Ended June 30, ($ in millions) Derivatives Investments Employee Benefit Plans Cumulative Translation Adjustment Accumulated Other Comprehensive Income (Loss) Balance April 1, 2019, net of taxes $ 118 $ 4 $ (3,541 ) $ (1,927 ) $ (5,346 ) Other comprehensive income (loss) before reclassification adjustments, pretax 10 55 — (25 ) 40 Tax (2 ) — — 6 4 Other comprehensive income (loss) before reclassification adjustments, net of taxes 8 55 — (19 ) 44 Reclassification adjustments, pretax (76 ) (1) (11 ) (2) 14 (3) — (73 ) Tax 16 — (3 ) — 13 Reclassification adjustments, net of taxes (60 ) (11 ) 11 — (60 ) Other comprehensive income (loss), net of taxes (52 ) 44 11 (19 ) (16 ) Balance June 30, 2019, net of taxes $ 66 $ 48 $ (3,530 ) $ (1,946 ) $ (5,362 ) Balance April 1, 2020, net of taxes $ 135 $ — $ (4,201 ) $ (2,325 ) $ (6,391 ) Other comprehensive income (loss) before reclassification adjustments, pretax (110 ) — (21 ) 63 (68 ) Tax 23 — 6 16 45 Other comprehensive income (loss) before reclassification adjustments, net of taxes (87 ) — (15 ) 79 (23 ) Reclassification adjustments, pretax (42 ) (1) — 69 (3) — 27 Tax 9 — (15 ) — (6 ) Reclassification adjustments, net of taxes (33 ) — 54 — 21 Other comprehensive income (loss), net of taxes (120 ) — 39 79 (2 ) Balance June 30, 2020, net of taxes $ 15 $ — $ (4,162 ) $ (2,246 ) $ (6,393 ) Six Months Ended June 30, ($ in millions) Derivatives Investments Employee Benefit Plans Cumulative Translation Adjustment Accumulated Other Comprehensive Income (Loss) Balance January 1, 2019, net of taxes $ 166 $ (78 ) $ (3,556 ) $ (2,077 ) $ (5,545 ) Other comprehensive income (loss) before reclassification adjustments, pretax (3 ) 131 (1 ) 131 258 Tax 1 — 6 — 7 Other comprehensive income (loss) before reclassification adjustments, net of taxes (2 ) 131 5 131 265 Reclassification adjustments, pretax (124 ) (1) (5 ) (2) 28 (3) — (101 ) Tax 26 — (7 ) — 19 Reclassification adjustments, net of taxes (98 ) (5 ) 21 — (82 ) Other comprehensive income (loss), net of taxes (100 ) 126 26 131 183 Balance June 30, 2019, net of taxes $ 66 $ 48 $ (3,530 ) $ (1,946 ) $ (5,362 ) Balance January 1, 2020, net of taxes $ 31 $ 18 $ (4,261 ) $ (1,981 ) $ (6,193 ) Other comprehensive income (loss) before reclassification adjustments, pretax 68 3 (21 ) (270 ) (220 ) Tax (14 ) — 11 5 2 Other comprehensive income (loss) before reclassification adjustments, net of taxes 54 3 (10 ) (265 ) (218 ) Reclassification adjustments, pretax (89 ) (1) (21 ) (2) 138 (3) — 28 Tax 19 — (29 ) — (10 ) Reclassification adjustments, net of taxes (70 ) (21 ) 109 — 18 Other comprehensive income (loss), net of taxes (16 ) (18 ) 99 (265 ) (200 ) Balance June 30, 2020, net of taxes $ 15 $ — $ (4,162 ) $ (2,246 ) $ (6,393 ) (1) Relates to foreign currency cash flow hedges that were reclassified from AOCI to Sales . (2) Represents net realized (gains) losses on the sales of available-for-sale debt securities that were reclassified from AOCI to Other (income) expense, net . (3) Includes net amortization of prior service cost and actuarial gains and losses included in net periodic benefit cost (see Note 11).

Segment Reporting

Segment Reporting	6 Months Ended
	Jun. 30, 2020
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company’s operations are principally managed on a products basis and include three operating segments, which are the Pharmaceutical, Animal Health and Healthcare Services segments. The Pharmaceutical and Animal Health segments are the only reportable segments. The Pharmaceutical segment includes human health pharmaceutical and vaccine products. Human health pharmaceutical products consist of therapeutic and preventive agents, generally sold by prescription, for the treatment of human disorders. The Company sells these human health pharmaceutical products primarily to drug wholesalers and retailers, hospitals, government agencies and managed health care providers such as health maintenance organizations, pharmacy benefit managers and other institutions. Human health vaccine products consist of preventive pediatric, adolescent and adult vaccines, primarily administered at physician offices. The Company sells these human health vaccines primarily to physicians, wholesalers, physician distributors and government entities. A large component of pediatric and adolescent vaccine sales are made to the U.S. Centers for Disease Control and Prevention Vaccines for Children program, which is funded by the U.S. government. Additionally, the Company sells vaccines to the Federal government for placement into vaccine stockpiles. The Animal Health segment discovers, develops, manufactures and markets a wide range of veterinary pharmaceutical and vaccine products, as well as health management solutions and services, for the prevention, treatment and control of disease in all major livestock and companion animal species. The Company also offers an extensive suite of digitally connected identification, traceability and monitoring products. The Company sells its products to veterinarians, distributors and animal producers. The Healthcare Services segment provided services and solutions that focus on engagement, health analytics and clinical services to improve the value of care delivered to patients. The Company has been in the process of divesting the businesses in the Healthcare Services segment. The remaining businesses were divested during the first quarter of 2020. Sales of the Company’s products were as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 ($ in millions) U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total Pharmaceutical: Oncology Keytruda $ 2,043 $ 1,345 $ 3,388 $ 1,498 $ 1,136 $ 2,634 $ 3,949 $ 2,722 $ 6,672 $ 2,782 $ 2,121 $ 4,903 Alliance revenue - Lynparza (1) 105 73 178 66 45 111 190 133 323 116 74 190 Alliance revenue - Lenvima (1) 98 53 151 54 43 97 188 91 279 104 67 171 Emend 6 27 33 67 54 121 11 65 76 130 107 237 Vaccines Gardasil/Gardasil 9 168 488 656 456 430 886 629 1,124 1,753 818 906 1,724 ProQuad/M-M-R II /Varivax 263 115 378 500 174 675 596 217 813 843 328 1,171 RotaTeq 100 68 168 104 68 172 241 150 391 258 125 383 Pneumovax 23 21 96 117 123 47 170 203 170 373 248 107 355 Vaqta 17 11 28 38 20 58 47 41 88 67 39 105 Hospital Acute Care Bridion 107 117 224 129 149 278 250 274 524 248 285 533 Noxafil 6 67 73 100 93 193 14 154 168 191 192 383 Prevymis 28 35 63 19 18 38 55 68 123 37 33 70 Primaxin 1 63 64 — 70 71 1 114 115 1 129 130 Invanz — 43 43 18 60 78 6 102 108 31 118 150 Cancidas (2 ) 45 43 3 64 67 1 98 98 4 125 129 Cubicin 10 21 32 22 45 67 25 53 78 64 91 155 Zerbaxa 17 15 32 13 14 27 37 32 69 25 28 53 Immunology Simponi — 191 191 — 214 214 — 406 406 — 422 422 Remicade — 73 73 — 98 98 — 160 160 — 221 221 Neuroscience Belsomra 22 61 84 21 55 76 49 114 163 45 98 143 Virology Isentress/Isentress HD 76 120 196 94 153 247 151 290 441 202 300 502 Zepatier 15 24 39 39 68 108 33 62 94 72 149 221 Cardiovascular Zetia (1 ) 138 137 6 150 156 (4 ) 285 282 6 290 296 Vytorin 2 37 39 3 73 76 5 86 92 6 167 174 Atozet — 115 115 — 92 92 — 238 238 — 186 186 Alliance revenue - Adempas (2) 73 6 79 49 2 51 122 11 133 89 5 94 Adempas — 57 57 — 53 53 — 113 113 — 100 100 Diabetes Januvia 413 441 854 471 437 908 768 860 1,628 855 877 1,732 Janumet 143 348 490 166 366 533 256 737 993 333 730 1,063 Women’s Health Implanon/Nexplanon 87 44 132 136 48 183 237 90 326 285 98 382 NuvaRing 35 28 63 206 34 240 61 65 126 391 68 459 Diversified Brands Singulair 4 96 100 8 153 160 9 246 255 13 338 352 Cozaar/Hyzaar 4 94 98 6 103 109 12 189 200 10 202 213 Arcoxia — 65 65 — 75 75 — 135 135 — 149 149 Nasonex 4 45 49 (1 ) 73 72 10 110 120 (2 ) 170 168 Follistim AQ 20 24 44 24 39 63 40 45 85 53 67 121 Other pharmaceutical (3) 385 720 1,103 369 837 1,203 792 1,500 2,293 697 1,589 2,283 Total Pharmaceutical segment sales 4,270 5,409 9,679 4,807 5,653 10,460 8,984 11,350 20,334 9,022 11,101 20,123 Animal Health: Livestock 122 526 648 145 526 671 284 1,102 1,386 261 1,021 1,282 Companion Animals 220 233 453 190 263 453 442 486 928 367 500 867 Total Animal Health segment sales 342 759 1,101 335 789 1,124 726 1,588 2,314 628 1,521 2,149 Other segment sales (4) — — — 47 — 48 23 — 23 86 — 87 Total segment sales 4,612 6,168 10,780 5,189 6,442 11,632 9,733 12,938 22,671 9,736 12,622 22,359 Other (5) 22 70 92 4 125 128 38 220 258 12 206 216 $ 4,634 $ 6,238 $ 10,872 $ 5,193 $ 6,567 $ 11,760 $ 9,771 $ 13,158 $ 22,929 $ 9,748 $ 12,828 $ 22,575 U.S. plus international may not equal total due to rounding. (1) Alliance revenue represents Merck’s share of profits, which are product sales net of cost of sales and commercialization costs (see Note 3). (2) Alliance revenue represents Merck’s share of profits from sales in Bayer’s marketing territories, which are product sales net of cost of sales and commercialization costs (see Note 3). (3) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (4) Represents sales for the Healthcare Services segment. All the businesses in the Healthcare Services segment were divested as of March 31, 2020. (5) Other is primarily comprised of miscellaneous corporate revenues, including revenue hedging activities, as well as third-party manufacturing sales. Other in the first six months of 2020 and 2019 also includes approximately $85 million and $15 million , respectively, related to the sale of the marketing rights for certain products. Product sales are recorded net of the provision for discounts, including chargebacks, which are customer discounts that occur when a contracted customer purchases through an intermediary wholesale purchaser, and rebates that are owed based upon definitive contractual agreements or legal requirements with private sector and public sector (Medicaid and Medicare Part D) benefit providers, after the final dispensing of the product by a pharmacy to a benefit plan participant. These discounts, in the aggregate, reduced U.S. sales by $3.0 billion and $2.9 billion for the three months ended June 30, 2020 and 2019 , respectively, and $6.2 billion and $5.5 billion for the six months ended June 30, 2020 and 2019 , respectively. Consolidated sales by geographic area where derived are as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 United States $ 4,634 $ 5,193 $ 9,771 $ 9,748 Europe, Middle East and Africa 3,071 3,163 6,605 6,265 China 834 763 1,699 1,509 Japan 867 921 1,678 1,720 Asia Pacific (other than China and Japan) 666 716 1,394 1,461 Latin America 510 658 1,066 1,219 Other 290 346 716 653 $ 10,872 $ 11,760 $ 22,929 $ 22,575 A reconciliation of segment profits to Income before taxes is as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Segment profits: Pharmaceutical segment $ 6,560 $ 7,115 $ 14,036 $ 13,690 Animal Health segment 407 405 885 820 Other segment — (2 ) 2 — Total segment profits 6,967 7,518 14,923 14,510 Other profits 61 94 200 124 Unallocated: Interest income 14 75 39 164 Interest expense (209 ) (233 ) (421 ) (442 ) Depreciation and amortization (390 ) (427 ) (772 ) (786 ) Research and development (1,994 ) (2,093 ) (4,092 ) (3,935 ) Amortization of purchase accounting adjustments (299 ) (378 ) (594 ) (775 ) Restructuring costs (83 ) (59 ) (155 ) (212 ) Other unallocated, net (548 ) (1,238 ) (1,771 ) (2,322 ) $ 3,519 $ 3,259 $ 7,357 $ 6,326 Pharmaceutical segment profits are comprised of segment sales less standard costs, as well as selling, general and administrative expenses directly incurred by the segment. Animal Health segment profits are comprised of segment sales, less all cost of sales, as well as selling, general and administrative expenses and research and development costs directly incurred by the segment. For internal management reporting presented to the chief operating decision maker, Merck does not allocate the remaining cost of sales not included in segment profits as described above, research and development expenses incurred in Merck Research Laboratories, the Company’s research and development division that focuses on human health-related activities, or general and administrative expenses, nor the cost of financing these activities. Separate divisions maintain responsibility for monitoring and managing these costs, including depreciation related to fixed assets utilized by these divisions and, therefore, they are not included in segment profits. In addition, costs related to restructuring activities, as well as the amortization of purchase accounting adjustments are not allocated to segments. Other profits are primarily comprised of miscellaneous corporate profits, as well as operating profits related to third-party manufacturing sales. Other unallocated, net, includes expenses from corporate and manufacturing cost centers, goodwill and other intangible asset impairment charges, gains or losses on sales of businesses, expense or income related to changes in the estimated fair value measurement of liabilities for contingent consideration, and other miscellaneous income or expense items.

Basis of Presentation (Policies

Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements of Merck & Co., Inc. (Merck or the Company) have been prepared pursuant to the rules and regulations for reporting on Form 10-Q. Accordingly, certain information and disclosures required by accounting principles generally accepted in the United States (GAAP) for complete consolidated financial statements are not included herein. These interim statements should be read in conjunction with the audited financial statements and notes thereto included in Merck’s Form 10-K filed on February 26, 2020. The results of operations of any interim period are not necessarily indicative of the results of operations for the full year. In the Company’s opinion, all adjustments necessary for a fair statement of these interim statements have been included and are of a normal and recurring nature.
Recently Adopted and Issued Accounting Standards	Recently Adopted Accounting Standards In June 2016, the Financial Accounting Standards Board (FASB) issued new guidance on the accounting for credit losses on financial instruments. The new guidance introduces an expected loss model for estimating credit losses, replacing the incurred loss model. The new guidance also changes the impairment model for available-for-sale debt securities, requiring the use of an allowance to record estimated credit losses (and subsequent recoveries). The Company adopted the new guidance effective January 1, 2020. There was no impact to the Company’s consolidated financial statements upon adoption. In November 2018, the FASB issued new guidance for collaborative arrangements intended to reduce diversity in practice by clarifying whether certain transactions between collaborative arrangement participants should be accounted for under revenue recognition guidance (ASC 606). The Company adopted the new guidance effective January 1, 2020, which resulted in minor changes to the presentation of information related to the Company’s collaborative arrangements. Recently Issued Accounting Standards Not Yet Adopted In December 2019, the FASB issued amended guidance on the accounting and reporting of income taxes. The guidance is intended to simplify the accounting for income taxes by removing exceptions related to certain intraperiod tax allocations and deferred tax liabilities; clarifying guidance primarily related to evaluating the step-up tax basis for goodwill in a business combination; and reflecting enacted changes in tax laws or rates in the annual effective tax rate. The amended guidance is effective for interim and annual periods in 2021. Early adoption is permitted. The amendments in the new guidance are to be applied on a retrospective basis, on a modified retrospective basis through a cumulative-effect adjustment to retained earnings or prospectively, depending on the amendment. The Company is currently evaluating the impact of adoption on its consolidated financial statements. In January 2020, the FASB issued new guidance intended to clarify certain interactions between accounting standards related to equity securities, equity method investments and certain derivatives. The guidance addresses accounting for the transition into and out of the equity method of accounting and measuring certain purchased options and forward contracts to acquire investments. The new guidance is effective for interim and annual periods in 2021 and is to be applied prospectively. Early adoption is permitted. The Company is currently evaluating the impact of adoption on its consolidated financial statements. In March 2020, the FASB issued optional guidance to ease the potential burden in accounting for (or recognizing the effects of) reference rate reform on financial reporting. The guidance provides optional expedients and exceptions for applying GAAP to contracts, hedging relationships, and other transactions affected by reference rate reform. The optional guidance is effective upon issuance and can be applied on a prospective basis at any time between January 1, 2020 through December 31, 2022. The Company is currently evaluating the impact of adoption on its consolidated financial statements.

Contingencies Commitments and C

Contingencies Commitments and Contingencies (Policies)	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Legal Costs, Policy	Legal defense costs expected to be incurred in connection with a loss contingency are accrued when probable and reasonably estimable.

Acquisitions, Research Collab_2

Acquisitions, Research Collaborations and License Agreements (Tables)	6 Months Ended
	Jun. 30, 2020
Business Combinations [Abstract]
Fair Value of Assets Acquired and Liabilities Assumed	The estimated fair value of assets acquired and liabilities assumed from Antelliq is as follows: ($ in millions) April 1, 2019 Cash and cash equivalents $ 31 Accounts receivable 73 Inventories 93 Property, plant and equipment 60 Identifiable intangible assets (useful lives ranging from 18-24 years) (1) 2,689 Deferred income tax liabilities (589 ) Other assets and liabilities, net (82 ) Total identifiable net assets 2,275 Goodwill (2) 1,376 Consideration transferred $ 3,651 (1) The estimated fair values of identifiable intangible assets relate primarily to trade names and were determined using an income approach. The future net cash flows were discounted to present value utilizing a discount rate of 11.5% . Actual cash flows are likely to be different than those assumed. (2) The goodwill recognized is largely attributable to anticipated synergies expected to arise after the acquisition and was allocated to the Animal Health segment. The goodwill is not deductible for tax purposes. The estimated fair value of assets acquired and liabilities assumed from ArQule is as follows: ($ in millions) January 16, 2020 Cash and cash equivalents $ 145 IPR&D MK-1026 (formerly ARQ 531) (1) 2,280 IPR&D MK-7075 (formerly ARQ 092) (1) 170 Licensing arrangement for ARQ 087 80 Deferred income tax liabilities (434 ) Other assets and liabilities, net 35 Total identifiable net assets 2,276 Goodwill (2) 414 Consideration transferred $ 2,690 (1) The estimated fair values of the identifiable intangible assets related to in-process research and development (IPR&D) were determined using an income approach. The future net cash flows were discounted to present value utilizing a discount rate of 12.5% . Actual cash flows are likely to be different than those assumed. (2) The goodwill was allocated to the Pharmaceutical segment and is not deductible for tax purposes.

Collaborative Arrangements (Tab

Collaborative Arrangements (Tables)	6 Months Ended
	Jun. 30, 2020
Collaborative Arrangements [Abstract]
Collaboration Arrangements	Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Alliance revenue - Lynparza $ 178 $ 111 $ 323 $ 190 Cost of sales (1) 137 73 164 92 Selling, general and administrative 39 33 72 59 Research and development 37 33 73 78 ($ in millions) June 30, 2020 December 31, 2019 Receivables from AstraZeneca included in Other current assets $ 168 $ 128 Payables to AstraZeneca included in Accrued and other current liabilities (2) 324 577 Payables to AstraZeneca included in Other Noncurrent Liabilities (2) 400 — (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone payments. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Alliance revenue - Adempas $ 79 $ 51 $ 133 $ 94 Net sales of Adempas recorded by Merck 57 53 113 100 Total sales $ 136 $ 104 $ 246 $ 194 Cost of sales (1) 28 29 57 58 Selling, general and administrative 17 11 28 20 Research and development 16 32 41 62 ($ in millions) June 30, 2020 December 31, 2019 Receivables from Bayer included in Other current assets $ 62 $ 49 Payables to Bayer included in Other Noncurrent Liabilities (2) 375 375 (1) Includes amortization of intangible assets. (2) Represents accrued milestone payment. Summarized financial information related to this collaboration is as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Alliance revenue - Lenvima $ 151 $ 97 $ 279 $ 171 Cost of sales (1) 135 23 170 74 Selling, general and administrative 19 19 31 38 Research and development 56 62 120 109 ($ in millions) June 30, 2020 December 31, 2019 Receivables from Eisai included in Other current assets $ 173 $ 150 Payables to Eisai included in Accrued and other current liabilities (2) 325 700 Payables to Eisai included in Other Noncurrent Liabilities (3) 570 525 (1) Represents amortization of capitalized milestone payments. (2) Includes accrued milestone and future option payments. (3) Includes accrued milestone payments.

Restructuring (Tables)

Restructuring (Tables)	6 Months Ended
	Jun. 30, 2020
Restructuring and Related Activities [Abstract]
Charges Related to Restructuring Program Activities by Type of Cost	The following tables summarize the charges related to restructuring program activities by type of cost: Three Months Ended June 30, 2020 Six Months Ended June 30, 2020 ($ in millions) Separation Costs Accelerated Depreciation Other Total Separation Costs Accelerated Depreciation Other Total Cost of sales $ — $ 31 $ (6 ) $ 25 $ — $ 56 $ 37 $ 93 Selling, general and administrative — 11 — 11 — 22 — 22 Research and development — 31 — 31 — 48 — 48 Restructuring costs 35 — 48 83 82 — 73 155 $ 35 $ 73 $ 42 $ 150 $ 82 $ 126 $ 110 $ 318 Three Months Ended June 30, 2019 Six Months Ended June 30, 2019 ($ in millions) Separation Costs Accelerated Depreciation Other Total Separation Costs Accelerated Depreciation Other Total Cost of sales $ — $ 64 $ 1 $ 65 $ — $ 98 $ 1 $ 99 Selling, general and administrative — 32 — 32 — 32 — 32 Research and development — 2 1 3 — 2 1 3 Restructuring costs 25 — 34 59 153 — 59 212 $ 25 $ 98 $ 36 $ 159 $ 153 $ 132 $ 61 $ 346
Charges and Spending Relating to Restructuring Activities by Program	The following table summarizes the charges and spending relating to restructuring program activities for the six months ended June 30, 2020 : ($ in millions) Separation Costs Accelerated Depreciation Other Total Restructuring reserves January 1, 2020 $ 690 $ — $ 69 $ 759 Expense 82 126 110 318 (Payments) receipts, net (328 ) — (163 ) (491 ) Non-cash activity — (126 ) 34 (92 ) Restructuring reserves June 30, 2020 (1) $ 444 $ — $ 50 $ 494 (1)

Financial Instruments (Tables)

Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Effect of Net Investment Hedges on OCI and the Consolidated Statement of Income	The effects of the Company’s net investment hedges on OCI and the Consolidated Statement of Income are shown below: Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income (1) Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing Three Months Ended June 30, Six Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, ($ in millions) 2020 2019 2020 2019 2020 2019 2020 2019 Net Investment Hedging Relationships Foreign exchange contracts $ 8 $ 17 $ 5 $ 7 $ (4 ) $ (8 ) $ (11 ) $ (15 ) Euro-denominated notes 72 28 21 (2 ) — — — — (1) No amounts were reclassified from AOCI into income related to the sale of a subsidiary.
Summary of Interest Rate Swaps Held	At June 30, 2020 , the Company was a party to 14 pay-floating, receive-fixed interest rate swap contracts designated as fair value hedges of fixed-rate notes in which the notional amounts match the amount of the hedged fixed-rate notes as detailed in the table below. June 30, 2020 ($ in millions) Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 3.875% notes due 2021 $ 1,150 5 $ 1,150 2.40% notes due 2022 1,000 4 1,000 2.35% notes due 2022 1,250 5 1,250
Amounts Recorded on Balance Sheet Related to Fair Value Hedges	The table below presents the location of amounts recorded on the Consolidated Balance Sheet related to cumulative basis adjustments for fair value hedges: Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount ($ in millions) June 30, 2020 December 31, 2019 June 30, 2020 December 31, 2019 Balance Sheet Line Item in which Hedged Item is Included Loans payable and current portion of long-term debt $ 1,160 $ 1,249 $ 10 $ (1 ) Long-Term Debt 2,318 3,409 71 14
Fair Value of Derivatives on a Gross Basis Segregated between those Derivatives that are Designated as Hedging Instruments and those that are Not Designated as Hedging Instruments	Presented in the table below is the fair value of derivatives on a gross basis segregated between those derivatives that are designated as hedging instruments and those that are not designated as hedging instruments: June 30, 2020 December 31, 2019 Fair Value of Derivative U.S. Dollar Notional Fair Value of Derivative U.S. Dollar Notional ($ in millions) Balance Sheet Caption Asset Liability Asset Liability Derivatives Designated as Hedging Instruments Interest rate swap contracts Other current assets $ 10 $ — $ 1,150 $ — $ — $ — Interest rate swap contracts Other Assets 72 — 2,250 15 — 3,400 Interest rate swap contracts Accrued and other current liabilities — — — — 1 1,250 Foreign exchange contracts Other current assets 83 — 4,959 152 — 6,117 Foreign exchange contracts Other Assets 70 — 1,993 55 — 2,160 Foreign exchange contracts Accrued and other current liabilities — 27 1,884 — 22 1,748 Foreign exchange contracts Other Noncurrent Liabilities — 1 11 — 1 53 $ 235 $ 28 $ 12,247 $ 222 $ 24 $ 14,728 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts Other current assets $ 93 $ — $ 5,324 $ 66 $ — $ 7,245 Foreign exchange contracts Accrued and other current liabilities — 103 5,865 — 73 8,693 $ 93 $ 103 $ 11,189 $ 66 $ 73 $ 15,938 $ 328 $ 131 $ 23,436 $ 288 $ 97 $ 30,666
Information on Derivative Positions Subject to Master Netting Arrangements as if they were Presented on a Net Basis	The following table provides information on the Company’s derivative positions subject to these master netting arrangements as if they were presented on a net basis, allowing for the right of offset by counterparty and cash collateral exchanged per the master agreements and related credit support annexes: June 30, 2020 December 31, 2019 ($ in millions) Asset Liability Asset Liability Gross amounts recognized in the condensed consolidated balance sheet $ 328 $ 131 $ 288 $ 97 Gross amounts subject to offset in master netting arrangements not offset in the condensed consolidated balance sheet (115 ) (115 ) (84 ) (84 ) Cash collateral received (38 ) — (34 ) — Net amounts $ 175 $ 16 $ 170 $ 13
Location and Amount of Pretax (Gains) Losses of Derivatives	The table below provides information regarding the location and amount of pretax (gains) losses of derivatives designated in fair value or cash flow hedging relationships: Sales Other (income) expense, net (1) Other comprehensive income (loss) Sales Other (income) expense, net (1) Other comprehensive income (loss) Three Months Ended June 30, Three Months Ended June 30, Three Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, Six Months Ended June 30, ($ in millions) 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 2020 2019 Financial Statement Line Items in which Effects of Fair Value or Cash Flow Hedges are Recorded $ 10,872 $ 11,760 $ (390 ) $ 140 $ (2 ) $ (16 ) $ 22,929 $ 22,575 $ (318 ) $ 327 $ (200 ) $ 183 (Gain) loss on fair value hedging relationships Interest rate swap contracts Hedged items — — 1 55 — — — — 68 88 — — Derivatives designated as hedging instruments — — (8 ) (45 ) — — — — (76 ) (68 ) — — Impact of cash flow hedging relationships Foreign exchange contracts Amount of (loss) gain recognized in OCI on derivatives — — — — (109 ) 10 — — — — 69 (2 ) Increase (decrease) in Sales as a result of AOCI reclassifications 42 75 — — (42 ) (75 ) 88 119 — — (88 ) (119 ) Interest rate contracts Amount of gain recognized in Other (income) expense, net on derivatives — — (1 ) (1 ) — — — — (2 ) (2 ) — — Amount of loss recognized in OCI on derivatives — — — — (1 ) (1 ) — — — — (2 ) (5 ) (1) Interest expense is a component of Other (income) expense, net.
Income Statement Effects of Derivatives Not Designated as Hedging Instruments	The table below provides information regarding the income statement effects of derivatives not designated as hedging instruments: Amount of Derivative Pretax (Gain) Loss Recognized in Income Three Months Ended June 30, Six Months Ended June 30, ($ in millions) Income Statement Caption 2020 2019 2020 2019 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts (1) Other (income) expense, net $ 49 $ 2 $ (131 ) $ 120 Foreign exchange contracts (2) Sales 4 (6 ) (3 ) 4 Interest rate contracts (3) Other (income) expense, net 9 — 9 — (1) These derivative contracts mitigate changes in the value of remeasured foreign currency denominated monetary assets and liabilities attributable to changes in foreign currency exchange rates. (2) These derivative contracts serve as economic hedges of forecasted transactions.
Information on Investments in Debt and Equity Securities	Information on investments in debt and equity securities is as follows: June 30, 2020 December 31, 2019 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Value ($ in millions) Gains Losses Gains Losses U.S. government and agency securities $ 74 $ — $ — $ 74 $ 266 $ 3 $ — $ 269 Foreign government bonds 2 — — 2 — — — — Commercial paper — — — — 668 — — 668 Corporate notes and bonds — — — — 608 13 — 621 Asset-backed securities — — — — 226 1 — 227 Total debt securities $ 76 $ — $ — $ 76 $ 1,768 $ 17 $ — $ 1,785 Publicly traded equity securities (1) 1,307 838 Total debt and publicly traded equity securities $ 1,383 $ 2,623 (1) Unrealized net (gains) losses recognized in Other (income) expense, net on equity securities still held at June 30, 2020 were $(464) million and $(469) million in the second quarter and first six months of 2020 , respectively. Unrealized net losses (gains) recognized in Other (income) expense, net on equity securities still held at June 30, 2019 were $39 million and $(75) million in the second quarter and first six months of 2019 , respectively.
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	Financial assets and liabilities measured at fair value on a recurring basis are summarized below: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total ($ in millions) June 30, 2020 December 31, 2019 Assets Investments Foreign government bonds $ — $ 2 $ — $ 2 $ — $ — $ — $ — Commercial paper — — — — — 668 — 668 Corporate notes and bonds — — — — — 621 — 621 Asset-backed securities (1) — — — — — 227 — 227 U.S. government and agency securities — — — — — 209 — 209 Publicly traded equity securities 1,249 — — 1,249 518 — — 518 1,249 2 — 1,251 518 1,725 — 2,243 Other assets (2) U.S. government and agency securities 74 — — 74 60 — — 60 Publicly traded equity securities 58 — — 58 320 — — 320 132 — — 132 380 — — 380 Derivative assets (3) Forward exchange contracts — 142 — 142 — 169 — 169 Purchased currency options — 104 — 104 — 104 — 104 Interest rate swaps — 82 — 82 — 15 — 15 — 328 — 328 — 288 — 288 Total assets $ 1,381 $ 330 $ — $ 1,711 $ 898 $ 2,013 $ — $ 2,911 Liabilities Other liabilities Contingent consideration $ — $ — $ 798 $ 798 $ — $ — $ 767 $ 767 Derivative liabilities (3) Forward exchange contracts — 128 — 128 — 95 — 95 Written currency options — 3 — 3 — 1 — 1 Interest rate swaps — — — — — 1 — 1 — 131 — 131 — 97 — 97 Total liabilities $ — $ 131 $ 798 $ 929 $ — $ 97 $ 767 $ 864 (1) Primarily all of the asset-backed securities were highly rated (Standard & Poor’s rating of AAA and Moody’s Investors Service rating of Aaa), secured primarily by auto loan, credit card and student loan receivables, with weighted-average lives of primarily 5 years or less. (2) Investments included in other assets are restricted as to use, including for the payment of benefits under employee benefit plans. (3) The fair value determination of derivatives includes the impact of the credit risk of counterparties to the derivatives and the Company’s own credit risk, the effects of which were not significant.
Information About the Changes in Liabilities for Contingent Consideration	Summarized information about the changes in liabilities for contingent consideration associated with business acquisitions is as follows: Six Months Ended June 30, ($ in millions) 2020 2019 Fair value January 1 $ 767 $ 788 Additions 97 — Changes in estimated fair value (1) 40 50 Payments (106 ) (85 ) Fair value June 30 (2)(3) $ 798 $ 753 (1) Recorded in Cost of sales, Research and development expenses, and Other (income) expense, net . Includes cumulative translation adjustments. (2) Balance at June 30, 2020 includes $138 million recorded as a current liability for amounts expected to be paid within the next 12 months. (3) At June 30, 2020 and December 31, 2019 , $608 million and $625 million , respectively, of the liabilities relate to the termination of the Sanofi-Pasteur MSD joint venture in 2016. As part of the termination, Merck recorded a liability for contingent future royalty payments of 11.5% on net sales of all Merck products that were previously sold by the joint venture through December 31, 2024. The fair value of this liability is determined utilizing the estimated amount and timing of projected cash flows using a risk-adjusted discount rate of 8% to present value the cash flows.

Inventories (Tables)

Inventories (Tables)	6 Months Ended
	Jun. 30, 2020
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories consisted of: ($ in millions) June 30, 2020 December 31, 2019 Finished goods $ 2,032 $ 1,772 Raw materials and work in process 5,874 5,650 Supplies 190 207 Total (approximates current cost) 8,096 7,629 Decrease to LIFO cost (119 ) (171 ) $ 7,977 $ 7,458 Recognized as: Inventories $ 6,056 $ 5,978 Other assets 1,921 1,480

Equity (Tables)

Equity (Tables)	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Equity	Three Months Ended June 30, Common Stock Other Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss Treasury Stock Non- controlling Interests Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at April 1, 2019 3,577 $ 1,788 $ 38,768 $ 44,065 $ (5,346 ) 994 $ (51,736 ) $ 131 $ 27,670 Net income attributable to Merck & Co., Inc. — — — 2,670 — — — — 2,670 Other comprehensive loss, net of taxes — — — — (16 ) — — — (16 ) Cash dividends declared on common stock ($0.55 per share) — — — (1,440 ) — — — — (1,440 ) Treasury stock shares purchased — — 1,000 — — 24 (2,235 ) — (1,235 ) Share-based compensation plans and other — — (284 ) — — (8 ) 401 — 117 Net loss attributable to noncontrolling interests — — — — — — — (26 ) (26 ) Other changes in noncontrolling interests — — — — — — — (3 ) (3 ) Balance at June 30, 2019 3,577 $ 1,788 $ 39,484 $ 45,295 $ (5,362 ) 1,010 $ (53,570 ) $ 102 $ 27,737 Balance at April 1, 2020 3,577 $ 1,788 $ 39,697 $ 48,272 $ (6,391 ) 1,053 $ (57,161 ) $ 95 $ 26,300 Net income attributable to Merck & Co., Inc. — — — 3,002 — — — — 3,002 Other comprehensive loss, net of taxes — — — — (2 ) — — — (2 ) Cash dividends declared on common stock ($0.61 per share) — — — (1,550 ) — — — — (1,550 ) Share-based compensation plans and other — — (324 ) — — (5 ) 311 — (13 ) Net income attributable to noncontrolling interests — — — — — — — 8 8 Distributions attributable to noncontrolling interests — — — — — — — (1 ) (1 ) Balance at June 30, 2020 3,577 $ 1,788 $ 39,373 $ 49,724 $ (6,393 ) 1,048 $ (56,850 ) $ 102 $ 27,744 Six Months Ended June 30, Common Stock Other Paid-In Capital Retained Earnings Accumulated Other Comprehensive Loss Treasury Stock Non- controlling Interests Total ($ and shares in millions except per share amounts) Shares Par Value Shares Cost Balance at January 1, 2019 3,577 $ 1,788 $ 38,808 $ 42,579 $ (5,545 ) 985 $ (50,929 ) $ 181 $ 26,882 Net income attributable to Merck & Co., Inc. — — — 5,585 — — — — 5,585 Other comprehensive income, net of taxes — — — — 183 — — — 183 Cash dividends declared on common stock ($1.10 per share) — — — (2,869 ) — — — — (2,869 ) Treasury stock shares purchased — — 1,000 — — 38 (3,325 ) — (2,325 ) Share-based compensation plans and other — — (324 ) — — (13 ) 684 — 360 Net loss attributable to noncontrolling interests — — — — — — — (79 ) (79 ) Balance at June 30, 2019 3,577 $ 1,788 $ 39,484 $ 45,295 $ (5,362 ) 1,010 $ (53,570 ) $ 102 $ 27,737 Balance at January 1, 2020 3,577 $ 1,788 $ 39,660 $ 46,602 $ (6,193 ) 1,038 $ (55,950 ) $ 94 $ 26,001 Net income attributable to Merck & Co., Inc. — — — 6,221 — — — — 6,221 Other comprehensive loss, net of taxes — — — — (200 ) — — — (200 ) Cash dividends declared on common stock ($1.22 per share) — — — (3,099 ) — — — — (3,099 ) Treasury stock shares purchased — — — — — 16 (1,281 ) — (1,281 ) Share-based compensation plans and other — — (287 ) — — (6 ) 381 — 94 Net income attributable to noncontrolling interests — — — — — — — 8 8 Balance at June 30, 2020 3,577 $ 1,788 $ 39,373 $ 49,724 $ (6,393 ) 1,048 $ (56,850 ) $ 102 $ 27,744

Share-Based Compensation Plans

Share-Based Compensation Plans (Tables)	6 Months Ended
	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Amounts of Share-Based Compensation Cost Recorded in Consolidated Statement of Income	The following table provides the amounts of share-based compensation cost recorded in the Condensed Consolidated Statement of Income: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Pretax share-based compensation expense $ 121 $ 111 $ 229 $ 204 Income tax benefit (16 ) (15 ) (31 ) (28 ) Total share-based compensation expense, net of taxes $ 105 $ 96 $ 198 $ 176
Assumptions Used to Determine Weighted-Average Fair Value of Options Granted	During the first six months of 2020, the Company granted 4 million stock options with a weighted-average exercise price of $77.67 per option and during the first six months of 2019 granted 3 million stock options with a weighted-average exercise price of $80.00 per option. The weighted-average fair value of options granted during the first six months of 2020 and 2019 was $9.93 and $10.63 per option, respectively, and was determined using the following assumptions: Six Months Ended 2020 2019 Expected dividend yield 3.1 % 3.2 % Risk-free interest rate 0.4 % 2.4 % Expected volatility 22.1 % 18.7 % Expected life (years) 5.8 5.9

Pension and Other Postretirem_2

Pension and Other Postretirement Benefit Plans (Tables)	6 Months Ended
	Jun. 30, 2020
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Components of net cost of defined benefit plans	The Company has defined benefit pension plans covering eligible employees in the United States and in certain of its international subsidiaries. The net periodic benefit cost of such plans consisted of the following components: Three Months Ended Six Months Ended 2020 2019 2020 2019 ($ in millions) U.S. International U.S. International U.S. International U.S. International Service cost $ 88 $ 74 $ 74 $ 60 $ 175 $ 148 $ 144 $ 120 Interest cost 109 33 113 44 217 68 228 89 Expected return on plan assets (195 ) (101 ) (205 ) (107 ) (388 ) (205 ) (411 ) (214 ) Amortization of unrecognized prior service credit (12 ) (3 ) (12 ) (3 ) (25 ) (6 ) (25 ) (6 ) Net loss amortization 76 31 35 16 152 62 70 31 Termination benefits 1 — 3 1 4 1 5 1 Curtailments — — — — 2 (1 ) 1 — Settlements 9 2 — — 9 2 — — $ 76 $ 36 $ 8 $ 11 $ 146 $ 69 $ 12 $ 21
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Components of net cost of defined benefit plans	The Company provides medical benefits, principally to its eligible U.S. retirees and similar benefits to their dependents, through its other postretirement benefit plans. The net credit of such plans consisted of the following components: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Service cost $ 13 $ 12 $ 26 $ 24 Interest cost 14 18 29 35 Expected return on plan assets (19 ) (18 ) (37 ) (36 ) Amortization of unrecognized prior service credit (22 ) (21 ) (45 ) (43 ) Curtailments — (1 ) (1 ) (1 ) $ (14 ) $ (10 ) $ (28 ) $ (21 )

Other (Income) Expense, Net (Ta

Other (Income) Expense, Net (Tables)	6 Months Ended
	Jun. 30, 2020
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (income) expense, net, consisted of: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Interest income $ (14 ) $ (75 ) $ (39 ) $ (164 ) Interest expense 209 233 421 442 Exchange losses 24 27 78 128 Income from investments in equity securities, net (1) (551 ) (58 ) (603 ) (32 ) Net periodic defined benefit plan (credit) cost other than service cost (80 ) (140 ) (170 ) (281 ) Other, net 22 153 (5 ) 234 $ (390 ) $ 140 $ (318 ) $ 327 (1) Includes net realized and unrealized gains and losses from investments in equity securities either owned directly or through ownership interests in investment funds. Unrealized gains and losses from investments that are directly owned are determined at the end of the reporting period, while ownership interests in investment funds are accounted for on a one quarter lag. The Company estimates that gains of approximately $300 million will be recognized in the third quarter of 2020 from ownership interests in investment funds.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Calculations of Earnings Per Share	The calculations of earnings per share are as follows: Three Months Ended Six Months Ended ($ and shares in millions except per share amounts) 2020 2019 2020 2019 Net income attributable to Merck & Co., Inc. $ 3,002 $ 2,670 $ 6,221 $ 5,585 Average common shares outstanding 2,527 2,574 2,531 2,579 Common shares issuable (1) 9 14 11 17 Average common shares outstanding assuming dilution 2,536 2,588 2,542 2,596 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders $ 1.19 $ 1.04 $ 2.46 $ 2.17 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders $ 1.18 $ 1.03 $ 2.45 $ 2.15 (1) Issuable primarily under share-based compensation plans.

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Changes in AOCI by Component	Changes in AOCI by component are as follows: Three Months Ended June 30, ($ in millions) Derivatives Investments Employee Benefit Plans Cumulative Translation Adjustment Accumulated Other Comprehensive Income (Loss) Balance April 1, 2019, net of taxes $ 118 $ 4 $ (3,541 ) $ (1,927 ) $ (5,346 ) Other comprehensive income (loss) before reclassification adjustments, pretax 10 55 — (25 ) 40 Tax (2 ) — — 6 4 Other comprehensive income (loss) before reclassification adjustments, net of taxes 8 55 — (19 ) 44 Reclassification adjustments, pretax (76 ) (1) (11 ) (2) 14 (3) — (73 ) Tax 16 — (3 ) — 13 Reclassification adjustments, net of taxes (60 ) (11 ) 11 — (60 ) Other comprehensive income (loss), net of taxes (52 ) 44 11 (19 ) (16 ) Balance June 30, 2019, net of taxes $ 66 $ 48 $ (3,530 ) $ (1,946 ) $ (5,362 ) Balance April 1, 2020, net of taxes $ 135 $ — $ (4,201 ) $ (2,325 ) $ (6,391 ) Other comprehensive income (loss) before reclassification adjustments, pretax (110 ) — (21 ) 63 (68 ) Tax 23 — 6 16 45 Other comprehensive income (loss) before reclassification adjustments, net of taxes (87 ) — (15 ) 79 (23 ) Reclassification adjustments, pretax (42 ) (1) — 69 (3) — 27 Tax 9 — (15 ) — (6 ) Reclassification adjustments, net of taxes (33 ) — 54 — 21 Other comprehensive income (loss), net of taxes (120 ) — 39 79 (2 ) Balance June 30, 2020, net of taxes $ 15 $ — $ (4,162 ) $ (2,246 ) $ (6,393 ) Six Months Ended June 30, ($ in millions) Derivatives Investments Employee Benefit Plans Cumulative Translation Adjustment Accumulated Other Comprehensive Income (Loss) Balance January 1, 2019, net of taxes $ 166 $ (78 ) $ (3,556 ) $ (2,077 ) $ (5,545 ) Other comprehensive income (loss) before reclassification adjustments, pretax (3 ) 131 (1 ) 131 258 Tax 1 — 6 — 7 Other comprehensive income (loss) before reclassification adjustments, net of taxes (2 ) 131 5 131 265 Reclassification adjustments, pretax (124 ) (1) (5 ) (2) 28 (3) — (101 ) Tax 26 — (7 ) — 19 Reclassification adjustments, net of taxes (98 ) (5 ) 21 — (82 ) Other comprehensive income (loss), net of taxes (100 ) 126 26 131 183 Balance June 30, 2019, net of taxes $ 66 $ 48 $ (3,530 ) $ (1,946 ) $ (5,362 ) Balance January 1, 2020, net of taxes $ 31 $ 18 $ (4,261 ) $ (1,981 ) $ (6,193 ) Other comprehensive income (loss) before reclassification adjustments, pretax 68 3 (21 ) (270 ) (220 ) Tax (14 ) — 11 5 2 Other comprehensive income (loss) before reclassification adjustments, net of taxes 54 3 (10 ) (265 ) (218 ) Reclassification adjustments, pretax (89 ) (1) (21 ) (2) 138 (3) — 28 Tax 19 — (29 ) — (10 ) Reclassification adjustments, net of taxes (70 ) (21 ) 109 — 18 Other comprehensive income (loss), net of taxes (16 ) (18 ) 99 (265 ) (200 ) Balance June 30, 2020, net of taxes $ 15 $ — $ (4,162 ) $ (2,246 ) $ (6,393 ) (1) Relates to foreign currency cash flow hedges that were reclassified from AOCI to Sales . (2) Represents net realized (gains) losses on the sales of available-for-sale debt securities that were reclassified from AOCI to Other (income) expense, net . (3) Includes net amortization of prior service cost and actuarial gains and losses included in net periodic benefit cost (see Note 11).

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Jun. 30, 2020
Segment Reporting [Abstract]
Sales of Company's products	Sales of the Company’s products were as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 ($ in millions) U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total Pharmaceutical: Oncology Keytruda $ 2,043 $ 1,345 $ 3,388 $ 1,498 $ 1,136 $ 2,634 $ 3,949 $ 2,722 $ 6,672 $ 2,782 $ 2,121 $ 4,903 Alliance revenue - Lynparza (1) 105 73 178 66 45 111 190 133 323 116 74 190 Alliance revenue - Lenvima (1) 98 53 151 54 43 97 188 91 279 104 67 171 Emend 6 27 33 67 54 121 11 65 76 130 107 237 Vaccines Gardasil/Gardasil 9 168 488 656 456 430 886 629 1,124 1,753 818 906 1,724 ProQuad/M-M-R II /Varivax 263 115 378 500 174 675 596 217 813 843 328 1,171 RotaTeq 100 68 168 104 68 172 241 150 391 258 125 383 Pneumovax 23 21 96 117 123 47 170 203 170 373 248 107 355 Vaqta 17 11 28 38 20 58 47 41 88 67 39 105 Hospital Acute Care Bridion 107 117 224 129 149 278 250 274 524 248 285 533 Noxafil 6 67 73 100 93 193 14 154 168 191 192 383 Prevymis 28 35 63 19 18 38 55 68 123 37 33 70 Primaxin 1 63 64 — 70 71 1 114 115 1 129 130 Invanz — 43 43 18 60 78 6 102 108 31 118 150 Cancidas (2 ) 45 43 3 64 67 1 98 98 4 125 129 Cubicin 10 21 32 22 45 67 25 53 78 64 91 155 Zerbaxa 17 15 32 13 14 27 37 32 69 25 28 53 Immunology Simponi — 191 191 — 214 214 — 406 406 — 422 422 Remicade — 73 73 — 98 98 — 160 160 — 221 221 Neuroscience Belsomra 22 61 84 21 55 76 49 114 163 45 98 143 Virology Isentress/Isentress HD 76 120 196 94 153 247 151 290 441 202 300 502 Zepatier 15 24 39 39 68 108 33 62 94 72 149 221 Cardiovascular Zetia (1 ) 138 137 6 150 156 (4 ) 285 282 6 290 296 Vytorin 2 37 39 3 73 76 5 86 92 6 167 174 Atozet — 115 115 — 92 92 — 238 238 — 186 186 Alliance revenue - Adempas (2) 73 6 79 49 2 51 122 11 133 89 5 94 Adempas — 57 57 — 53 53 — 113 113 — 100 100 Diabetes Januvia 413 441 854 471 437 908 768 860 1,628 855 877 1,732 Janumet 143 348 490 166 366 533 256 737 993 333 730 1,063 Women’s Health Implanon/Nexplanon 87 44 132 136 48 183 237 90 326 285 98 382 NuvaRing 35 28 63 206 34 240 61 65 126 391 68 459 Diversified Brands Singulair 4 96 100 8 153 160 9 246 255 13 338 352 Cozaar/Hyzaar 4 94 98 6 103 109 12 189 200 10 202 213 Arcoxia — 65 65 — 75 75 — 135 135 — 149 149 Nasonex 4 45 49 (1 ) 73 72 10 110 120 (2 ) 170 168 Follistim AQ 20 24 44 24 39 63 40 45 85 53 67 121 Other pharmaceutical (3) 385 720 1,103 369 837 1,203 792 1,500 2,293 697 1,589 2,283 Total Pharmaceutical segment sales 4,270 5,409 9,679 4,807 5,653 10,460 8,984 11,350 20,334 9,022 11,101 20,123 Animal Health: Livestock 122 526 648 145 526 671 284 1,102 1,386 261 1,021 1,282 Companion Animals 220 233 453 190 263 453 442 486 928 367 500 867 Total Animal Health segment sales 342 759 1,101 335 789 1,124 726 1,588 2,314 628 1,521 2,149 Other segment sales (4) — — — 47 — 48 23 — 23 86 — 87 Total segment sales 4,612 6,168 10,780 5,189 6,442 11,632 9,733 12,938 22,671 9,736 12,622 22,359 Other (5) 22 70 92 4 125 128 38 220 258 12 206 216 $ 4,634 $ 6,238 $ 10,872 $ 5,193 $ 6,567 $ 11,760 $ 9,771 $ 13,158 $ 22,929 $ 9,748 $ 12,828 $ 22,575 U.S. plus international may not equal total due to rounding. (1) Alliance revenue represents Merck’s share of profits, which are product sales net of cost of sales and commercialization costs (see Note 3). (2) Alliance revenue represents Merck’s share of profits from sales in Bayer’s marketing territories, which are product sales net of cost of sales and commercialization costs (see Note 3). (3) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (4) Represents sales for the Healthcare Services segment. All the businesses in the Healthcare Services segment were divested as of March 31, 2020. (5) Other is primarily comprised of miscellaneous corporate revenues, including revenue hedging activities, as well as third-party manufacturing sales. Other in the first six months of 2020 and 2019 also includes approximately $85 million and $15 million , respectively, related to the sale of the marketing rights for certain products.
Consolidated revenues by geographic area	Consolidated sales by geographic area where derived are as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 United States $ 4,634 $ 5,193 $ 9,771 $ 9,748 Europe, Middle East and Africa 3,071 3,163 6,605 6,265 China 834 763 1,699 1,509 Japan 867 921 1,678 1,720 Asia Pacific (other than China and Japan) 666 716 1,394 1,461 Latin America 510 658 1,066 1,219 Other 290 346 716 653 $ 10,872 $ 11,760 $ 22,929 $ 22,575
Reconciliation of segment profits to income before taxes	A reconciliation of segment profits to Income before taxes is as follows: Three Months Ended Six Months Ended ($ in millions) 2020 2019 2020 2019 Segment profits: Pharmaceutical segment $ 6,560 $ 7,115 $ 14,036 $ 13,690 Animal Health segment 407 405 885 820 Other segment — (2 ) 2 — Total segment profits 6,967 7,518 14,923 14,510 Other profits 61 94 200 124 Unallocated: Interest income 14 75 39 164 Interest expense (209 ) (233 ) (421 ) (442 ) Depreciation and amortization (390 ) (427 ) (772 ) (786 ) Research and development (1,994 ) (2,093 ) (4,092 ) (3,935 ) Amortization of purchase accounting adjustments (299 ) (378 ) (594 ) (775 ) Restructuring costs (83 ) (59 ) (155 ) (212 ) Other unallocated, net (548 ) (1,238 ) (1,771 ) (2,322 ) $ 3,519 $ 3,259 $ 7,357 $ 6,326

Acquisitions, Research Collab_3

Acquisitions, Research Collaborations and License Agreements - Acquisitions (Details) - USD ($) $ in Millions	Jan. 16, 2020	Apr. 01, 2019	Jul. 31, 2020	Jun. 30, 2020	May 31, 2020	Apr. 30, 2019	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration				$ 798			$ 767	$ 753	$ 788
Goodwill				20,067			$ 19,425
Themis
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Payment to acquire business				366
Contingent consideration, maximum				740
Contingent consideration				97
IPR&D				136
Cash and cash equivalents				62
Goodwill				215
Deferred tax assets				72
Other assets and liabilities, net				(22)
ArQule
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Payment to acquire business	$ 2,700
Share-based compensation payments attributable to precombination service	138
Transaction costs	95
Cash and cash equivalents	145
Goodwill	414
Other assets and liabilities, net	$ 35
Antelliq
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Payment to acquire business		$ 2,300
Transaction costs		47
Cash and cash equivalents		31
Goodwill		1,376
Debt assumed and paid		1,300
Other assets and liabilities, net		$ (82)
Immune Design
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Payment to acquire business						$ 301
IPR&D						156
Cash and cash equivalents						83
Other net assets						42
Goodwill						$ 20
Development Milestones | Themis
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration, maximum				80
Sales-Based Milestones | Themis
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration, maximum				400
Regulatory Milestones | Themis
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration, maximum				$ 260
IAVI
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Upfront and milestone payments					$ 6.5
Contingent milestone payments collaborative arrangement					$ 100
Technology Rights | Subsequent Event | Virbac
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Acquired rights			$ 400

Acquisitions, Research Collab_4

Acquisitions, Research Collaborations and License Agreements - Fair Value of Assets Acquired and Liabilities Assumed (Details) $ in Millions	Jun. 30, 2020USD ($)	Jan. 16, 2020USD ($)	Dec. 31, 2019USD ($)	Apr. 01, 2019USD ($)
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Goodwill	$ 20,067		$ 19,425
ArQule
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Cash and cash equivalents		$ 145
Licensing arrangement		80
Deferred income tax liabilities		(434)
Other assets and liabilities, net		35
Total identifiable net assets		2,276
Goodwill		414
Consideration transferred		$ 2,690
Antelliq
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Cash and cash equivalents				$ 31
Accounts receivable				73
Inventories				93
Property, plan and equipment				60
Licensing arrangement				2,689
Deferred income tax liabilities				(589)
Other assets and liabilities, net				(82)
Total identifiable net assets				2,275
Goodwill				1,376
Consideration transferred				$ 3,651
Measurement Input, Discount Rate | ArQule
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Present value discount rate		0.125
Measurement Input, Discount Rate | Antelliq
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
Present value discount rate				0.115
IPR&D MK-1026 | ArQule
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
IPR&D		$ 2,280
IPR&D MK-7075 | ArQule
Acquisitions Research Collaborations And License Agreements Transactions [Line Items]
IPR&D		$ 170

Collaborative Arrangements - Na

Collaborative Arrangements - Narrative (Details) - USD ($) $ in Millions

1 Months Ended

3 Months Ended

6 Months Ended

12 Months Ended

21 Months Ended

29 Months Ended

37 Months Ended

Mar. 31, 2021

Mar. 31, 2020

Mar. 31, 2019

Mar. 31, 2018

Jul. 31, 2017

Jun. 30, 2020

Jun. 30, 2019

Jun. 30, 2020

Jun. 30, 2019

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2019

Dec. 31, 2019

Mar. 31, 2021

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Research and development

$ 2,123

$ 2,189

$ 4,331

$ 4,119

Other liabilities, noncurrent

12,446

12,446

$ 11,970

$ 11,970

$ 11,970

Lynparza | Other Assets

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Finite-lived intangible assets

1,300

1,300

Lenvima | Other Assets

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Finite-lived intangible assets

1,200

1,200

Adempas | Other intangible assets

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Finite-lived intangible assets

832

832

AstraZeneca

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Upfront and milestone payments

$ 1,600

License option payment related to collaborative arrangement

$ 750

AstraZeneca | Sales-Based Milestones

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Contingent milestone payments collaborative arrangement

2,700

AstraZeneca | Sales-Based Milestones | Lynparza

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Probable contingent payments collaborative arrangement

400

$ 1,000

Liabilities

400

400

Milestone payments made to collaborative partner

250

200

$ 250

AstraZeneca | Regulatory Milestones | Lynparza

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Milestone payments made to collaborative partner

135

60

140

Contingent milestone payments collaborative arrangement

1,400

Eisai

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Upfront and milestone payments

$ 750

License option payment related to collaborative arrangement

$ 200

$ 325

Eisai | Forecast

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

License option payment related to collaborative arrangement

$ 125

$ 650

Eisai | Sales-Based Milestones

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Contingent milestone payments collaborative arrangement

2,700

Eisai | Sales-Based Milestones | Lenvima

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Probable contingent payments collaborative arrangement

370

$ 950

Liabilities

$ 370

370

Milestone payments made to collaborative partner

500

$ 50

Eisai | Regulatory Milestones

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Contingent milestone payments collaborative arrangement

135

Eisai | Regulatory Milestones | Lenvima

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Milestone payments made to collaborative partner

250

Bayer AG | Sales-Based Milestones

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Probable contingent payments collaborative arrangement

725

Milestone payments made to collaborative partner

$ 350

Contingent milestone payments collaborative arrangement

$ 400

Collaborative Arrangements - Sc

Collaborative Arrangements - Schedule of Transactions (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Sales	$ 10,872	$ 11,760	$ 22,929	$ 22,575
Cost of sales	3,159	3,401	6,471	6,453
Selling, general and administrative	2,378	2,712	4,933	5,138
Research and development	2,123	2,189	4,331	4,119
Payables, current	22,178		22,178		$ 22,220
Other current assets | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Receivables	168		168		128
Other current assets | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Receivables	173		173		150
Other current assets | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Receivables	62		62		49
Accounts payable and accrued liabilities | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables, current	324		324		577
Payables, Noncurrent	400		400		0
Accounts payable and accrued liabilities | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables, current	325		325		700
Other Noncurrent Liabilities | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables, Noncurrent	570		570		525
Other Noncurrent Liabilities | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables, Noncurrent	375		375		$ 375
Revenue | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Alliance revenue - profit sharing	178	111	323	190
Revenue | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Alliance revenue - profit sharing	151	97	279	171
Revenue | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Alliance revenue - profit sharing	79	51	133	94
Collaborative Arrangement, Sales, Net	57	53	113	100
Sales	136	104	246	194
Cost of sales | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost of sales	137	73	164	92
Cost of sales | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost of sales	135	23	170	74
Cost of sales | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost of sales	28	29	57	58
Selling, general and administrative | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	39	33	72	59
Selling, general and administrative | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	19	19	31	38
Selling, general and administrative | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Selling, general and administrative	17	11	28	20
Research and development | AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	37	33	73	78
Research and development | Eisai | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	56	62	120	109
Research and development | Bayer AG | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development	$ 16	$ 32	$ 41	$ 62

Restructuring - Narrative (Deta

Restructuring - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Cumulative costs since program inception	$ 1,200		$ 1,200
Estimate of cumulative pre tax costs that will result in cash outlays			60.00%
Estimate of cumulative pre tax costs that will be noncash			40.00%
Expected restructuring and related cost	2,500		$ 2,500
Total pretax restructuring costs	$ 150	$ 159	$ 318	$ 346
Forecast
Restructuring Cost and Reserve [Line Items]
Expected restructuring and related cost					$ 800

Restructuring - Charges Activit

Restructuring - Charges Activities by Type of Cost (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	$ 150	$ 159	$ 318	$ 346
Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	35	25	82	153
Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	73	98	126	132
Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	42	36	110	61
Cost of sales
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	25	65	93	99
Cost of sales | Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Cost of sales | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	31	64	56	98
Cost of sales | Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	(6)	1	37	1
Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	11	32	22	32
Selling, general and administrative | Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Selling, general and administrative | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	11	32	22	32
Selling, general and administrative | Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Research and development
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	31	3	48	3
Research and development | Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Research and development | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	31	2	48	2
Research and development | Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	1	0	1
Restructuring costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	83	59	155	212
Restructuring costs | Separation Costs
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	35	25	82	153
Restructuring costs | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	0	0	0	0
Restructuring costs | Other
Restructuring Cost and Reserve [Line Items]
Total pretax restructuring costs	$ 48	$ 34	$ 73	$ 59

Restructuring - Activities by P

Restructuring - Activities by Program (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			$ 759
Expense	$ 150	$ 159	318	$ 346
(Payments) receipts, net			(491)
Non-cash activity			(92)
Restructuring reserve, ending balance	494		494
Separation Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			690
Expense	35	25	82	153
(Payments) receipts, net			(328)
Non-cash activity			0
Restructuring reserve, ending balance	444		444
Accelerated Depreciation
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			0
Expense	73	98	126	132
(Payments) receipts, net			0
Non-cash activity			(126)
Restructuring reserve, ending balance	0		0
Other
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance			69
Expense	42	$ 36	110	$ 61
(Payments) receipts, net			(163)
Non-cash activity			34
Restructuring reserve, ending balance	$ 50		$ 50

Financial Instruments - Narrati

Financial Instruments - Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2020USD ($)interest_rate_swap	Dec. 31, 2019USD ($)	Jun. 30, 2020USD ($)interest_rate_swap	Jun. 30, 2019USD ($)	Feb. 29, 2020USD ($)
Derivative [Line Items]
Pretax net unrealized gain on derivatives maturing within next 12 months estimated to be reclassified from AOCI to sales			$ 9,000,000
Equity investments without readily determinable fair values	$ 487,000,000		487,000,000	$ 465,000,000
Unrealized gains recognized on investments in equity securities without readily determinable fair value			18,000,000	4,000,000
Unrealized losses recognized on investments in equity securities without readily determinable fair values			3,000,000	10,000,000
Cumulative unrealized gains on investments	127,000,000		127,000,000
Cumulative unrealized losses on investments	24,000,000		24,000,000
Payments of contingent consideration			106,000,000	$ 85,000,000
Fair value of loans payable and long-term debt, including current portion	34,500,000,000	$ 28,800,000,000	34,500,000,000
Debt, carrying amount	30,900,000,000	26,300,000,000	30,900,000,000
Accounts Receivable, Sale	1,900,000,000	2,700,000,000
Cash collateral received from counterparties	38,000,000	34,000,000	38,000,000
Cash collateral advanced to counterparties	0	0	0
Total swap notional amount	23,436,000,000	30,666,000,000	23,436,000,000
Face amount of debt	4,500,000,000		4,500,000,000
Level 2
Derivative [Line Items]
Cash equivalents	10,400,000,000	8,900,000,000	10,400,000,000
Derivatives Designated as Hedging Instruments
Derivative [Line Items]
Total swap notional amount	12,247,000,000	14,728,000,000	$ 12,247,000,000
Derivatives Designated as Hedging Instruments | Maximum
Derivative [Line Items]
Maximum average period of maturities of contracts in years (less than)			2 years
Derivatives Not Designated as Hedging Instruments
Derivative [Line Items]
Total swap notional amount	$ 11,189,000,000	$ 15,938,000,000	$ 11,189,000,000
Derivatives Not Designated as Hedging Instruments | Maximum
Derivative [Line Items]
Maximum average period of maturities of contracts in years (less than)			1 year
1.85% Notes Due 2020
Derivative [Line Items]
Face amount of debt					$ 1,250,000,000
Stated interest rate (as percent)					1.85%
Interest rate swap contracts
Derivative [Line Items]
Number of interest rate swaps held (in interest rate swaps)	14		14		5
Total swap notional amount					$ 250,000,000

Financial Instruments - Effect

Financial Instruments - Effect of Net Investment Hedges (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income	$ 8	$ 17	$ 5	$ 7
Foreign exchange contracts | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing	(4)	(8)	(11)	(15)
Euro-denominated notes
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income	72	28	21	(2)
Euro-denominated notes | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing	$ 0	$ 0	$ 0	$ 0

Financial Instruments - Summary

Financial Instruments - Summary of Interest Rate Swaps Held (Details)	Jun. 30, 2020USD ($)interest_rate_swap	Feb. 29, 2020USD ($)	Dec. 31, 2019USD ($)
Derivative [Line Items]
Par Value of Debt	$ 4,500,000,000
Total swap notional amount	$ 23,436,000,000		$ 30,666,000,000
Interest rate swap contracts
Derivative [Line Items]
Number of Interest Rate Swaps Held (in interest rate swaps)	14	5
Total swap notional amount		$ 250,000,000
3.875% notes due 2021 | Interest rate swap contracts
Derivative [Line Items]
Stated interest rate (as percent)	3.875%
Par Value of Debt	$ 1,150,000,000
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap	5
Total swap notional amount	$ 1,150,000,000
2.40% notes due 2022 | Interest rate swap contracts
Derivative [Line Items]
Stated interest rate (as percent)	2.40%
Par Value of Debt	$ 1,000,000,000
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap	4
Total swap notional amount	$ 1,000,000,000
2.35% notes due 2022 | Interest rate swap contracts
Derivative [Line Items]
Stated interest rate (as percent)	2.35%
Par Value of Debt	$ 1,250,000,000
Number of Interest Rate Swaps Held (in interest rate swaps) | interest_rate_swap	5
Total swap notional amount	$ 1,250,000,000

Financial Instruments - Fair Va

Financial Instruments - Fair Value Hedges (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Loans payable and current portion of long-term debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Hedged Liabilities	$ 1,160	$ 1,249
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount	10	(1)
Long-Term Debt
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Carrying Amount of Hedged Liabilities	2,318	3,409
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount	$ 71	$ 14

Financial Instruments - Fair _2

Financial Instruments - Fair Value of Derivatives Segregated between those Derivatives that are Designated as Hedging Instruments and those that are Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	$ 328	$ 288
Fair Value of Derivative, Liability	131	97
U.S Dollar Notional Amount	23,436	30,666
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	235	222
Fair Value of Derivative, Liability	28	24
U.S Dollar Notional Amount	12,247	14,728
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	93	66
Fair Value of Derivative, Liability	103	73
U.S Dollar Notional Amount	11,189	15,938
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	10	0
U.S Dollar Notional Amount	1,150	0
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	72	15
U.S Dollar Notional Amount	2,250	3,400
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	0	1
U.S Dollar Notional Amount	0	1,250
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	83	152
U.S Dollar Notional Amount	4,959	6,117
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	70	55
U.S Dollar Notional Amount	1,993	2,160
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	27	22
U.S Dollar Notional Amount	1,884	1,748
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1	1
U.S Dollar Notional Amount	11	53
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	93	66
U.S Dollar Notional Amount	5,324	7,245
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	103	73
U.S Dollar Notional Amount	$ 5,865	$ 8,693

Financial Instruments - Informa

Financial Instruments - Information on Derivative Positions Subject to Master Netting Arrangements as if they were Presented on a Net Basis (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross amounts recognized in the consolidated balance sheet, asset	$ 328,000,000	$ 288,000,000
Gross amount subject to offset in master netting arrangements not offset in the condensed balance sheet, asset	(115,000,000)	(84,000,000)
Cash collateral received, asset	(38,000,000)	(34,000,000)
Net amounts, asset	175,000,000	170,000,000
Gross amounts recognized in the consolidated balance sheet, liability	131,000,000	97,000,000
Gross amount subject to offset in master netting arrangements not offset in the condensed balance sheet, liability	(115,000,000)	(84,000,000)
Cash collateral received, liability	0	0
Net amounts, liability	$ 16,000,000	$ 13,000,000

Financial Instruments - Locatio

Financial Instruments - Location and Amount of Pretax (Gains) Losses of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 10,872	$ 11,760	$ 22,929	$ 22,575
Other (income) expense, net	(390)	140	(318)	327
Other comprehensive income (loss)	(2)	(16)	(200)	183
Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in OCI on derivatives	(1)	(1)	(2)	(5)
Interest rate swap contracts | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	1	55	68	88
Derivatives designated as hedging instruments	(8)	(45)	(76)	(68)
Amount of gain recognized in Other (income) expense, net on derivatives	(1)	(1)	(2)	(2)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (loss) gain recognized in OCI on derivatives	(109)	10	69	(2)
Increase (decrease) in Sales as a result of AOCI reclassifications	(42)	(75)	(88)	(119)
Foreign exchange contracts | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 42	$ 75	$ 88	$ 119

Financial Instruments - Income

Financial Instruments - Income Statement Effects on Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Foreign currency | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	$ 49	$ 2	$ (131)	$ 120
Forecasted transactions | Sales
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	4	(6)	(3)	4
Treasury lock | Other (income) expense, net
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	$ 9	$ 0	$ 9	$ 0

Financial Instruments - Infor_2

Financial Instruments - Information on Available-for-sale Investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	$ 76		$ 76		$ 1,768
Debt securities, unrealized gains	0		0		17
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	76		76		1,785
Publicly traded equity securities, fair value	1,307		1,307		838
Total debt and publicly traded equity securities, fair value	1,383		1,383		2,623
Unrealized net losses (gains)	(464)	$ 39	(469)	$ (75)
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	74		74		266
Debt securities, unrealized gains	0		0		3
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	74		74		269
Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	2		2		0
Debt securities, unrealized gains	0		0		0
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	2		2		0
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	0		0		668
Debt securities, unrealized gains	0		0		0
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	0		0		668
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	0		0		608
Debt securities, unrealized gains	0		0		13
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	0		0		621
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	0		0		226
Debt securities, unrealized gains	0		0		1
Debt securities, unrealized losses	0		0		0
Debt securities, fair value	$ 0		$ 0		$ 227

Financial Instruments - Financi

Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Assets
Investments	$ 76	$ 1,785
Publicly traded equity securities	1,307	838
Derivative assets	328	288
Liabilities
Contingent consideration	798	767	$ 753	$ 788
Derivative liabilities	131	97
Foreign government bonds
Assets
Investments	2	0
Corporate notes and bonds
Assets
Investments	0	621
Commercial paper
Assets
Investments	0	668
Asset-backed securities
Assets
Investments	$ 0	227
Liabilities
Primary weighted average life of collateral	5 years
U.S. government and agency securities
Assets
Investments	$ 74	269
Fair Value, Measurements, Recurring
Assets
Investments	1,251	2,243
Other assets	132	380
Derivative assets	328	288
Total assets	1,711	2,911
Liabilities
Contingent consideration	798	767
Derivative liabilities	131	97
Total liabilities	929	864
Fair Value, Measurements, Recurring | Foreign exchange contracts
Assets
Derivative assets	142	169
Liabilities
Derivative liabilities	128	95
Fair Value, Measurements, Recurring | Interest rate swap contracts
Assets
Derivative assets	82	15
Fair Value, Measurements, Recurring | Currency options
Assets
Derivative assets	104	104
Liabilities
Derivative liabilities	3	1
Fair Value, Measurements, Recurring | Interest rate swap contracts
Liabilities
Derivative liabilities	0	1
Fair Value, Measurements, Recurring | Level 1
Assets
Investments	1,249	518
Other assets	132	380
Derivative assets	0	0
Total assets	1,381	898
Liabilities
Contingent consideration	0	0
Derivative liabilities	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Foreign exchange contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Interest rate swap contracts
Assets
Derivative assets	0	0
Fair Value, Measurements, Recurring | Level 1 | Currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Interest rate swap contracts
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 2
Assets
Investments	2	1,725
Other assets	0	0
Derivative assets	328	288
Total assets	330	2,013
Liabilities
Contingent consideration	0	0
Derivative liabilities	131	97
Total liabilities	131	97
Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Assets
Derivative assets	142	169
Liabilities
Derivative liabilities	128	95
Fair Value, Measurements, Recurring | Level 2 | Interest rate swap contracts
Assets
Derivative assets	82	15
Fair Value, Measurements, Recurring | Level 2 | Currency options
Assets
Derivative assets	104	104
Liabilities
Derivative liabilities	3	1
Fair Value, Measurements, Recurring | Level 2 | Interest rate swap contracts
Liabilities
Derivative liabilities	0	1
Fair Value, Measurements, Recurring | Level 3
Assets
Investments	0	0
Other assets	0	0
Derivative assets	0	0
Total assets	0	0
Liabilities
Contingent consideration	798	767
Derivative liabilities	0	0
Total liabilities	798	767
Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 3 | Interest rate swap contracts
Assets
Derivative assets	0	0
Fair Value, Measurements, Recurring | Level 3 | Currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 3 | Interest rate swap contracts
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Foreign government bonds
Assets
Investments	2	0
Fair Value, Measurements, Recurring | Foreign government bonds | Level 1
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Foreign government bonds | Level 2
Assets
Investments	2	0
Fair Value, Measurements, Recurring | Foreign government bonds | Level 3
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Corporate notes and bonds
Assets
Investments	0	621
Fair Value, Measurements, Recurring | Corporate notes and bonds | Level 1
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Corporate notes and bonds | Level 2
Assets
Investments	0	621
Fair Value, Measurements, Recurring | Corporate notes and bonds | Level 3
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Commercial paper
Assets
Investments	0	668
Fair Value, Measurements, Recurring | Commercial paper | Level 1
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Commercial paper | Level 2
Assets
Investments	0	668
Fair Value, Measurements, Recurring | Commercial paper | Level 3
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Asset-backed securities
Assets
Investments	0	227
Fair Value, Measurements, Recurring | Asset-backed securities | Level 1
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Asset-backed securities | Level 2
Assets
Investments	0	227
Fair Value, Measurements, Recurring | Asset-backed securities | Level 3
Assets
Investments	0	0
Fair Value, Measurements, Recurring | U.S. government and agency securities
Assets
Investments	0	209
Other assets	74	60
Fair Value, Measurements, Recurring | U.S. government and agency securities | Level 1
Assets
Investments	0	0
Other assets	74	60
Fair Value, Measurements, Recurring | U.S. government and agency securities | Level 2
Assets
Investments	0	209
Other assets	0	0
Fair Value, Measurements, Recurring | U.S. government and agency securities | Level 3
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Publicly traded equity securities
Assets
Publicly traded equity securities	1,249	518
Other assets	58	320
Fair Value, Measurements, Recurring | Publicly traded equity securities | Level 1
Assets
Publicly traded equity securities	1,249	518
Other assets	58	320
Fair Value, Measurements, Recurring | Publicly traded equity securities | Level 2
Assets
Publicly traded equity securities	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Publicly traded equity securities | Level 3
Assets
Publicly traded equity securities	0	0
Other assets	$ 0	$ 0

Financial Instruments - Infor_3

Financial Instruments - Information About Changes in Liabilities for Contingent Consideration (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ 767	$ 788
Additions	97	0
Changes in estimated fair value	40	50
Payments	(106)	(85)
Fair value, ending balance	798	753
Current liability			$ 138
Contingent consideration	798	$ 753	798
Sanofi Pasteur
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	625
Fair value, ending balance	608
Contingent consideration	$ 625		$ 608
Contingent consideration, measurement input, discount rate (as percent)			0.115
Measurement Input, Discount Rate | Sanofi Pasteur
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration, measurement input, discount rate (as percent)			0.08

Inventories - Inventories (Deta

Inventories - Inventories (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Finished goods	$ 2,032	$ 1,772
Raw materials and work in process	5,874	5,650
Supplies	190	207
Total (approximates current cost)	8,096	7,629
Decrease to LIFO cost	(119)	(171)
Total current and noncurrent inventories	7,977	7,458
Recognized as:
Inventories	6,056	5,978
Other assets	$ 1,921	$ 1,480

Inventories - Narrative (Detail

Inventories - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Inventory [Line Items]
Inventories classified in Other assets	$ 1,921	$ 1,480
Inventories Not Expected to be Sold Within One Year
Inventory [Line Items]
Inventories classified in Other assets	1,700	1,300
Inventories Produced in Preparation for Product Launches
Inventory [Line Items]
Inventories classified in Other assets	$ 266	$ 168

Long-Term Debt - Narrative (Det

Long-Term Debt - Narrative (Details)	Jun. 30, 2020USD ($)
Debt Instrument [Line Items]
Face amount of debt	$ 4,500,000,000
0.75% notes due 2026
Debt Instrument [Line Items]
Face amount of debt	$ 1,000,000,000
Stated interest rate (as percent)	0.75%
1.45% notes due 2030
Debt Instrument [Line Items]
Face amount of debt	$ 1,250,000,000
Stated interest rate (as percent)	1.45%
2.35% notes due 2040
Debt Instrument [Line Items]
Face amount of debt	$ 1,000,000,000
Stated interest rate (as percent)	2.35%
2.45% notes due 2050
Debt Instrument [Line Items]
Face amount of debt	$ 1,250,000,000
Stated interest rate (as percent)	2.45%

Contingencies - Narrative (Deta

Contingencies - Narrative (Details) $ in Millions	1 Months Ended	6 Months Ended
	Mar. 31, 2014Case	Jun. 30, 2020USD ($)ClaimCase	Dec. 31, 2019USD ($)
Legal Defense Costs
Loss Contingencies [Line Items]
Legal defense costs reserve | $		$ 265	$ 240
Zetia antitrust litigation [Member]
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters) | Claim		35
Patents [Member]
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters)		3
Loss Contingency, Claims Settled, Number		5
Fosamax
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters)		3,590
Fosamax | Femur Fracture Litigation | Federal
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters)		970
Loss contingency, claims dismissed, number (in legal matters)	650
Loss contingency, claims on appeal, number (in legal matters)	515
Fosamax | Femur Fracture Litigation | New Jersey state court
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters)		2,345
Fosamax | Femur Fracture Litigation | California state court
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters)		275
Fosamax | Femur Fracture Litigation | Other state courts
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters)		4
Januvia
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters) | Claim		1,440
Januvia | Other state courts
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters) | Claim		6
Januvia | Cases Company Agreed To Toll Statute Of Limitations
Loss Contingencies [Line Items]
Loss contingency, pending claims, number (in legal matters) | Claim		50

Equity - Rollforward Reconcilia

Equity - Rollforward Reconciliations (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, beginning balance (in shares)			3,577,103,522
Equity, beginning balance	$ 26,300	$ 27,670	$ 26,001	$ 26,882
Net income attributable to Merck & Co., Inc.	3,002	2,670	6,221	5,585
Other comprehensive income (loss), net of taxes	(2)	(16)	(200)	183
Cash dividends declared on common stock	(1,550)	(1,440)	(3,099)	(2,869)
Treasury stock shares purchased		(1,235)	(1,281)	(2,325)
Share-based compensation plans and other	(13)	117	94	360
Net income (loss) attributable to noncontrolling interests	8	(26)	$ 8	(79)
Noncontrolling interest, changes in ownership interest, other		(3)
Distributions attributable to noncontrolling interests	$ (1)
Shares, ending balance (in shares)	3,577,103,522		3,577,103,522
Equity, ending balance	$ 27,744	$ 27,737	$ 27,744	$ 27,737
Cash dividends declared on common stock (in dollars per share)	$ 0.61	$ 0.55	$ 1.22	$ 1.10
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, beginning balance (in shares)	3,577,000,000	3,577,000,000	3,577,000,000	3,577,000,000
Equity, beginning balance	$ 1,788	$ 1,788	$ 1,788	$ 1,788
Shares, ending balance (in shares)	3,577,000,000	3,577,000,000	3,577,000,000	3,577,000,000
Equity, ending balance	$ 1,788	$ 1,788	$ 1,788	$ 1,788
Other Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	39,697	38,768	39,660	38,808
Treasury stock shares purchased		1,000		1,000
Share-based compensation plans and other	(324)	(284)	(287)	(324)
Equity, ending balance	39,373	39,484	39,373	39,484
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	48,272	44,065	46,602	42,579
Net income attributable to Merck & Co., Inc.	3,002	2,670	6,221	5,585
Cash dividends declared on common stock	(1,550)	(1,440)	(3,099)	(2,869)
Equity, ending balance	49,724	45,295	49,724	45,295
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	(6,391)	(5,346)	(6,193)	(5,545)
Other comprehensive income (loss), net of taxes	(2)	(16)	(200)	183
Equity, ending balance	$ (6,393)	$ (5,362)	$ (6,393)	$ (5,362)
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares, beginning balance (in shares)	1,053,000,000	994,000,000	1,038,000,000	985,000,000
Equity, beginning balance	$ (57,161)	$ (51,736)	$ (55,950)	$ (50,929)
Treasury stock shares purchased (in shares)		24,000,000	16,000,000	38,000,000
Treasury stock shares purchased		$ (2,235)	$ (1,281)	$ (3,325)
Share-based compensation plans and other (in shares)	(5,000,000)	(8,000,000)	(6,000,000)	(13,000,000)
Share-based compensation plans and other	$ 311	$ 401	$ 381	$ 684
Shares, ending balance (in shares)	1,048,000,000	1,010,000,000	1,048,000,000	1,010,000,000
Equity, ending balance	$ (56,850)	$ (53,570)	$ (56,850)	$ (53,570)
Non- controlling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity, beginning balance	95	131	94	181
Net income (loss) attributable to noncontrolling interests	8	(26)	8	(79)
Noncontrolling interest, changes in ownership interest, other		(3)
Distributions attributable to noncontrolling interests	(1)
Equity, ending balance	$ 102	$ 102	$ 102	$ 102

Share-Based Compensation Plan_2

Share-Based Compensation Plans - Expense Allocations (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Payment Arrangement [Abstract]
Pretax share-based compensation expense	$ 121	$ 111	$ 229	$ 204
Income tax benefit	(16)	(15)	(31)	(28)
Total share-based compensation expense, net of taxes	$ 105	$ 96	$ 198	$ 176

Share-Based Compensation Plan_3

Share-Based Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	4,000	3,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 77.67	$ 80
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 9.93	$ 10.63
Total pretax unrecognized compensation expense related to nonvested stock options, RSU and PSU awards	$ 908
Weighted average period in years of recognition for nonvested stock options, RSU and PSU awards	2 years 2 months 12 days
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	6,000	6,000
Weighted-average fair value per share granted (in dollars per share)	$ 77.74	$ 76.31
Performance Share Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	773	609
Weighted-average fair value per share granted (in dollars per share)	$ 75.22	$ 90.50

Share-Based Compensation Plan_4

Share-Based Compensation Plans - Assumptions Used for Options Granted (Details)	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Share-based Payment Arrangement [Abstract]
Expected dividend yield	3.10%	3.20%
Risk-free interest rate	0.40%	2.40%
Expected volatility	22.10%	18.70%
Expected life (years)	5 years 9 months 18 days	5 years 10 months 24 days

Pension and Other Postretirem_3

Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Postretirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 13	$ 12	$ 26	$ 24
Interest cost	14	18	29	35
Expected return on plan assets	(19)	(18)	(37)	(36)
Amortization of unrecognized prior service credit	(22)	(21)	(45)	(43)
Curtailments	0	(1)	(1)	(1)
Net periodic benefit cost	(14)	(10)	(28)	(21)
U.S. | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	88	74	175	144
Interest cost	109	113	217	228
Expected return on plan assets	(195)	(205)	(388)	(411)
Amortization of unrecognized prior service credit	(12)	(12)	(25)	(25)
Net loss amortization	76	35	152	70
Termination benefits	1	3	4	5
Curtailments	0	0	2	1
Settlements	9	0	9	0
Net periodic benefit cost	76	8	146	12
International | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	74	60	148	120
Interest cost	33	44	68	89
Expected return on plan assets	(101)	(107)	(205)	(214)
Amortization of unrecognized prior service credit	(3)	(3)	(6)	(6)
Net loss amortization	31	16	62	31
Termination benefits	0	1	1	1
Curtailments	0	0	(1)	0
Settlements	2	0	2	0
Net periodic benefit cost	$ 36	$ 11	$ 69	$ 21

Pension and Other Postretirem_4

Pension and Other Postretirement Benefit Plans Pension and Other Postretirement Benefit Plans (Narrative) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020USD ($)
Pension and Other Postretirement Benefit Plans (Narrative) [Abstract]
Defined Benefit Plan, Expected Future Employer Contributions, Current Fiscal Year, Description	$ 220
Defined Benefit Plan, Plan Assets, Contributions by Employer	$ 170

Other (Income) Expense, Net (De

Other (Income) Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Component of Other Income / Expense of Nonoperating [Line Items]
Interest income		$ (14)	$ (75)	$ (39)	$ (164)
Interest expense		209	233	421	442
Exchange losses		24	27	78	128
Income from investments in equity securities, net (1)		(551)	(58)	(603)	(32)
Net periodic defined benefit plan (credit) cost other than service cost		(80)	(140)	(170)	(281)
Other, net		22	153	(5)	234
Other (income) expense, net		$ (390)	$ 140	$ (318)	$ 327
Forecast
Component of Other Income / Expense of Nonoperating [Line Items]
Income from investments in equity securities, net (1)	$ 300

Other (Income) Expense, Net Oth

Other (Income) Expense, Net Other (Income) Expense, Net - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Component of Other Income / Expense of Nonoperating [Line Items]
Interest paid		$ 387	$ 356
Healthcare Services Segment
Component of Other Income / Expense of Nonoperating [Line Items]
Goodwill, Impairment Loss	$ 78		$ 162

Taxes on Income (Details)

Taxes on Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Examination [Line Items]
Effective income tax rate (as percent)	14.50%	18.90%	15.30%	13.00%
Internal Revenue Service (IRS) | Domestic Tax Authority
Income Tax Examination [Line Items]
Tax benefit recognized related to settlement				$ 360
Income taxes paid				$ 107

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income attributable to Merck & Co., Inc.	$ 3,002	$ 2,670	$ 6,221	$ 5,585
Average common shares outstanding	2,527	2,574	2,531	2,579
Common shares issuable (1)	9	14	11	17
Average common shares outstanding assuming dilution	2,536	2,588	2,542	2,596
Basic earnings per common share attributable to Merck & Co., Inc. common shareholders	$ 1.19	$ 1.04	$ 2.46	$ 2.17
Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders	$ 1.18	$ 1.03	$ 2.45	$ 2.15
Common shares issuable under share-based compensation plans excluded from diluted earnings per common share because the effect would have been antidilutive (in shares)	8	3	4	4

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	$ 26,300	$ 27,670	$ 26,001	$ 26,882
Other comprehensive income (loss) before reclassification adjustments, pretax	(68)	40	(220)	258
Tax	45	4	2	7
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(23)	44	(218)	265
Reclassification adjustments, pretax	27	(73)	28	(101)
Tax	(6)	13	(10)	19
Reclassification adjustments, net of taxes	21	(60)	18	(82)
Other comprehensive income (loss), net of taxes	(2)	(16)	(200)	183
Equity, ending balance	27,744	27,737	27,744	27,737
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	135	118	31	166
Other comprehensive income (loss) before reclassification adjustments, pretax	(110)	10	68	(3)
Tax	23	(2)	(14)	1
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(87)	8	54	(2)
Reclassification adjustments, pretax	(42)	(76)	(89)	(124)
Tax	9	16	19	26
Reclassification adjustments, net of taxes	(33)	(60)	(70)	(98)
Other comprehensive income (loss), net of taxes	(120)	(52)	(16)	(100)
Equity, ending balance	15	66	15	66
Investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	0	4	18	(78)
Other comprehensive income (loss) before reclassification adjustments, pretax	0	55	3	131
Tax	0	0	0	0
Other comprehensive income (loss) before reclassification adjustments, net of taxes	0	55	3	131
Reclassification adjustments, pretax	0	(11)	(21)	(5)
Tax	0	0	0	0
Reclassification adjustments, net of taxes	0	(11)	(21)	(5)
Other comprehensive income (loss), net of taxes	0	44	(18)	126
Equity, ending balance	0	48	0	48
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(4,201)	(3,541)	(4,261)	(3,556)
Other comprehensive income (loss) before reclassification adjustments, pretax	(21)	0	(21)	(1)
Tax	6	0	11	6
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(15)	0	(10)	5
Reclassification adjustments, pretax	69	14	138	28
Tax	(15)	(3)	(29)	(7)
Reclassification adjustments, net of taxes	54	11	109	21
Other comprehensive income (loss), net of taxes	39	11	99	26
Equity, ending balance	(4,162)	(3,530)	(4,162)	(3,530)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(2,325)	(1,927)	(1,981)	(2,077)
Other comprehensive income (loss) before reclassification adjustments, pretax	63	(25)	(270)	131
Tax	16	6	5	0
Other comprehensive income (loss) before reclassification adjustments, net of taxes	79	(19)	(265)	131
Reclassification adjustments, pretax	0	0	0	0
Tax	0	0	0	0
Reclassification adjustments, net of taxes	0	0	0	0
Other comprehensive income (loss), net of taxes	79	(19)	(265)	131
Equity, ending balance	(2,246)	(1,946)	(2,246)	(1,946)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Equity, beginning balance	(6,391)	(5,346)	(6,193)	(5,545)
Equity, ending balance	$ (6,393)	$ (5,362)	$ (6,393)	$ (5,362)

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details) $ in Billions	3 Months Ended		6 Months Ended
	Jun. 30, 2020USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)segment	Jun. 30, 2019USD ($)
Segment Reporting [Abstract]
Number of operating segments | segment			3
Sales discounts | $	$ 3	$ 2.9	$ 6.2	$ 5.5

Segment Reporting - Sales of Co

Segment Reporting - Sales of Company's Products (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Sales	$ 10,872	$ 11,760	$ 22,929	$ 22,575
Proceeds from Sale of Intangible Assets			85	15
Operating Segments
Segment Reporting Information [Line Items]
Sales	10,780	11,632	22,671	22,359
Other
Segment Reporting Information [Line Items]
Sales	92	128	258	216
United States
Segment Reporting Information [Line Items]
Sales	4,634	5,193	9,771	9,748
United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	4,612	5,189	9,733	9,736
United States | Other
Segment Reporting Information [Line Items]
Sales	22	4	38	12
International
Segment Reporting Information [Line Items]
Sales	6,238	6,567	13,158	12,828
International | Operating Segments
Segment Reporting Information [Line Items]
Sales	6,168	6,442	12,938	12,622
International | Other
Segment Reporting Information [Line Items]
Sales	70	125	220	206
Total Pharmaceutical segment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	9,679	10,460	20,334	20,123
Total Pharmaceutical segment sales | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	3,388	2,634	6,672	4,903
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	178	111	323	190
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	151	97	279	171
Total Pharmaceutical segment sales | Operating Segments | Emend
Segment Reporting Information [Line Items]
Sales	33	121	76	237
Total Pharmaceutical segment sales | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	656	886	1,753	1,724
Total Pharmaceutical segment sales | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	378	675	813	1,171
Total Pharmaceutical segment sales | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	168	172	391	383
Total Pharmaceutical segment sales | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	117	170	373	355
Total Pharmaceutical segment sales | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	28	58	88	105
Total Pharmaceutical segment sales | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	224	278	524	533
Total Pharmaceutical segment sales | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	73	193	168	383
Total Pharmaceutical segment sales | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	63	38	123	70
Total Pharmaceutical segment sales | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	64	71	115	130
Total Pharmaceutical segment sales | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	43	78	108	150
Total Pharmaceutical segment sales | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	43	67	98	129
Total Pharmaceutical segment sales | Operating Segments | Cubicin
Segment Reporting Information [Line Items]
Sales	32	67	78	155
Total Pharmaceutical segment sales | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	32	27	69	53
Total Pharmaceutical segment sales | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	191	214	406	422
Total Pharmaceutical segment sales | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	73	98	160	221
Total Pharmaceutical segment sales | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	84	76	163	143
Total Pharmaceutical segment sales | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	196	247	441	502
Total Pharmaceutical segment sales | Operating Segments | Zepatier
Segment Reporting Information [Line Items]
Sales	39	108	94	221
Total Pharmaceutical segment sales | Operating Segments | Zetia
Segment Reporting Information [Line Items]
Sales	137	156	282	296
Total Pharmaceutical segment sales | Operating Segments | Vytorin
Segment Reporting Information [Line Items]
Sales	39	76	92	174
Total Pharmaceutical segment sales | Operating Segments | Atozet
Segment Reporting Information [Line Items]
Sales	115	92	238	186
Total Pharmaceutical segment sales | Operating Segments | Alliance revenue - Adempas (2)
Segment Reporting Information [Line Items]
Sales	79	51	133	94
Total Pharmaceutical segment sales | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	57	53	113	100
Total Pharmaceutical segment sales | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	854	908	1,628	1,732
Total Pharmaceutical segment sales | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	490	533	993	1,063
Total Pharmaceutical segment sales | Operating Segments | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	132	183	326	382
Total Pharmaceutical segment sales | Operating Segments | NuvaRing
Segment Reporting Information [Line Items]
Sales	63	240	126	459
Total Pharmaceutical segment sales | Operating Segments | Singulair
Segment Reporting Information [Line Items]
Sales	100	160	255	352
Total Pharmaceutical segment sales | Operating Segments | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	98	109	200	213
Total Pharmaceutical segment sales | Operating Segments | Arcoxia
Segment Reporting Information [Line Items]
Sales	65	75	135	149
Total Pharmaceutical segment sales | Operating Segments | Nasonex
Segment Reporting Information [Line Items]
Sales	49	72	120	168
Total Pharmaceutical segment sales | Operating Segments | Follistim AQ
Segment Reporting Information [Line Items]
Sales	44	63	85	121
Total Pharmaceutical segment sales | Operating Segments | Other pharmaceutical (3)
Segment Reporting Information [Line Items]
Sales	1,103	1,203	2,293	2,283
Total Pharmaceutical segment sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	4,270	4,807	8,984	9,022
Total Pharmaceutical segment sales | United States | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	2,043	1,498	3,949	2,782
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	105	66	190	116
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	98	54	188	104
Total Pharmaceutical segment sales | United States | Operating Segments | Emend
Segment Reporting Information [Line Items]
Sales	6	67	11	130
Total Pharmaceutical segment sales | United States | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	168	456	629	818
Total Pharmaceutical segment sales | United States | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	263	500	596	843
Total Pharmaceutical segment sales | United States | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	100	104	241	258
Total Pharmaceutical segment sales | United States | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	21	123	203	248
Total Pharmaceutical segment sales | United States | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	17	38	47	67
Total Pharmaceutical segment sales | United States | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	107	129	250	248
Total Pharmaceutical segment sales | United States | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	6	100	14	191
Total Pharmaceutical segment sales | United States | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	28	19	55	37
Total Pharmaceutical segment sales | United States | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	1	0	1	1
Total Pharmaceutical segment sales | United States | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	0	18	6	31
Total Pharmaceutical segment sales | United States | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	(2)	3	1	4
Total Pharmaceutical segment sales | United States | Operating Segments | Cubicin
Segment Reporting Information [Line Items]
Sales	10	22	25	64
Total Pharmaceutical segment sales | United States | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	17	13	37	25
Total Pharmaceutical segment sales | United States | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	22	21	49	45
Total Pharmaceutical segment sales | United States | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	76	94	151	202
Total Pharmaceutical segment sales | United States | Operating Segments | Zepatier
Segment Reporting Information [Line Items]
Sales	15	39	33	72
Total Pharmaceutical segment sales | United States | Operating Segments | Zetia
Segment Reporting Information [Line Items]
Sales	(1)	6	(4)	6
Total Pharmaceutical segment sales | United States | Operating Segments | Vytorin
Segment Reporting Information [Line Items]
Sales	2	3	5	6
Total Pharmaceutical segment sales | United States | Operating Segments | Atozet
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Alliance revenue - Adempas (2)
Segment Reporting Information [Line Items]
Sales	73	49	122	89
Total Pharmaceutical segment sales | United States | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	413	471	768	855
Total Pharmaceutical segment sales | United States | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	143	166	256	333
Total Pharmaceutical segment sales | United States | Operating Segments | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	87	136	237	285
Total Pharmaceutical segment sales | United States | Operating Segments | NuvaRing
Segment Reporting Information [Line Items]
Sales	35	206	61	391
Total Pharmaceutical segment sales | United States | Operating Segments | Singulair
Segment Reporting Information [Line Items]
Sales	4	8	9	13
Total Pharmaceutical segment sales | United States | Operating Segments | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	4	6	12	10
Total Pharmaceutical segment sales | United States | Operating Segments | Arcoxia
Segment Reporting Information [Line Items]
Sales	0	0	0	0
Total Pharmaceutical segment sales | United States | Operating Segments | Nasonex
Segment Reporting Information [Line Items]
Sales	4	(1)	10	(2)
Total Pharmaceutical segment sales | United States | Operating Segments | Follistim AQ
Segment Reporting Information [Line Items]
Sales	20	24	40	53
Total Pharmaceutical segment sales | United States | Operating Segments | Other pharmaceutical (3)
Segment Reporting Information [Line Items]
Sales	385	369	792	697
Total Pharmaceutical segment sales | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	5,409	5,653	11,350	11,101
Total Pharmaceutical segment sales | International | Operating Segments | Keytruda
Segment Reporting Information [Line Items]
Sales	1,345	1,136	2,722	2,121
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	73	45	133	74
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	53	43	91	67
Total Pharmaceutical segment sales | International | Operating Segments | Emend
Segment Reporting Information [Line Items]
Sales	27	54	65	107
Total Pharmaceutical segment sales | International | Operating Segments | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	488	430	1,124	906
Total Pharmaceutical segment sales | International | Operating Segments | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	115	174	217	328
Total Pharmaceutical segment sales | International | Operating Segments | RotaTeq
Segment Reporting Information [Line Items]
Sales	68	68	150	125
Total Pharmaceutical segment sales | International | Operating Segments | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	96	47	170	107
Total Pharmaceutical segment sales | International | Operating Segments | Vaqta
Segment Reporting Information [Line Items]
Sales	11	20	41	39
Total Pharmaceutical segment sales | International | Operating Segments | Bridion
Segment Reporting Information [Line Items]
Sales	117	149	274	285
Total Pharmaceutical segment sales | International | Operating Segments | Noxafil
Segment Reporting Information [Line Items]
Sales	67	93	154	192
Total Pharmaceutical segment sales | International | Operating Segments | Prevymis
Segment Reporting Information [Line Items]
Sales	35	18	68	33
Total Pharmaceutical segment sales | International | Operating Segments | Primaxin
Segment Reporting Information [Line Items]
Sales	63	70	114	129
Total Pharmaceutical segment sales | International | Operating Segments | Invanz
Segment Reporting Information [Line Items]
Sales	43	60	102	118
Total Pharmaceutical segment sales | International | Operating Segments | Cancidas
Segment Reporting Information [Line Items]
Sales	45	64	98	125
Total Pharmaceutical segment sales | International | Operating Segments | Cubicin
Segment Reporting Information [Line Items]
Sales	21	45	53	91
Total Pharmaceutical segment sales | International | Operating Segments | Zerbaxa
Segment Reporting Information [Line Items]
Sales	15	14	32	28
Total Pharmaceutical segment sales | International | Operating Segments | Simponi
Segment Reporting Information [Line Items]
Sales	191	214	406	422
Total Pharmaceutical segment sales | International | Operating Segments | Remicade
Segment Reporting Information [Line Items]
Sales	73	98	160	221
Total Pharmaceutical segment sales | International | Operating Segments | Belsomra
Segment Reporting Information [Line Items]
Sales	61	55	114	98
Total Pharmaceutical segment sales | International | Operating Segments | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	120	153	290	300
Total Pharmaceutical segment sales | International | Operating Segments | Zepatier
Segment Reporting Information [Line Items]
Sales	24	68	62	149
Total Pharmaceutical segment sales | International | Operating Segments | Zetia
Segment Reporting Information [Line Items]
Sales	138	150	285	290
Total Pharmaceutical segment sales | International | Operating Segments | Vytorin
Segment Reporting Information [Line Items]
Sales	37	73	86	167
Total Pharmaceutical segment sales | International | Operating Segments | Atozet
Segment Reporting Information [Line Items]
Sales	115	92	238	186
Total Pharmaceutical segment sales | International | Operating Segments | Alliance revenue - Adempas (2)
Segment Reporting Information [Line Items]
Sales	6	2	11	5
Total Pharmaceutical segment sales | International | Operating Segments | Adempas
Segment Reporting Information [Line Items]
Sales	57	53	113	100
Total Pharmaceutical segment sales | International | Operating Segments | Januvia
Segment Reporting Information [Line Items]
Sales	441	437	860	877
Total Pharmaceutical segment sales | International | Operating Segments | Janumet
Segment Reporting Information [Line Items]
Sales	348	366	737	730
Total Pharmaceutical segment sales | International | Operating Segments | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	44	48	90	98
Total Pharmaceutical segment sales | International | Operating Segments | NuvaRing
Segment Reporting Information [Line Items]
Sales	28	34	65	68
Total Pharmaceutical segment sales | International | Operating Segments | Singulair
Segment Reporting Information [Line Items]
Sales	96	153	246	338
Total Pharmaceutical segment sales | International | Operating Segments | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	94	103	189	202
Total Pharmaceutical segment sales | International | Operating Segments | Arcoxia
Segment Reporting Information [Line Items]
Sales	65	75	135	149
Total Pharmaceutical segment sales | International | Operating Segments | Nasonex
Segment Reporting Information [Line Items]
Sales	45	73	110	170
Total Pharmaceutical segment sales | International | Operating Segments | Follistim AQ
Segment Reporting Information [Line Items]
Sales	24	39	45	67
Total Pharmaceutical segment sales | International | Operating Segments | Other pharmaceutical (3)
Segment Reporting Information [Line Items]
Sales	720	837	1,500	1,589
Total Animal Health segment sales | Operating Segments
Segment Reporting Information [Line Items]
Sales	1,101	1,124	2,314	2,149
Total Animal Health segment sales | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	648	671	1,386	1,282
Total Animal Health segment sales | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	453	453	928	867
Total Animal Health segment sales | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	342	335	726	628
Total Animal Health segment sales | United States | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	122	145	284	261
Total Animal Health segment sales | United States | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	220	190	442	367
Total Animal Health segment sales | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	759	789	1,588	1,521
Total Animal Health segment sales | International | Operating Segments | Livestock
Segment Reporting Information [Line Items]
Sales	526	526	1,102	1,021
Total Animal Health segment sales | International | Operating Segments | Companion Animals
Segment Reporting Information [Line Items]
Sales	233	263	486	500
Other segment sales (4) | Operating Segments
Segment Reporting Information [Line Items]
Sales	0	48	23	87
Other segment sales (4) | United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	0	47	23	86
Other segment sales (4) | International | Operating Segments
Segment Reporting Information [Line Items]
Sales	$ 0	$ 0	$ 0	$ 0

Segment Reporting - Revenues by

Segment Reporting - Revenues by Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue from External Customer [Line Items]
Sales	$ 10,872	$ 11,760	$ 22,929	$ 22,575
United States
Revenue from External Customer [Line Items]
Sales	4,634	5,193	9,771	9,748
Europe, Middle East and Africa
Revenue from External Customer [Line Items]
Sales	3,071	3,163	6,605	6,265
China
Revenue from External Customer [Line Items]
Sales	834	763	1,699	1,509
Japan
Revenue from External Customer [Line Items]
Sales	867	921	1,678	1,720
Asia Pacific (other than China and Japan)
Revenue from External Customer [Line Items]
Sales	666	716	1,394	1,461
Latin America
Revenue from External Customer [Line Items]
Sales	510	658	1,066	1,219
Other
Revenue from External Customer [Line Items]
Sales	$ 290	$ 346	$ 716	$ 653

Segment Reporting - Profits to

Segment Reporting - Profits to Income Before Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Profits	$ 3,519	$ 3,259	$ 7,357	$ 6,326
Interest income	14	75	39	164
Interest expense	(209)	(233)	(421)	(442)
Depreciation and amortization			(1,869)	(1,871)
Research and development	(2,123)	(2,189)	(4,331)	(4,119)
Restructuring costs	(83)	(59)	(155)	(212)
Total segment profits
Segment Reporting Information [Line Items]
Profits	6,967	7,518	14,923	14,510
Total segment profits | Pharmaceutical segment
Segment Reporting Information [Line Items]
Profits	6,560	7,115	14,036	13,690
Total segment profits | Animal Health segment
Segment Reporting Information [Line Items]
Profits	407	405	885	820
Total segment profits | Other segment
Segment Reporting Information [Line Items]
Profits	0	(2)	2	0
Other profits
Segment Reporting Information [Line Items]
Profits	61	94	200	124
Unallocated
Segment Reporting Information [Line Items]
Interest income	14	75	39	164
Interest expense	(209)	(233)	(421)	(442)
Depreciation and amortization	(390)	(427)	(772)	(786)
Research and development	(1,994)	(2,093)	(4,092)	(3,935)
Amortization of purchase accounting adjustments	(299)	(378)	(594)	(775)
Restructuring costs	(83)	(59)	(155)	(212)
Other unallocated, net	$ (548)	$ (1,238)	$ (1,771)	$ (2,322)