Merck & Co. (MRK) 10-K 26 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Jan. 31, 2020	Jun. 30, 2019
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Entity File Number	1-6571
Entity Registrant Name	Merck & Co., Inc.
City Area Code	908
Local Phone Number	740-4000
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
Title of 12(b) Security	Common Stock ($0.50 par value)
Trading Symbol	MRK
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		2,536,268,760
Entity Public Float			$ 215,106,000,000
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0000310158
Current Fiscal Year End Date	--12-31
Documents Incorporated by Reference	Proxy Statement for the Annual Meeting of Shareholders to be held May 26, 2020, to be filed with the
1.125% Notes due 2021
Document 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
Document 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
Document 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
Document 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
Document Information [Line Items]
Title of 12(b) Security	1.375% Notes due 2036
Trading Symbol	MRK 36A
Security Exchange Name	NYSE

Consolidated Statement of Incom

Consolidated Statement of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Sales	$ 46,840	$ 42,294	$ 40,122
Costs, Expenses and Other
Cost of sales	14,112	13,509	12,912
Selling, general and administrative	10,615	10,102	10,074
Research and development	9,872	9,752	10,339
Restructuring costs	638	632	776
Other (income) expense, net	139	(402)	(500)
Total Costs, Expenses and Other	35,376	33,593	33,601
Income Before Taxes	11,464	8,701	6,521
Taxes on Income	1,687	2,508	4,103
Net Income	9,777	6,193	2,418
Less: Net (Loss) Income Attributable to Noncontrolling Interests	(66)	(27)	24
Net Income Attributable to Merck & Co., Inc.	$ 9,843	$ 6,220	$ 2,394
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 3.84	$ 2.34	$ 0.88
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 3.81	$ 2.32	$ 0.87

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 9,843	$ 6,220	$ 2,394
Other Comprehensive (Loss) Income Net of Taxes:
Net unrealized (loss) gain on derivatives, net of reclassifications	(135)	297
Net unrealized (loss) gain on derivatives, net of reclassifications			(446)
Net unrealized gain (loss) on investments, net of reclassifications	96	(10)	(58)
Benefit plan net (loss) gain and prior service (cost) credit, net of amortization	(705)	(425)	419
Cumulative translation adjustment	96	(223)	401
Other comprehensive income (loss), net of taxes	(648)	(361)	316
Comprehensive Income Attributable to Merck & Co., Inc.	$ 9,195	$ 5,859	$ 2,710

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Current Assets
Cash and cash equivalents	$ 9,676	$ 7,965
Short-term investments	774	899
Accounts receivable (net of allowance for doubtful accounts of $86 in 2019 and $119 in 2018)	6,778	7,071
Inventories (excludes inventories of $1,480 in 2019 and $1,417 in 2018 classified in Other assets - see Note 7)	5,978	5,440
Other current assets	4,277	4,500
Total current assets	27,483	25,875
Investments	1,469	6,233
Property, Plant and Equipment (at cost)
Land	343	333
Buildings	11,989	11,486
Machinery, equipment and office furnishings	15,394	14,441
Construction in progress	5,013	3,355
Property, plant and equipment (at cost)	32,739	29,615
Less: accumulated depreciation	17,686	16,324
Property, plant and equipment, net	15,053	13,291
Goodwill	19,425	18,253
Other Intangibles, Net	14,196	13,104
Other Assets	6,771	5,881
Total Assets	84,397	82,637
Current Liabilities
Loans payable and current portion of long-term debt	3,610	5,308
Trade accounts payable	3,738	3,318
Accrued and other current liabilities	12,549	10,151
Income taxes payable	736	1,971
Dividends payable	1,587	1,458
Total current liabilities	22,220	22,206
Long-Term Debt	22,736	19,806
Deferred Income Taxes	1,470	1,702
Other Noncurrent Liabilities	11,970	12,041
Merck & Co., Inc. Stockholders’ Equity
Common stock, $0.50 par value Authorized - 6,500,000,000 shares Issued - 3,577,103,522 shares in 2019 and 2018	1,788	1,788
Other paid-in capital	39,660	38,808
Retained earnings	46,602	42,579
Accumulated other comprehensive loss	(6,193)	(5,545)
Stockholders' equity before deduction for treasury stock	81,857	77,630
Less treasury stock, at cost: 1,038,087,496 shares in 2019 and 984,543,979 shares in 2018	55,950	50,929
Total Merck & Co., Inc. stockholders’ equity	25,907	26,701
Noncontrolling Interests	94	181
Total equity	26,001	26,882
Total Liabilities and Equity	$ 84,397	$ 82,637

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 86	$ 119
Inventories classified in other assets	$ 1,480	$ 1,417
Common stock, par value (in dollars per share)	$ 0.50	$ 0.50
Common stock, shares authorized (in 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 (in shares)	1,038,087,496	984,543,979

Consolidated Statement of Equit

Consolidated Statement of Equity - USD ($) $ in Millions	Total	Common Stock	Other Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Non- controlling Interests
Beginning Balance at Dec. 31, 2016	$ 40,308	$ 1,788	$ 39,939	$ 44,133	$ (5,226)	$ (40,546)	$ 220
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Merck & Co., Inc.	2,394			2,394
Other comprehensive income (loss), net of taxes	316				316
Cash dividends declared on common stock ($2.26 per share in 2019, $1.99 per share in 2018 and $1.89 per share in 2017)	(5,177)			(5,177)
Treasury stock shares purchased	(4,014)					(4,014)
Acquisition of Vallée S.A.	7						7
Net income (loss) attributable to noncontrolling interests	24						24
Distributions attributable to noncontrolling interests	(18)						(18)
Share-based compensation plans and other	729		(37)			766
Ending Balance at Dec. 31, 2017	34,569	1,788	39,902	41,350	(4,910)	(43,794)	233
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Adoption of new accounting standards	48			322	(274)
Net Income Attributable to Merck & Co., Inc.	6,220			6,220
Other comprehensive income (loss), net of taxes	(361)				(361)
Cash dividends declared on common stock ($2.26 per share in 2019, $1.99 per share in 2018 and $1.89 per share in 2017)	(5,313)			(5,313)
Treasury stock shares purchased	(9,091)		(1,000)			(8,091)
Net income (loss) attributable to noncontrolling interests	(27)						(27)
Distributions attributable to noncontrolling interests	(25)						(25)
Share-based compensation plans and other	862		(94)			956
Ending Balance at Dec. 31, 2018	26,882	1,788	38,808	42,579	(5,545)	(50,929)	181
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Merck & Co., Inc.	9,843			9,843
Other comprehensive income (loss), net of taxes	(648)				(648)
Cash dividends declared on common stock ($2.26 per share in 2019, $1.99 per share in 2018 and $1.89 per share in 2017)	(5,820)			(5,820)
Treasury stock shares purchased	(4,780)		1,000			(5,780)
Net income (loss) attributable to noncontrolling interests	(66)						(66)
Distributions attributable to noncontrolling interests	(21)						(21)
Share-based compensation plans and other	611		(148)			759
Ending Balance at Dec. 31, 2019	$ 26,001	$ 1,788	$ 39,660	$ 46,602	$ (6,193)	$ (55,950)	$ 94

Consolidated Statement of Equ_2

Consolidated Statement of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Common stock, dividends declared (in dollars per share)	$ 2.26	$ 1.99	$ 1.89

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities
Net income	$ 9,777	$ 6,193	$ 2,418
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,652	4,519	4,676
Intangible asset impairment charges	1,040	296	646
Charge for the acquisition of Peloton Therapeutics, Inc.	993	0	0
Charge for future payments related to collaboration license options	0	650	500
Provisional charge for one-time transition tax related to the enactment of U.S. tax legislation	0	0	5,347
Deferred income taxes	(556)	(509)	(2,621)
Share-based compensation	417	348	312
Other	184	978	190
Net changes in assets and liabilities:
Accounts receivable	294	(418)	297
Inventories	(508)	(911)	(145)
Trade accounts payable	399	230	254
Accrued and other current liabilities	376	(341)	(922)
Income taxes payable	(2,359)	827	(3,291)
Noncurrent liabilities	(237)	(266)	(123)
Other	(32)	(674)	(1,087)
Net Cash Provided by Operating Activities	13,440	10,922	6,451
Cash Flows from Investing Activities
Capital expenditures	(3,473)	(2,615)	(1,888)
Purchases of securities and other investments	(3,202)	(7,994)	(10,739)
Proceeds from sales of securities and other investments	8,622	15,252	15,664
Acquisition of Antelliq Corporation, net of cash acquired	(3,620)	0	0
Acquisition of Peloton Therapeutics, Inc., net of cash acquired	(1,040)	0	0
Other acquisitions, net of cash acquired	(294)	(431)	(396)
Other	378	102	38
Net Cash (Used in) Provided by Investing Activities	(2,629)	4,314	2,679
Cash Flows from Financing Activities
Net change in short-term borrowings	(3,710)	5,124	(26)
Payments on debt	0	(4,287)	(1,103)
Proceeds from issuance of debt	4,958	0	0
Purchases of treasury stock	(4,780)	(9,091)	(4,014)
Dividends paid to stockholders	(5,695)	(5,172)	(5,167)
Proceeds from exercise of stock options	361	591	499
Other	5	(325)	(195)
Net Cash Used in Financing Activities	(8,861)	(13,160)	(10,006)
Effect of Exchange Rate Changes on Cash, Cash Equivalents and Restricted Cash	17	(205)	457
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	1,967	1,871	(419)
Cash, Cash Equivalents and Restricted Cash at Beginning of Year (includes $2 million of restricted cash at January 1, 2019 included in Other Assets)	7,967	6,096	6,515
Cash, Cash Equivalents and Restricted Cash at End of Year (includes $258 million of restricted cash at December 31, 2019 included in Other Assets - see Note 6)	$ 9,934	$ 7,967	$ 6,096

Consolidated Statement of Cas_2

Consolidated Statement of Cash Flows (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Cash Flows [Abstract]
Restricted Cash	$ 258	$ 2

Nature of Operations

Nature of Operations	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations Merck & Co., Inc. (Merck or the Company) is a global health care company that delivers innovative health solutions through its prescription medicines, vaccines, biologic therapies and animal health products. The Company’s operations are principally managed on a products basis and include four operating segments, which are the Pharmaceutical, Animal Health, Healthcare Services and Alliances 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. 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 provides services and solutions that focus on engagement, health analytics and clinical services to improve the value of care delivered to patients. The Company has recently sold certain businesses in the Healthcare Services segment and is in the process of divesting the remaining businesses. The Alliances segment primarily includes activity from the Company’s relationship with AstraZeneca LP related to sales of Nexium and Prilosec, which concluded in 2018. 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, trusted legacy brands and biosimilars businesses into a new, yet-to-be-named, independent, publicly traded company (NewCo) through a distribution of NewCo’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, pain, respiratory, and select cardiovascular products including Zetia and Vytorin , 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. NewCo 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 woman’s health, legacy brands and biosimilars businesses will be reflected as discontinued operations in the Company’s consolidated financial statements.

Summary of Accounting Policies

Summary of Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Accounting Policies	Summary of Accounting Policies Principles of Consolidation — The consolidated financial statements include the accounts of the Company and all of its subsidiaries in which a controlling interest is maintained. Intercompany balances and transactions are eliminated. Controlling interest is determined by majority ownership interest and the absence of substantive third-party participating rights or, in the case of variable interest entities, by majority exposure to expected losses, residual returns or both. For those consolidated subsidiaries where Merck ownership is less than 100%, the outside shareholders’ interests are shown as Noncontrolling interests in equity. Investments in affiliates over which the Company has significant influence but not a controlling interest, such as interests in entities owned equally by the Company and a third party that are under shared control, are carried on the equity basis. Acquisitions — In a business combination, the acquisition method of accounting requires that the assets acquired and liabilities assumed be recorded as of the date of the acquisition at their respective fair values with limited exceptions. Assets acquired and liabilities assumed in a business combination that arise from contingencies are generally recognized at fair value. If fair value cannot be determined, the asset or liability is recognized if probable and reasonably estimable; if these criteria are not met, no asset or liability is recognized. 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. Accordingly, the Company may be required to value assets at fair value measures that do not reflect the Company’s intended use of those assets. Any excess of the purchase price (consideration transferred) over the estimated fair values of net assets acquired is recorded as goodwill. Transaction costs and costs to restructure the acquired company are expensed as incurred. The operating results of the acquired business are reflected in the Company’s consolidated financial statements after the date of the acquisition. If the Company determines the assets acquired do not meet the definition of a business under the acquisition method of accounting, the transaction will be accounted for as an acquisition of assets rather than a business combination and, therefore, no goodwill will be recorded. In an asset acquisition, acquired in-process research and development (IPR&D) with no alternative future use is charged to expense and contingent consideration is not recognized at the acquisition date. Foreign Currency Translation — The net assets of international subsidiaries where the local currencies have been determined to be the functional currencies are translated into U.S. dollars using current exchange rates. The U.S. dollar effects that arise from translating the net assets of these subsidiaries at changing rates are recorded in the foreign currency translation account, which is included in Accumulated other comprehensive income (loss) ( AOCI ) and reflected as a separate component of equity. For those subsidiaries that operate in highly inflationary economies and for those subsidiaries where the U.S. dollar has been determined to be the functional currency, non-monetary foreign currency assets and liabilities are translated using historical rates, while monetary assets and liabilities are translated at current rates, with the U.S. dollar effects of rate changes included in Other (income) expense, net . Cash Equivalents — Cash equivalents are comprised of certain highly liquid investments with original maturities of less than three months. Inventories — Inventories are valued at the lower of cost or net realizable value. The cost of a substantial majority of U.S. pharmaceutical and vaccine inventories is determined using the last-in, first-out (LIFO) method for both financial reporting and tax purposes. The cost of all other inventories is determined using the first-in, first-out (FIFO) method. Inventories consist of currently marketed products, as well as certain inventories produced in preparation for product launches that are considered to have a high probability of regulatory approval. In evaluating the recoverability of inventories produced in preparation for product launches, the Company considers the likelihood that revenue will be obtained from the future sale of the related inventory together with the status of the product within the regulatory approval process. Investments — Investments in marketable debt securities classified as available-for-sale are reported at fair value. Fair values of the Company’s investments in marketable debt securities are determined using quoted market prices in active markets for identical assets or liabilities or 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. Changes in fair value that are considered temporary are reported net of tax in Other Comprehensive Income ( OCI ). The Company considers available evidence in evaluating potential impairments of its investments in marketable debt securities, including the duration and extent to which fair value is less than cost. An other-than-temporary impairment has occurred if the Company does not expect to recover the entire amortized cost basis of the marketable debt security. If the Company does not intend to sell the impaired debt security, and it is not more likely than not it will be required to sell the debt security before the recovery of its amortized cost basis, the amount of the other-than-temporary impairment recognized in earnings, recorded in Other (income) expense, net , is limited to the portion attributed to credit loss. The remaining portion of the other-than-temporary impairment related to other factors is recognized in OCI . Realized gains and losses for debt securities are included in Other (income) expense, net . Investments in publicly traded equity securities are reported at fair value determined using quoted market prices in active markets for identical assets or quoted prices for similar assets or other inputs that are observable or can be corroborated by observable market data. Changes in fair value are included in Other (income) expense, net . Investments in equity securities without readily determinable fair values are recorded at cost, plus or minus subsequent observable price changes in orderly transactions for identical or similar investments, minus impairments. Such adjustments are recognized in Other (income) expense, net . Realized gains and losses for equity securities are included in Other (income) expense, net . Revenue Recognition — On January 1, 2018, the Company adopted ASU 2014-09, Revenue from Contracts with Customers , and subsequent amendments (ASC 606 or new guidance), using the modified retrospective method. Comparative information for prior periods has not been restated and continues to be reported under the accounting standards in effect for those periods. Recognition of revenue requires evidence of a contract, probable collection of sales proceeds and completion of substantially all performance obligations. Merck acts as the principal in substantially all of its customer arrangements and therefore records revenue on a gross basis. The majority of the Company’s contracts related to the Pharmaceutical and Animal Health segments have a single performance obligation - the promise to transfer goods. Shipping is considered immaterial in the context of the overall customer arrangement and damages or loss of goods in transit are rare. Therefore, shipping is not deemed a separately recognized performance obligation. The vast majority of revenues from sales of products are recognized at a point in time when control of the goods is transferred to the customer, which the Company has determined is when title and risks and rewards of ownership transfer to the customer and the Company is entitled to payment. The Company recognizes revenue from the sales of vaccines to the Federal government for placement into vaccine stockpiles in accordance with Securities and Exchange Commission (SEC) Interpretation , Commission Guidance Regarding Accounting for Sales of Vaccines and BioTerror Countermeasures to the Federal Government for Placement into the Pediatric Vaccine Stockpile or the Strategic National Stockpile . This interpretation allows companies to recognize revenue for sales of vaccines into U.S. government stockpiles even though these sales might not meet the criteria for revenue recognition under other accounting guidance. For businesses within the Company’s Healthcare Services segment and certain services in the Animal Health segment, revenue is recognized over time, generally ratably over the contract term as services are provided. These service revenues are not material. The nature of the Company’s business gives rise to several types of variable consideration including discounts and returns, which are estimated at the time of sale generally using the expected value method, although the most likely amount method is used for prompt pay discounts. In the United States, sales discounts are issued to customers at the point-of-sale, through an intermediary wholesaler (known as chargebacks), or in the form of rebates. Additionally, sales are generally made with a limited right of return under certain conditions. Revenues are recorded net of provisions for sales discounts and returns, which are established at the time of sale. In addition, revenues are recorded net of time value of money discounts if collection of accounts receivable is expected to be in excess of one year. The U.S. provision for aggregate customer discounts covering chargebacks and rebates was $11.8 billion in 2019 , $10.7 billion in 2018 and $10.7 billion in 2017 . Chargebacks are discounts that occur when a contracted customer purchases through an intermediary wholesaler. The contracted customer generally purchases product from the wholesaler at its contracted price plus a mark-up. The wholesaler, in turn, charges the Company back for the difference between the price initially paid by the wholesaler and the contract price paid to the wholesaler by the customer. The provision for chargebacks is based on expected sell-through levels by the Company’s wholesale customers to contracted customers, as well as estimated wholesaler inventory levels. Rebates are amounts 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. The provision for rebates is based on expected patient usage, as well as inventory levels in the distribution channel to determine the contractual obligation to the benefit providers. The Company uses historical customer segment utilization mix, sales forecasts, changes to product mix and price, inventory levels in the distribution channel, government pricing calculations and prior payment history in order to estimate the expected provision. Amounts accrued for aggregate customer discounts are evaluated on a quarterly basis through comparison of information provided by the wholesalers, health maintenance organizations, pharmacy benefit managers, federal and state agencies, and other customers to the amounts accrued. The accrued balances relative to the provisions for chargebacks and rebates included in Accounts receivable and Accrued and other current liabilities were $233 million and $2.2 billion , respectively, at December 31, 2019 and were $245 million and $2.4 billion , respectively, at December 31, 2018 . Outside of the United States, variable consideration in the form of discounts and rebates are a combination of commercially-driven discounts in highly competitive product classes, discounts required to gain or maintain reimbursement, or legislatively mandated rebates. In certain European countries, legislatively mandated rebates are calculated based on an estimate of the government’s total unbudgeted spending and the Company’s specific payback obligation. Rebates may also be required based on specific product sales thresholds. The Company applies an estimated factor against its actual invoiced sales to represent the expected level of future discount or rebate obligations associated with the sale. The Company maintains a returns policy that allows its U.S. pharmaceutical customers to return product within a specified period prior to and subsequent to the expiration date (generally, three to six months before and 12 months after product expiration). The estimate of the provision for returns is based upon historical experience with actual returns. Additionally, the Company considers factors such as levels of inventory in the distribution channel, product dating and expiration period, whether products have been discontinued, entrance in the market of generic competition, changes in formularies or launch of over-the-counter products, among others. Outside of the United States, returns are only allowed in certain countries on a limited basis. Merck’s payment terms for U.S. pharmaceutical customers are typically 36 days from receipt of invoice and for U.S. animal health customers are typically 30 days from receipt of invoice; however, certain products, including Keytruda , have longer payment terms up to 90 days. Outside of the United States, payment terms are typically 30 days to 90 days, although certain markets have longer payment terms. Depreciation — Depreciation is provided over the estimated useful lives of the assets, principally using the straight-line method. For tax purposes, accelerated tax methods are used. The estimated useful lives primarily range from 25 to 45 years for Buildings , and from 3 to 15 years for Machinery, equipment and office furnishings . Depreciation expense was $1.7 billion in 2019 , $1.4 billion in 2018 and $1.5 billion in 2017 . Advertising and Promotion Costs — Advertising and promotion costs are expensed as incurred. The Company recorded advertising and promotion expenses of $2.1 billion , $2.1 billion and $2.2 billion in 2019 , 2018 and 2017 , respectively. Software Capitalization — The Company capitalizes certain costs incurred in connection with obtaining or developing internal-use software including external direct costs of material and services, and payroll costs for employees directly involved with the software development. These costs are included in Property, plant and equipment . In addition, the Company capitalizes certain costs incurred to implement a cloud computing arrangement that is considered a service agreement, which are included in Other Assets . Capitalized software costs are amortized beginning when the software project is substantially complete and the asset is ready for its intended use. Capitalized software costs associated with projects that are being amortized over 6 to 10 years (including the Company’s on-going multi-year implementation of an enterprise-wide resource planning system) were $548 million and $439 million , net of accumulated amortization at December 31, 2019 and 2018 , respectively. All other capitalized software costs are being amortized over periods ranging from 3 to 5 years. Costs incurred during the preliminary project stage and post-implementation stage, as well as maintenance and training costs, are expensed as incurred. Goodwill — Goodwill represents the excess of the consideration transferred over the fair value of net assets of businesses acquired. Goodwill is assigned to reporting units and evaluated for impairment on at least an annual basis, or more frequently if impairment indicators exist, by first assessing qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the Company concludes it is more likely than not that the fair value of a reporting unit is less than its carrying amount, a quantitative fair value test is performed. If the carrying value of a reporting unit is greater than its fair value, a goodwill impairment charge will be recorded for the difference (up to the carrying value of goodwill). Acquired Intangibles — Acquired intangibles include products and product rights, licenses, trade names and patents, which are initially recorded at fair value, assigned an estimated useful life, and amortized primarily on a straight-line basis over their estimated useful lives ranging from 2 to 24 years (see Note 8). The Company periodically evaluates whether current facts or circumstances indicate that the carrying values of its acquired intangibles may not be recoverable. If such circumstances are determined to exist, an estimate of the undiscounted future cash flows of these assets, or appropriate asset groupings, is compared to the carrying value to determine whether an impairment exists. If the asset is determined to be impaired, the loss is measured based on the difference between the carrying value of the intangible asset and its fair value, which is determined based on the net present value of estimated future cash flows. Acquired In-Process Research and Development — IPR&D that the Company acquires in conjunction with the acquisition of a business represents the fair value assigned to incomplete research projects which, at the time of acquisition, have not reached technological feasibility. The amounts are capitalized and are accounted for as indefinite-lived intangible assets, subject to impairment testing until completion or abandonment of the projects. Upon successful completion of each project, Merck will make a determination as to the then-useful life of the intangible asset, generally determined by the period in which the substantial majority of the cash flows are expected to be generated, and begin amortization. The Company evaluates IPR&D for impairment at least annually, or more frequently if impairment indicators exist, by performing a quantitative test that compares the fair value of the IPR&D intangible asset with its carrying value. If the fair value is less than the carrying amount, an impairment loss is recognized in operating results. Contingent Consideration — Certain of the Company’s acquisitions involve the potential for future payment of consideration that is contingent upon the achievement of performance milestones, including product development milestones and royalty payments on future product sales. If the transaction is accounted for as an acquisition of a business, the fair value of contingent consideration liabilities is determined at the acquisition date using unobservable inputs. These inputs include the estimated amount and timing of projected cash flows, the probability of success (achievement of the contingent event) and the risk-adjusted discount rate used to present value the probability-weighted cash flows. Subsequent to the acquisition date, at each reporting period until the contingency is resolved, the contingent consideration liability is remeasured at current fair value with changes (either expense or income) recorded in earnings. Significant events that increase or decrease the probability of achieving development and regulatory milestones or that increase or decrease projected cash flows will result in corresponding increases or decreases in the fair values of the related contingent consideration obligations. If the transaction is accounted for as an acquisition of an asset rather than a business, contingent consideration is not recognized at the acquisition date. In these instances, product development milestones are recognized upon achievement and sales-based milestones are recognized when the milestone is deemed probable by the Company of being achieved. Research and Development — Research and development is expensed as incurred. Nonrefundable advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received rather than when the payment is made. Research and development expenses include restructuring costs and IPR&D impairment charges. In addition, research and development expenses include expense or income related to changes in the estimated fair value measurement of liabilities for contingent consideration. Research and development expenses also include upfront and milestone payments related to asset acquisitions and licensing transactions involving clinical development programs that have not yet received regulatory approval. 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. When Merck is the principal on sales transactions with third parties, the Company recognizes sales, cost of sales and selling, general and administrative expenses on a gross basis. Profit sharing amounts it pays to its collaborative partners are recorded within Cost of sales . When the collaborative partner is the principal on sales transactions with third parties, the Company records profit sharing amounts received from its collaborative partners as alliance revenue (within Sales ). Alliance revenue is recorded net of cost of sales and includes an adjustment to share commercialization costs between the partners in accordance with the collaboration agreement. The adjustment is determined by comparing the commercialization costs Merck has incurred directly and reported within Selling, general and administrative expenses with the costs the collaborative partner has incurred. Research and development costs Merck incurs related to collaborations are recorded within Research and development expenses. Cost reimbursements to the collaborative partner or payments received from the collaborative partner to share these costs pursuant to the terms of the collaboration agreements are recorded as increases or decreases to Research and development expenses. In addition, the terms of the collaboration agreements may require the Company to make payments based upon the achievement of certain developmental, regulatory approval or commercial milestones. Upfront and milestone payments payable by Merck to collaborative partners prior to regulatory approval are expensed as incurred and included in Research and development expenses. Payments due to collaborative partners upon or subsequent to regulatory approval are capitalized and amortized over the estimated useful life of the corresponding intangible asset to Cost of sales provided that future cash flows support the amounts capitalized. Sales-based milestones payable by Merck to collaborative partners are accrued and capitalized, subject to cumulative amortization catch-up, when probable of being achieved. The amortization catch-up is calculated either from the time of the first regulatory approval for indications that were unapproved at the time the collaboration was formed, or from time of the formation of the collaboration for approved products. The related intangible asset that is recognized is amortized to Cost of sales over its remaining useful life, subject to impairment testing. Share-Based Compensation — The Company expenses all share-based payments to employees over the requisite service period based on the grant-date fair value of the awards. Restructuring Costs — The Company records liabilities for costs associated with exit or disposal activities in the period in which the liability is incurred. In accordance with existing benefit arrangements, employee termination costs are accrued when the restructuring actions are probable and estimable. When accruing these costs, the Company will recognize the amount within a range of costs that is the best estimate within the range. When no amount within the range is a better estimate than any other amount, the Company recognizes the minimum amount within the range. Costs for one-time termination benefits in which the employee is required to render service until termination in order to receive the benefits are recognized ratably over the future service period. Contingencies and Legal Defense Costs — The Company records accruals for contingencies and legal defense costs expected to be incurred in connection with a loss contingency when it is probable that a liability has been incurred and the amount can be reasonably estimated. Taxes on Income — Deferred taxes are recognized for the future tax effects of temporary differences between financial and income tax reporting based on enacted tax laws and rates. The Company evaluates tax positions to determine whether the benefits of tax positions are more likely than not of being sustained upon audit based on the technical merits of the tax position. For tax positions that are more likely than not of being sustained upon audit, the Company recognizes the largest amount of the benefit that is greater than 50% likely of being realized upon ultimate settlement in the financial statements. For tax positions that are not more likely than not of being sustained upon audit, the Company does not recognize any portion of the benefit in the financial statements. The Company recognizes interest and penalties associated with uncertain tax positions as a component of Taxes on income in the Consolidated Statement of Income. The Company accounts for the tax effects of the tax on global intangible low-taxed income (GILTI) of certain foreign subsidiaries in the income tax provision in the period the tax arises. Use of Estimates — The consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (GAAP) and, accordingly, include certain amounts that are based on management’s best estimates and judgments. Estimates are used when accounting for amounts recorded in connection with acquisitions, including initial fair value determinations of assets and liabilities, primarily IPR&D, other intangible assets and contingent consideration, as well as subsequent fair value measurements. Additionally, estimates are used in determining such items as provisions for sales discounts and returns, depreciable and amortizable lives, recoverability of inventories, including those produced in preparation for product launches, amounts recorded for contingencies, environmental liabilities, accruals for contingent sales-based milestone payments and other reserves, pension and other postretirement benefit plan assumptions, share-based compensation assumptions, restructuring costs, impairments of long-lived assets (including intangible assets and goodwill) and investments, and taxes on income. Because of the uncertainty inherent in such estimates, actual results may differ from these estimates. Reclassifications — Certain reclassifications have been made to prior year amounts to conform to the current year presentation. Recently Adopted Accounting Standards — In February 2016, the Financial Accounting Standards Board (FASB) issued new accounting guidance for the accounting and reporting of leases (ASU 2016-02) and subsequently issued several updates to the new guidance (ASC 842 or new leasing guidance). The new leasing guidance requires that lessees recognize a right-of-use asset and a lease liability for each of its leases (other than leases that meet the definition of a short-term lease). Leases are classified as either operating or finance. Operating leases result in straight-line expense in the income statement (similar to previous operating leases), while finance leases result in more expense being recognized in the earlier years of the lease term (similar to previous capital leases). The Company adopted the new standard on January 1, 2019 using a modified retrospective approach. Merck elected the transition method that allows for application of the standard at the adoption date rather than at the beginning of the earliest comparative period presented in the financial statements. The Company also elected available practical expedients. Upon adoption, the Company recognized $1.1 billion of additional assets and related liabilities on its consolidated balance sheet (see Note 9). The adoption of the new leasing guidance did not impact the Company’s consolidated statements of income or of cash flows. In April 2018, the FASB issued new guidance on the accounting for costs incurred to implement a cloud computing arrangement that is considered a service arrangement. The new guidance requires the capitalization of such costs, aligning it with the accounting for costs associated with developing or obtaining internal-use software. The Company adopted the new standard in the third quarter of 2019 using prospective application for eligible costs, which were immaterial. In August 2018, the FASB issued new guidance modifying the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The new guidance removes disclosures that no longer are considered cost beneficial, clarifies the specific requirements of certain disclosures, and adds disclosure requirements identified as relevant. The Company elected to early adopt the new guidance in 2019 on a retrospective basis resulting in minor changes to its employee benefit plan disclosures (see Note 13). Also, in August 2018, the FASB issued new guidance on fair value measurements that adds, removes, and modifies certain disclosure requirements. The Company elected to early adopt the new guidance in 2019 resulting in minor changes to its fair value disclosures (see Note 6). Recently Issued Accounting Standards Not Yet Adopted — In June 2016, the 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 will result in minor changes to the footnote presentation of information related to the Company’s collaborative arrangements. 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 application of 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.

Acquisitions, Divestitures, Res

Acquisitions, Divestitures, Research Collaborations and License Agreements	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Acquisitions, Divestitures, Research Collaborations and License Agreements	Acquisitions, Divestitures, Research Collaborations and License Agreements The Company continues to pursue the acquisition of businesses and 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. Recently Completed Transaction 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 for $2.7 billion . ArQule’s lead investigational candidate, MK-1026 (formerly ARQ 531), is a novel, oral Bruton’s tyrosine kinase (BTK) inhibitor currently in a Phase 2 dose expansion study for the treatment of B-cell malignancies. The Company is in the process of determining the preliminary fair value of assets acquired, liabilities assumed and total consideration transferred in this transaction, which will be accounted for as an acquisition of a business. 2019 Transactions In July 2019, Merck acquired Peloton Therapeutics, Inc. (Peloton), a clinical-stage biopharmaceutical company focused on the development of novel small molecule therapeutic candidates targeting hypoxia-inducible factor-2α (HIF-2α) for the treatment of patients with cancer and other non-oncology diseases. Peloton’s lead candidate, MK-6482 (formerly PT2977), is a novel oral HIF-2α inhibitor in late-stage development for renal cell carcinoma. Merck made an upfront payment of $1.2 billion in cash; additionally, former Peloton shareholders will be eligible to receive $50 million upon U.S. regulatory approval, $50 million upon first commercial sale in the United States, and up to $1.05 billion of sales-based milestones. The transaction was accounted for as an acquisition of an asset. Merck recorded cash of $157 million , deferred tax liabilities of $52 million , and other net liabilities of $4 million at the acquisition date and Research and development expenses of $993 million in 2019 related to the transaction. 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 95 Property, plant and equipment 62 Identifiable intangible assets (useful lives ranging from 18-24 years) (1) 2,689 Deferred income tax liabilities (520 ) Other assets and liabilities, net (81 ) Total identifiable net assets 2,349 Goodwill (2) 1,302 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 2019 include eight 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 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 for IPR&D 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 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. 2018 Transactions In 2018, the Company recorded an aggregate charge of $423 million within Cost of sales in conjunction with the termination of a collaboration agreement entered into in 2014 with Samsung Bioepis Co., Ltd. (Samsung) for insulin glargine. The charge reflects a termination payment of $155 million , which represents the reimbursement of all fees previously paid by Samsung to Merck under the agreement, plus interest, as well as the release of Merck’s ongoing obligations under the agreement. The charge also included fixed asset abandonment charges of $137 million , inventory write-offs of $122 million , as well as other related costs of $9 million . The termination of this agreement has no impact on the Company’s other collaboration with Samsung. In June 2018, Merck acquired Viralytics Limited (Viralytics), an Australian publicly traded company focused on oncolytic immunotherapy treatments for a range of cancers, for AUD 502 million ( $378 million ). The transaction provided Merck with full rights to V937 (formerly CVA21), Viralytics’s investigational oncolytic immunotherapy. V937 is based on Viralytics’s proprietary formulation of an oncolytic virus (Coxsackievirus Type A21) that has been shown to preferentially infect and kill cancer cells. V937 is currently being evaluated in multiple clinical trials, both as an intratumoral and intravenous agent, including in combination with Keytruda . Under a previous agreement between Merck and Viralytics, a study is investigating the use of the Keytruda and V937 combination in melanoma, prostate, lung and bladder cancers. The transaction was accounted for as an acquisition of an asset. Merck recorded net assets of $34 million (primarily cash) at the acquisition date and Research and development expenses of $344 million in 2018 related to the transaction. There are no future contingent payments associated with the acquisition. In March 2018, Merck and Eisai Co., Ltd. (Eisai) entered into a strategic collaboration for the worldwide co-development and co-commercialization of Lenvima, an orally available tyrosine kinase inhibitor discovered by Eisai (see Note 4). 2017 Transactions In October 2017, Merck acquired Rigontec GmbH (Rigontec), a leader in accessing the retinoic acid-inducible gene I pathway, part of the innate immune system, as a novel and distinct approach in cancer immunotherapy to induce both immediate and long-term anti-tumor immunity. Rigontec’s lead candidate, MK-4621 (formerly RGT100), is in development for the treatment in patients with various tumors. Under the terms of the agreement, Merck made an upfront cash payment of €119 million ( $140 million ) and may make additional contingent payments of up to €349 million (of which €184 million are related to the achievement of research milestones and regulatory approvals and €165 million are related to the achievement of commercial targets). The transaction was accounted for as an acquisition of an asset and the upfront payment is reflected within Research and development expenses in 2017. In July 2017, Merck and AstraZeneca PLC (AstraZeneca) entered into a global strategic oncology collaboration to co-develop and co-commercialize AstraZeneca’s Lynparza for multiple cancer types (see Note 4). In March 2017, Merck acquired a controlling interest in Vallée S.A. (Vallée), a leading privately held producer of animal health products in Brazil. Vallée has an extensive portfolio of products spanning parasiticides, anti-infectives and vaccines that include products for livestock, horses, and companion animals. Under the terms of the agreement, Merck acquired 93.5% of the shares of Vallée for $358 million . Of the total purchase price, $176 million was placed into escrow pending resolution of certain contingent items. The transaction was accounted for as an acquisition of a business. Merck recognized intangible assets of $297 million related to currently marketed products, net deferred tax liabilities of $102 million , other net assets of $32 million and noncontrolling interest of $25 million . In addition, the Company recorded liabilities of $37 million for contingencies identified at the acquisition date and corresponding indemnification assets of $37 million , representing the amounts to be reimbursed to Merck if and when the contingent liabilities are paid. The excess of the consideration transferred over the fair value of net assets acquired of $156 million was recorded as goodwill. The goodwill was allocated to the Animal Health segment and is not deductible for tax purposes. The estimated fair values of identifiable intangible assets related to currently marketed products were determined using an income approach. Actual cash flows are likely to be different than those assumed. The intangible assets related to currently marketed products are being amortized over their estimated useful lives of 15 years. In the fourth quarter of 2017, Merck acquired an additional 4.5% interest in Vallée for $18 million , which reduced the noncontrolling interest related to Vallée. Remicade/Simponi In 1998, a subsidiary of Schering-Plough entered into a licensing agreement with Centocor Ortho Biotech Inc. (Centocor), a Johnson & Johnson (J&J) company, to market Remicade, which is prescribed for the treatment of inflammatory diseases. In 2005, Schering-Plough’s subsidiary exercised an option under its contract with Centocor for license rights to develop and commercialize Simponi , a fully human monoclonal antibody. The Company has marketing rights to both products throughout Europe, Russia and Turkey. Remicade lost market exclusivity in major European markets in 2015 and the Company no longer has market exclusivity in any of its marketing territories . The Company continues to have market exclusivity for Simponi in all of its marketing territories. All profits derived from Merck’s distribution of the two products in these countries are equally divided between Merck and J&J.

Collaborative Arrangements

Collaborative Arrangements	12 Months Ended
	Dec. 31, 2019
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 for multiple cancer types. Lynparza is an oral poly (ADP-ribose) polymerase (PARP) inhibitor currently approved for certain types of ovarian and breast cancer. 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 and Imfinzi. The companies will also jointly develop and commercialize AstraZeneca’s selumetinib, an oral, potent, selective inhibitor of MEK, part of the mitogen-activated protein kinase (MAPK) pathway, currently being developed for multiple indications. Under the terms of the agreement, AstraZeneca and Merck will share the development and commercialization costs for Lynparza and selumetinib monotherapy and non-PD-L1/PD-1 combination therapy opportunities. Gross profits from Lynparza and selumetinib 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 selumetinib. AstraZeneca will fund all development and commercialization costs of Imfinzi in combination with Lynparza or selumetinib. AstraZeneca is the principal on Lynparza sales transactions. Merck records its share of Lynparza 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 (of which $250 million was paid in December 2017, $400 million was paid in December 2018 and $100 million was paid in December 2019). The Company recorded an aggregate charge of $2.35 billion in Research and development expenses in 2017 related to the upfront payment and license option payments. 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 2019, Merck determined it was probable that annual sales of Lynparza in the future would trigger a $300 million sales-based milestone payment from Merck to AstraZeneca. Accordingly, in 2019, Merck recorded a $300 million liability and a corresponding increase to the intangible asset related to Lynparza. Prior to 2019, Merck accrued sales-based milestone payments aggregating $700 million , of which $200 million and $250 million was paid to AstraZeneca in 2019 and 2018, respectively, and the remainder of $250 million was paid in January 2020. Potential future sales-based milestone payments of $3.1 billion have not yet been accrued as they are not deemed by the Company to be probable at this time. In 2019, Lynparza received regulatory approval in the European Union (EU) both as a monotherapy for the treatment of certain adult patients with advanced breast cancer and as a monotherapy for the maintenance treatment of certain adult patients with BRCA -mutated advanced ovarian cancer. Each of these approvals triggered a $30 million capitalized milestone payment from Merck to AstraZeneca. In 2018, Lynparza received regulatory approvals triggering capitalized milestone payments of $140 million in the aggregate from Merck to AstraZeneca. Potential future regulatory milestone payments of $1.7 billion remain under the agreement. The intangible asset balance related to Lynparza (which includes capitalized sales-based and regulatory milestone payments) was $955 million at December 31, 2019 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: Years Ended December 31 2019 2018 2017 Alliance revenue $ 444 $ 187 $ 20 Cost of sales (1) 148 93 4 Selling, general and administrative 138 48 1 Research and development (2) 168 152 2,419 December 31 2019 2018 Receivables from AstraZeneca included in Other current assets $ 128 $ 52 Payables to AstraZeneca included in Accrued and other current liabilities (3) 577 405 Payables to AstraZeneca included Other Noncurrent Liabilities (3) — 250 (1) Represents amortization of capitalized milestone payments. (2) Amount for 2017 includes $2.35 billion related to the upfront payment and license option payments. (3) Includes accrued milestone payments. Eisai In March 2018, Merck and Eisai announced a strategic collaboration for the worldwide co-development and co-commercialization of Lenvima, an orally available tyrosine kinase inhibitor discovered by Eisai. Under the agreement, Merck and Eisai will develop and commercialize Lenvima jointly, both as monotherapy and in combination with Merck’s Keytruda . Eisai records Lenvima product sales globally (Eisai is the principal on Lenvima sales transactions), and Merck and Eisai share gross 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 will make payments of up to $650 million for certain option rights through 2021 (of which $325 million was paid in March 2019, $200 million is expected to be paid in March 2020 and $125 million is expected to be paid in March 2021). The Company recorded an aggregate charge of $1.4 billion in Research and development expenses in 2018 related to the upfront payment and future option payments. 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 2019, Merck determined it was probable that annual sales of Lenvima in the future would trigger sales-based milestone payments from Merck to Eisai aggregating $682 million . Accordingly, in 2019, Merck recorded $682 million of liabilities and corresponding increases to the intangible asset related to Lenvima. In 2018, Merck accrued sales-based milestone payments aggregating $268 million related to Lenvima. Of these amounts, $50 million was paid to Eisai in 2019 and an additional $150 million was paid in January 2020. Potential future sales-based milestone payments of $3.0 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 $956 million at December 31, 2019 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: Years Ended December 31 2019 2018 Alliance revenue $ 404 $ 149 Cost of sales (1) 206 39 Selling, general and administrative 80 13 Research and development (2) 189 1,489 December 31 2019 2018 Receivables from Eisai included in Other current assets $ 150 $ 71 Payables to Eisai included in Accrued and other current liabilities (3) 700 375 Payables to Eisai included in Other Noncurrent Liabilities (3) 525 543 (1) Represents amortization of capitalized milestone payments. (2) Amount for 2018 includes $1.4 billion related to the upfront payment and option payments. (3) Includes accrued milestone and future option 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, 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 Phase 3 trials for worsening heart failure, as well as opt-in rights for other early-stage sGC compounds in development by Bayer. Merck in turn made available its early-stage sGC compounds under similar terms. Under the agreement, Bayer leads commercialization of Adempas in the Americas, while Merck leads commercialization in the rest of the world. For vericiguat and other potential opt-in products, Bayer will lead commercialization in the rest of world and Merck will lead in the Americas. For all products and candidates included in the agreement, both companies will share in development costs and profits on sales and will have the right to co-promote in territories where they are not the lead. Revenue from Adempas includes sales in Merck’s marketing territories, as well as 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. In 2018, Merck determined it was probable that annual worldwide sales of Adempas in the future would trigger a $375 million sales-based milestone payment from Merck to Bayer. Accordingly, Merck recorded a $375 million liability and a corresponding increase to the intangible asset related to Adempas. In 2018, the Company made a $350 million milestone payment to Bayer, which was accrued for in 2016 when Merck deemed the payment to be probable. 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 Adempas (which includes the acquired intangible asset balance, as well as capitalized sales-based milestone payments) was $883 million at December 31, 2019 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: Years Ended December 31 2019 2018 2017 Net product sales recorded by Merck $ 215 $ 190 $ 149 Merck’s profit share from sales in Bayer’s marketing territories 204 139 151 Total sales 419 329 300 Cost of sales (1) 113 216 99 Selling, general and administrative 41 35 27 Research and development 126 127 101 December 31 2019 2018 Receivables from Bayer included in Other current assets $ 49 $ 32 Payables to Bayer included in Other Noncurrent Liabilities (2) 375 375 (1) Includes amortization of intangible assets. (2) Represents accrued milestone payment.

Restructuring

Restructuring	12 Months Ended
	Dec. 31, 2019
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 NewCo. As the Company continues to evaluate its global footprint and overall operating model, it has 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 now 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 $927 million in 2019 , $658 million in 2018 and $927 million in 2017 related to restructuring program activities. For segment reporting, restructuring charges are unallocated expenses. The following table summarizes the charges related to restructuring program activities by type of cost: Separation Costs Accelerated Depreciation Other Total Year Ended December 31, 2019 Cost of sales $ — $ 198 $ 53 $ 251 Selling, general and administrative — 33 1 34 Research and development — 2 2 4 Restructuring costs 572 — 66 638 $ 572 $ 233 $ 122 $ 927 Year Ended December 31, 2018 Cost of sales $ — $ 10 $ 11 $ 21 Selling, general and administrative — 2 1 3 Research and development — (13 ) 15 2 Restructuring costs 473 — 159 632 $ 473 $ (1 ) $ 186 $ 658 Year Ended December 31, 2017 Cost of sales $ — $ 52 $ 86 $ 138 Selling, general and administrative — 2 — 2 Research and development — 6 5 11 Restructuring costs 552 — 224 776 $ 552 $ 60 $ 315 $ 927 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 2019 , 2018 and 2017 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 13) and share-based compensation. The following table summarizes the charges and spending relating to restructuring program activities: Separation Costs Accelerated Depreciation Other Total Restructuring reserves January 1, 2018 $ 619 $ — $ 128 $ 747 Expenses 473 (1 ) 186 658 (Payments) receipts, net (649 ) — (238 ) (887 ) Non-cash activity — 1 15 16 Restructuring reserves December 31, 2018 443 — 91 534 Expenses 572 233 122 927 (Payments) receipts, net (325 ) — (136 ) (461 ) Non-cash activity — (233 ) (8 ) (241 ) Restructuring reserves December 31, 2019 (1) $ 690 $ — $ 69 $ 759 (1)

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2019
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 Consolidated Balance Sheet. Changes in the fair value of derivative contracts are recorded each period in either current earnings or 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 is recorded in 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 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 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 component). Changes in fair value of the excluded components are recognized in OCI . The Company recognizes in earnings the initial value of the excluded component 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 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 Years Ended December 31 2019 2018 2017 2019 2018 2017 Net Investment Hedging Relationships Foreign exchange contracts $ (10 ) $ (18 ) $ — $ (31 ) $ (11 ) $ — Euro-denominated notes (75 ) (183 ) 520 — — — (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. At December 31, 2019 , the Company was a party to 19 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. 2019 Debt Instrument Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 1.85% notes due 2020 $ 1,250 5 $ 1,250 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 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 as of December 31: Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount 2019 2018 2019 2018 Balance Sheet Line Item in which Hedged Item is Included Loans payable and current portion of long-term debt $ 1,249 $ — $ (1 ) $ — Long-Term Debt 3,409 4,560 14 (82 ) 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 as of December 31: 2019 2018 Fair Value of Derivative U.S. Dollar Notional Fair Value of Derivative U.S. Dollar Notional Balance Sheet Caption Asset Liability Asset Liability Derivatives Designated as Hedging Instruments Interest rate swap contracts Other Assets $ 15 $ — $ 3,400 $ — $ — $ — Interest rate swap contracts Accrued and other current liabilities — 1 1,250 — — — Interest rate swap contracts Other Noncurrent Liabilities — — — — 81 4,650 Foreign exchange contracts Other current assets 152 — 6,117 263 — 6,222 Foreign exchange contracts Other Assets 55 — 2,160 75 — 2,655 Foreign exchange contracts Accrued and other current liabilities — 22 1,748 — 7 774 Foreign exchange contracts Other Noncurrent Liabilities — 1 53 — 1 89 $ 222 $ 24 $ 14,728 $ 338 $ 89 $ 14,390 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts Other current assets $ 66 $ — $ 7,245 $ 116 $ — $ 5,430 Foreign exchange contracts Accrued and other current liabilities — 73 8,693 — 71 9,922 $ 66 $ 73 $ 15,938 $ 116 $ 71 $ 15,352 $ 288 $ 97 $ 30,666 $ 454 $ 160 $ 29,742 As noted above, the Company records its derivatives on a gross basis in the 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 at December 31: 2019 2018 Asset Liability Asset Liability Gross amounts recognized in the consolidated balance sheet $ 288 $ 97 $ 454 $ 160 Gross amounts subject to offset in master netting arrangements not offset in the consolidated balance sheet (84 ) (84 ) (121 ) (121 ) Cash collateral received (34 ) — (107 ) — Net amounts $ 170 $ 13 $ 226 $ 39 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) Years Ended December 31 2019 2018 2017 2019 2018 2017 2019 2018 2017 Financial Statement Line Items in which Effects of Fair Value or Cash Flow Hedges are Recorded $ 46,840 $ 42,294 $ 40,122 $ 139 (402 ) (500 ) $ (648 ) $ (361 ) $ 316 (Gain) loss on fair value hedging relationships Interest rate swap contracts Hedged items — — — 95 (27 ) (48 ) — — — Derivatives designated as hedging instruments — — — (65 ) 50 12 — — — Impact of cash flow hedging relationships Foreign exchange contracts Amount of gain (loss) recognized in OCI on derivatives — — — — — — 87 228 (562 ) (Decrease) increase in Sales as a result of AOCI reclassifications 255 (160 ) 138 — — — (255 ) 160 (138 ) Interest rate contracts Amount of gain recognized in Other (income) expense, net on derivatives — — — (4 ) (4 ) (3 ) — — — Amount of loss recognized in OCI on derivatives — — — — — — (6 ) (4 ) (3 ) (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 Years Ended December 31 Income Statement Caption 2019 2018 2017 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts (1) Other (income) expense, net $ 174 $ (260 ) $ 110 Foreign exchange contracts (2) Sales 1 (8 ) (3 ) (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. At December 31, 2019 , the Company estimates $31 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 at December 31 is as follows: 2019 2018 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Value Gains Losses Gains Losses Commercial paper $ 668 $ — $ — $ 668 $ — $ — $ — $ — Corporate notes and bonds 608 13 — 621 4,985 3 (68 ) 4,920 U.S. government and agency securities 266 3 — 269 895 2 (5 ) 892 Asset-backed securities 226 1 — 227 1,285 1 (11 ) 1,275 Foreign government bonds — — — — 167 — (1 ) 166 Mortgage-backed securities — — — — 8 — — 8 Total debt securities 1,768 17 — 1,785 7,340 6 (85 ) 7,261 Publicly traded equity securities (1) 838 456 Total debt and publicly traded equity securities $ 2,623 $ 7,717 (1) Unrealized net gains recognized in Other (income) expense, net on equity securities still held at December 31, 2019 were $160 million during 2019. Unrealized net losses recognized in Other (income) expense, net on equity securities still held at December 31, 2018 were $35 million during 2018. At December 31, 2019 and 2018 , the Company also had $420 million and $568 million , respectively, of equity investments without readily determinable fair values included in Other Assets . During 2019 and 2018 , the Company recognized unrealized gains of $20 million and $167 million , respectively, in Other (income) expense, net , on certain of these equity investments based on favorable observable price changes from transactions involving similar investments of the same investee. In addition, during 2019 and 2018 , the Company recognized unrealized losses of $13 million and $26 million , respectively, in Other (income) expense, net , related to certain of these investments based on unfavorable observable price changes. Cumulative unrealized gains and cumulative unrealized losses based on observable prices changes for investments in equity investments without readily determinable fair values were $109 million and $21 million , respectively. Available-for-sale debt securities included in Short-term investments totaled $749 million at December 31, 2019 . Of the remaining debt securities, $933 million mature within five years. At December 31, 2019 and 2018 , there were no debt securities pledged as collateral. 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 at December 31 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 2019 2018 Assets Investments Commercial paper $ — $ 668 $ — $ 668 $ — $ — $ — $ — Corporate notes and bonds — 621 — 621 — 4,835 — 4,835 Asset-backed securities (1) — 227 — 227 — 1,253 — 1,253 U.S. government and agency securities — 209 — 209 — 731 — 731 Foreign government bonds — — — — — 166 — 166 Publicly traded equity securities 518 — — 518 147 — — 147 518 1,725 — 2,243 147 6,985 — 7,132 Other assets (2) U.S. government and agency securities 60 — — 60 55 106 — 161 Corporate notes and bonds — — — — — 85 — 85 Asset-backed securities (1) — — — — — 22 — 22 Mortgage-backed securities — — — — — 8 — 8 Publicly traded equity securities 320 — — 320 309 — — 309 380 — — 380 364 221 — 585 Derivative assets (3) Forward exchange contracts — 169 — 169 — 241 — 241 Purchased currency options — 104 — 104 — 213 — 213 Interest rate swaps — 15 — 15 — — — — — 288 — 288 — 454 — 454 Total assets $ 898 $ 2,013 $ — $ 2,911 $ 511 $ 7,660 $ — $ 8,171 Liabilities Other liabilities Contingent consideration $ — $ — $ 767 $ 767 $ — $ — $ 788 $ 788 Derivative liabilities (3) Forward exchange contracts — 95 — 95 — 74 — 74 Interest rate swaps — 1 — 1 — 81 — 81 Written currency options — 1 — 1 — 5 — 5 — 97 — 97 — 160 — 160 Total liabilities $ — $ 97 $ 767 $ 864 $ — $ 160 $ 788 $ 948 (1) Primarily all of the asset-backed securities are 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 December 31, 2019 , Cash and cash equivalents of $9.7 billion include $8.9 billion of cash equivalents (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: 2019 2018 Fair value January 1 $ 788 $ 935 Changes in estimated fair value (1) 64 89 Additions — 8 Payments (85 ) (244 ) Fair value December 31 (2)(3) $ 767 $ 788 (1) Recorded in Cost of sales, Research and development expenses, and Other (income) expense, net . Includes cumulative translation adjustments. (2) Balance at December 31, 2019 includes $114 million recorded as a current liability for amounts expected to be paid within the next 12 months. (3) At December 31, 2019 and 2018 , $625 million and $614 million , respectively, of the liabilities relate to the termination of the SPMSD 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 and a risk-adjusted discount rate of 8% is used to present value the cash flows. The changes in the estimated fair value of liabilities for contingent consideration in 2019 and 2018 were largely attributable to increases in the liabilities recorded in connection with the termination of the Sanofi Pasteur MSD (SPMSD) joint venture in 2016. In 2018, these increases were partially offset by the reversal of a liability related to the discontinuation of a program obtained in connection with the acquisition of SmartCells (see Note 8). The payments of contingent consideration in both years relate to the SPMSD termination liabilities described above. The payments of contingent consideration in 2018 also include $175 million related to the achievement of a clinical development milestone for MK-7264 (gefapixant), a program obtained in connection with the acquisition of Afferent Pharmaceuticals. 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 December 31, 2019 , was $28.8 billion compared with a carrying value of $26.3 billion and at December 31, 2018 , was $25.6 billion compared with a carrying value of $25.1 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’s customers with the largest accounts receivable balances are: McKesson Corporation, AmerisourceBergen Corporation and Cardinal Health, Inc., which represented, in aggregate, approximately 35% of total accounts receivable at December 31, 2019 . The Company monitors the creditworthiness of its customers to which it grants credit terms in the normal course of business. Bad debts have been minimal. The Company does not normally require collateral or other security to support credit sales. The Company has accounts receivable factoring agreements with financial institutions in certain countries to sell accounts receivable. In 2019, the Company expanded its factoring arrangements in China and entered into factoring agreements to sell accounts receivable from the Company’s major U.S. distributors. The Company factored $2.7 billion and $1.1 billion of accounts receivable in the fourth quarter of 2019 and 2018 , 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. At December 31, 2019 , the Company had collected $256 million on behalf of the financial institutions, which is reflected as restricted cash in Other current assets and the related obligation to remit the cash within Accrued and other current liabilities . The Company remitted the cash to the financial institutions in January 2020. The net cash flows relating to these collections are reported as financing activities in the Consolidated Statement of Cash Flows. The costs of factoring such accounts receivable were 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 $34 million and $107 million at December 31, 2019 and 2018 , 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 December 31, 2019 or 2018 .

Inventories

Inventories	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories at December 31 consisted of: 2019 2018 Finished goods $ 1,772 $ 1,658 Raw materials and work in process 5,650 5,004 Supplies 207 194 Total (approximates current cost) 7,629 6,856 (Decrease) increase to LIFO cost (171 ) 1 $ 7,458 $ 6,857 Recognized as: Inventories $ 5,978 $ 5,440 Other assets 1,480 1,417 Inventories valued under the LIFO method comprised approximately $2.6 billion and $2.5 billion at December 31, 2019 and 2018 , respectively. Amounts recognized as Other assets are comprised almost entirely of raw materials and work in process inventories. At December 31, 2019 and 2018 , these amounts included $1.3 billion and $1.4 billion , respectively, of inventories not expected to be sold within one year. In addition, these amounts included $168 million and $7 million at December 31, 2019 and 2018 , respectively, of inventories produced in preparation for product launches.

Goodwill and Other Intangibles

Goodwill and Other Intangibles	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles	Goodwill and Other Intangibles The following table summarizes goodwill activity by segment: Pharmaceutical Animal Health All Other Total Balance January 1, 2018 $ 16,066 $ 1,877 $ 341 $ 18,284 Acquisitions — 17 24 41 Impairments — — (144 ) (144 ) Other (1) 96 (24 ) — 72 Balance December 31, 2018 (2) 16,162 1,870 221 18,253 Acquisitions 19 1,322 — 1,341 Impairments — — (162 ) (162 ) Other (1) — — (7 ) (7 ) Balance December 31, 2019 (2) $ 16,181 $ 3,192 $ 52 $ 19,425 (1) Other includes cumulative translation adjustments on goodwill balances and certain other adjustments. (2) Accumulated goodwill impairment losses at December 31, 2019 and 2018 were $531 million and $369 million , respectively. The additions to goodwill within the Animal Health segment in 2019 primarily relate to the acquisition of Antelliq (see Note 3). The impairments of goodwill within other non-reportable segments in 2019 and 2018 relate to certain businesses within the Healthcare Services segment. Other intangibles at December 31 consisted of: 2019 2018 Gross Carrying Amount Accumulated Amortization Net Gross Carrying Amount Accumulated Amortization Net Products and product rights $ 45,947 $ 38,852 $ 7,095 $ 46,615 $ 37,585 $ 9,030 Licenses 3,185 824 2,361 2,081 408 1,673 IPR&D 1,032 — 1,032 1,064 — 1,064 Trade names 2,899 217 2,682 209 107 102 Other 2,261 1,235 1,026 2,403 1,168 1,235 $ 55,324 $ 41,128 $ 14,196 $ 52,372 $ 39,268 $ 13,104 Acquired intangibles include products and product rights, licenses, trade names and patents, which are initially recorded at fair value, assigned an estimated useful life, and amortized primarily on a straight-line basis over their estimated useful lives. Some of the Company’s more significant acquired intangibles, on a net basis, related to human health marketed products (included in products and product rights above) at December 31, 2019 include Zerbaxa , $2.4 billion ; Implanon/Nexplanon, $412 million ; Gardasil/Gardasil 9, $314 million ; Dificid , $312 million ; Bridion , $230 million ; Sivextro , $171 million ; and Simponi , $163 million . Additionally, the Company had $2.4 billion of acquired intangibles related to animal health marketed products at December 31, 2019 . Some of the Company’s more significant intangible assets included in licenses above at December 31, 2019 include Lenvima, $956 million and Lynparza, $955 million as a result of collaborations with Eisai and AstraZeneca (see Note 4). The increase in trade names in 2019 reflects $2.7 billion of intangibles acquired in the Antelliq acquisition in 2019 (see Note 3). The Company has an intangible asset related to Adempas as a result of a collaboration with Bayer (see Note 4) that had a carrying value of $883 million at December 31, 2019 reflected in “Other” in the table above. In 2019, the Company recorded impairment charges related to marketed products and other intangibles of $705 million within Cost of sales . Of this amount, $612 million related to Sivextro , a product for the treatment of acute bacterial skin and skin structure infections caused by designated susceptible Gram-positive organisms. As part of a reorganization and reprioritization of its internal sales force, the Company made the decision to cease promotion of Sivextro in the U.S. market by the end of 2019. This decision resulted in reduced ca sh flow projections for Sivextro , which indicated that the Sivextro intangible asset value was not fully recoverable on an undiscounted cash flows basis. The Company utilized market participant assumptions to determine its best estimate of the fair value of the intangible asset related to Sivextro that, when compared with its related carrying value, resulted in the impairment charge noted above. In 2017, the Company recorded impairment charges related to marketed products and other intangibles of $58 million . Of this amount, $47 million related to Intron A , a treatment for certain types of cancers. Sales of Intron A were being adversely affected by the availability of new therapeutic options. In 2017, sales of Intron A in the United States eroded more rapidly than previously anticipated by the Company, which led to changes in the cash flow assumptions for Intron A. These revisions to cash flows indicated that the Intron A intangible asset value was not fully recoverable on an undiscounted cash flows basis. The Company utilized market participant assumptions to determine its best estimate of the fair value of the intangible asset related to Intron A that, when compared with its related carrying value, resulted in the impairment charge noted above. The remaining charges in 2017 relate to the impairment of customer relationship, tradename and developed technology intangibles for certain businesses in the Healthcare Services segment. IPR&D that the Company acquires through business combinations represents the fair value assigned to incomplete research projects which, at the time of acquisition, have not reached technological feasibility. Amounts capitalized as IPR&D are accounted for as indefinite-lived intangible assets, subject to impairment testing until completion or abandonment of the projects. Upon successful completion of each project, the Company will make a separate determination as to the then useful life of the asset and begin amortization. In 2019, the Company recorded $172 million of IPR&D impairment charges within Research and development expenses. Of this amount, $155 million relates to the write-off of the intangible asset balance for programs obtained in connection with the acquisition of IOmet Pharma Ltd following a review of clinical trial results conducted by Merck, along with external clinical trial results for similar compounds. The discontinuation of this clinical development program resulted in a reversal of the related liability for contingent consideration of $11 million . In 2018, the Company recorded $152 million of IPR&D impairment charges. Of this amount, $139 million relates to the write-off of the remaining intangible asset balance for a program obtained in connection with the SmartCells acquisition following a decision to terminate the program due to product development issues. The discontinuation of this clinical development program resulted in a reversal of the related liability for contingent consideration of $60 million (see Note 6). In 2017, the Company recorded $483 million of IPR&D impairment charges. Of this amount, $240 million resulted from a strategic decision to discontinue the development of the investigational combination regimens MK-3682B (grazoprevir/ruzasvir/uprifosbuvir) and MK-3682C (ruzasvir/uprifosbuvir) for the treatment of chronic hepatitis C virus (HCV) infection. This decision was made based on a review of available Phase 2 efficacy data and in consideration of the evolving marketplace and the growing number of treatment options available for patients with chronic HCV infection, including Zepatier , which is marketed by the Company for the treatment of adult patients with chronic HCV infection. As a result of this decision, the Company recorded an IPR&D impairment charge to write-off the remaining intangible asset related to uprifosbuvir. The IPR&D impairment charges in 2017 also include a charge of $226 million to write-off the intangible asset related to verubecestat, an investigational small molecule inhibitor of the beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), resulting from a decision in February 2018 to stop a Phase 3 study evaluating verubecestat in people with prodromal Alzheimer’s disease. The decision to stop the study followed a recommendation by the external Data Monitoring Committee (eDMC), which assessed overall benefit/risk during an interim safety analysis. The eDMC concluded that it was unlikely that positive benefit/risk could be established if the trial continued. The IPR&D projects that remain in development are subject to the inherent risks and uncertainties in drug development and it is possible that the Company will not be able to successfully develop and complete the IPR&D programs and profitably commercialize the underlying product candidates. The Company may recognize additional non-cash impairment charges in the future related to other marketed products or pipeline programs and such charges could be material. Aggregate amortization expense recorded within Cost of sales was $2.0 billion in 2019 , $3.1 billion in 2018 and $3.2 billion in 2017 . The estimated aggregate amortization expense for each of the next five years is as follows: 2020 , $1.6 billion ; 2021 , $1.5 billion ; 2022 , $1.5 billion ; 2023 , $1.5 billion ; 2024 , $1.4 billion .

Loans Payable, Long-Term Debt a

Loans Payable, Long-Term Debt and Leases	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Loans Payable, Long-Term Debt and Other Commitments	Loans Payable, Long-Term Debt and Leases Loans Payable Loans payable at December 31, 2019 included $1.9 billion of notes due in 2020, $1.4 billion of commercial paper and $226 million of long-dated notes that are subject to repayment at the option of the holders. Loans payable at December 31, 2018 included $5.1 billion of commercial paper and $149 million of long-dated notes that are subject to repayment at the option of the holders. The weighted-average interest rate of commercial paper borrowings was 2.23% and 2.09% for the years ended December 31, 2019 and 2018 , respectively. Long-Term Debt Long-term debt at December 31 consisted of: 2019 2018 2.75% notes due 2025 $ 2,492 $ 2,490 3.70% notes due 2045 1,975 1,974 2.80% notes due 2023 1,747 1,745 3.40% notes due 2029 1,732 — 4.00% notes due 2049 1,468 — 2.35% notes due 2022 1,248 1,214 4.15% notes due 2043 1,238 1,237 3.875% notes due 2021 1,151 1,132 1.125% euro-denominated notes due 2021 1,113 1,134 1.875% euro-denominated notes due 2026 1,107 1,127 2.40% notes due 2022 1,010 983 3.90% notes due 2039 982 — 2.90% notes due 2024 745 — 6.50% notes due 2033 722 726 0.50% euro-denominated notes due 2024 555 565 1.375% euro-denominated notes due 2036 551 561 2.50% euro-denominated notes due 2034 550 560 3.60% notes due 2042 490 490 6.55% notes due 2037 412 414 5.75% notes due 2036 338 338 5.95% debentures due 2028 306 306 5.85% notes due 2039 271 270 6.40% debentures due 2028 250 250 6.30% debentures due 2026 135 135 1.85% notes due 2020 — 1,231 Floating-rate notes due 2020 — 699 Other 148 225 $ 22,736 $ 19,806 Other (as presented in the table above) includes $147 million and $223 million at December 31, 2019 and 2018 , respectively, of borrowings at variable rates that resulted in effective interest rates of 2.54% and 2.27% for 2019 and 2018 , respectively. With the exception of the 6.30% debentures due 2026, the notes listed in the table above are redeemable in whole or in part, at Merck’s option at any time, at varying redemption prices. In March 2019, the Company issued $5.0 billion principal amount of senior unsecured notes consisting of $750 million of 2.90% notes due 2024, $1.75 billion of 3.40% notes due 2029, $1.0 billion of 3.90% notes due 2039, and $1.5 billion of 4.00% notes due 2049. The Company used the net proceeds from the offering of $5.0 billion for general corporate purposes, including the repayment of outstanding commercial paper borrowings. Effective as of November 3, 2009, the Company executed a full and unconditional guarantee of the then existing debt of its subsidiary Merck Sharp & Dohme Corp. (MSD) and MSD executed a full and unconditional guarantee of the then existing debt of the Company (excluding commercial paper), including for payments of principal and interest. These guarantees do not extend to debt issued subsequent to that date. Certain of the Company’s borrowings require that Merck comply with covenants and, at December 31, 2019 , the Company was in compliance with these covenants. The aggregate maturities of long-term debt for each of the next five years are as follows: 2020 , $1.9 billion ; 2021 , $2.3 billion ; 2022 , $2.3 billion ; 2023 , $1.7 billion ; 2024 , $1.3 billion . The Company has a $6.0 billion credit facility that matures in June 2024. The facility provides backup liquidity for the Company’s commercial paper borrowing facility and is to be used for general corporate purposes. The Company has not drawn funding from this facility. Leases As discussed in Note 1, on January 1, 2019, Merck adopted new guidance for the accounting and reporting of leases. The Company has operating leases primarily for manufacturing facilities, research and development facilities, corporate offices, employee housing, vehicles and certain equipment. As permitted under the transition guidance in ASC 842, the Company elected a package of practical expedients which, among other provisions, allowed the Company to carry forward historical lease classifications. The Company determines if an arrangement is a lease at inception. When evaluating contracts for embedded leases, the Company exercises judgment to determine if there is an explicit or implicit identified asset in the contract and if Merck controls the use of that asset. Embedded leases, primarily associated with contract manufacturing organizations, are immaterial. Under ASC 842 transition guidance, Merck elected the hindsight practical expedient to determine the lease term for existing leases, which permits companies to consider available information prior to the effective date of the new guidance as to the actual or likely exercise of options to extend or terminate the lease. The lease term includes options to extend or terminate the lease when it is reasonably certain that Merck will exercise that option. Real estate leases for facilities have an average remaining lease term of eight years , which include options to extend the leases for up to four years where applicable. Vehicle leases are generally in effect for four years . The Company has made an accounting policy election not to record short-term leases (leases with an initial term of 12 months or less) on the balance sheet; however, Merck currently has no short-term leases. Lease expense for operating lease payments is recognized on a straight-line basis over the term of the lease. Operating lease assets and liabilities are recognized based on the present value of lease payments over the lease term. Since the Company’s leases do not have a readily determinable implicit discount rate, the Company uses its incremental borrowing rate to calculate the present value of lease payments by asset class. On a quarterly basis, an updated incremental borrowing rate is determined based on the average remaining lease term of each asset class and the Company’s pretax cost of debt for that same term. The updated rates for each asset class are applied prospectively to new leases. As a practical expedient, the Company has made an accounting policy election for all asset classes not to separate lease components (e.g. payments for rent, real estate taxes and insurance costs) from non-lease components (e.g. common-area maintenance costs) in the event that the agreement contains both. Merck includes both the lease and non-lease components for purposes of calculating the right-of-use asset and related lease liability (if the non-lease components are fixed). For vehicle leases and employee housing, the Company applies a portfolio approach to effectively account for the operating lease assets and liabilities. Certain of the Company’s lease agreements contain variable lease payments that are adjusted periodically for inflation or for actual operating expense true-ups compared with estimated amounts; however, these amounts are immaterial. Sublease income and activity related to sale and leaseback transactions are immaterial. Merck’s lease agreements do not contain any material residual value guarantees or material restrictive covenants. Operating lease cost was $339 million in 2019. Cash paid for amounts included in the measurement of operating lease liabilities was $281 million in 2019. Operating lease assets obtained in exchange for lease obligations was $129 million in 2019. Supplemental balance sheet information related to operating leases is as follows: December 31 2019 Assets Other Assets (1) $ 1,073 Liabilities Accrued and other current liabilities 236 Other Noncurrent Liabilities 768 $ 1,004 Weighted-average remaining lease term (years) 7.4 Weighted-average discount rate 3.2 % (1) Includes prepaid leases that have no related lease liability. Maturities of operating leases liabilities are as follows: 2020 $ 264 2021 200 2022 168 2023 113 2024 89 Thereafter 297 Total lease payments 1,131 Less: Imputed interest 127 $ 1,004 At December 31, 2019 , the Company had entered into additional real estate operating leases that had not yet commenced. The obligations associated with these leases total $538 million , of which $221 million relates to a lease that will commence in April 2020 and has a lease term of 10 years . As of December 31, 2018, prior to the adoption of ASC 842, the minimum aggregate rental commitments under noncancellable leases were as follows: 2019, $188 million ; 2020, $198 million ; 2021, $150 million ; 2022, $ 134 million ; 2023, $84 million and thereafter, $243 million

Contingencies and Environmental

Contingencies and Environmental Liabilities	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Contingencies and Environmental Liabilities	Contingencies and Environmental Liabilities 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 December 31, 2019 , approximately 3,750 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. Merck filed a petition for a writ of certiorari to the U.S. Supreme Court in August 2017, seeking review of the Third Circuit’s decision. The Supreme Court granted Merck’s petition in June 2018, and in May 2019, the Supreme Court issued its opinion and 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. On November 15, 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. On December 13, 2019, the District Court ordered Merck to serve its opening brief on or before February 21, 2020, and plaintiffs to file their responsive brief on or before April 22, 2020. Merck may then file a reply on or before May 22, 2020. Accordingly, as of December 31, 2019 , approximately 970 cases were actively pending in the Femur Fracture MDL. As of December 31, 2019 , approximately 2,510 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 December 31, 2019 , 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 December 31, 2019 , Merck is aware of approximately 1,380 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 proceeding 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 June 2020. As of December 31, 2019 , 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 on September 25, 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 is currently scheduled for April 20, 2020. Governmental Proceedings As previously disclosed, in the fall of 2018, the Company received a records subpoena from the U.S. Attorney’s Office for the District of Vermont (VT USAO) pursuant to Section 248 of the Health Insurance Portability and Accountability Act of 1996 (HIPAA) relating to an investigation of potential health care offenses. The subpoena sought information relating to any actual or potential business relationship or arrangement Merck has had with Practice Fusion, Inc. (PFI), a cloud-based, electronic health records (EHR) company that was acquired by Allscripts in January 2018. The Company cooperated with the government and responded to that subpoena. Subsequently, on May 21, 2019, Merck received a second records subpoena from the VT USAO that broadened the government’s information request by seeking information relating to Merck’s relationship with any EHR company. Shortly thereafter, the VT USAO served a Civil Investigation Demand (CID) upon Merck similarly seeking information on the Company’s relationships with EHR vendors. The CID explains that the government is conducting a False Claims Act investigation concerning whether Merck and/or PFI submitted claims to federal healthcare programs that violate the Federal Anti-Kickback Statute. Merck is cooperating with the government’s investigation. As previously disclosed, on April 15, 2019, Merck received a set of investigative interrogatories from the California Attorney General’s Office pursuant to its investigation of conduct and agreements that allegedly affected or delayed competition to Lantus in the insulin market. The interrogatories seek information concerning Merck’s development of an insulin glargine product, and its subsequent termination, as well as Merck’s patent litigation against Sanofi S.A. concerning Lantus and the resolution of that litigation. Merck is cooperating with the California Attorney General’s investigation. 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. On August 9, 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, on June 27, 2019, the representatives of the putative direct purchaser class filed an amended complaint and, on August 1, 2019, retailer opt-out plaintiffs filed an amended complaint. The Merck Defendants moved to dismiss the new allegations in both complaints. On October 15, 2019, the magistrate judge issued a report and recommendation recommending that the district judge grant the motions in their entirety. On December 20, 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. Trial is currently scheduled to begin on October 28, 2020. Rotavirus Vaccines Antitrust Litigation As previously disclosed, MSD is a defendant in putative class action lawsuits filed in 2018 on behalf of direct purchasers of RotaTeq , alleging violations of federal antitrust laws. The cases were consolidated in the Eastern District of Pennsylvania. On January 23, 2019, the court denied MSD’s motions to compel arbitration and to dismiss the consolidated complaint. On February 19, 2019, MSD appealed the court’s order on arbitration to the Third Circuit. On October 28, 2019, the Third Circuit vacated the district court’s order and remanded for limited discovery on the issue of arbitrability, after which MSD may file a renewed motion to compel arbitration. Sales Force Litigation As previously disclosed, in May 2013, Ms. Kelli Smith filed a complaint against the Company in the U.S. District Court for the District of New Jersey on behalf of herself and a putative class of female sales representatives and a putative sub-class of female sales representatives with children, claiming (a) discriminatory policies and practices in selection, promotion and advancement, (b) disparate pay, (c) differential treatment, (d) hostile work environment and (e) retaliation under federal and state discrimination laws. In April 2016, the Magistrate Judge granted plaintiffs’ request to amend the complaint to add the following: (i) a Company subsidiary as a corporate defendant; (ii) an ERISA claim and (iii) an individual constructive discharge claim for one of the named plaintiffs. Approximately 700 individuals opted-in to this action; the opt-in period has closed. In August 2017, plaintiffs filed their motion to certify a Title VII pay discrimination class and also sought final collective action certification of plaintiffs’ Equal Pay Act claim. On October 1, 2018, the parties entered into an agreement to fully resolve the Smith sales force litigation. As part of the settlement and in exchange for a full and general release of all individual and class claims, the Company agreed to pay $8.5 million . On December 3, 2019, the court approved the settlement. Qui Tam Litigation As previously disclosed, in June 2012, the U.S. District Court for the Eastern District of Pennsylvania unsealed a complaint that has been filed against the Company under the federal False Claims Act by two former employees alleging, among other things, that the Company defrauded the U.S. government by falsifying data in connection with a clinical study conducted on the mumps component of the Company’s M-M-R II vaccine. The complaint alleges the fraud took place between 1999 and 2001. The U.S. government had the right to participate in and take over the prosecution of this lawsuit but notified the court that it declined to exercise that right. The two former employees are pursuing the lawsuit without the involvement of the U.S. government. In addition, as previously disclosed, two putative class action lawsuits on behalf of direct purchasers of the M‑M‑R II vaccine, which charge that the Company misrepresented the efficacy of the M-M-R II vaccine in violation of federal antitrust laws and various state consumer protection laws, are pending in the Eastern District of Pennsylvania. In September 2014, the court denied Merck’s motion to dismiss the False Claims Act suit and granted in part and denied in part its motion to dismiss the then-pending antitrust suit. As a result, both the False Claims Act suit and the antitrust suits have proceeded into discovery, which is now complete, and the parties have filed and briefed cross-motions for summary judgment, which are currently pending before the Court. The Company continues to defend against these lawsuits. Merck KGaA Litigation As previously disclosed, in January 2016, to protect its long-established brand rights in the United States, the Company filed a lawsuit against Merck KGaA, Darmstadt, Germany (KGaA), historically operating as the EMD Group in the United States, alleging it improperly uses the name “Merck” in the United States. KGaA has filed suit against the Company in France, the UK, Germany, Switzerland, Mexico, India, Australia, Singapore, Hong Kong, and China alleging, among other things, unfair competition, trademark infringement and/or corporate name infringement. In the UK, Australia, Singapore, Hong Kong, and India, KGaA also alleges breach of the parties’ coexistence agreement. The litigation is ongoing in the United States with no trial date set, and also ongoing in numerous jurisdictions outside of the United States; the Company is defending those suits in each jurisdiction. Patent Litigation From time to time, generic manufacturers of pharmaceutical products file abbreviated New Drug Applications (NDAs) with the U.S. Food and Drug Administration (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. 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 October 2019, Mylan filed a petition for Inter Partes Review (IPR) at the United States Patent and Trademark Office (USPTO) seeking invalidity of the 2026 patent. The USPTO has six months from filing to determine whether it will institute the requested IPR proceeding. 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 December 31, 2019 and 2018 of approximately $240 million and $245 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. Environmental Matters The Company and its subsidiaries are parties to a number of proceedings brought under the Comprehensive Environmental Response, Compensation and Liability Act, commonly known as Superfund, and other federal and state equivalents. These proceedings seek to require the operators of hazardous waste disposal facilities, transporters of waste to the sites and generators of hazardous waste disposed of at the sites to clean up the sites or to reimburse the government for cleanup costs. The Company has been made a party to these proceedings as an alleged generator of waste disposed of at the sites. In each case, the government alleges that the defendants are jointly and severally liable for the cleanup costs. Although joint and several liability is alleged, these proceedings are frequently resolved so that the allocation of cleanup costs among the parties more nearly reflects the relative contributions of the parties to the site situation. The Company’s potential liability varies greatly from site to site. For some sites the potential liability is de minimis and for others the final costs of cleanup have not yet been determined. While it is not feasible to predict the outcome of many of these proceedings brought by federal or state agencies or private litigants, in the opinion of the Company, such proceedings should not ultimately result in any liability which would have a material adverse effect on the financial condition, results of operations or liquidity of the Company. The Company has taken an active role in identifying and accruing for these costs and such amounts do not include any reduction for anticipated recoveries of cleanup costs from former site owners or operators or other recalcitrant potentially responsible parties. In management’s opinion, the liabilities for all environmental matters that are probable and reasonably estimable have been accrued and totaled $67 million and $71 million at December 31, 2019 and 2018 , respectively. These liabilities are undiscounted, do not consider potential recoveries from other parties and will be paid out over the periods of remediation for the applicable sites, which are expected to occur primarily over the next 15 years. Although it is not possible to predict with certainty the outcome of these matters, or the ultimate costs of remediation, management does not believe that any reasonably possible expenditures that may be incurred in excess of the liabilities accrued should exceed $58 million in the aggregate. Management also does not believe that these expenditures should result in a material adverse effect on the Company’s financial condition, results of operations or liquidity for any year.

Equity

Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Equity	Equity The Merck certificate of incorporation authorizes 6,500,000,000 shares of common stock and 20,000,000 shares of preferred stock. Capital Stock A summary of common stock and treasury stock transactions (shares in millions) is as follows: 2019 2018 2017 Common Stock Treasury Stock Common Stock Treasury Stock Common Stock Treasury Stock Balance January 1 3,577 985 3,577 880 3,577 828 Purchases of treasury stock — 66 — 122 — 67 Issuances (1) — (13 ) — (17 ) — (15 ) Balance December 31 3,577 1,038 3,577 985 3,577 880 (1) Issuances primarily reflect activity under share-based compensation plans. On October 25, 2018, the Company entered into accelerated share repurchase (ASR) agreements with two third-party financial institutions (Dealers). Under the ASR agreements, Merck agreed to purchase $5 billion of Merck’s common stock, in total, with an initial delivery of 56.7 million shares of Merck’s common stock, based on the then-current market price, made by the Dealers to Merck, and payments of $5 billion made by Merck to the Dealers on October 29, 2018, which were funded with existing cash and investments, as well as short-term borrowings. The payments to the Dealers were recorded as reductions to shareholders’ equity, consisting of a $4 billion increase in treasury stock, which reflected the value of the initial 56.7 million shares received on October 29, 2018, and a $1 billion decrease in other-paid-in capital, which reflected the value of the stock held back by the Dealers pending final settlement. Upon settlement of the ASR agreements in April 2019, Merck received an additional 7.7 million shares as determined by the average daily volume weighted-average price of Merck’s common stock during the term of the ASR program, less a negotiated discount, bringing the total shares received by Merck under this program to 64.4 million .

Share-Based Compensation Plans

Share-Based Compensation Plans	12 Months Ended
	Dec. 31, 2019
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. These plans were approved by the Company’s shareholders. At December 31, 2019 , 111 million shares collectively were authorized for future grants under the Company’s share-based compensation plans. These awards are settled with treasury shares. Employee stock options are granted to purchase shares of Company stock at the fair market value at the time of grant. These awards generally vest one-third each year over a three -year period, with a contractual term of 7 - 10 years. RSUs are stock awards that are granted to employees and entitle the holder to shares of common stock as the awards vest. The fair value of the stock option and RSU awards is determined and fixed on the grant date based on the Company’s stock price. PSUs are stock awards where the ultimate number of shares issued will be contingent on the Company’s performance against a pre-set objective or set of objectives. The fair value of each PSU is determined on the date of grant based on the Company’s stock price. For RSUs and PSUs, dividends declared during the vesting period are payable to the employees only upon vesting. Over the PSU performance period, the number of shares of stock that are expected to be issued will be adjusted based on the probability of achievement of a performance target and final compensation expense will be recognized based on the ultimate number of shares issued. RSU and PSU distributions will be in shares of Company stock after the end of the vesting or performance period, subject to the terms applicable to such awards. PSU awards generally vest after three years. Prior to 2018, RSU awards generally vested after three years; beginning with awards granted in 2018, RSU awards generally vest one-third each year over a three -year period. Total pretax share-based compensation cost recorded in 2019 , 2018 and 2017 was $417 million , $348 million and $312 million , respectively, with related income tax benefits of $57 million , $55 million and $57 million , respectively. The Company uses the Black-Scholes option pricing model for determining the fair value of option grants. In applying this model, the Company uses both historical data and current market data to estimate the fair value of its options. The Black-Scholes model requires several assumptions including expected dividend yield, risk-free interest rate, volatility, and term of the options. The expected dividend yield is based on historical patterns of dividend payments. The risk-free interest rate is based on the rate at grant date of zero-coupon U.S. Treasury Notes with a term equal to the expected term of the option. Expected volatility is estimated using a blend of historical and implied volatility. The historical component is based on historical monthly price changes. The implied volatility is obtained from market data on the Company’s traded options. The expected life represents the amount of time that options granted are expected to be outstanding, based on historical and forecasted exercise behavior. The weighted average exercise price of options granted in 2019 , 2018 and 2017 was $80.05 , $58.15 and $63.88 per option, respectively. The weighted average fair value of options granted in 2019 , 2018 and 2017 was $10.63 , $8.26 and $7.04 per option, respectively, and were determined using the following assumptions: Years Ended December 31 2019 2018 2017 Expected dividend yield 3.2 % 3.4 % 3.6 % Risk-free interest rate 2.4 % 2.9 % 2.0 % Expected volatility 18.7 % 19.1 % 17.8 % Expected life (years) 5.9 6.1 6.1 Summarized information relative to stock option plan activity (options in thousands) is as follows: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Outstanding January 1, 2019 23,807 $ 51.89 Granted 2,796 80.05 Exercised (8,119 ) 44.48 Forfeited (616 ) 45.48 Outstanding December 31, 2019 17,868 $ 59.88 6.48 $ 555 Exercisable December 31, 2019 11,837 $ 55.40 5.45 $ 421 Additional information pertaining to stock option plans is provided in the table below: Years Ended December 31 2019 2018 2017 Total intrinsic value of stock options exercised $ 295 $ 348 $ 236 Fair value of stock options vested 27 29 30 Cash received from the exercise of stock options 361 591 499 A summary of nonvested RSU and PSU activity (shares in thousands) is as follows: RSUs PSUs Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Nonvested January 1, 2019 16,128 $ 58.85 2,039 $ 59.42 Granted 4,811 80.08 763 83.90 Vested (6,594 ) 55.70 (748 ) 57.87 Forfeited (818 ) 64.75 (82 ) 66.68 Nonvested December 31, 2019 13,527 $ 67.58 1,972 $ 69.18 At December 31, 2019 , there was $603 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 1.9 years. For segment reporting, share-based compensation costs are unallocated expenses.

Pension and Other Postretiremen

Pension and Other Postretirement Benefit Plans	12 Months Ended
	Dec. 31, 2019
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. In addition, the Company provides medical benefits, principally to its eligible U.S. retirees and their dependents, through its other postretirement benefit plans. The Company uses December 31 as the year-end measurement date for all of its pension plans and other postretirement benefit plans. Net Periodic Benefit Cost The net periodic benefit cost (credit) for pension and other postretirement benefit plans consisted of the following components: Pension Benefits U.S. International Other Postretirement Benefits Years Ended December 31 2019 2018 2017 2019 2018 2017 2019 2018 2017 Service cost $ 293 $ 326 $ 312 $ 238 $ 238 $ 252 $ 48 $ 57 $ 57 Interest cost 458 432 454 177 178 172 69 69 81 Expected return on plan assets (817 ) (851 ) (862 ) (426 ) (431 ) (393 ) (72 ) (83 ) (78 ) Amortization of unrecognized prior service cost (49 ) (50 ) (53 ) (12 ) (13 ) (11 ) (78 ) (84 ) (98 ) Net loss amortization 151 232 180 64 84 98 (10 ) 1 1 Termination benefits 31 19 44 8 2 4 5 3 8 Curtailments 14 10 3 6 1 (4 ) (11 ) (8 ) (31 ) Settlements — 5 — 1 13 5 — — — Net periodic benefit cost (credit) $ 81 $ 123 $ 78 $ 56 $ 72 $ 123 $ (49 ) $ (45 ) $ (60 ) The changes in net periodic benefit cost (credit) year over year for pension plans are largely attributable to changes in the discount rate affecting net loss amortization. In connection with restructuring actions (see Note 5), termination charges were recorded in 2019 , 2018 and 2017 on pension and other postretirement benefit plans related to expanded eligibility for certain employees exiting Merck. Also, in connection with these restructuring activities, 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 table above. The components of net periodic benefit cost (credit) other than the service cost component are included in Other (income) expense, net (see Note 14), 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. Obligations and Funded Status Summarized information about the changes in plan assets and benefit obligations, the funded status and the amounts recorded at December 31 is as follows: Pension Benefits Other Postretirement Benefits U.S. International 2019 2018 2019 2018 2019 2018 Fair value of plan assets January 1 $ 9,648 $ 10,896 $ 8,580 $ 9,339 $ 968 $ 1,114 Actual return on plan assets 2,165 (810 ) 1,505 (289 ) 203 (72 ) Company contributions 130 378 262 167 14 6 Effects of exchange rate changes — — 31 (352 ) — — Benefits paid (582 ) (772 ) (230 ) (202 ) (104 ) (80 ) Settlements — (44 ) (12 ) (106 ) — — Other — — 27 23 21 — Fair value of plan assets December 31 $ 11,361 $ 9,648 $ 10,163 $ 8,580 $ 1,102 $ 968 Benefit obligation January 1 $ 10,620 $ 11,904 $ 9,083 $ 9,483 $ 1,615 $ 1,922 Service cost 293 326 238 238 48 57 Interest cost 458 432 177 178 69 69 Actuarial losses (gains) (1) 2,165 (1,258 ) 1,313 (154 ) 21 (341 ) Benefits paid (582 ) (772 ) (230 ) (202 ) (104 ) (80 ) Effects of exchange rate changes — — 4 (387 ) 1 (6 ) Plan amendments — — 1 10 — (9 ) Curtailments 18 13 3 (2 ) — — Termination benefits 31 19 8 2 5 3 Settlements — (44 ) (12 ) (106 ) — — Other — — 27 23 18 — Benefit obligation December 31 $ 13,003 $ 10,620 $ 10,612 $ 9,083 $ 1,673 $ 1,615 Funded status December 31 $ (1,642 ) $ (972 ) $ (449 ) $ (503 ) $ (571 ) $ (647 ) Recognized as: Other Assets $ — $ — $ 837 $ 659 $ — $ — Accrued and other current liabilities (92 ) (47 ) (18 ) (14 ) (10 ) (10 ) Other Noncurrent Liabilities (1,550 ) (925 ) (1,268 ) (1,148 ) (561 ) (637 ) (1) Actuarial losses (gains) primarily reflect changes in discount rates. At December 31, 2019 and 2018 , the accumulated benefit obligation was $22.8 billion and $19.0 billion , respectively, for all pension plans, of which $12.8 billion and $10.4 billion , respectively, related to U.S. pension plans. Information related to the funded status of selected pension plans at December 31 is as follows: U.S. International 2019 2018 2019 2018 Pension plans with a projected benefit obligation in excess of plan assets Projected benefit obligation $ 13,003 $ 10,620 $ 7,421 $ 6,251 Fair value of plan assets 11,361 9,648 6,135 5,089 Pension plans with an accumulated benefit obligation in excess of plan assets Accumulated benefit obligation $ 12,009 $ 9,702 $ 2,476 $ 5,936 Fair value of plan assets 10,484 8,966 1,501 5,071 Plan Assets Entities are required to use 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. The Level 3 assets are those whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques with significant unobservable inputs, as well as instruments for which the determination of fair value requires significant judgment or estimation. At December 31, 2019 and 2018 , $860 million and $826 million , respectively, or approximately 4% and 5% , respectively, of the Company’s pension investments were categorized as Level 3 assets. If the inputs used to measure the financial assets 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. The fair values of the Company’s pension plan assets at December 31 by asset category are as follows: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 NAV (1) Total Level 1 Level 2 Level 3 NAV (1) Total 2019 2018 U.S. Pension Plans Assets Cash and cash equivalents $ 3 $ — $ — $ 236 $ 239 $ 40 $ — $ — $ 182 $ 222 Investment funds Developed markets equities 205 — — 3,542 3,747 169 — — 3,021 3,190 Emerging markets equities 165 — — 723 888 121 — — 720 841 Government and agency obligations — — — 173 173 — — — 161 161 Corporate obligations — — — — — — — — 32 32 Equity securities Developed markets 2,451 — — — 2,451 2,172 — — — 2,172 Fixed income securities — Government and agency obligations — 2,094 — — 2,094 — 1,509 — — 1,509 Corporate obligations — 1,582 — — 1,582 — 1,246 — — 1,246 Mortgage and asset-backed securities — 178 — — 178 — 262 — — 262 Other investments — — 9 — 9 — — 13 — 13 Plan assets at fair value $ 2,824 $ 3,854 $ 9 $ 4,674 $ 11,361 $ 2,502 $ 3,017 $ 13 $ 4,116 $ 9,648 International Pension Plans Assets Cash and cash equivalents $ 70 $ 1 $ — $ 15 $ 86 $ 50 $ 3 $ — $ 16 $ 69 Investment funds Developed markets equities 546 3,761 — 96 4,403 461 3,071 — 75 3,607 Government and agency obligations 462 2,534 — 207 3,203 372 2,082 — 180 2,634 Emerging markets equities 66 96 — 90 252 56 112 — 83 251 Corporate obligations 5 11 — 109 125 4 7 — 94 105 Fixed income obligations 9 6 — — 15 7 4 — — 11 Real estate — 1 — — 1 — 1 1 — 2 Equity securities Developed markets 565 — — — 565 544 — — — 544 Fixed income securities Government and agency obligations 3 376 — — 379 2 291 — — 293 Corporate obligations 1 135 — — 136 1 113 — — 114 Mortgage and asset-backed securities — 61 — — 61 — 55 — — 55 Other investments Insurance contracts (2) — 65 851 — 916 — 66 811 — 877 Other — 5 — 16 21 — 4 1 13 18 Plan assets at fair value $ 1,727 $ 7,052 $ 851 $ 533 $ 10,163 $ 1,497 $ 5,809 $ 813 $ 461 $ 8,580 (1) Certain investments that were measured at net asset value (NAV) per share or its equivalent have not been classified in the fair value hierarchy. The NAV amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the fair value of plan assets at December 31, 2019 and 2018 . (2) The plans’ Level 3 investments in insurance contracts are generally valued using a crediting rate that approximates market returns and invest in underlying securities whose market values are unobservable and determined using pricing models, discounted cash flow methodologies, or similar techniques. The table below provides a summary of the changes in fair value, including transfers in and/or out, of all financial assets measured at fair value using significant unobservable inputs (Level 3) for the Company’s pension plan assets: 2019 2018 Insurance Contracts Real Estate Other Total Insurance Contracts Real Estate Other Total U.S. Pension Plans Balance January 1 $ — $ — $ 13 $ 13 $ — $ — $ 15 $ 15 Actual return on plan assets: Relating to assets still held at December 31 — — (8 ) (8 ) — — (3 ) (3 ) Relating to assets sold during the year — — 8 8 — — 4 4 Purchases and sales, net — — (4 ) (4 ) — — (3 ) (3 ) Balance December 31 $ — $ — $ 9 $ 9 $ — $ — $ 13 $ 13 International Pension Plans Balance January 1 $ 811 $ 1 $ 1 $ 813 $ 470 $ 2 $ 1 $ 473 Actual return on plan assets: Relating to assets still held at December 31 54 — — 54 (32 ) — — (32 ) Purchases and sales, net (14 ) (1 ) (1 ) (16 ) 380 (1 ) — 379 Transfers out of Level 3 — — — — (7 ) — — (7 ) Balance December 31 $ 851 $ — $ — $ 851 $ 811 $ 1 $ 1 $ 813 The fair values of the Company’s other postretirement benefit plan assets at December 31 by asset category are as follows: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 NAV (1) Total Level 1 Level 2 Level 3 NAV (1) Total 2019 2018 Assets Cash and cash equivalents $ 52 $ — $ — $ 22 $ 74 $ 78 $ — $ — $ 16 $ 94 Investment funds Developed markets equities 19 — — 324 343 16 — — 279 295 Emerging markets equities 15 — — 66 81 12 — — 67 79 Government and agency obligations 1 — — 16 17 1 — — 15 16 Corporate obligations — — — — — — — — 3 3 Equity securities — Developed markets 225 — — — 225 200 — — — 200 Fixed income securities Government and agency obligations — 196 — — 196 — 141 — — 141 Corporate obligations — 149 — — 149 — 116 — — 116 Mortgage and asset-backed securities — 17 — — 17 — 24 — — 24 Plan assets at fair value $ 312 $ 362 $ — $ 428 $ 1,102 $ 307 $ 281 $ — $ 380 $ 968 (1) Certain investments that were measured at net asset value (NAV) per share or its equivalent have not been classified in the fair value hierarchy. The NAV amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the fair value of plan assets at December 31, 2019 and 2018 . The Company has established investment guidelines for its U.S. pension and other postretirement plans to create an asset allocation that is expected to deliver a rate of return sufficient to meet the long-term obligation of each plan, given an acceptable level of risk. The target investment portfolio of the Company’s U.S. pension and other postretirement benefit plans is allocated 30% to 45% in U.S. equities, 15% to 30% in international equities, 35% to 45% in fixed-income investments, and up to 5% in cash and other investments. The portfolio’s equity weighting is consistent with the long-term nature of the plans’ benefit obligations. The expected annual standard deviation of returns of the target portfolio, which approximates 10% , reflects both the equity allocation and the diversification benefits among the asset classes in which the portfolio invests. For international pension plans, the targeted investment portfolio varies based on the duration of pension liabilities and local government rules and regulations. Although a significant percentage of plan assets are invested in U.S. equities, concentration risk is mitigated through the use of strategies that are diversified within management guidelines. Expected Contributions Expected contributions during 2020 are approximately $100 million for U.S. pension plans, approximately $150 million for international pension plans and approximately $15 million for other postretirement benefit plans. Expected Benefit Payments Expected benefit payments are as follows: U.S. Pension Benefits International Pension Benefits Other Postretirement Benefits 2020 $ 747 $ 242 $ 88 2021 717 225 92 2022 710 243 94 2023 718 250 98 2024 708 250 100 2025 — 2029 3,943 1,417 540 Expected benefit payments are based on the same assumptions used to measure the benefit obligations and include estimated future employee service. Amounts Recognized in Other Comprehensive Income Net loss amounts reflect experience differentials primarily relating to differences between expected and actual returns on plan assets as well as the effects of changes in actuarial assumptions. Net loss amounts in excess of certain thresholds are amortized into net periodic benefit cost over the average remaining service life of employees. The following amounts were reflected as components of OCI : Pension Plans Other Postretirement Benefit Plans U.S. International Years Ended December 31 2019 2018 2017 2019 2018 2017 2019 2018 2017 Net (loss) gain arising during the period $ (816 ) $ (397 ) $ (19 ) $ (227 ) $ (505 ) $ 309 $ 112 $ 186 $ 170 Prior service (cost) credit arising during the period (4 ) (4 ) (13 ) (1 ) (10 ) 22 (11 ) 2 (31 ) $ (820 ) $ (401 ) $ (32 ) $ (228 ) $ (515 ) $ 331 $ 101 $ 188 $ 139 Net loss amortization included in benefit cost $ 151 $ 232 $ 180 $ 64 $ 84 $ 98 $ (10 ) $ 1 $ 1 Prior service credit amortization included in benefit cost (49 ) (50 ) (53 ) (12 ) (13 ) (11 ) (78 ) (84 ) (98 ) $ 102 $ 182 $ 127 $ 52 $ 71 $ 87 $ (88 ) $ (83 ) $ (97 ) Actuarial Assumptions The Company reassesses its benefit plan assumptions on a regular basis. The weighted average assumptions used in determining U.S. pension and other postretirement benefit plan and international pension plan information are as follows: U.S. Pension and Other Postretirement Benefit Plans International Pension Plans December 31 2019 2018 2017 2019 2018 2017 Net periodic benefit cost Discount rate 4.40 % 3.70 % 4.30 % 2.20 % 2.10 % 2.20 % Expected rate of return on plan assets 8.10 % 8.20 % 8.70 % 4.90 % 5.10 % 5.10 % Salary growth rate 4.30 % 4.30 % 4.30 % 2.80 % 2.90 % 2.90 % Interest crediting rate 3.40 % 3.30 % 3.30 % 2.90 % 2.80 % 3.00 % Benefit obligation Discount rate 3.40 % 4.40 % 3.70 % 1.50 % 2.20 % 2.10 % Salary growth rate 4.20 % 4.30 % 4.30 % 2.80 % 2.80 % 2.90 % Interest crediting rate 4.90 % 3.40 % 3.30 % 2.80 % 2.90 % 2.80 % For both the pension and other postretirement benefit plans, the discount rate is evaluated on measurement dates and modified to reflect the prevailing market rate of a portfolio of high-quality fixed-income debt instruments that would provide the future cash flows needed to pay the benefits included in the benefit obligation as they come due. The expected rate of return for both the pension and other postretirement benefit plans represents the average rate of return to be earned on plan assets over the period the benefits included in the benefit obligation are to be paid and is determined on a plan basis. The expected rate of return for each plan is developed considering long-term historical returns data, current market conditions, and actual returns on the plan assets. Using this reference information, the long-term return expectations for each asset category and a weighted-average expected return for each plan’s target portfolio is developed, according to the allocation among those investment categories. The expected portfolio performance reflects the contribution of active management as appropriate. For 2020 , the expected rate of return for the Company’s U.S. pension and other postretirement benefit plans will range from 7.00% to 7.30% , as compared to a range of 7.70% to 8.10% in 2019 . The decrease reflects lower expected asset returns and a modest shift in asset allocation. The change in the weighted-average expected return on U.S. pension and other postretirement benefit plan assets from 2017 to 2019 is due to the relative weighting of the referenced plans’ assets. The health care cost trend rate assumptions for other postretirement benefit plans are as follows: December 31 2019 2018 Health care cost trend rate assumed for next year 6.8 % 7.0 % Rate to which the cost trend rate is assumed to decline 4.5 % 4.5 % Year that the trend rate reaches the ultimate trend rate 2032 2032 Savings Plans The Company also maintains defined contribution savings plans in the United States. The Company matches a percentage of each employee’s contributions consistent with the provisions of the plan for which the employee is eligible. Total employer contributions to these plans in 2019 , 2018 and 2017 were $149 million , $136 million and $131 million , respectively.

Other (Income) Expense, Net

Other (Income) Expense, Net	12 Months Ended
	Dec. 31, 2019
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (Income) Expense, Net Other (income) expense, net, consisted of: Years Ended December 31 2019 2018 2017 Interest income $ (274 ) $ (343 ) $ (385 ) Interest expense 893 772 754 Exchange losses (gains) 187 145 (11 ) Income from investments in equity securities, net (1) (170 ) (324 ) (352 ) Net periodic defined benefit plan (credit) cost other than service cost (545 ) (512 ) (512 ) Other, net 48 (140 ) 6 $ 139 $ (402 ) $ (500 ) (1) Includes net realized and unrealized gains and losses from investments in equity securities either owned directly or through ownership interests in investment funds. Other, net (as presented in the table above) in 2019 includes $162 million of goodwill impairment charges related to certain businesses in the Healthcare Services segment (see Note 8). Other, net in 2018 includes a gain of $115 million related to the settlement of certain patent litigation, income of $99 million related to AstraZeneca’s option exercise in 2014 in connection with the termination of the Company’s relationship with AstraZeneca LP (AZLP), and a gain of $85 million resulting from the receipt of a milestone payment for an out-licensed migraine clinical development program. Other, net in 2018 also includes $144 million of goodwill impairment charges related to certain businesses in the Healthcare Services segment (see Note 8), as well as $41 million of charges related to the write-down of assets held for sale to fair value in anticipation of the dissolution of the Company’s joint venture with Supera Farma Laboratorios S.A. in Brazil. Other, net in 2017 includes income of $232 million related to AstraZeneca’s option exercise and a $191 million loss on extinguishment of debt. Interest paid was $841 million in 2019 , $777 million in 2018 and $723 million in 2017 .

Taxes on Income

Taxes on Income	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Taxes on Income	Taxes on Income A reconciliation between the effective tax rate and the U.S. statutory rate is as follows: 2019 2018 2017 Amount Tax Rate Amount Tax Rate Amount Tax Rate U.S. statutory rate applied to income before taxes $ 2,408 21.0 % $ 1,827 21.0 % $ 2,282 35.0 % Differential arising from: Foreign earnings (1,020 ) (8.9 ) (245 ) (2.8 ) (1,654 ) (25.4 ) GILTI and the foreign-derived intangible income deduction 336 2.9 (25 ) (0.3 ) — — Tax settlements (403 ) (3.5 ) (22 ) (0.3 ) (356 ) (5.5 ) R&D tax credit (118 ) (1.0 ) (96 ) (1.1 ) (71 ) (1.1 ) State taxes (2 ) — 201 2.3 77 1.2 Acquisition of Peloton 209 1.8 — — — — TCJA 117 1.0 289 3.3 2,625 40.3 Valuation allowances 113 1.0 269 3.1 632 9.7 Acquisition-related costs, including amortization 95 0.8 267 3.1 713 10.9 Restructuring 39 0.3 56 0.6 142 2.2 Other (1) (87 ) (0.7 ) (13 ) (0.1 ) (287 ) (4.4 ) $ 1,687 14.7 % $ 2,508 28.8 % $ 4,103 62.9 % (1) Other includes the tax effects of losses on foreign subsidiaries and miscellaneous items. The Tax Cuts and Jobs Act (TCJA) was enacted in December 2017. Among other provisions, the TCJA reduced the U.S. federal corporate statutory tax rate from 35% to 21% effective January 1, 2018, required companies to pay a one-time transition tax on undistributed earnings of certain foreign subsidiaries, and created new taxes on certain foreign sourced earnings. The Company reflected the impact of the TCJA in its 2017 financial statements. However, since application of certain provisions of the TCJA remained subject to further interpretation, in certain instances the Company made reasonable estimates of the effects of the TCJA, which were since finalized as described below. The one-time transition tax is based on the Company’s post-1986 undistributed earnings and profits (E&P). For a substantial portion of these undistributed E&P, the Company had not previously provided deferred taxes as these earnings were deemed by Merck to be retained indefinitely by subsidiary companies for reinvestment. The Company recorded a provisional amount in 2017 for its one-time transition tax liability of $5.3 billion . This provisional amount was reduced by the reversal of $2.0 billion of deferred taxes that were previously recorded in connection with the merger of Schering-Plough Corporation in 2009 for certain undistributed foreign E&P. On the basis of revised calculations of post-1986 undistributed foreign E&P and finalization of the amounts held in cash or other specified assets, the Company recognized a measurement-period adjustment of $124 million in 2018 related to the transition tax obligation, with a corresponding adjustment to income tax expense during the period, resulting in a revised transition tax obligation of $5.5 billion . In 2019, the Company recorded additional charges of $117 million related to the finalization of treasury regulations associated with the TCJA. As permitted under the TCJA, the Company has elected to pay the one-time transition tax over a period of eight years through 2025. The Company’s remaining transition tax liability, which has been reduced by payments and the utilization of foreign tax credits, was $3.4 billion at December 31, 2019 , of which $390 million is included in Income taxes payable and the remainder of $3.0 billion is included in Other Noncurrent Liabilities . In 2017, the Company remeasured its deferred tax assets and liabilities at the new federal statutory tax rate of 21%, which resulted in a provisional deferred tax benefit of $779 million . On the basis of clarifications to the deferred tax benefit calculation, the Company recorded measurement-period adjustments in 2018 of $32 million related to deferred income taxes. The foreign earnings tax rate differentials in the tax rate reconciliation above primarily reflect the impacts of operations in jurisdictions with different tax rates than the United States, particularly Ireland and Switzerland, as well as Singapore and Puerto Rico which operate under tax incentive grants (which begin to expire in 2022), where the earnings had been indefinitely reinvested, thereby yielding a favorable impact on the effective tax rate compared with the U.S. statutory rate of 21% in 2019 and 2018 and 35% in 2017. The foreign earnings tax rate differentials do not include the impact of intangible asset impairment charges, amortization of purchase accounting adjustments or restructuring costs. These items are presented separately as they each represent a significant, separately disclosed pretax cost or charge, and a substantial portion of each of these items relates to jurisdictions with lower tax rates than the United States. Therefore, the impact of recording these expense items in lower tax rate jurisdictions is an unfavorable impact on the effective tax rate compared to the U.S. statutory rate. Income before taxes consisted of: Years Ended December 31 2019 2018 2017 Domestic $ 439 $ 3,717 $ 3,483 Foreign 11,025 4,984 3,038 $ 11,464 $ 8,701 $ 6,521 Taxes on income consisted of: Years Ended December 31 2019 2018 2017 Current provision Federal $ 514 $ 536 $ 5,585 Foreign 1,806 2,281 1,229 State (77 ) 200 (90 ) 2,243 3,017 6,724 Deferred provision Federal (330 ) (402 ) (2,958 ) Foreign (240 ) (64 ) 75 State 14 (43 ) 262 (556 ) (509 ) (2,621 ) $ 1,687 $ 2,508 $ 4,103 Deferred income taxes at December 31 consisted of: 2019 2018 Assets Liabilities Assets Liabilities Product intangibles and licenses $ 442 $ 1,778 $ 720 $ 1,640 Inventory related 32 354 32 377 Accelerated depreciation — 594 — 582 Pensions and other postretirement benefits 785 191 565 151 Compensation related 322 — 291 — Unrecognized tax benefits 109 — 174 — Net operating losses and other tax credit carryforwards 897 — 715 — Other 764 84 621 66 Subtotal 3,351 3,001 3,118 2,816 Valuation allowance (1,100 ) (1,348 ) Total deferred taxes $ 2,251 $ 3,001 $ 1,770 $ 2,816 Net deferred income taxes $ 750 $ 1,046 Recognized as: Other Assets $ 719 $ 656 Deferred Income Taxes $ 1,470 $ 1,702 The Company has net operating loss (NOL) carryforwards in several jurisdictions. As of December 31, 2019 , $762 million of deferred taxes on NOL carryforwards relate to foreign jurisdictions. Valuation allowances of $1.1 billion have been established on these foreign NOL carryforwards and other foreign deferred tax assets. In addition, the Company has $135 million of deferred tax assets relating to various U.S. tax credit carryforwards and NOL carryforwards, all of which are expected to be fully utilized prior to expiry. Income taxes paid in 2019 , 2018 and 2017 were $4.5 billion , $1.5 billion and $4.9 billion , respectively. Tax benefits relating to stock option exercises were $65 million in 2019 , $77 million in 2018 and $73 million in 2017 . A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2019 2018 2017 Balance January 1 $ 1,893 $ 1,723 $ 3,494 Additions related to current year positions 199 221 146 Additions related to prior year positions 46 142 520 Reductions for tax positions of prior years (1) (454 ) (73 ) (1,038 ) Settlements (1) (356 ) (91 ) (1,388 ) Lapse of statute of limitations (2) (103 ) (29 ) (11 ) Balance December 31 $ 1,225 $ 1,893 $ 1,723 (1) Amounts reflect the settlements with the IRS as discussed below. (2) Amount in 2019 includes $78 million related to the divestiture of Merck’s Consumer Care business in 2014. If the Company were to recognize the unrecognized tax benefits of $1.2 billion at December 31, 2019 , the income tax provision would reflect a favorable net impact of $1.1 billion . The Company is under examination by numerous tax authorities in various jurisdictions globally. The Company believes that it is reasonably possible that the total amount of unrecognized tax benefits as of December 31, 2019 could decrease by up to approximately $40 million in the next 12 months as a result of various audit closures, settlements or the expiration of the statute of limitations. The ultimate finalization of the Company’s examinations with relevant taxing authorities can include formal administrative and legal proceedings, which could have a significant impact on the timing of the reversal of unrecognized tax benefits. The Company believes that its reserves for uncertain tax positions are adequate to cover existing risks or exposures. Interest and penalties associated with uncertain tax positions amounted to a (benefit) expense of $(101) million in 2019 , $51 million in 2018 and $183 million in 2017 . These amounts reflect the beneficial impacts of various tax settlements, including those discussed below. Liabilities for accrued interest and penalties were $243 million and $372 million as of December 31, 2019 and 2018 , respectively. In 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 $364 million net tax benefit in 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. In 2017, the IRS concluded its examinations of Merck’s 2006-2011 U.S. federal income tax returns. As a result, the Company was required to make a payment of approximately $2.8 billion . 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 net $234 million tax benefit in 2017. 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, as well as adjustments to reserves for unrecognized tax benefits relating to years which remain open to examination that are affected by this settlement. The IRS is currently conducting examinations of the Company’s tax returns for the years 2015 and 2016. In addition, various state and foreign tax examinations are in progress and for these jurisdictions, the Company’s income tax returns are open for examination for the period 2003 through 2019.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings per Share	Earnings per Share The calculations of earnings per share (shares in millions) are as follows: Years Ended December 31 2019 2018 2017 Net income attributable to Merck & Co., Inc. $ 9,843 $ 6,220 $ 2,394 Average common shares outstanding 2,565 2,664 2,730 Common shares issuable (1) 15 15 18 Average common shares outstanding assuming dilution 2,580 2,679 2,748 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders $ 3.84 $ 2.34 $ 0.88 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders $ 3.81 $ 2.32 $ 0.87 (1) Issuable primarily under share-based compensation plans. In 2019 , 2018 and 2017 , 2 million , 6 million and 5 million , respectively, of common shares issuable under share-based compensation plans were excluded from the computation of earnings per common share assuming dilution because the effect would have been antidilutive.

Other Comprehensive Income (Los

Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Other Comprehensive Income (Loss)	Other Comprehensive Income (Loss) Changes in AOCI by component are as follows: Derivatives Investments Employee Benefit Plans Cumulative Translation Adjustment Accumulated Other Comprehensive Income (Loss) Balance January 1, 2017, net of taxes $ 338 $ (3 ) $ (3,206 ) $ (2,355 ) $ (5,226 ) Other comprehensive income (loss) before reclassification adjustments, pretax (561 ) 212 438 235 324 Tax 207 (35 ) (106 ) 166 232 Other comprehensive income (loss) before reclassification adjustments, net of taxes (354 ) 177 332 401 556 Reclassification adjustments, pretax (141 ) (1) (291 ) (2) 117 (3) — (315 ) Tax 49 56 (30 ) — 75 Reclassification adjustments, net of taxes (92 ) (235 ) 87 — (240 ) Other comprehensive income (loss), net of taxes (446 ) (58 ) 419 401 316 Balance at December 31, 2017, net of taxes (108 ) (61 ) (2,787 ) (1,954 ) (4,910 ) Other comprehensive income (loss) before reclassification adjustments, pretax 228 (108 ) (728 ) (84 ) (692 ) Tax (55 ) 1 169 (139 ) (24 ) Other comprehensive income (loss) before reclassification adjustments, net of taxes 173 (107 ) (559 ) (223 ) (716 ) Reclassification adjustments, pretax 157 (1) 97 (2) 170 (3) — 424 Tax (33 ) — (36 ) — (69 ) Reclassification adjustments, net of taxes 124 97 134 — 355 Other comprehensive income (loss), net of taxes 297 (10 ) (425 ) (223 ) (361 ) Adoption of ASU 2018-02 (23 ) 1 (344 ) 100 (266 ) Adoption of ASU 2016-01 — (8 ) — — (8 ) Balance at December 31, 2018, net of taxes 166 (78 ) (3,556 ) (4) (2,077 ) (5,545 ) Other comprehensive income (loss) before reclassification adjustments, pretax 86 140 (948 ) 112 (610 ) Tax (15 ) — 192 (16 ) 161 Other comprehensive income (loss) before reclassification adjustments, net of taxes 71 140 (756 ) 96 (449 ) Reclassification adjustments, pretax (261 ) (1) (44 ) (2) 66 (3) — (239 ) Tax 55 — (15 ) — 40 Reclassification adjustments, net of taxes (206 ) (44 ) 51 — (199 ) Other comprehensive income (loss), net of taxes (135 ) 96 (705 ) 96 (648 ) Balance at December 31, 2019, net of taxes $ 31 $ 18 $ (4,261 ) (4) $ (1,981 ) $ (6,193 ) (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 investments that were reclassified from AOCI to Other (income) expense, net . In 2017, these amounts included both investments in debt and equity securities; however, as a result of the adoption of ASU 2016-01 in 2018, these amounts relate only to investments in available-for-sale debt securities. (3) Includes net amortization of prior service cost and actuarial gains and losses included in net periodic benefit cost (see Note 13). (4) Includes pension plan net loss of $ 5.1 billion and $4.4 billion at December 31, 2019 and 2018 , respectively, and other postretirement benefit plan net gain of $247 million and $170 million at December 31, 2019 and 2018 , respectively, as well as pension plan prior service credit of $263 million and $314 million at December 31, 2019 and 2018 , respectively, and other postretirement benefit plan prior service credit of $305 million and $375 million at December 31, 2019 and 2018 , respectively.

Segment Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company’s operations are principally managed on a products basis and include four operating segments, which are the Pharmaceutical, Animal Health, Healthcare Services and Alliances 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. During 2019, as a result of changes to the Company’s internal reporting structure, certain costs that were previously included in the Pharmaceutical segment are now being included as part of non-segment expenses within Merck Research Laboratories. Prior period Pharmaceutical segment profits have been recast to reflect these changes on a comparable basis. 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 provides services and solutions that focus on engagement, health analytics and clinical services to improve the value of care delivered to patients. The Company has recently sold certain businesses in the Healthcare Services segment and is in the process of divesting the remaining businesses. The Alliances segment primarily includes activity from the Company’s relationship with AstraZeneca LP related to sales of Nexium and Prilosec, which concluded in 2018. Sales of the Company’s products were as follows: Years Ended December 31 2019 2018 2017 U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total Pharmaceutical: Oncology Keytruda $ 6,305 $ 4,779 $ 11,084 $ 4,150 $ 3,021 $ 7,171 $ 2,309 $ 1,500 $ 3,809 Alliance revenue - Lynparza (1) 269 176 444 127 61 187 — 20 20 Alliance revenue - Lenvima (1) 239 165 404 95 54 149 — — — Emend 183 205 388 312 210 522 342 213 556 Vaccines Gardasil/Gardasil 9 1,831 1,905 3,737 1,873 1,279 3,151 1,565 743 2,308 ProQuad/M-M-R II/Varivax 1,683 592 2,275 1,430 368 1,798 1,374 303 1,676 Pneumovax 23 679 247 926 627 281 907 581 240 821 RotaTeq 506 284 791 496 232 728 481 204 686 Vaqta 130 108 238 127 112 239 94 124 218 Hospital Acute Care Bridion 533 598 1,131 386 531 917 239 465 704 Noxafil 282 380 662 353 389 742 309 327 636 Primaxin 2 271 273 7 258 265 10 270 280 Invanz 30 233 263 253 243 496 361 241 602 Cubicin 92 165 257 191 176 367 189 193 382 Cancidas 6 242 249 12 314 326 20 402 422 Immunology Simponi — 830 830 — 893 893 — 819 819 Remicade — 411 411 — 582 582 — 837 837 Neuroscience Belsomra 92 214 306 96 164 260 98 112 210 Virology Isentress/Isentress HD 398 576 975 513 627 1,140 565 639 1,204 Zepatier 118 252 370 8 447 455 771 888 1,660 Cardiovascular Zetia 14 575 590 45 813 857 352 992 1,344 Vytorin 16 269 285 10 487 497 124 627 751 Atozet — 391 391 — 347 347 — 225 225 Adempas — 419 419 — 329 329 — 300 300 Diabetes Januvia 1,724 1,758 3,482 1,969 1,718 3,686 2,153 1,584 3,737 Janumet 589 1,452 2,041 811 1,417 2,228 863 1,296 2,158 Women’s Health NuvaRing 742 136 879 722 180 902 564 197 761 Implanon/Nexplanon 568 219 787 495 208 703 496 191 686 Diversified Brands Singulair 29 669 698 20 688 708 40 692 732 Cozaar/Hyzaar 24 418 442 23 431 453 18 466 484 Nasonex 9 284 293 23 353 376 54 333 387 Arcoxia — 288 288 — 335 335 — 363 363 Follistim AQ 103 138 241 115 153 268 123 174 298 Other pharmaceutical (2) 1,563 3,343 4,901 1,319 3,380 4,705 1,759 3,556 5,314 Total Pharmaceutical segment sales 18,759 22,992 41,751 16,608 21,081 37,689 15,854 19,536 35,390 Animal Health: Livestock 582 2,201 2,784 528 2,102 2,630 471 2,013 2,484 Companion Animals 724 885 1,609 710 872 1,582 619 772 1,391 Total Animal Health segment sales 1,306 3,086 4,393 1,238 2,974 4,212 1,090 2,785 3,875 Other segment sales (3) 174 1 175 248 2 250 396 1 397 Total segment sales 20,239 26,079 46,319 18,094 24,057 42,151 17,340 22,322 39,662 Other (4) 86 436 521 118 26 143 84 376 460 $ 20,325 $ 26,515 $ 46,840 $ 18,212 $ 24,083 $ 42,294 $ 17,424 $ 22,698 $ 40,122 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 4). (2) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (3) Represents the non-reportable segments of Healthcare Services and Alliances. (4) Other is primarily comprised of miscellaneous corporate revenues, including revenue hedging activities, as well as third-party manufacturing sales. Other in 2019 , 2018 and 2017 also includes approximately $80 million , $95 million and $85 million , respectively, related to the sale of the marketing rights to certain products. Consolidated sales by geographic area where derived are as follows: Years Ended December 31 2019 2018 2017 United States $ 20,325 $ 18,212 $ 17,424 Europe, Middle East and Africa 12,707 12,213 11,478 Japan 3,583 3,212 3,122 China 3,207 2,184 1,586 Asia Pacific (other than Japan and China) 2,943 2,909 2,751 Latin America 2,469 2,415 2,339 Other 1,606 1,149 1,422 $ 46,840 $ 42,294 $ 40,122 A reconciliation of segment profits to Income before taxes is as follows: Years Ended December 31 2019 2018 2017 Segment profits: Pharmaceutical segment $ 28,324 $ 24,871 $ 23,018 Animal Health segment 1,609 1,659 1,552 Other segments (7 ) 103 275 Total segment profits 29,926 26,633 24,845 Other profits 363 6 26 Unallocated: Interest income 274 343 385 Interest expense (893 ) (772 ) (754 ) Depreciation and amortization (1,573 ) (1,334 ) (1,378 ) Research and development (9,499 ) (9,432 ) (10,004 ) Amortization of purchase accounting adjustments (1,419 ) (2,664 ) (3,056 ) Restructuring costs (638 ) (632 ) (776 ) Charge related to the termination of a collaboration with Samsung — (423 ) — Loss on extinguishment of debt — — (191 ) Other unallocated, net (5,077 ) (3,024 ) (2,576 ) Income Before Taxes $ 11,464 $ 8,701 $ 6,521 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 of liabilities for contingent consideration, and other miscellaneous income or expense items. Equity (income) loss from affiliates and depreciation and amortization included in segment profits is as follows: Pharmaceutical Animal Health All Other Total Year Ended December 31, 2019 Included in segment profits: Equity (income) loss from affiliates $ — $ — $ — $ — Depreciation and amortization 137 109 10 256 Year Ended December 31, 2018 Included in segment profits: Equity (income) loss from affiliates $ 4 $ — $ — $ 4 Depreciation and amortization 243 82 10 335 Year Ended December 31, 2017 Included in segment profits: Equity (income) loss from affiliates $ 7 $ — $ — $ 7 Depreciation and amortization 125 75 12 212 Property, plant and equipment, net, by geographic area where located is as follows: December 31 2019 2018 2017 United States $ 8,974 $ 8,306 $ 8,070 Europe, Middle East and Africa 4,767 3,706 3,151 Asia Pacific (other than Japan and China) 714 684 632 Latin America 266 264 271 China 174 167 150 Japan 152 159 158 Other 6 5 7 $ 15,053 $ 13,291 $ 12,439 The Company does not disaggregate assets on a products and services basis for internal management reporting and, therefore, such information is not presented.

Summary of Accounting Policies

Summary of Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation — The consolidated financial statements include the accounts of the Company and all of its subsidiaries in which a controlling interest is maintained. Intercompany balances and transactions are eliminated. Controlling interest is determined by majority ownership interest and the absence of substantive third-party participating rights or, in the case of variable interest entities, by majority exposure to expected losses, residual returns or both. For those consolidated subsidiaries where Merck ownership is less than 100%, the outside shareholders’ interests are shown as Noncontrolling interests in equity. Investments in affiliates over which the Company has significant influence but not a controlling interest, such as interests in entities owned equally by the Company and a third party that are under shared control, are carried on the equity basis.
Acquisitions	Acquisitions — In a business combination, the acquisition method of accounting requires that the assets acquired and liabilities assumed be recorded as of the date of the acquisition at their respective fair values with limited exceptions. Assets acquired and liabilities assumed in a business combination that arise from contingencies are generally recognized at fair value. If fair value cannot be determined, the asset or liability is recognized if probable and reasonably estimable; if these criteria are not met, no asset or liability is recognized. 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. Accordingly, the Company may be required to value assets at fair value measures that do not reflect the Company’s intended use of those assets. Any excess of the purchase price (consideration transferred) over the estimated fair values of net assets acquired is recorded as goodwill. Transaction costs and costs to restructure the acquired company are expensed as incurred. The operating results of the acquired business are reflected in the Company’s consolidated financial statements after the date of the acquisition. If the Company determines the assets acquired do not meet the definition of a business under the acquisition method of accounting, the transaction will be accounted for as an acquisition of assets rather than a business combination and, therefore, no goodwill will be recorded. In an asset acquisition, acquired in-process research and development (IPR&D) with no alternative future use is charged to expense and contingent consideration is not recognized at the acquisition date.
Foreign Currency Translation	Foreign Currency Translation — The net assets of international subsidiaries where the local currencies have been determined to be the functional currencies are translated into U.S. dollars using current exchange rates. The U.S. dollar effects that arise from translating the net assets of these subsidiaries at changing rates are recorded in the foreign currency translation account, which is included in Accumulated other comprehensive income (loss) ( AOCI ) and reflected as a separate component of equity. For those subsidiaries that operate in highly inflationary economies and for those subsidiaries where the U.S. dollar has been determined to be the functional currency, non-monetary foreign currency assets and liabilities are translated using historical rates, while monetary assets and liabilities are translated at current rates, with the U.S. dollar effects of rate changes included in Other (income) expense, net .
Cash Equivalents	Cash Equivalents — Cash equivalents are comprised of certain highly liquid investments with original maturities of less than three months.
Inventories	Inventories — Inventories are valued at the lower of cost or net realizable value. The cost of a substantial majority of U.S. pharmaceutical and vaccine inventories is determined using the last-in, first-out (LIFO) method for both financial reporting and tax purposes. The cost of all other inventories is determined using the first-in, first-out (FIFO) method. Inventories consist of currently marketed products, as well as certain inventories produced in preparation for product launches that are considered to have a high probability of regulatory approval. In evaluating the recoverability of inventories produced in preparation for product launches, the Company considers the likelihood that revenue will be obtained from the future sale of the related inventory together with the status of the product within the regulatory approval process.
Investments	Investments — Investments in marketable debt securities classified as available-for-sale are reported at fair value. Fair values of the Company’s investments in marketable debt securities are determined using quoted market prices in active markets for identical assets or liabilities or 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. Changes in fair value that are considered temporary are reported net of tax in Other Comprehensive Income ( OCI ). The Company considers available evidence in evaluating potential impairments of its investments in marketable debt securities, including the duration and extent to which fair value is less than cost. An other-than-temporary impairment has occurred if the Company does not expect to recover the entire amortized cost basis of the marketable debt security. If the Company does not intend to sell the impaired debt security, and it is not more likely than not it will be required to sell the debt security before the recovery of its amortized cost basis, the amount of the other-than-temporary impairment recognized in earnings, recorded in Other (income) expense, net , is limited to the portion attributed to credit loss. The remaining portion of the other-than-temporary impairment related to other factors is recognized in OCI . Realized gains and losses for debt securities are included in Other (income) expense, net . Investments in publicly traded equity securities are reported at fair value determined using quoted market prices in active markets for identical assets or quoted prices for similar assets or other inputs that are observable or can be corroborated by observable market data. Changes in fair value are included in Other (income) expense, net . Investments in equity securities without readily determinable fair values are recorded at cost, plus or minus subsequent observable price changes in orderly transactions for identical or similar investments, minus impairments. Such adjustments are recognized in Other (income) expense, net . Realized gains and losses for equity securities are included in Other (income) expense, net .
Revenue Recognition	Revenue Recognition — On January 1, 2018, the Company adopted ASU 2014-09, Revenue from Contracts with Customers , and subsequent amendments (ASC 606 or new guidance), using the modified retrospective method. Comparative information for prior periods has not been restated and continues to be reported under the accounting standards in effect for those periods. Recognition of revenue requires evidence of a contract, probable collection of sales proceeds and completion of substantially all performance obligations. Merck acts as the principal in substantially all of its customer arrangements and therefore records revenue on a gross basis. The majority of the Company’s contracts related to the Pharmaceutical and Animal Health segments have a single performance obligation - the promise to transfer goods. Shipping is considered immaterial in the context of the overall customer arrangement and damages or loss of goods in transit are rare. Therefore, shipping is not deemed a separately recognized performance obligation. The vast majority of revenues from sales of products are recognized at a point in time when control of the goods is transferred to the customer, which the Company has determined is when title and risks and rewards of ownership transfer to the customer and the Company is entitled to payment. The Company recognizes revenue from the sales of vaccines to the Federal government for placement into vaccine stockpiles in accordance with Securities and Exchange Commission (SEC) Interpretation , Commission Guidance Regarding Accounting for Sales of Vaccines and BioTerror Countermeasures to the Federal Government for Placement into the Pediatric Vaccine Stockpile or the Strategic National Stockpile . This interpretation allows companies to recognize revenue for sales of vaccines into U.S. government stockpiles even though these sales might not meet the criteria for revenue recognition under other accounting guidance. For businesses within the Company’s Healthcare Services segment and certain services in the Animal Health segment, revenue is recognized over time, generally ratably over the contract term as services are provided. These service revenues are not material. The nature of the Company’s business gives rise to several types of variable consideration including discounts and returns, which are estimated at the time of sale generally using the expected value method, although the most likely amount method is used for prompt pay discounts. In the United States, sales discounts are issued to customers at the point-of-sale, through an intermediary wholesaler (known as chargebacks), or in the form of rebates. Additionally, sales are generally made with a limited right of return under certain conditions. Revenues are recorded net of provisions for sales discounts and returns, which are established at the time of sale. In addition, revenues are recorded net of time value of money discounts if collection of accounts receivable is expected to be in excess of one year. The U.S. provision for aggregate customer discounts covering chargebacks and rebates was $11.8 billion in 2019 , $10.7 billion in 2018 and $10.7 billion in 2017 . Chargebacks are discounts that occur when a contracted customer purchases through an intermediary wholesaler. The contracted customer generally purchases product from the wholesaler at its contracted price plus a mark-up. The wholesaler, in turn, charges the Company back for the difference between the price initially paid by the wholesaler and the contract price paid to the wholesaler by the customer. The provision for chargebacks is based on expected sell-through levels by the Company’s wholesale customers to contracted customers, as well as estimated wholesaler inventory levels. Rebates are amounts 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. The provision for rebates is based on expected patient usage, as well as inventory levels in the distribution channel to determine the contractual obligation to the benefit providers. The Company uses historical customer segment utilization mix, sales forecasts, changes to product mix and price, inventory levels in the distribution channel, government pricing calculations and prior payment history in order to estimate the expected provision. Amounts accrued for aggregate customer discounts are evaluated on a quarterly basis through comparison of information provided by the wholesalers, health maintenance organizations, pharmacy benefit managers, federal and state agencies, and other customers to the amounts accrued. The accrued balances relative to the provisions for chargebacks and rebates included in Accounts receivable and Accrued and other current liabilities were $233 million and $2.2 billion , respectively, at December 31, 2019 and were $245 million and $2.4 billion , respectively, at December 31, 2018 . Outside of the United States, variable consideration in the form of discounts and rebates are a combination of commercially-driven discounts in highly competitive product classes, discounts required to gain or maintain reimbursement, or legislatively mandated rebates. In certain European countries, legislatively mandated rebates are calculated based on an estimate of the government’s total unbudgeted spending and the Company’s specific payback obligation. Rebates may also be required based on specific product sales thresholds. The Company applies an estimated factor against its actual invoiced sales to represent the expected level of future discount or rebate obligations associated with the sale. The Company maintains a returns policy that allows its U.S. pharmaceutical customers to return product within a specified period prior to and subsequent to the expiration date (generally, three to six months before and 12 months after product expiration). The estimate of the provision for returns is based upon historical experience with actual returns. Additionally, the Company considers factors such as levels of inventory in the distribution channel, product dating and expiration period, whether products have been discontinued, entrance in the market of generic competition, changes in formularies or launch of over-the-counter products, among others. Outside of the United States, returns are only allowed in certain countries on a limited basis. Merck’s payment terms for U.S. pharmaceutical customers are typically 36 days from receipt of invoice and for U.S. animal health customers are typically 30 days from receipt of invoice; however, certain products, including Keytruda , have longer payment terms up to 90 days. Outside of the United States, payment terms are typically 30 days to 90 days, although certain markets have longer payment terms.
Depreciation	Depreciation — Depreciation is provided over the estimated useful lives of the assets, principally using the straight-line method. For tax purposes, accelerated tax methods are used. The estimated useful lives primarily range from 25 to 45 years for Buildings , and from 3 to 15 years for Machinery, equipment and office furnishings
Advertising and Promotion Costs	Advertising and Promotion Costs —
Software Capitalization	Software Capitalization — The Company capitalizes certain costs incurred in connection with obtaining or developing internal-use software including external direct costs of material and services, and payroll costs for employees directly involved with the software development. These costs are included in Property, plant and equipment . In addition, the Company capitalizes certain costs incurred to implement a cloud computing arrangement that is considered a service agreement, which are included in Other Assets . Capitalized software costs are amortized beginning when the software project is substantially complete and the asset is ready for its intended use. Capitalized software costs associated with projects that are being amortized over 6 to 10 years (including the Company’s on-going multi-year implementation of an enterprise-wide resource planning system) were $548 million and $439 million , net of accumulated amortization at December 31, 2019 and 2018 , respectively. All other capitalized software costs are being amortized over periods ranging from 3 to 5 years. Costs incurred during the preliminary project stage and post-implementation stage, as well as maintenance and training costs, are expensed as incurred.
Goodwill	Goodwill — Goodwill represents the excess of the consideration transferred over the fair value of net assets of businesses acquired. Goodwill is assigned to reporting units and evaluated for impairment on at least an annual basis, or more frequently if impairment indicators exist, by first assessing qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the Company concludes it is more likely than not that the fair value of a reporting unit is less than its carrying amount, a quantitative fair value test is performed. If the carrying value of a reporting unit is greater than its fair value, a goodwill impairment charge will be recorded for the difference (up to the carrying value of goodwill).
Acquired Intangibles	Acquired Intangibles — Acquired intangibles include products and product rights, licenses, trade names and patents, which are initially recorded at fair value, assigned an estimated useful life, and amortized primarily on a straight-line basis over their estimated useful lives ranging from 2 to 24 years (see Note 8). The Company periodically evaluates whether current facts or circumstances indicate that the carrying values of its acquired intangibles may not be recoverable. If such circumstances are determined to exist, an estimate of the undiscounted future cash flows of these assets, or appropriate asset groupings, is compared to the carrying value to determine whether an impairment exists. If the asset is determined to be impaired, the loss is measured based on the difference between the carrying value of the intangible asset and its fair value, which is determined based on the net present value of estimated future cash flows.
Acquired In-Process Research and Development	Acquired In-Process Research and Development — IPR&D that the Company acquires in conjunction with the acquisition of a business represents the fair value assigned to incomplete research projects which, at the time of acquisition, have not reached technological feasibility. The amounts are capitalized and are accounted for as indefinite-lived intangible assets, subject to impairment testing until completion or abandonment of the projects. Upon successful completion of each project, Merck will make a determination as to the then-useful life of the intangible asset, generally determined by the period in which the substantial majority of the cash flows are expected to be generated, and begin amortization. The Company evaluates IPR&D for impairment at least annually, or more frequently if impairment indicators exist, by performing a quantitative test that compares the fair value of the IPR&D intangible asset with its carrying value. If the fair value is less than the carrying amount, an impairment loss is recognized in operating results.
Contingent Consideration	Contingent Consideration — Certain of the Company’s acquisitions involve the potential for future payment of consideration that is contingent upon the achievement of performance milestones, including product development milestones and royalty payments on future product sales. If the transaction is accounted for as an acquisition of a business, the fair value of contingent consideration liabilities is determined at the acquisition date using unobservable inputs. These inputs include the estimated amount and timing of projected cash flows, the probability of success (achievement of the contingent event) and the risk-adjusted discount rate used to present value the probability-weighted cash flows. Subsequent to the acquisition date, at each reporting period until the contingency is resolved, the contingent consideration liability is remeasured at current fair value with changes (either expense or income) recorded in earnings. Significant events that increase or decrease the probability of achieving development and regulatory milestones or that increase or decrease projected cash flows will result in corresponding increases or decreases in the fair values of the related contingent consideration obligations. If the transaction is accounted for as an acquisition of an asset rather than a business, contingent consideration is not recognized at the acquisition date. In these instances, product development milestones are recognized upon achievement and sales-based milestones are recognized when the milestone is deemed probable by the Company of being achieved.
Research and Development	Research and Development —
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. When Merck is the principal on sales transactions with third parties, the Company recognizes sales, cost of sales and selling, general and administrative expenses on a gross basis. Profit sharing amounts it pays to its collaborative partners are recorded within Cost of sales . When the collaborative partner is the principal on sales transactions with third parties, the Company records profit sharing amounts received from its collaborative partners as alliance revenue (within Sales ). Alliance revenue is recorded net of cost of sales and includes an adjustment to share commercialization costs between the partners in accordance with the collaboration agreement. The adjustment is determined by comparing the commercialization costs Merck has incurred directly and reported within Selling, general and administrative expenses with the costs the collaborative partner has incurred. Research and development costs Merck incurs related to collaborations are recorded within Research and development expenses. Cost reimbursements to the collaborative partner or payments received from the collaborative partner to share these costs pursuant to the terms of the collaboration agreements are recorded as increases or decreases to Research and development expenses. In addition, the terms of the collaboration agreements may require the Company to make payments based upon the achievement of certain developmental, regulatory approval or commercial milestones. Upfront and milestone payments payable by Merck to collaborative partners prior to regulatory approval are expensed as incurred and included in Research and development expenses. Payments due to collaborative partners upon or subsequent to regulatory approval are capitalized and amortized over the estimated useful life of the corresponding intangible asset to Cost of sales provided that future cash flows support the amounts capitalized. Sales-based milestones payable by Merck to collaborative partners are accrued and capitalized, subject to cumulative amortization catch-up, when probable of being achieved. The amortization catch-up is calculated either from the time of the first regulatory approval for indications that were unapproved at the time the collaboration was formed, or from time of the formation of the collaboration for approved products. The related intangible asset that is recognized is amortized to Cost of sales over its remaining useful life, subject to impairment testing.
Share-Based Compensation	Share-Based Compensation — The Company expenses all share-based payments to employees over the requisite service period based on the grant-date fair value of the awards.
Restructuring Costs	Restructuring Costs — The Company records liabilities for costs associated with exit or disposal activities in the period in which the liability is incurred. In accordance with existing benefit arrangements, employee termination costs are accrued when the restructuring actions are probable and estimable. When accruing these costs, the Company will recognize the amount within a range of costs that is the best estimate within the range. When no amount within the range is a better estimate than any other amount, the Company recognizes the minimum amount within the range. Costs for one-time termination benefits in which the employee is required to render service until termination in order to receive the benefits are recognized ratably over the future service period.
Contingencies and Legal Defense Costs	Contingencies and Legal Defense Costs — The Company records accruals for contingencies and legal defense costs expected to be incurred in connection with a loss contingency when it is probable that a liability has been incurred and the amount can be reasonably estimated.
Taxes on Income	Taxes on Income — Deferred taxes are recognized for the future tax effects of temporary differences between financial and income tax reporting based on enacted tax laws and rates. The Company evaluates tax positions to determine whether the benefits of tax positions are more likely than not of being sustained upon audit based on the technical merits of the tax position. For tax positions that are more likely than not of being sustained upon audit, the Company recognizes the largest amount of the benefit that is greater than 50% likely of being realized upon ultimate settlement in the financial statements. For tax positions that are not more likely than not of being sustained upon audit, the Company does not recognize any portion of the benefit in the financial statements. The Company recognizes interest and penalties associated with uncertain tax positions as a component of Taxes on income in the Consolidated Statement of Income. The Company accounts for the tax effects of the tax on global intangible low-taxed income (GILTI) of certain foreign subsidiaries in the income tax provision in the period the tax arises.
Use of Estimates	Use of Estimates — The consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States (GAAP) and, accordingly, include certain amounts that are based on management’s best estimates and judgments. Estimates are used when accounting for amounts recorded in connection with acquisitions, including initial fair value determinations of assets and liabilities, primarily IPR&D, other intangible assets and contingent consideration, as well as subsequent fair value measurements. Additionally, estimates are used in determining such items as provisions for sales discounts and returns, depreciable and amortizable lives, recoverability of inventories, including those produced in preparation for product launches, amounts recorded for contingencies, environmental liabilities, accruals for contingent sales-based milestone payments and other reserves, pension and other postretirement benefit plan assumptions, share-based compensation assumptions, restructuring costs, impairments of long-lived assets (including intangible assets and goodwill) and investments, and taxes on income. Because of the uncertainty inherent in such estimates, actual results may differ from these estimates.
Reclassifications	Reclassifications — Certain reclassifications have been made to prior year amounts to conform to the current year presentation.
Recently Adopted Accounting Standards	Recently Adopted Accounting Standards — In February 2016, the Financial Accounting Standards Board (FASB) issued new accounting guidance for the accounting and reporting of leases (ASU 2016-02) and subsequently issued several updates to the new guidance (ASC 842 or new leasing guidance). The new leasing guidance requires that lessees recognize a right-of-use asset and a lease liability for each of its leases (other than leases that meet the definition of a short-term lease). Leases are classified as either operating or finance. Operating leases result in straight-line expense in the income statement (similar to previous operating leases), while finance leases result in more expense being recognized in the earlier years of the lease term (similar to previous capital leases). The Company adopted the new standard on January 1, 2019 using a modified retrospective approach. Merck elected the transition method that allows for application of the standard at the adoption date rather than at the beginning of the earliest comparative period presented in the financial statements. The Company also elected available practical expedients. Upon adoption, the Company recognized $1.1 billion of additional assets and related liabilities on its consolidated balance sheet (see Note 9). The adoption of the new leasing guidance did not impact the Company’s consolidated statements of income or of cash flows. In April 2018, the FASB issued new guidance on the accounting for costs incurred to implement a cloud computing arrangement that is considered a service arrangement. The new guidance requires the capitalization of such costs, aligning it with the accounting for costs associated with developing or obtaining internal-use software. The Company adopted the new standard in the third quarter of 2019 using prospective application for eligible costs, which were immaterial. In August 2018, the FASB issued new guidance modifying the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The new guidance removes disclosures that no longer are considered cost beneficial, clarifies the specific requirements of certain disclosures, and adds disclosure requirements identified as relevant. The Company elected to early adopt the new guidance in 2019 on a retrospective basis resulting in minor changes to its employee benefit plan disclosures (see Note 13). Also, in August 2018, the FASB issued new guidance on fair value measurements that adds, removes, and modifies certain disclosure requirements. The Company elected to early adopt the new guidance in 2019 resulting in minor changes to its fair value disclosures (see Note 6). Recently Issued Accounting Standards Not Yet Adopted — In June 2016, the 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 will result in minor changes to the footnote presentation of information related to the Company’s collaborative arrangements. 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 application of 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.

Acquisitions, Divestitures, R_2

Acquisitions, Divestitures, Research Collaborations and License Agreements (Tables)	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Schedule of Recognized Identified 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 95 Property, plant and equipment 62 Identifiable intangible assets (useful lives ranging from 18-24 years) (1) 2,689 Deferred income tax liabilities (520 ) Other assets and liabilities, net (81 ) Total identifiable net assets 2,349 Goodwill (2) 1,302 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.

Collaborative Arrangements (Tab

Collaborative Arrangements (Tables)	12 Months Ended
	Dec. 31, 2019
Collaborative Arrangements [Abstract]
Schedule of Collaborative Arrangements	Summarized financial information related to this collaboration is as follows: Years Ended December 31 2019 2018 Alliance revenue $ 404 $ 149 Cost of sales (1) 206 39 Selling, general and administrative 80 13 Research and development (2) 189 1,489 December 31 2019 2018 Receivables from Eisai included in Other current assets $ 150 $ 71 Payables to Eisai included in Accrued and other current liabilities (3) 700 375 Payables to Eisai included in Other Noncurrent Liabilities (3) 525 543 (1) Represents amortization of capitalized milestone payments. (2) Amount for 2018 includes $1.4 billion related to the upfront payment and option payments. (3) Includes accrued milestone and future option payments. Summarized financial information related to this collaboration is as follows: Years Ended December 31 2019 2018 2017 Net product sales recorded by Merck $ 215 $ 190 $ 149 Merck’s profit share from sales in Bayer’s marketing territories 204 139 151 Total sales 419 329 300 Cost of sales (1) 113 216 99 Selling, general and administrative 41 35 27 Research and development 126 127 101 December 31 2019 2018 Receivables from Bayer included in Other current assets $ 49 $ 32 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: Years Ended December 31 2019 2018 2017 Alliance revenue $ 444 $ 187 $ 20 Cost of sales (1) 148 93 4 Selling, general and administrative 138 48 1 Research and development (2) 168 152 2,419 December 31 2019 2018 Receivables from AstraZeneca included in Other current assets $ 128 $ 52 Payables to AstraZeneca included in Accrued and other current liabilities (3) 577 405 Payables to AstraZeneca included Other Noncurrent Liabilities (3) — 250 (1) Represents amortization of capitalized milestone payments. (2) Amount for 2017 includes $2.35 billion related to the upfront payment and license option payments. (3) Includes accrued milestone payments.

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Dec. 31, 2019
Restructuring and Related Activities [Abstract]
Charges Related to Restructuring Program Activities by Type of Cost	The following table summarizes the charges related to restructuring program activities by type of cost: Separation Costs Accelerated Depreciation Other Total Year Ended December 31, 2019 Cost of sales $ — $ 198 $ 53 $ 251 Selling, general and administrative — 33 1 34 Research and development — 2 2 4 Restructuring costs 572 — 66 638 $ 572 $ 233 $ 122 $ 927 Year Ended December 31, 2018 Cost of sales $ — $ 10 $ 11 $ 21 Selling, general and administrative — 2 1 3 Research and development — (13 ) 15 2 Restructuring costs 473 — 159 632 $ 473 $ (1 ) $ 186 $ 658 Year Ended December 31, 2017 Cost of sales $ — $ 52 $ 86 $ 138 Selling, general and administrative — 2 — 2 Research and development — 6 5 11 Restructuring costs 552 — 224 776 $ 552 $ 60 $ 315 $ 927
Charges and Spending Relating to Restructuring Activities by Program	The following table summarizes the charges and spending relating to restructuring program activities: Separation Costs Accelerated Depreciation Other Total Restructuring reserves January 1, 2018 $ 619 $ — $ 128 $ 747 Expenses 473 (1 ) 186 658 (Payments) receipts, net (649 ) — (238 ) (887 ) Non-cash activity — 1 15 16 Restructuring reserves December 31, 2018 443 — 91 534 Expenses 572 233 122 927 (Payments) receipts, net (325 ) — (136 ) (461 ) Non-cash activity — (233 ) (8 ) (241 ) Restructuring reserves December 31, 2019 (1) $ 690 $ — $ 69 $ 759 (1) The remaining cash outlays are expected to be substantially completed by the end of 2023.

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Effect of Net Investment Hedges	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 Years Ended December 31 2019 2018 2017 2019 2018 2017 Net Investment Hedging Relationships Foreign exchange contracts $ (10 ) $ (18 ) $ — $ (31 ) $ (11 ) $ — Euro-denominated notes (75 ) (183 ) 520 — — — (1) No amounts were reclassified from AOCI into income related to the sale of a subsidiary.
Summary of Interest Rate Derivatives	At December 31, 2019 , the Company was a party to 19 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. 2019 Debt Instrument Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 1.85% notes due 2020 $ 1,250 5 $ 1,250 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
Schedule of Fair Value Hedging Instruments, Statements of Financial Performance and Financial Position	The table below presents the location of amounts recorded on the Consolidated Balance Sheet related to cumulative basis adjustments for fair value hedges as of December 31: Carrying Amount of Hedged Liabilities Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount 2019 2018 2019 2018 Balance Sheet Line Item in which Hedged Item is Included Loans payable and current portion of long-term debt $ 1,249 $ — $ (1 ) $ — Long-Term Debt 3,409 4,560 14 (82 )
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 as of December 31: 2019 2018 Fair Value of Derivative U.S. Dollar Notional Fair Value of Derivative U.S. Dollar Notional Balance Sheet Caption Asset Liability Asset Liability Derivatives Designated as Hedging Instruments Interest rate swap contracts Other Assets $ 15 $ — $ 3,400 $ — $ — $ — Interest rate swap contracts Accrued and other current liabilities — 1 1,250 — — — Interest rate swap contracts Other Noncurrent Liabilities — — — — 81 4,650 Foreign exchange contracts Other current assets 152 — 6,117 263 — 6,222 Foreign exchange contracts Other Assets 55 — 2,160 75 — 2,655 Foreign exchange contracts Accrued and other current liabilities — 22 1,748 — 7 774 Foreign exchange contracts Other Noncurrent Liabilities — 1 53 — 1 89 $ 222 $ 24 $ 14,728 $ 338 $ 89 $ 14,390 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts Other current assets $ 66 $ — $ 7,245 $ 116 $ — $ 5,430 Foreign exchange contracts Accrued and other current liabilities — 73 8,693 — 71 9,922 $ 66 $ 73 $ 15,938 $ 116 $ 71 $ 15,352 $ 288 $ 97 $ 30,666 $ 454 $ 160 $ 29,742
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 at December 31: 2019 2018 Asset Liability Asset Liability Gross amounts recognized in the consolidated balance sheet $ 288 $ 97 $ 454 $ 160 Gross amounts subject to offset in master netting arrangements not offset in the consolidated balance sheet (84 ) (84 ) (121 ) (121 ) Cash collateral received (34 ) — (107 ) — Net amounts $ 170 $ 13 $ 226 $ 39
Location and Pretax Gain or Loss Amounts for 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) Years Ended December 31 2019 2018 2017 2019 2018 2017 2019 2018 2017 Financial Statement Line Items in which Effects of Fair Value or Cash Flow Hedges are Recorded $ 46,840 $ 42,294 $ 40,122 $ 139 (402 ) (500 ) $ (648 ) $ (361 ) $ 316 (Gain) loss on fair value hedging relationships Interest rate swap contracts Hedged items — — — 95 (27 ) (48 ) — — — Derivatives designated as hedging instruments — — — (65 ) 50 12 — — — Impact of cash flow hedging relationships Foreign exchange contracts Amount of gain (loss) recognized in OCI on derivatives — — — — — — 87 228 (562 ) (Decrease) increase in Sales as a result of AOCI reclassifications 255 (160 ) 138 — — — (255 ) 160 (138 ) Interest rate contracts Amount of gain recognized in Other (income) expense, net on derivatives — — — (4 ) (4 ) (3 ) — — — Amount of loss recognized in OCI on derivatives — — — — — — (6 ) (4 ) (3 ) (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 Years Ended December 31 Income Statement Caption 2019 2018 2017 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts (1) Other (income) expense, net $ 174 $ (260 ) $ 110 Foreign exchange contracts (2) Sales 1 (8 ) (3 ) (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 at December 31 is as follows: 2019 2018 Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Fair Value Gains Losses Gains Losses Commercial paper $ 668 $ — $ — $ 668 $ — $ — $ — $ — Corporate notes and bonds 608 13 — 621 4,985 3 (68 ) 4,920 U.S. government and agency securities 266 3 — 269 895 2 (5 ) 892 Asset-backed securities 226 1 — 227 1,285 1 (11 ) 1,275 Foreign government bonds — — — — 167 — (1 ) 166 Mortgage-backed securities — — — — 8 — — 8 Total debt securities 1,768 17 — 1,785 7,340 6 (85 ) 7,261 Publicly traded equity securities (1) 838 456 Total debt and publicly traded equity securities $ 2,623 $ 7,717 (1) Unrealized net gains recognized in Other (income) expense, net on equity securities still held at December 31, 2019 were $160 million during 2019. Unrealized net losses recognized in Other (income) expense, net on equity securities still held at December 31, 2018 were $35 million during 2018.
Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	Financial assets and liabilities measured at fair value on a recurring basis at December 31 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 2019 2018 Assets Investments Commercial paper $ — $ 668 $ — $ 668 $ — $ — $ — $ — Corporate notes and bonds — 621 — 621 — 4,835 — 4,835 Asset-backed securities (1) — 227 — 227 — 1,253 — 1,253 U.S. government and agency securities — 209 — 209 — 731 — 731 Foreign government bonds — — — — — 166 — 166 Publicly traded equity securities 518 — — 518 147 — — 147 518 1,725 — 2,243 147 6,985 — 7,132 Other assets (2) U.S. government and agency securities 60 — — 60 55 106 — 161 Corporate notes and bonds — — — — — 85 — 85 Asset-backed securities (1) — — — — — 22 — 22 Mortgage-backed securities — — — — — 8 — 8 Publicly traded equity securities 320 — — 320 309 — — 309 380 — — 380 364 221 — 585 Derivative assets (3) Forward exchange contracts — 169 — 169 — 241 — 241 Purchased currency options — 104 — 104 — 213 — 213 Interest rate swaps — 15 — 15 — — — — — 288 — 288 — 454 — 454 Total assets $ 898 $ 2,013 $ — $ 2,911 $ 511 $ 7,660 $ — $ 8,171 Liabilities Other liabilities Contingent consideration $ — $ — $ 767 $ 767 $ — $ — $ 788 $ 788 Derivative liabilities (3) Forward exchange contracts — 95 — 95 — 74 — 74 Interest rate swaps — 1 — 1 — 81 — 81 Written currency options — 1 — 1 — 5 — 5 — 97 — 97 — 160 — 160 Total liabilities $ — $ 97 $ 767 $ 864 $ — $ 160 $ 788 $ 948 (1) Primarily all of the asset-backed securities are 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.
Summarized 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: 2019 2018 Fair value January 1 $ 788 $ 935 Changes in estimated fair value (1) 64 89 Additions — 8 Payments (85 ) (244 ) Fair value December 31 (2)(3) $ 767 $ 788 (1) Recorded in Cost of sales, Research and development expenses, and Other (income) expense, net . Includes cumulative translation adjustments. (2) Balance at December 31, 2019 includes $114 million recorded as a current liability for amounts expected to be paid within the next 12 months. (3) At December 31, 2019 and 2018 , $625 million and $614 million , respectively, of the liabilities relate to the termination of the SPMSD 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 and a risk-adjusted discount rate of 8% is used to present value the cash flows.

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventories	Inventories at December 31 consisted of: 2019 2018 Finished goods $ 1,772 $ 1,658 Raw materials and work in process 5,650 5,004 Supplies 207 194 Total (approximates current cost) 7,629 6,856 (Decrease) increase to LIFO cost (171 ) 1 $ 7,458 $ 6,857 Recognized as: Inventories $ 5,978 $ 5,440 Other assets 1,480 1,417

Goodwill and Other Intangibles

Goodwill and Other Intangibles (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill Activity by Segment	The following table summarizes goodwill activity by segment: Pharmaceutical Animal Health All Other Total Balance January 1, 2018 $ 16,066 $ 1,877 $ 341 $ 18,284 Acquisitions — 17 24 41 Impairments — — (144 ) (144 ) Other (1) 96 (24 ) — 72 Balance December 31, 2018 (2) 16,162 1,870 221 18,253 Acquisitions 19 1,322 — 1,341 Impairments — — (162 ) (162 ) Other (1) — — (7 ) (7 ) Balance December 31, 2019 (2) $ 16,181 $ 3,192 $ 52 $ 19,425 (1) Other includes cumulative translation adjustments on goodwill balances and certain other adjustments. (2) Accumulated goodwill impairment losses at December 31, 2019 and 2018 were $531 million and $369 million , respectively.
Other Intangibles	Other intangibles at December 31 consisted of: 2019 2018 Gross Carrying Amount Accumulated Amortization Net Gross Carrying Amount Accumulated Amortization Net Products and product rights $ 45,947 $ 38,852 $ 7,095 $ 46,615 $ 37,585 $ 9,030 Licenses 3,185 824 2,361 2,081 408 1,673 IPR&D 1,032 — 1,032 1,064 — 1,064 Trade names 2,899 217 2,682 209 107 102 Other 2,261 1,235 1,026 2,403 1,168 1,235 $ 55,324 $ 41,128 $ 14,196 $ 52,372 $ 39,268 $ 13,104

Loans Payable, Long-Term Debt_2

Loans Payable, Long-Term Debt and Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term debt at December 31 consisted of: 2019 2018 2.75% notes due 2025 $ 2,492 $ 2,490 3.70% notes due 2045 1,975 1,974 2.80% notes due 2023 1,747 1,745 3.40% notes due 2029 1,732 — 4.00% notes due 2049 1,468 — 2.35% notes due 2022 1,248 1,214 4.15% notes due 2043 1,238 1,237 3.875% notes due 2021 1,151 1,132 1.125% euro-denominated notes due 2021 1,113 1,134 1.875% euro-denominated notes due 2026 1,107 1,127 2.40% notes due 2022 1,010 983 3.90% notes due 2039 982 — 2.90% notes due 2024 745 — 6.50% notes due 2033 722 726 0.50% euro-denominated notes due 2024 555 565 1.375% euro-denominated notes due 2036 551 561 2.50% euro-denominated notes due 2034 550 560 3.60% notes due 2042 490 490 6.55% notes due 2037 412 414 5.75% notes due 2036 338 338 5.95% debentures due 2028 306 306 5.85% notes due 2039 271 270 6.40% debentures due 2028 250 250 6.30% debentures due 2026 135 135 1.85% notes due 2020 — 1,231 Floating-rate notes due 2020 — 699 Other 148 225 $ 22,736 $ 19,806
Supplemental Balance Sheet Information	Supplemental balance sheet information related to operating leases is as follows: December 31 2019 Assets Other Assets (1) $ 1,073 Liabilities Accrued and other current liabilities 236 Other Noncurrent Liabilities 768 $ 1,004 Weighted-average remaining lease term (years) 7.4 Weighted-average discount rate 3.2 % (1) Includes prepaid leases that have no related lease liability.
Schedule of Maturities of Operating Lease Liabilities	Maturities of operating leases liabilities are as follows: 2020 $ 264 2021 200 2022 168 2023 113 2024 89 Thereafter 297 Total lease payments 1,131 Less: Imputed interest 127 $ 1,004

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Summary of Common Stock and Treasury Stock Transactions	A summary of common stock and treasury stock transactions (shares in millions) is as follows: 2019 2018 2017 Common Stock Treasury Stock Common Stock Treasury Stock Common Stock Treasury Stock Balance January 1 3,577 985 3,577 880 3,577 828 Purchases of treasury stock — 66 — 122 — 67 Issuances (1) — (13 ) — (17 ) — (15 ) Balance December 31 3,577 1,038 3,577 985 3,577 880 (1) Issuances primarily reflect activity under share-based compensation plans.

Share-Based Compensation Plans

Share-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Assumptions Used to Determine Weighted-Average Fair Value of Options Granted	The weighted average fair value of options granted in 2019 , 2018 and 2017 was $10.63 , $8.26 and $7.04 per option, respectively, and were determined using the following assumptions: Years Ended December 31 2019 2018 2017 Expected dividend yield 3.2 % 3.4 % 3.6 % Risk-free interest rate 2.4 % 2.9 % 2.0 % Expected volatility 18.7 % 19.1 % 17.8 % Expected life (years) 5.9 6.1 6.1
Summarized Information Relative to Stock Option Plan Activity	Summarized information relative to stock option plan activity (options in thousands) is as follows: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Term (Years) Aggregate Intrinsic Value Outstanding January 1, 2019 23,807 $ 51.89 Granted 2,796 80.05 Exercised (8,119 ) 44.48 Forfeited (616 ) 45.48 Outstanding December 31, 2019 17,868 $ 59.88 6.48 $ 555 Exercisable December 31, 2019 11,837 $ 55.40 5.45 $ 421
Additional Information Pertaining to Stock Option Plans	Additional information pertaining to stock option plans is provided in the table below: Years Ended December 31 2019 2018 2017 Total intrinsic value of stock options exercised $ 295 $ 348 $ 236 Fair value of stock options vested 27 29 30 Cash received from the exercise of stock options 361 591 499
Summary of Nonvested RSU and PSU Activity	A summary of nonvested RSU and PSU activity (shares in thousands) is as follows: RSUs PSUs Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Nonvested January 1, 2019 16,128 $ 58.85 2,039 $ 59.42 Granted 4,811 80.08 763 83.90 Vested (6,594 ) 55.70 (748 ) 57.87 Forfeited (818 ) 64.75 (82 ) 66.68 Nonvested December 31, 2019 13,527 $ 67.58 1,972 $ 69.18

Pension and Other Postretirem_2

Pension and Other Postretirement Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost	The net periodic benefit cost (credit) for pension and other postretirement benefit plans consisted of the following components: Pension Benefits U.S. International Other Postretirement Benefits Years Ended December 31 2019 2018 2017 2019 2018 2017 2019 2018 2017 Service cost $ 293 $ 326 $ 312 $ 238 $ 238 $ 252 $ 48 $ 57 $ 57 Interest cost 458 432 454 177 178 172 69 69 81 Expected return on plan assets (817 ) (851 ) (862 ) (426 ) (431 ) (393 ) (72 ) (83 ) (78 ) Amortization of unrecognized prior service cost (49 ) (50 ) (53 ) (12 ) (13 ) (11 ) (78 ) (84 ) (98 ) Net loss amortization 151 232 180 64 84 98 (10 ) 1 1 Termination benefits 31 19 44 8 2 4 5 3 8 Curtailments 14 10 3 6 1 (4 ) (11 ) (8 ) (31 ) Settlements — 5 — 1 13 5 — — — Net periodic benefit cost (credit) $ 81 $ 123 $ 78 $ 56 $ 72 $ 123 $ (49 ) $ (45 ) $ (60 )
Obligation and Funded Status	Summarized information about the changes in plan assets and benefit obligations, the funded status and the amounts recorded at December 31 is as follows: Pension Benefits Other Postretirement Benefits U.S. International 2019 2018 2019 2018 2019 2018 Fair value of plan assets January 1 $ 9,648 $ 10,896 $ 8,580 $ 9,339 $ 968 $ 1,114 Actual return on plan assets 2,165 (810 ) 1,505 (289 ) 203 (72 ) Company contributions 130 378 262 167 14 6 Effects of exchange rate changes — — 31 (352 ) — — Benefits paid (582 ) (772 ) (230 ) (202 ) (104 ) (80 ) Settlements — (44 ) (12 ) (106 ) — — Other — — 27 23 21 — Fair value of plan assets December 31 $ 11,361 $ 9,648 $ 10,163 $ 8,580 $ 1,102 $ 968 Benefit obligation January 1 $ 10,620 $ 11,904 $ 9,083 $ 9,483 $ 1,615 $ 1,922 Service cost 293 326 238 238 48 57 Interest cost 458 432 177 178 69 69 Actuarial losses (gains) (1) 2,165 (1,258 ) 1,313 (154 ) 21 (341 ) Benefits paid (582 ) (772 ) (230 ) (202 ) (104 ) (80 ) Effects of exchange rate changes — — 4 (387 ) 1 (6 ) Plan amendments — — 1 10 — (9 ) Curtailments 18 13 3 (2 ) — — Termination benefits 31 19 8 2 5 3 Settlements — (44 ) (12 ) (106 ) — — Other — — 27 23 18 — Benefit obligation December 31 $ 13,003 $ 10,620 $ 10,612 $ 9,083 $ 1,673 $ 1,615 Funded status December 31 $ (1,642 ) $ (972 ) $ (449 ) $ (503 ) $ (571 ) $ (647 ) Recognized as: Other Assets $ — $ — $ 837 $ 659 $ — $ — Accrued and other current liabilities (92 ) (47 ) (18 ) (14 ) (10 ) (10 ) Other Noncurrent Liabilities (1,550 ) (925 ) (1,268 ) (1,148 ) (561 ) (637 ) (1) Actuarial losses (gains) primarily reflect changes in discount rates.
Schedule of Accumulated and Projected Benefit Obligations in Excess of Fair Value of Plan Assets	Information related to the funded status of selected pension plans at December 31 is as follows: U.S. International 2019 2018 2019 2018 Pension plans with a projected benefit obligation in excess of plan assets Projected benefit obligation $ 13,003 $ 10,620 $ 7,421 $ 6,251 Fair value of plan assets 11,361 9,648 6,135 5,089 Pension plans with an accumulated benefit obligation in excess of plan assets Accumulated benefit obligation $ 12,009 $ 9,702 $ 2,476 $ 5,936 Fair value of plan assets 10,484 8,966 1,501 5,071
Schedule of Allocation of Plan Assets	The fair values of the Company’s other postretirement benefit plan assets at December 31 by asset category are as follows: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 NAV (1) Total Level 1 Level 2 Level 3 NAV (1) Total 2019 2018 Assets Cash and cash equivalents $ 52 $ — $ — $ 22 $ 74 $ 78 $ — $ — $ 16 $ 94 Investment funds Developed markets equities 19 — — 324 343 16 — — 279 295 Emerging markets equities 15 — — 66 81 12 — — 67 79 Government and agency obligations 1 — — 16 17 1 — — 15 16 Corporate obligations — — — — — — — — 3 3 Equity securities — Developed markets 225 — — — 225 200 — — — 200 Fixed income securities Government and agency obligations — 196 — — 196 — 141 — — 141 Corporate obligations — 149 — — 149 — 116 — — 116 Mortgage and asset-backed securities — 17 — — 17 — 24 — — 24 Plan assets at fair value $ 312 $ 362 $ — $ 428 $ 1,102 $ 307 $ 281 $ — $ 380 $ 968 (1) Certain investments that were measured at net asset value (NAV) per share or its equivalent have not been classified in the fair value hierarchy. The NAV amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the fair value of plan assets at December 31, 2019 and 2018 . The fair values of the Company’s pension plan assets at December 31 by asset category are as follows: Fair Value Measurements Using Fair Value Measurements Using Level 1 Level 2 Level 3 NAV (1) Total Level 1 Level 2 Level 3 NAV (1) Total 2019 2018 U.S. Pension Plans Assets Cash and cash equivalents $ 3 $ — $ — $ 236 $ 239 $ 40 $ — $ — $ 182 $ 222 Investment funds Developed markets equities 205 — — 3,542 3,747 169 — — 3,021 3,190 Emerging markets equities 165 — — 723 888 121 — — 720 841 Government and agency obligations — — — 173 173 — — — 161 161 Corporate obligations — — — — — — — — 32 32 Equity securities Developed markets 2,451 — — — 2,451 2,172 — — — 2,172 Fixed income securities — Government and agency obligations — 2,094 — — 2,094 — 1,509 — — 1,509 Corporate obligations — 1,582 — — 1,582 — 1,246 — — 1,246 Mortgage and asset-backed securities — 178 — — 178 — 262 — — 262 Other investments — — 9 — 9 — — 13 — 13 Plan assets at fair value $ 2,824 $ 3,854 $ 9 $ 4,674 $ 11,361 $ 2,502 $ 3,017 $ 13 $ 4,116 $ 9,648 International Pension Plans Assets Cash and cash equivalents $ 70 $ 1 $ — $ 15 $ 86 $ 50 $ 3 $ — $ 16 $ 69 Investment funds Developed markets equities 546 3,761 — 96 4,403 461 3,071 — 75 3,607 Government and agency obligations 462 2,534 — 207 3,203 372 2,082 — 180 2,634 Emerging markets equities 66 96 — 90 252 56 112 — 83 251 Corporate obligations 5 11 — 109 125 4 7 — 94 105 Fixed income obligations 9 6 — — 15 7 4 — — 11 Real estate — 1 — — 1 — 1 1 — 2 Equity securities Developed markets 565 — — — 565 544 — — — 544 Fixed income securities Government and agency obligations 3 376 — — 379 2 291 — — 293 Corporate obligations 1 135 — — 136 1 113 — — 114 Mortgage and asset-backed securities — 61 — — 61 — 55 — — 55 Other investments Insurance contracts (2) — 65 851 — 916 — 66 811 — 877 Other — 5 — 16 21 — 4 1 13 18 Plan assets at fair value $ 1,727 $ 7,052 $ 851 $ 533 $ 10,163 $ 1,497 $ 5,809 $ 813 $ 461 $ 8,580 (1) Certain investments that were measured at net asset value (NAV) per share or its equivalent have not been classified in the fair value hierarchy. The NAV amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the fair value of plan assets at December 31, 2019 and 2018 . (2) The plans’ Level 3 investments in insurance contracts are generally valued using a crediting rate that approximates market returns and invest in underlying securities whose market values are unobservable and determined using pricing models, discounted cash flow methodologies, or similar techniques.
Summary of Changes in Fair Value of Company's Level 3 Pension Plan Assets	The table below provides a summary of the changes in fair value, including transfers in and/or out, of all financial assets measured at fair value using significant unobservable inputs (Level 3) for the Company’s pension plan assets: 2019 2018 Insurance Contracts Real Estate Other Total Insurance Contracts Real Estate Other Total U.S. Pension Plans Balance January 1 $ — $ — $ 13 $ 13 $ — $ — $ 15 $ 15 Actual return on plan assets: Relating to assets still held at December 31 — — (8 ) (8 ) — — (3 ) (3 ) Relating to assets sold during the year — — 8 8 — — 4 4 Purchases and sales, net — — (4 ) (4 ) — — (3 ) (3 ) Balance December 31 $ — $ — $ 9 $ 9 $ — $ — $ 13 $ 13 International Pension Plans Balance January 1 $ 811 $ 1 $ 1 $ 813 $ 470 $ 2 $ 1 $ 473 Actual return on plan assets: Relating to assets still held at December 31 54 — — 54 (32 ) — — (32 ) Purchases and sales, net (14 ) (1 ) (1 ) (16 ) 380 (1 ) — 379 Transfers out of Level 3 — — — — (7 ) — — (7 ) Balance December 31 $ 851 $ — $ — $ 851 $ 811 $ 1 $ 1 $ 813
Summary of Expected Benefit Payments	Expected benefit payments are as follows: U.S. Pension Benefits International Pension Benefits Other Postretirement Benefits 2020 $ 747 $ 242 $ 88 2021 717 225 92 2022 710 243 94 2023 718 250 98 2024 708 250 100 2025 — 2029 3,943 1,417 540
Components of Other Comprehensive Income	The following amounts were reflected as components of OCI : Pension Plans Other Postretirement Benefit Plans U.S. International Years Ended December 31 2019 2018 2017 2019 2018 2017 2019 2018 2017 Net (loss) gain arising during the period $ (816 ) $ (397 ) $ (19 ) $ (227 ) $ (505 ) $ 309 $ 112 $ 186 $ 170 Prior service (cost) credit arising during the period (4 ) (4 ) (13 ) (1 ) (10 ) 22 (11 ) 2 (31 ) $ (820 ) $ (401 ) $ (32 ) $ (228 ) $ (515 ) $ 331 $ 101 $ 188 $ 139 Net loss amortization included in benefit cost $ 151 $ 232 $ 180 $ 64 $ 84 $ 98 $ (10 ) $ 1 $ 1 Prior service credit amortization included in benefit cost (49 ) (50 ) (53 ) (12 ) (13 ) (11 ) (78 ) (84 ) (98 ) $ 102 $ 182 $ 127 $ 52 $ 71 $ 87 $ (88 ) $ (83 ) $ (97 )
Summary of Weighted Average Assumptions Used in Determining Pension Plan and U.S. Pension and Other Postretirement Benefit Plan Information	The Company reassesses its benefit plan assumptions on a regular basis. The weighted average assumptions used in determining U.S. pension and other postretirement benefit plan and international pension plan information are as follows: U.S. Pension and Other Postretirement Benefit Plans International Pension Plans December 31 2019 2018 2017 2019 2018 2017 Net periodic benefit cost Discount rate 4.40 % 3.70 % 4.30 % 2.20 % 2.10 % 2.20 % Expected rate of return on plan assets 8.10 % 8.20 % 8.70 % 4.90 % 5.10 % 5.10 % Salary growth rate 4.30 % 4.30 % 4.30 % 2.80 % 2.90 % 2.90 % Interest crediting rate 3.40 % 3.30 % 3.30 % 2.90 % 2.80 % 3.00 % Benefit obligation Discount rate 3.40 % 4.40 % 3.70 % 1.50 % 2.20 % 2.10 % Salary growth rate 4.20 % 4.30 % 4.30 % 2.80 % 2.80 % 2.90 % Interest crediting rate 4.90 % 3.40 % 3.30 % 2.80 % 2.90 % 2.80 %
Summary of Health Care Cost Trend Rate Assumptions for Other Postretirement Benefit Plans	The health care cost trend rate assumptions for other postretirement benefit plans are as follows: December 31 2019 2018 Health care cost trend rate assumed for next year 6.8 % 7.0 % Rate to which the cost trend rate is assumed to decline 4.5 % 4.5 % Year that the trend rate reaches the ultimate trend rate 2032 2032

Other (Income) Expense, Net (Ta

Other (Income) Expense, Net (Tables)	12 Months Ended
	Dec. 31, 2019
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (income) expense, net, consisted of: Years Ended December 31 2019 2018 2017 Interest income $ (274 ) $ (343 ) $ (385 ) Interest expense 893 772 754 Exchange losses (gains) 187 145 (11 ) Income from investments in equity securities, net (1) (170 ) (324 ) (352 ) Net periodic defined benefit plan (credit) cost other than service cost (545 ) (512 ) (512 ) Other, net 48 (140 ) 6 $ 139 $ (402 ) $ (500 ) (1) Includes net realized and unrealized gains and losses from investments in equity securities either owned directly or through ownership interests in investment funds.

Taxes on Income (Tables)

Taxes on Income (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Reconciliation Between Effective Tax Rate and U.S. Statutory Rate	A reconciliation between the effective tax rate and the U.S. statutory rate is as follows: 2019 2018 2017 Amount Tax Rate Amount Tax Rate Amount Tax Rate U.S. statutory rate applied to income before taxes $ 2,408 21.0 % $ 1,827 21.0 % $ 2,282 35.0 % Differential arising from: Foreign earnings (1,020 ) (8.9 ) (245 ) (2.8 ) (1,654 ) (25.4 ) GILTI and the foreign-derived intangible income deduction 336 2.9 (25 ) (0.3 ) — — Tax settlements (403 ) (3.5 ) (22 ) (0.3 ) (356 ) (5.5 ) R&D tax credit (118 ) (1.0 ) (96 ) (1.1 ) (71 ) (1.1 ) State taxes (2 ) — 201 2.3 77 1.2 Acquisition of Peloton 209 1.8 — — — — TCJA 117 1.0 289 3.3 2,625 40.3 Valuation allowances 113 1.0 269 3.1 632 9.7 Acquisition-related costs, including amortization 95 0.8 267 3.1 713 10.9 Restructuring 39 0.3 56 0.6 142 2.2 Other (1) (87 ) (0.7 ) (13 ) (0.1 ) (287 ) (4.4 ) $ 1,687 14.7 % $ 2,508 28.8 % $ 4,103 62.9 % (1) Other includes the tax effects of losses on foreign subsidiaries and miscellaneous items.
Income Before Taxes	Income before taxes consisted of: Years Ended December 31 2019 2018 2017 Domestic $ 439 $ 3,717 $ 3,483 Foreign 11,025 4,984 3,038 $ 11,464 $ 8,701 $ 6,521
Taxes on Income	Taxes on income consisted of: Years Ended December 31 2019 2018 2017 Current provision Federal $ 514 $ 536 $ 5,585 Foreign 1,806 2,281 1,229 State (77 ) 200 (90 ) 2,243 3,017 6,724 Deferred provision Federal (330 ) (402 ) (2,958 ) Foreign (240 ) (64 ) 75 State 14 (43 ) 262 (556 ) (509 ) (2,621 ) $ 1,687 $ 2,508 $ 4,103
Deferred Income Taxes	Deferred income taxes at December 31 consisted of: 2019 2018 Assets Liabilities Assets Liabilities Product intangibles and licenses $ 442 $ 1,778 $ 720 $ 1,640 Inventory related 32 354 32 377 Accelerated depreciation — 594 — 582 Pensions and other postretirement benefits 785 191 565 151 Compensation related 322 — 291 — Unrecognized tax benefits 109 — 174 — Net operating losses and other tax credit carryforwards 897 — 715 — Other 764 84 621 66 Subtotal 3,351 3,001 3,118 2,816 Valuation allowance (1,100 ) (1,348 ) Total deferred taxes $ 2,251 $ 3,001 $ 1,770 $ 2,816 Net deferred income taxes $ 750 $ 1,046 Recognized as: Other Assets $ 719 $ 656 Deferred Income Taxes $ 1,470 $ 1,702
Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2019 2018 2017 Balance January 1 $ 1,893 $ 1,723 $ 3,494 Additions related to current year positions 199 221 146 Additions related to prior year positions 46 142 520 Reductions for tax positions of prior years (1) (454 ) (73 ) (1,038 ) Settlements (1) (356 ) (91 ) (1,388 ) Lapse of statute of limitations (2) (103 ) (29 ) (11 ) Balance December 31 $ 1,225 $ 1,893 $ 1,723 (1) Amounts reflect the settlements with the IRS as discussed below. (2) Amount in 2019 includes $78 million related to the divestiture of Merck’s Consumer Care business in 2014.

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Calculations of Earnings Per Share	The calculations of earnings per share (shares in millions) are as follows: Years Ended December 31 2019 2018 2017 Net income attributable to Merck & Co., Inc. $ 9,843 $ 6,220 $ 2,394 Average common shares outstanding 2,565 2,664 2,730 Common shares issuable (1) 15 15 18 Average common shares outstanding assuming dilution 2,580 2,679 2,748 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders $ 3.84 $ 2.34 $ 0.88 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders $ 3.81 $ 2.32 $ 0.87 (1) Issuable primarily under share-based compensation plans.

Other Comprehensive Income (L_2

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Changes in AOCI by Component	Changes in AOCI by component are as follows: Derivatives Investments Employee Benefit Plans Cumulative Translation Adjustment Accumulated Other Comprehensive Income (Loss) Balance January 1, 2017, net of taxes $ 338 $ (3 ) $ (3,206 ) $ (2,355 ) $ (5,226 ) Other comprehensive income (loss) before reclassification adjustments, pretax (561 ) 212 438 235 324 Tax 207 (35 ) (106 ) 166 232 Other comprehensive income (loss) before reclassification adjustments, net of taxes (354 ) 177 332 401 556 Reclassification adjustments, pretax (141 ) (1) (291 ) (2) 117 (3) — (315 ) Tax 49 56 (30 ) — 75 Reclassification adjustments, net of taxes (92 ) (235 ) 87 — (240 ) Other comprehensive income (loss), net of taxes (446 ) (58 ) 419 401 316 Balance at December 31, 2017, net of taxes (108 ) (61 ) (2,787 ) (1,954 ) (4,910 ) Other comprehensive income (loss) before reclassification adjustments, pretax 228 (108 ) (728 ) (84 ) (692 ) Tax (55 ) 1 169 (139 ) (24 ) Other comprehensive income (loss) before reclassification adjustments, net of taxes 173 (107 ) (559 ) (223 ) (716 ) Reclassification adjustments, pretax 157 (1) 97 (2) 170 (3) — 424 Tax (33 ) — (36 ) — (69 ) Reclassification adjustments, net of taxes 124 97 134 — 355 Other comprehensive income (loss), net of taxes 297 (10 ) (425 ) (223 ) (361 ) Adoption of ASU 2018-02 (23 ) 1 (344 ) 100 (266 ) Adoption of ASU 2016-01 — (8 ) — — (8 ) Balance at December 31, 2018, net of taxes 166 (78 ) (3,556 ) (4) (2,077 ) (5,545 ) Other comprehensive income (loss) before reclassification adjustments, pretax 86 140 (948 ) 112 (610 ) Tax (15 ) — 192 (16 ) 161 Other comprehensive income (loss) before reclassification adjustments, net of taxes 71 140 (756 ) 96 (449 ) Reclassification adjustments, pretax (261 ) (1) (44 ) (2) 66 (3) — (239 ) Tax 55 — (15 ) — 40 Reclassification adjustments, net of taxes (206 ) (44 ) 51 — (199 ) Other comprehensive income (loss), net of taxes (135 ) 96 (705 ) 96 (648 ) Balance at December 31, 2019, net of taxes $ 31 $ 18 $ (4,261 ) (4) $ (1,981 ) $ (6,193 ) (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 investments that were reclassified from AOCI to Other (income) expense, net . In 2017, these amounts included both investments in debt and equity securities; however, as a result of the adoption of ASU 2016-01 in 2018, these amounts relate only to investments in available-for-sale debt securities. (3) Includes net amortization of prior service cost and actuarial gains and losses included in net periodic benefit cost (see Note 13). (4) Includes pension plan net loss of $ 5.1 billion and $4.4 billion at December 31, 2019 and 2018 , respectively, and other postretirement benefit plan net gain of $247 million and $170 million at December 31, 2019 and 2018 , respectively, as well as pension plan prior service credit of $263 million and $314 million at December 31, 2019 and 2018 , respectively, and other postretirement benefit plan prior service credit of $305 million and $375 million at December 31, 2019 and 2018 , respectively.

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Sales of Company's Products	Sales of the Company’s products were as follows: Years Ended December 31 2019 2018 2017 U.S. Int’l Total U.S. Int’l Total U.S. Int’l Total Pharmaceutical: Oncology Keytruda $ 6,305 $ 4,779 $ 11,084 $ 4,150 $ 3,021 $ 7,171 $ 2,309 $ 1,500 $ 3,809 Alliance revenue - Lynparza (1) 269 176 444 127 61 187 — 20 20 Alliance revenue - Lenvima (1) 239 165 404 95 54 149 — — — Emend 183 205 388 312 210 522 342 213 556 Vaccines Gardasil/Gardasil 9 1,831 1,905 3,737 1,873 1,279 3,151 1,565 743 2,308 ProQuad/M-M-R II/Varivax 1,683 592 2,275 1,430 368 1,798 1,374 303 1,676 Pneumovax 23 679 247 926 627 281 907 581 240 821 RotaTeq 506 284 791 496 232 728 481 204 686 Vaqta 130 108 238 127 112 239 94 124 218 Hospital Acute Care Bridion 533 598 1,131 386 531 917 239 465 704 Noxafil 282 380 662 353 389 742 309 327 636 Primaxin 2 271 273 7 258 265 10 270 280 Invanz 30 233 263 253 243 496 361 241 602 Cubicin 92 165 257 191 176 367 189 193 382 Cancidas 6 242 249 12 314 326 20 402 422 Immunology Simponi — 830 830 — 893 893 — 819 819 Remicade — 411 411 — 582 582 — 837 837 Neuroscience Belsomra 92 214 306 96 164 260 98 112 210 Virology Isentress/Isentress HD 398 576 975 513 627 1,140 565 639 1,204 Zepatier 118 252 370 8 447 455 771 888 1,660 Cardiovascular Zetia 14 575 590 45 813 857 352 992 1,344 Vytorin 16 269 285 10 487 497 124 627 751 Atozet — 391 391 — 347 347 — 225 225 Adempas — 419 419 — 329 329 — 300 300 Diabetes Januvia 1,724 1,758 3,482 1,969 1,718 3,686 2,153 1,584 3,737 Janumet 589 1,452 2,041 811 1,417 2,228 863 1,296 2,158 Women’s Health NuvaRing 742 136 879 722 180 902 564 197 761 Implanon/Nexplanon 568 219 787 495 208 703 496 191 686 Diversified Brands Singulair 29 669 698 20 688 708 40 692 732 Cozaar/Hyzaar 24 418 442 23 431 453 18 466 484 Nasonex 9 284 293 23 353 376 54 333 387 Arcoxia — 288 288 — 335 335 — 363 363 Follistim AQ 103 138 241 115 153 268 123 174 298 Other pharmaceutical (2) 1,563 3,343 4,901 1,319 3,380 4,705 1,759 3,556 5,314 Total Pharmaceutical segment sales 18,759 22,992 41,751 16,608 21,081 37,689 15,854 19,536 35,390 Animal Health: Livestock 582 2,201 2,784 528 2,102 2,630 471 2,013 2,484 Companion Animals 724 885 1,609 710 872 1,582 619 772 1,391 Total Animal Health segment sales 1,306 3,086 4,393 1,238 2,974 4,212 1,090 2,785 3,875 Other segment sales (3) 174 1 175 248 2 250 396 1 397 Total segment sales 20,239 26,079 46,319 18,094 24,057 42,151 17,340 22,322 39,662 Other (4) 86 436 521 118 26 143 84 376 460 $ 20,325 $ 26,515 $ 46,840 $ 18,212 $ 24,083 $ 42,294 $ 17,424 $ 22,698 $ 40,122 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 4). (2) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (3) Represents the non-reportable segments of Healthcare Services and Alliances. (4) Other is primarily comprised of miscellaneous corporate revenues, including revenue hedging activities, as well as third-party manufacturing sales. Other in 2019 , 2018 and 2017 also includes approximately $80 million , $95 million and $85 million , respectively, related to the sale of the marketing rights to certain products.
Consolidated Revenues by Geographic Area	Consolidated sales by geographic area where derived are as follows: Years Ended December 31 2019 2018 2017 United States $ 20,325 $ 18,212 $ 17,424 Europe, Middle East and Africa 12,707 12,213 11,478 Japan 3,583 3,212 3,122 China 3,207 2,184 1,586 Asia Pacific (other than Japan and China) 2,943 2,909 2,751 Latin America 2,469 2,415 2,339 Other 1,606 1,149 1,422 $ 46,840 $ 42,294 $ 40,122
Reconciliation of Segment Profits to Income Before Taxes	A reconciliation of segment profits to Income before taxes is as follows: Years Ended December 31 2019 2018 2017 Segment profits: Pharmaceutical segment $ 28,324 $ 24,871 $ 23,018 Animal Health segment 1,609 1,659 1,552 Other segments (7 ) 103 275 Total segment profits 29,926 26,633 24,845 Other profits 363 6 26 Unallocated: Interest income 274 343 385 Interest expense (893 ) (772 ) (754 ) Depreciation and amortization (1,573 ) (1,334 ) (1,378 ) Research and development (9,499 ) (9,432 ) (10,004 ) Amortization of purchase accounting adjustments (1,419 ) (2,664 ) (3,056 ) Restructuring costs (638 ) (632 ) (776 ) Charge related to the termination of a collaboration with Samsung — (423 ) — Loss on extinguishment of debt — — (191 ) Other unallocated, net (5,077 ) (3,024 ) (2,576 ) Income Before Taxes $ 11,464 $ 8,701 $ 6,521
Equity Income from Affiliates and Depreciation and Amortization Included in Segment Profits	Equity (income) loss from affiliates and depreciation and amortization included in segment profits is as follows: Pharmaceutical Animal Health All Other Total Year Ended December 31, 2019 Included in segment profits: Equity (income) loss from affiliates $ — $ — $ — $ — Depreciation and amortization 137 109 10 256 Year Ended December 31, 2018 Included in segment profits: Equity (income) loss from affiliates $ 4 $ — $ — $ 4 Depreciation and amortization 243 82 10 335 Year Ended December 31, 2017 Included in segment profits: Equity (income) loss from affiliates $ 7 $ — $ — $ 7 Depreciation and amortization 125 75 12 212
Property, Plant and Equipment, Net by Geographic Area	Property, plant and equipment, net, by geographic area where located is as follows: December 31 2019 2018 2017 United States $ 8,974 $ 8,306 $ 8,070 Europe, Middle East and Africa 4,767 3,706 3,151 Asia Pacific (other than Japan and China) 714 684 632 Latin America 266 264 271 China 174 167 150 Japan 152 159 158 Other 6 5 7 $ 15,053 $ 13,291 $ 12,439

Nature of Operations (Details)

Nature of Operations (Details)	12 Months Ended
	Dec. 31, 2019segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments	4

Summary of Accounting Policie_2

Summary of Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Summary Of Significant Accounting Policies [Line Items]
Product return period and expiration	12 months
Customer discounts	$ 11,800	$ 10,700	$ 10,700
Accrual for chargebacks reflected as direct reduction to accounts receivable	233	245
Accrual for rebates included in accrued and other current liabilities	2,200	2,400
Depreciation	1,700	1,400	1,500
Advertising and promotion costs	2,100	2,100	2,200
Decrease in deferred income taxes	(1,470)	(1,702)
Accumulated other comprehensive loss	6,193	5,545
Net periodic defined benefit plan (credit) cost other than service cost	(545)	(512)	$ (512)
Operating lease, right-of-use assets	1,073
Operating lease, liability	1,004
Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Operating lease, right-of-use assets				$ 1,100
Operating lease, liability				$ 1,100
Enterprise wide resource planning system
Summary Of Significant Accounting Policies [Line Items]
Unamortized capitalized software costs	$ 548	$ 439
Minimum
Summary Of Significant Accounting Policies [Line Items]
Product return period	3 months
Estimated useful life of intangible assets	2 years
Minimum | Enterprise wide resource planning system
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets	6 years
Minimum | Capitalized Software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets	3 years
Minimum | Buildings
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property, plant and equipment	25 years
Minimum | Machinery, equipment and office furnishings
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property, plant and equipment	3 years
Minimum | United States | Pharmaceutical segment
Summary Of Significant Accounting Policies [Line Items]
Payment terms	36 days
Minimum | United States | Animal Health
Summary Of Significant Accounting Policies [Line Items]
Payment terms	30 days
Minimum | Outside of the United States
Summary Of Significant Accounting Policies [Line Items]
Payment terms	30 days
Maximum
Summary Of Significant Accounting Policies [Line Items]
Product return period	6 months
Estimated useful life of intangible assets	24 years
Maximum | Enterprise wide resource planning system
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets	10 years
Maximum | Capitalized Software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets	5 years
Maximum | Buildings
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property, plant and equipment	45 years
Maximum | Machinery, equipment and office furnishings
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property, plant and equipment	15 years
Maximum | Outside of the United States
Summary Of Significant Accounting Policies [Line Items]
Payment terms	90 days
Keytruda | Maximum | United States
Summary Of Significant Accounting Policies [Line Items]
Payment terms	90 days

Acquisitions, Divestitures, R_3

Acquisitions, Divestitures, Research Collaborations and License Agreements - Acquisitions Narrative (Detail) € in Millions, $ in Millions, $ in Millions

Apr. 01, 2019USD ($)

Jan. 31, 2020USD ($)

Jul. 31, 2019USD ($)

Apr. 30, 2019USD ($)

Jun. 30, 2018AUD ($)

Jun. 30, 2018USD ($)

Oct. 31, 2017USD ($)

Oct. 31, 2017EUR (€)

Mar. 31, 2017USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2019USD ($)

Dec. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Research and development

$ 9,872

$ 9,752

$ 10,339

Goodwill

$ 18,284

19,425

18,253

$ 18,284

Peloton

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Cash paid for acquisition of business

$ 1,200

Research and development

$ 993

Deferred tax liabilities

52

Other assets and liabilities, net

4

Cash and cash equivalents

157

Antelliq

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Cash paid for acquisition of business

$ 2,300

Debt assumed

1,300

Deferred tax liabilities

520

Other assets and liabilities, net

(81)

Goodwill

1,302

Transaction costs

47

Cash and cash equivalents

$ 31

Immune Design

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Cash paid for acquisition of business

$ 301

Other net assets

42

Goodwill

20

In-process research and development (IPR&D)

156

Cash and cash equivalents

$ 83

Viralytics

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Cash paid for acquisition of business

$ 502

$ 378

Other net assets

$ 34

Research and development

$ 344

Rigontec

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Cash paid for acquisition of business

$ 140

€ 119

Potential future milestone payments, maximum | €

349

Potential future milestone payment, research milestones and regulatory approvals | €

184

Potential future milestone payment, commercial targets | €

€ 165

Vallee SA

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Cash paid for acquisition of business

$ 358

Other net assets

$ 32

Voting rights acquired (as percent)

93.50%

4.50%

4.50%

Escrow deposit

$ 176

Identifiable intangible assets

297

Deferred tax liabilities

102

Noncontrolling interest

25

Contingent liabilities

37

Indemnification assets

37

Goodwill

$ 156

Estimated useful life of intangible assets, acquired

15 years

Payments to acquire additional interest

$ 18

Regulatory Milestones | Peloton

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Potential future milestone payments, maximum

50

Commercial Milestone | Peloton

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Potential future milestone payments, maximum

50

Sales-Based Milestones | Peloton

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Potential future milestone payments, maximum

$ 1,050

Subsequent Event | ArQule

Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]

Cash paid for acquisition of business

$ 2,700

Acquisitions, Divestitures, R_4

Acquisitions, Divestitures, Research Collaborations and License Agreements - Divestitures Narrative (Detail) - Samsung $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Gain (loss) on contract termination	$ (423)
Contract termination fee payment	155
Other contract termination costs	9
Fixed asset abandonment costs related to contract termination	137
Inventory write-off related to contract termination	$ 122

Acquisitions, Divestitures, R_5

Acquisitions, Divestitures, Research Collaborations and License Agreements - Estimated Fair Value of Assets Acquired and Liabilities Assumed (Details) $ in Millions	Apr. 01, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Goodwill		$ 19,425	$ 18,253	$ 18,284
Antelliq
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Cash and cash equivalents	$ 31
Accounts receivable	73
Inventories	95
Property, plant and equipment	62
Identifiable intangible assets (useful lives ranging from 18-24 years)	2,689
Deferred income tax liabilities	(520)
Other assets and liabilities, net	(81)
Total identifiable net assets	2,349
Goodwill	1,302
Consideration transferred	$ 3,651
Antelliq | Measurement Input, Discount Rate
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Present value discount rate	0.115
Minimum
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Estimated useful life of intangible assets		2 years
Minimum | Antelliq
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Estimated useful life of intangible assets	18 years
Maximum
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Estimated useful life of intangible assets		24 years
Maximum | Antelliq
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Estimated useful life of intangible assets	24 years

Collaborative Arrangements - Na

Collaborative Arrangements - Narrative (Details) - USD ($) $ in Millions	1 Months Ended									12 Months Ended			17 Months Ended	35 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Jan. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Jul. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Jan. 31, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development										$ 9,872	$ 9,752	$ 10,339
Noncurrent liabilities				$ 11,970		$ 12,041				11,970	12,041		$ 12,041
Amortization expense for intangible assets										2,000	3,100	3,200
Other intangibles, net				14,196		13,104				14,196	13,104		13,104
Estimated aggregate amortization expense, 2020				1,600						1,600
Estimated aggregate amortization expense, 2021				1,500						1,500
Estimated aggregate amortization expense, 2022				1,500						1,500
Estimated aggregate amortization expense, 2023				1,500						1,500
Estimated aggregate amortization expense, 2024				1,400						1,400
Licenses
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Other intangibles, net				2,361		1,673				2,361	1,673		1,673
Lynparza | Licenses
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Other intangibles, net				955						955
Lenvima | Licenses
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Other intangibles, net				956						956
Adempas | Other Intangible Assets, Net
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Intangible assets				883						883
AstraZeneca
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront and milestone payments									$ 1,600
Payments to acquire intangible assets				100		400		$ 250	$ 750
Research and development												$ 2,350
AstraZeneca | Sales-Based Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent payments collaborative arrangement										3,100
AstraZeneca | Regulatory Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent payments collaborative arrangement										1,700
AstraZeneca | Lynparza | Sales-Based Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Probable future contingent payments collaborative arrangement										300
Liabilities				300						300
Milestone payments made to collaborative partner										200	250		700
AstraZeneca | Lynparza | Regulatory Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments made to collaborative partner										30	140
Eisai
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront and milestone payments							$ 750
Payments to acquire intangible assets					$ 325
Research and development											1,400
Eisai | Sales-Based Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent payments collaborative arrangement										3,000
Eisai | Regulatory Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent payments collaborative arrangement										135
Eisai | Lenvima | Sales-Based Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Probable future contingent payments collaborative arrangement										682	268
Liabilities				$ 682						682
Milestone payments made to collaborative partner										50
Eisai | Lenvima | Regulatory Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments made to collaborative partner											250
Eisai | Forecast
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payments to acquire intangible assets	$ 125	$ 200												$ 650
Bayer AG | Sales-Based Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent payments collaborative arrangement										$ 400
Bayer AG | Adempas | Sales-Based Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Probable future contingent payments collaborative arrangement											375
Noncurrent liabilities						$ 375					375		$ 375
Milestone payments made to collaborative partner											$ 350
Subsequent Event | AstraZeneca | Lynparza | Sales-Based Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments made to collaborative partner			$ 250
Subsequent Event | Eisai | Lenvima | Sales-Based Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone payments made to collaborative partner			$ 150

Collaborative Arrangements - Sc

Collaborative Arrangements - Schedule of Collaborative Arrangement Transactions (Details) - Collaborative Arrangement - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AstraZeneca | Other current assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Receivables from counterparty	$ 128	$ 52
AstraZeneca | Accrued and other current liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables to counterparty	577	405
AstraZeneca | Other Noncurrent Liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables to counterparty	0	250
AstraZeneca | Total sales
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total sales	444	187	$ 20
AstraZeneca | Cost of sales
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expenses	148	93	4
AstraZeneca | Selling, general and administrative
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expenses	138	48	1
AstraZeneca | Research and development
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expenses	168	152	2,419
Eisai | Other current assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Receivables from counterparty	150	71
Eisai | Accrued and other current liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables to counterparty	700	375
Eisai | Other Noncurrent Liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables to counterparty	525	543
Eisai | Total sales
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total sales	404	149
Eisai | Cost of sales
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expenses	206	39
Eisai | Selling, general and administrative
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expenses	80	13
Eisai | Research and development
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expenses	189	1,489
Bayer AG | Other current assets
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Receivables from counterparty	49	32
Bayer AG | Other Noncurrent Liabilities
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payables to counterparty	375	375
Bayer AG | Total sales
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net product sales recorded by Merck	215	190	149
Merck’s profit share of sales in marketing territories	204	139	151
Total sales	419	329	300
Bayer AG | Cost of sales
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expenses	113	216	99
Bayer AG | Selling, general and administrative
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expenses	41	35	27
Bayer AG | Research and development
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Expenses	$ 126	$ 127	$ 101

Restructuring - Narrative (Deta

Restructuring - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 927	$ 658	$ 927
Expected costs	$ 2,500
Percentage estimate of cumulative pretax costs that will result in cash outlays (primarily from employee separation expense) (as percent)	60.00%
Percentage estimate of cumulative pretax costs that will be non-cash (primarily from accelerated depreciation of facilities) (as percent)	40.00%
Forecast
Restructuring Cost and Reserve [Line Items]
Expected costs				$ 800

Restructuring - Charges Related

Restructuring - Charges Related to Restructuring Program Activities by Type of Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 927	$ 658	$ 927
Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring costs	251	21	138
Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	34	3	2
Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring costs	4	2	11
Restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	638	632	776
Separation Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	572	473	552
Separation Costs | Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	0	0
Separation Costs | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	0	0
Separation Costs | Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	0	0
Separation Costs | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	572	473	552
Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Restructuring costs	233	(1)	60
Accelerated Depreciation | Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring costs	198	10	52
Accelerated Depreciation | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	33	2	2
Accelerated Depreciation | Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring costs	2	(13)	6
Accelerated Depreciation | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	0	0
Other
Restructuring Cost and Reserve [Line Items]
Restructuring costs	122	186	315
Other | Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring costs	53	11	86
Other | Selling, general and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1	1	0
Other | Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring costs	2	15	5
Other | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 66	$ 159	$ 224

Restructuring - Charges and Spe

Restructuring - Charges and Spending Relating to Restructuring Activities by Program (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 534	$ 747
Expenses	927	658	$ 927
(Payments) receipts, net	(461)	(887)
Non-cash activity	(241)	16
Restructuring reserve, ending balance	759	534	747
Separation Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	443	619
Expenses	572	473	552
(Payments) receipts, net	(325)	(649)
Non-cash activity	0	0
Restructuring reserve, ending balance	690	443	619
Accelerated Depreciation
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	0	0
Expenses	233	(1)	60
(Payments) receipts, net	0	0
Non-cash activity	(233)	1
Restructuring reserve, ending balance	0	0	0
Other
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	91	128
Expenses	122	186	315
(Payments) receipts, net	(136)	(238)
Non-cash activity	(8)	15
Restructuring reserve, ending balance	$ 69	$ 91	$ 128

Financial Instruments - Narrati

Financial Instruments - Narrative (Details)	3 Months Ended		12 Months Ended
	Dec. 31, 2019USD ($)interest_rate_swap	Dec. 31, 2018USD ($)	Dec. 31, 2019USD ($)interest_rate_swap	Dec. 31, 2018USD ($)	Mar. 31, 2019USD ($)
Derivative [Line Items]
Number of interest rate swaps held | interest_rate_swap	19		19
Notional amount of derivative	$ 30,666,000,000	$ 29,742,000,000	$ 30,666,000,000	$ 29,742,000,000
Face amount of debt					$ 5,000,000,000
Pre tax net unrealized gain (loss) on derivatives maturing within next 12 months estimated to be reclassified from AOCI to sales			31,000,000
Equity investments without readily determinable fair values	420,000,000	568,000,000	420,000,000	568,000,000
Unrealized gains based on favorable observable price changes			20,000,000	167,000,000
Unrealized loss related to unfavorable observable price changes			13,000,000	26,000,000
Upward price adjustment	109,000,000		109,000,000
Downward price adjustment	21,000,000		21,000,000
Available-for-sale debt securities included in Short-term investments	749,000,000		749,000,000
Available-for-sale debt securities maturing within five years	933,000,000		933,000,000
Cash and cash equivalents	9,676,000,000	7,965,000,000	9,676,000,000	7,965,000,000
Payments of contingent consideration			85,000,000	244,000,000
Fair value of loans payable and long-term debt, including current portion	28,800,000,000	25,600,000,000	28,800,000,000	25,600,000,000
Long term and short term debt	26,300,000,000	25,100,000,000	26,300,000,000	25,100,000,000
Accounts receivable factored	2,700,000,000	1,100,000,000
Funds collected from factoring of receivable, held in restricted cash	256,000,000		256,000,000
Cash collateral received from counterparties	34,000,000	107,000,000	34,000,000	107,000,000
Right to reclaim cash	0	0	$ 0	0
Customer Concentration Risk | Accounts Receivable | McKesson Corporation, AmerisourceBergen Corporation and Cardinal Health, Inc.
Derivative [Line Items]
Percentage of accounts receivable represented by customers with largest balances (as percent)			35.00%
Afferent Pharmaceuticals
Derivative [Line Items]
Payments of contingent consideration				175,000,000
Level 2
Derivative [Line Items]
Cash and cash equivalents	9,700,000,000		$ 9,700,000,000
Cash equivalents	8,900,000,000		8,900,000,000
Derivatives Designated as Hedging Instruments
Derivative [Line Items]
Notional amount of derivative	14,728,000,000	14,390,000,000	14,728,000,000	14,390,000,000
Derivatives Not Designated as Hedging Instruments
Derivative [Line Items]
Notional amount of derivative	$ 15,938,000,000	$ 15,352,000,000	$ 15,938,000,000	$ 15,352,000,000
Maximum | Derivatives Designated as Hedging Instruments
Derivative [Line Items]
Maximum planning cycle of hedges (no more than)			2 years
Maximum | Derivatives Not Designated as Hedging Instruments
Derivative [Line Items]
Maximum planning cycle of hedges (no more than)			1 year

Financial Instruments - Effect

Financial Instruments - Effect of Net Investment Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Foreign exchange contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income	$ (10)	$ (18)	$ 0
Foreign exchange contracts | Other (income) expense, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing	(31)	(11)	0
Euro-denominated notes
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other Comprehensive Income	(75)	(183)	520
Euro-denominated notes | Other (income) expense, net
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Amount of Pretax (Gain) Loss Recognized in Other (income) expense, net for Amounts Excluded from Effectiveness Testing	$ 0	$ 0	$ 0

Financial Instruments - Informa

Financial Instruments - Information About Interest Rate Swaps (Details)	Dec. 31, 2019USD ($)interest_rate_swap	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Derivative [Line Items]
Par Value of Debt		$ 5,000,000,000
Number of Interest Rate Swaps Held | interest_rate_swap	19
U.S. Dollar Notional	$ 30,666,000,000		$ 29,742,000,000
1.85% notes due 2020 | Interest Rate Swap
Derivative [Line Items]
Par Value of Debt	$ 1,250,000,000
Number of Interest Rate Swaps Held | interest_rate_swap	5
U.S. Dollar Notional	$ 1,250,000,000
Fixed-rate notes, stated interest rate (as percent)	1.85%
3.875% notes due 2021 | Interest Rate Swap
Derivative [Line Items]
Par Value of Debt	$ 1,150,000,000
Number of Interest Rate Swaps Held | interest_rate_swap	5
U.S. Dollar Notional	$ 1,150,000,000
Fixed-rate notes, stated interest rate (as percent)	3.875%
2.40% notes due 2022 | Interest Rate Swap
Derivative [Line Items]
Par Value of Debt	$ 1,000,000,000
Number of Interest Rate Swaps Held | interest_rate_swap	4
U.S. Dollar Notional	$ 1,000,000,000
Fixed-rate notes, stated interest rate (as percent)	2.40%
2.35% notes due 2022 | Interest Rate Swap
Derivative [Line Items]
Par Value of Debt	$ 1,250,000,000
Number of Interest Rate Swaps Held | interest_rate_swap	5
U.S. Dollar Notional	$ 1,250,000,000
Fixed-rate notes, stated interest rate (as percent)	2.35%

Financial Instruments - Fair Va

Financial Instruments - Fair Value of Hedges (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Loans payable and current portion of long-term debt
Derivative [Line Items]
Carrying Amount of Hedged Liabilities	$ 1,249	$ 0
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount	(1)	0
Long-Term Debt
Derivative [Line Items]
Carrying Amount of Hedged Liabilities	3,409	4,560
Cumulative Amount of Fair Value Hedging Adjustment Increase (Decrease) Included in the Carrying Amount	$ 14	$ (82)

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	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	$ 288	$ 454
Fair Value of Derivative, Liability	97	160
U.S. Dollar Notional	30,666	29,742
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	222	338
Fair Value of Derivative, Liability	24	89
U.S. Dollar Notional	14,728	14,390
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	66	116
Fair Value of Derivative, Liability	73	71
U.S. Dollar Notional	15,938	15,352
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	15	0
U.S. Dollar Notional	3,400	0
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1	0
U.S. Dollar Notional	1,250	0
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	0	81
U.S. Dollar Notional	0	4,650
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other Assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	55	75
Fair Value of Derivative, Liability	0	0
U.S. Dollar Notional	2,160	2,655
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	152	263
U.S. Dollar Notional	6,117	6,222
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	22	7
U.S. Dollar Notional	1,748	774
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	53	89
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	66	116
U.S. Dollar Notional	7,245	5,430
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	73	71
U.S. Dollar Notional	$ 8,693	$ 9,922

Financial Instruments - Infor_2

Financial Instruments - Information on Derivative Positions Subject to Master Netting Arrangements as if they were Presented on a Net Basis (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross amounts recognized in the consolidated balance sheet, Asset	$ 288,000,000	$ 454,000,000
Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet, Asset	(84,000,000)	(121,000,000)
Cash collateral received, Asset	(34,000,000)	(107,000,000)
Net amounts, Asset	170,000,000	226,000,000
Gross amounts recognized in the consolidated balance sheet, Liability	97,000,000	160,000,000
Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet, Liability	(84,000,000)	(121,000,000)
Cash collateral received, liability	0	0
Net amounts, Liability	$ 13,000,000	$ 39,000,000

Financial Instruments - Locatio

Financial Instruments - Location and Pretax (Gains) or Loss Amounts for Derivatives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 46,840	$ 42,294	$ 40,122
Other (income) expense, net	139	(402)	(500)
Other comprehensive income (loss)	(648)	(361)	316
Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in OCI on derivatives	(6)	(4)	(3)
Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in OCI on derivatives	87	228	(562)
(Decrease) increase in Sales as a result of AOCI reclassifications	(255)	160	(138)
Other (income) expense, net | Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Hedged items	(95)	27	48
Derivatives designated as hedging instruments	65	(50)	(12)
Derivative, Gain (Loss) on Derivative, Net	(4)	(4)	(3)
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Gain (Loss), Cash Flow Hedge, Including Noncontrolling Interest | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Sales	$ 255	$ (160)	$ 138

Financial Instruments - Effects

Financial Instruments - Effects of Derivatives Not Designated as Hedging Instruments (Details) - Foreign exchange contracts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other (income) expense, net
Derivative [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	$ 174	$ (260)	$ 110
Sales
Derivative [Line Items]
Amount of Derivative Pretax (Gain) Loss Recognized in Income	$ 1	$ (8)	$ (3)

Financial Instruments - Infor_3

Financial Instruments - Information on Debt and Equity Securities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	$ 1,768	$ 7,340
Debt securities, gross unrealized gains	17	6
Debt securities, gross unrealized losses	0	(85)
Debt securities, fair value	1,785	7,261
Publicly traded equity securities, fair value	838	456
Total debt and publicly traded equity securities, fair value	2,623	7,717
Unrealized net gains	160	(35)
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	668	0
Debt securities, gross unrealized gains	0	0
Debt securities, gross unrealized losses	0	0
Debt securities, fair value	668	0
Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	608	4,985
Debt securities, gross unrealized gains	13	3
Debt securities, gross unrealized losses	0	(68)
Debt securities, fair value	621	4,920
U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	266	895
Debt securities, gross unrealized gains	3	2
Debt securities, gross unrealized losses	0	(5)
Debt securities, fair value	269	892
Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	226	1,285
Debt securities, gross unrealized gains	1	1
Debt securities, gross unrealized losses	0	(11)
Debt securities, fair value	227	1,275
Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	0	167
Debt securities, gross unrealized gains	0	0
Debt securities, gross unrealized losses	0	(1)
Debt securities, fair value	0	166
Mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, amortized cost	0	8
Debt securities, gross unrealized gains	0	0
Debt securities, gross unrealized losses	0	0
Debt securities, fair value	0	8
Fair Value, Measurements, Recurring | Corporate notes and bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, fair value	621	4,835
Fair Value, Measurements, Recurring | U.S. government and agency securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, fair value	209	731
Fair Value, Measurements, Recurring | Asset-backed securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, fair value	227	1,253
Fair Value, Measurements, Recurring | Foreign government bonds
Debt Securities, Available-for-sale [Line Items]
Debt securities, fair value	0	166
Fair Value, Measurements, Recurring | Publicly traded equity securities
Debt Securities, Available-for-sale [Line Items]
Publicly traded equity securities, fair value	$ 518	$ 147

Financial Instruments - Financi

Financial Instruments - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assets
Investments, debt securities	$ 1,785	$ 7,261
Publicly traded equity securities	838	456
Derivative assets	288	454
Liabilities
Contingent consideration	767	788	$ 935
Derivative liabilities	97	160
Corporate notes and bonds
Assets
Investments, debt securities	621	4,920
Asset-backed securities
Assets
Investments, debt securities	$ 227	1,275
Liabilities
Primary weighted-average lives of investment collateral (or less)	5 years
U.S. government and agency securities
Assets
Investments, debt securities	$ 269	892
Foreign government bonds
Assets
Investments, debt securities	0	166
Mortgage-backed securities
Assets
Investments, debt securities	0	8
Fair Value, Measurements, Recurring
Assets
Investments	2,243	7,132
Other assets	380	585
Derivative assets	288	454
Total assets	2,911	8,171
Liabilities
Contingent consideration	767	788
Derivative liabilities	97	160
Total liabilities	864	948
Fair Value, Measurements, Recurring | Interest rate swap contracts
Assets
Derivative assets	15	0
Liabilities
Derivative liabilities	1	81
Fair Value, Measurements, Recurring | Foreign exchange contracts
Assets
Derivative assets	169	241
Liabilities
Derivative liabilities	95	74
Fair Value, Measurements, Recurring | Purchased currency options
Assets
Derivative assets	104	213
Liabilities
Derivative liabilities	1	5
Fair Value, Measurements, Recurring | Commercial paper
Assets
Investments, debt securities	668	0
Fair Value, Measurements, Recurring | Corporate notes and bonds
Assets
Investments, debt securities	621	4,835
Other assets	0	85
Fair Value, Measurements, Recurring | Asset-backed securities
Assets
Investments, debt securities	227	1,253
Other assets	0	22
Fair Value, Measurements, Recurring | U.S. government and agency securities
Assets
Investments, debt securities	209	731
Other assets	60	161
Fair Value, Measurements, Recurring | Foreign government bonds
Assets
Investments, debt securities	0	166
Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets
Other assets	0	8
Fair Value, Measurements, Recurring | Publicly traded equity securities
Assets
Publicly traded equity securities	518	147
Other assets	320	309
Fair Value, Measurements, Recurring | Level 1
Assets
Investments	518	147
Other assets	380	364
Derivative assets	0	0
Total assets	898	511
Liabilities
Contingent consideration	0	0
Derivative liabilities	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Interest rate swap contracts
Assets
Derivative assets	0	0
Liabilities
Derivative 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 | Purchased currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Commercial paper
Assets
Investments, debt securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Corporate notes and bonds
Assets
Investments, debt securities	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Level 1 | Asset-backed securities
Assets
Investments, debt securities	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Level 1 | U.S. government and agency securities
Assets
Investments, debt securities	0	0
Other assets	60	55
Fair Value, Measurements, Recurring | Level 1 | Foreign government bonds
Assets
Investments, debt securities	0	0
Fair Value, Measurements, Recurring | Level 1 | Mortgage-backed securities
Assets
Other assets	0	0
Fair Value, Measurements, Recurring | Level 1 | Publicly traded equity securities
Assets
Publicly traded equity securities	518	147
Other assets	320	309
Fair Value, Measurements, Recurring | Level 2
Assets
Investments	1,725	6,985
Other assets	0	221
Derivative assets	288	454
Total assets	2,013	7,660
Liabilities
Contingent consideration	0	0
Derivative liabilities	97	160
Total liabilities	97	160
Fair Value, Measurements, Recurring | Level 2 | Interest rate swap contracts
Assets
Derivative assets	15	0
Liabilities
Derivative liabilities	1	81
Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Assets
Derivative assets	169	241
Liabilities
Derivative liabilities	95	74
Fair Value, Measurements, Recurring | Level 2 | Purchased currency options
Assets
Derivative assets	104	213
Liabilities
Derivative liabilities	1	5
Fair Value, Measurements, Recurring | Level 2 | Commercial paper
Assets
Investments, debt securities	668	0
Fair Value, Measurements, Recurring | Level 2 | Corporate notes and bonds
Assets
Investments, debt securities	621	4,835
Other assets	0	85
Fair Value, Measurements, Recurring | Level 2 | Asset-backed securities
Assets
Investments, debt securities	227	1,253
Other assets	0	22
Fair Value, Measurements, Recurring | Level 2 | U.S. government and agency securities
Assets
Investments, debt securities	209	731
Other assets	0	106
Fair Value, Measurements, Recurring | Level 2 | Foreign government bonds
Assets
Investments, debt securities	0	166
Fair Value, Measurements, Recurring | Level 2 | Mortgage-backed securities
Assets
Other assets	0	8
Fair Value, Measurements, Recurring | Level 2 | Publicly traded equity securities
Assets
Publicly traded equity securities	0	0
Other assets	0	0
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	767	788
Derivative liabilities	0	0
Total liabilities	767	788
Fair Value, Measurements, Recurring | Level 3 | Interest rate swap contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
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 | Purchased currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Level 3 | Commercial paper
Assets
Investments, debt securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Corporate notes and bonds
Assets
Investments, debt securities	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Level 3 | Asset-backed securities
Assets
Investments, debt securities	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Level 3 | U.S. government and agency securities
Assets
Investments, debt securities	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Level 3 | Foreign government bonds
Assets
Investments, debt securities	0	0
Fair Value, Measurements, Recurring | Level 3 | Mortgage-backed securities
Assets
Other assets	0	0
Fair Value, Measurements, Recurring | Level 3 | Publicly traded equity securities
Assets
Publicly traded equity securities	0	0
Other assets	$ 0	$ 0

Financial Instruments - Summari

Financial Instruments - Summarized Information About Changes in Liabilities for Contingent Consideration (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration	$ 788	$ 935
Changes in estimated fair value	64	89
Additions	0	8
Payments	(85)	(244)
Contingent consideration	767	788
Contingent consideration, liability, current	$ 114
Sanofi Pasteur
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.115
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration	$ 614
Contingent consideration	$ 625	$ 614
Measurement Input, Discount Rate | Sanofi Pasteur
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Contingent Consideration, Liability, Measurement Input	0.08

Inventories - Narrative (Detail

Inventories - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Inventory [Line Items]
LIFO inventory amount	$ 2,600	$ 2,500
Inventories classified in other assets	1,480	1,417
Inventory Not Expected to be Sold Within One Year
Inventory [Line Items]
Inventories classified in other assets	1,300	1,400
Inventories Produced in Preparation for Product Launches
Inventory [Line Items]
Inventories classified in other assets	$ 168	$ 7

Inventories - Inventories (Deta

Inventories - Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Finished goods	$ 1,772	$ 1,658
Raw materials and work in process	5,650	5,004
Supplies	207	194
Total (approximates current cost)	7,629	6,856
(Decrease) increase to LIFO cost	(171)	1
Total current and noncurrent inventories	7,458	6,857
Recognized as:
Inventories	5,978	5,440
Other assets	$ 1,480	$ 1,417

Goodwill and Other Intangible_2

Goodwill and Other Intangibles - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Apr. 01, 2019
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	$ 14,196	$ 13,104
Intangible asset impairment charge related to marketed product	705		$ 58
IPR&D impairment charges	172	152	483
Changes in estimated fair value	64	89
Amortization expense for intangible assets	2,000	3,100	3,200
Estimated aggregate amortization expense, 2020	1,600
Estimated aggregate amortization expense, 2021	1,500
Estimated aggregate amortization expense, 2022	1,500
Estimated aggregate amortization expense, 2023	1,500
Estimated aggregate amortization expense, 2024	1,400
Sivextro
Intangible Assets Excluding Goodwill [Line Items]
Intangible asset impairment charge related to marketed product	612
Intron A
Intangible Assets Excluding Goodwill [Line Items]
Intangible asset impairment charge related to marketed product			47
IOmet Pharma Ltd
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges	155
Changes in estimated fair value	(11)
SmartCells Program
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges		139
Changes in estimated fair value		(60)
uprifosbuvir
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges			240
verubecestat
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges			$ 226
Products and product rights
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	7,095	9,030
Products and product rights | Zerbaxa
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	2,400
Products and product rights | Sivextro
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	171
Products and product rights | Implanon/Nexplanon
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	412
Products and product rights | Dificid
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	312
Products and product rights | Gardasil/Gardasil 9
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	314
Products and product rights | Bridion
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	230
Products and product rights | Simponi
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	163
Trade names
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	2,682	102
Trade names | Animal Health
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	2,400
Licenses
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	2,361	$ 1,673
Licenses | Lenvima
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	956
Licenses | Lynparza
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	$ 955
Antelliq
Intangible Assets Excluding Goodwill [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill				$ 2,689

Goodwill and Other Intangible_3

Goodwill and Other Intangibles - Goodwill Activity by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 18,253	$ 18,284
Acquisitions	1,341	41
Impairments	(162)	(144)
Other	(7)	72
Goodwill, Ending Balance	19,425	18,253
Accumulated goodwill impairment losses	531	369
Pharmaceutical
Goodwill [Roll Forward]
Goodwill, Beginning Balance	16,162	16,066
Acquisitions	19	0
Impairments	0	0
Other	0	96
Goodwill, Ending Balance	16,181	16,162
Animal Health
Goodwill [Roll Forward]
Goodwill, Beginning Balance	1,870	1,877
Acquisitions	1,322	17
Impairments	0	0
Other	0	(24)
Goodwill, Ending Balance	3,192	1,870
All Other
Goodwill [Roll Forward]
Goodwill, Beginning Balance	221	341
Acquisitions	0	24
Impairments	(162)	(144)
Other	(7)	0
Goodwill, Ending Balance	$ 52	$ 221

Goodwill and Other Intangible_4

Goodwill and Other Intangibles - Other Intangibles (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	$ 55,324	$ 52,372
Accumulated Amortization	41,128	39,268
Net	14,196	13,104
IPR&D
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	1,032	1,064
Net	1,032	1,064
Products and product rights
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	45,947	46,615
Accumulated Amortization	38,852	37,585
Net	7,095	9,030
Licenses
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	3,185	2,081
Accumulated Amortization	824	408
Net	2,361	1,673
Trade names
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	2,899	209
Accumulated Amortization	217	107
Net	2,682	102
Other
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	2,261	2,403
Accumulated Amortization	1,235	1,168
Net	$ 1,026	$ 1,235

Loans Payable, Long-Term Debt_3

Loans Payable, Long-Term Debt and Leases - Narrative (Details) - USD ($)	1 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2017	Apr. 30, 2020	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt, current maturities		$ 1,900,000,000
Loans payable and current portion of long-term debt		3,610,000,000			$ 5,308,000,000
Long-term debt		22,736,000,000			19,806,000,000
Proceeds from debt, net of issuance costs	$ 5,000,000,000
Face amount of debt	$ 5,000,000,000
Loss on extinguishment of debt			$ 191,000,000
Long-term debt, maturities, repayments of principal in 2020		1,900,000,000
Long-term debt, maturities, repayments of principal in 2021		2,300,000,000
Long-term debt, maturities, repayments of principal in 2022		2,300,000,000
Long-term debt, maturities, repayments of principal in 2023		1,700,000,000
Long-term debt, maturities, repayments of principal in 2024		1,300,000,000
Available borrowing capacity under credit facility		$ 6,000,000,000
Operating lease, weighted average remaining lease term		7 years 4 months 24 days
Operating lease, cost		$ 339,000,000
Operating lease, payments		281,000,000
Lessee, operating lease, lease not yet commenced, amount		538,000,000
Operating leases, future minimum payments due, next twelve months					188,000,000
Operating leases, future minimum payments, due in two years					198,000,000
Operating leases, future minimum payments, due in three years					150,000,000
Operating leases, future minimum payments, due in four years					134,000,000
Operating leases, future minimum payments, due in five years					84,000,000
Operating leases, future minimum payments, due thereafter					243,000,000
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability		129,000,000
Other Variable Rate Debt
Debt Instrument [Line Items]
Long-term debt		$ 147,000,000			$ 223,000,000
Effective interest rate (as percent)		2.54%			2.27%
6.30% debentures due 2026
Debt Instrument [Line Items]
Long-term debt		$ 135,000,000			$ 135,000,000
Stated interest rate (as percent)		6.30%
2.90% notes due 2024
Debt Instrument [Line Items]
Long-term debt		$ 745,000,000			0
Stated interest rate (as percent)	2.90%	2.90%
Face amount of debt	$ 750,000,000
3.40% notes due 2029
Debt Instrument [Line Items]
Long-term debt		$ 1,732,000,000			0
Stated interest rate (as percent)	3.40%	3.40%
Face amount of debt	$ 1,750,000,000
3.90% notes due 2039
Debt Instrument [Line Items]
Long-term debt		$ 982,000,000			0
Stated interest rate (as percent)	3.90%	3.90%
Face amount of debt	$ 1,000,000,000
4.00% notes due 2049
Debt Instrument [Line Items]
Long-term debt		$ 1,468,000,000			0
Stated interest rate (as percent)	4.00%	4.00%
Face amount of debt	$ 1,500,000,000
Notes Subject To Repayment At Option Of Holder
Debt Instrument [Line Items]
Loans payable and current portion of long-term debt		$ 226,000,000			149,000,000
Commercial paper
Debt Instrument [Line Items]
Loans payable and current portion of long-term debt		$ 1,400,000,000			$ 5,100,000,000
Weighted-average interest rate of commercial paper (as percent)		2.23%			2.09%
Buildings
Debt Instrument [Line Items]
Operating lease, weighted average remaining lease term		8 years
Lessee, operating lease, renewal term		4 years
Vehicles
Debt Instrument [Line Items]
Operating lease, weighted average remaining lease term		4 years
Forecast
Debt Instrument [Line Items]
Lessee, operating lease, lease not yet commenced, amount				$ 221,000,000
Lessee, operating lease,lease not yet commenced, term of contract (in years)				10 years

Loans Payable, Long-Term Debt_4

Loans Payable, Long-Term Debt and Leases - Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt	$ 22,736		$ 19,806
2.75% notes due 2025
Debt Instrument [Line Items]
Long-term debt	$ 2,492		2,490
Stated interest rate (as percent)	2.75%
3.70% notes due 2045
Debt Instrument [Line Items]
Long-term debt	$ 1,975		1,974
Stated interest rate (as percent)	3.70%
2.80% notes due 2023
Debt Instrument [Line Items]
Long-term debt	$ 1,747		1,745
Stated interest rate (as percent)	2.80%
3.40% notes due 2029
Debt Instrument [Line Items]
Long-term debt	$ 1,732		0
Stated interest rate (as percent)	3.40%	3.40%
4.00% notes due 2049
Debt Instrument [Line Items]
Long-term debt	$ 1,468		0
Stated interest rate (as percent)	4.00%	4.00%
2.35% notes due 2022
Debt Instrument [Line Items]
Long-term debt	$ 1,248		1,214
Stated interest rate (as percent)	2.35%
4.15% notes due 2043
Debt Instrument [Line Items]
Long-term debt	$ 1,238		1,237
Stated interest rate (as percent)	4.15%
3.875% notes due 2021
Debt Instrument [Line Items]
Long-term debt	$ 1,151		1,132
Stated interest rate (as percent)	3.875%
1.125% euro-denominated notes due 2021
Debt Instrument [Line Items]
Long-term debt	$ 1,113		1,134
Stated interest rate (as percent)	1.125%
1.875% euro-denominated notes due 2026
Debt Instrument [Line Items]
Long-term debt	$ 1,107		1,127
Stated interest rate (as percent)	1.875%
2.40% notes due 2022
Debt Instrument [Line Items]
Long-term debt	$ 1,010		983
Stated interest rate (as percent)	2.40%
3.90% notes due 2039
Debt Instrument [Line Items]
Long-term debt	$ 982		0
Stated interest rate (as percent)	3.90%	3.90%
2.90% notes due 2024
Debt Instrument [Line Items]
Long-term debt	$ 745		0
Stated interest rate (as percent)	2.90%	2.90%
6.50% notes due 2033
Debt Instrument [Line Items]
Long-term debt	$ 722		726
Stated interest rate (as percent)	6.50%
0.50% euro-denominated notes due 2024
Debt Instrument [Line Items]
Long-term debt	$ 555		565
Stated interest rate (as percent)	0.50%
1.375% euro-denominated notes due 2036
Debt Instrument [Line Items]
Long-term debt	$ 551		561
Stated interest rate (as percent)	1.375%
2.50% euro-denominated notes due 2034
Debt Instrument [Line Items]
Long-term debt	$ 550		560
Stated interest rate (as percent)	2.50%
3.60% notes due 2042
Debt Instrument [Line Items]
Long-term debt	$ 490		490
Stated interest rate (as percent)	3.60%
6.55% notes due 2037
Debt Instrument [Line Items]
Long-term debt	$ 412		414
Stated interest rate (as percent)	6.55%
5.75% notes due 2036
Debt Instrument [Line Items]
Long-term debt	$ 338		338
Stated interest rate (as percent)	5.75%
5.95% debentures due 2028
Debt Instrument [Line Items]
Long-term debt	$ 306		306
Stated interest rate (as percent)	5.95%
5.85% notes due 2039
Debt Instrument [Line Items]
Long-term debt	$ 271		270
Stated interest rate (as percent)	5.85%
6.40% debentures due 2028
Debt Instrument [Line Items]
Long-term debt	$ 250		250
Stated interest rate (as percent)	6.40%
6.30% debentures due 2026
Debt Instrument [Line Items]
Long-term debt	$ 135		135
Stated interest rate (as percent)	6.30%
1.85% notes due 2020
Debt Instrument [Line Items]
Long-term debt	$ 0		$ 1,231
Stated interest rate (as percent)			1.85%
Floating-rate notes due 2020
Debt Instrument [Line Items]
Long-term debt	0		$ 699
Other
Debt Instrument [Line Items]
Long-term debt	$ 148		$ 225

Loans Payable, Long-Term Debt_5

Loans Payable, Long-Term Debt and Leases - Balance Sheet Information (Details) $ in Millions	Dec. 31, 2019USD ($)
Loans Payable, Long-Term Debt and Leases - Balance Sheet Information [Abstract]
Other assets	$ 1,073
Accrued and other current liabilities	236
Other noncurrent liabilities	768
Total operating lease liability	$ 1,004
Weighted-average remaining lease term (years)	7 years 4 months 24 days
Weighted-average discount rate	3.20%

Loans Payable, Long-Term Debt_6

Loans Payable, Long-Term Debt and Leases - Maturity Schedule (Details) $ in Millions	Dec. 31, 2019USD ($)
Leases [Abstract]
2020	$ 264
2021	200
2022	168
2023	113
2024	89
Thereafter	297
Total lease payments	1,131
Less: imputed interest	127
Total operating lease liability	$ 1,004

Contingencies and Environment_2

Contingencies and Environmental Liabilities - Fosamax Product Liability Litigation - Narrative (Details) - Fosamax - legalmatter	1 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2019
Loss Contingencies [Line Items]
Loss contingency, pending claims number		3,750
Federal Court
Loss Contingencies [Line Items]
Loss contingency, pending claims number		970
Loss contingency, claims dismissed number	650
Loss contingency, claims on appeal, number		515
New Jersey State Court
Loss Contingencies [Line Items]
Loss contingency, pending claims number		2,510
California State Court
Loss Contingencies [Line Items]
Loss contingency, pending claims number		275
Other State Court
Loss Contingencies [Line Items]
Loss contingency, pending claims number		4

Contingencies and Environment_3

Contingencies and Environmental Liabilities - Januvia/Janumet Litigation - Narrative (Details) - Januvia	Dec. 31, 2019legalmatter
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1,380
Cases Company Agreed To Toll Statute Of Limitations
Loss Contingencies [Line Items]
Loss contingency, pending claims number	50
Other State Court
Loss Contingencies [Line Items]
Loss contingency, pending claims number	6

Contingencies and Environment_4

Contingencies and Environmental Liabilities - Commercial and Other Litigation- Narrative (Details) - Commercial Litigation $ in Millions	Oct. 01, 2018USD ($)legalmatter	Apr. 29, 2016legalmatter	Dec. 31, 2019legalmatter
Loss Contingencies [Line Items]
Additional claims filed		1
Loss Contingency, Claims Settled, Number	700
Loss contingency, pending claims number			2
Settlement awarded to other party | $	$ 8.5
Number of plaintiffs			2

Contingencies and Environment_5

Contingencies and Environmental Liabilities - Legal Defense Reserves - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Legal Defense Costs
Loss Contingencies [Line Items]
Legal defense costs reserve	$ 240	$ 245

Contingencies and Environment_6

Contingencies and Environmental Liabilities - Environmental Litigation and Matters - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Site Contingency [Line Items]
Accrued liabilities for environmental matters	$ 67	$ 71
Term for paying off environmental liabilities	15 years
Aggregate possible expenditure on environmental matters in excess of amounts accrued	$ 58

Equity - Narrative (Details)

Equity - Narrative (Details) - USD ($) $ in Millions	Oct. 29, 2018	Apr. 30, 2019	Apr. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Oct. 25, 2018
Equity [Abstract]
Common stock, shares authorized				6,500,000,000	6,500,000,000
Preferred stock, shares authorized				20,000,000
Accelerated Share Repurchases [Line Items]
Treasury stock acquired				$ 4,780	$ 9,091	$ 4,014
Accelerated Share Repurchase Agreement, October 29, 2018
Accelerated Share Repurchases [Line Items]
Purchases of treasury stock (in shares)	56,700,000
Accelerated Share Repurchase Agreement
Accelerated Share Repurchases [Line Items]
Shares authorized to be repurchased (in shares)							$ 5,000
Purchases of treasury stock (in shares)		7,700,000	64,400,000
Payment under ASR agreement	$ 5,000
Treasury stock acquired	4,000
Decrease in other-paid-in capital	$ 1,000

Equity - Shareholders' Equity (

Equity - Shareholders' Equity (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement in Common Stock and Treasury Stock [Roll Forward]
Balance January 1 (in shares)	3,577,103,522
Balance December 31 (in shares)	3,577,103,522	3,577,103,522
Common Stock
Movement in Common Stock and Treasury Stock [Roll Forward]
Balance January 1 (in shares)	3,577,000,000	3,577,000,000	3,577,000,000
Purchases of treasury stock (in shares)	0	0	0
Issuances (in shares)	0	0	0
Balance December 31 (in shares)	3,577,000,000	3,577,000,000	3,577,000,000
Treasury Stock
Movement in Common Stock and Treasury Stock [Roll Forward]
Balance January 1 (in shares)	985,000,000	880,000,000	828,000,000
Purchases of treasury stock (in shares)	66,000,000	122,000,000	67,000,000
Issuances (in shares)	(13,000,000)	(17,000,000)	(15,000,000)
Balance December 31 (in shares)	1,038,000,000	985,000,000	880,000,000

Share-Based Compensation Plan_2

Share-Based Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Shares collectively authorized for future grants under share-based compensation plans (in shares)	111,000,000
Quantity of stock options that vest per year (as percent)	33.33%
Period over which share-based payment awards vest	3 years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax share-based compensation cost	$ 417	$ 348	$ 312
Income tax benefits related to share-based compensation	$ 57	$ 55	$ 57
Weighted average exercise price of options granted (in dollars per share)	$ 80.05	$ 58.15	$ 63.88
Weighted average fair value of options granted (in dollars per share)	$ 10.63	$ 8.26	$ 7.04
Total pre tax unrecognized compensation expense related to nonvested stock options, RSU and PSU awards	$ 603
Weighted average period in years of recognition for nonvested stock options, RSU and PSU awards	1 year 10 months 24 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term of options	7 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term of options	10 years

Share-Based Compensation Plan_3

Share-Based Compensation Plans - Assumptions Used to Determine Weighted-Average Fair Value of Options Granted (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Expected dividend yield	3.20%	3.40%	3.60%
Risk-free interest rate	2.40%	2.90%	2.00%
Expected volatility	18.70%	19.10%	17.80%
Expected life (years)	5 years 10 months 24 days	6 years 1 month 6 days	6 years 1 month 6 days

Share-Based Compensation Plan_4

Share-Based Compensation Plans - Summary of Information Relative to Stock Option Plan Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Options, Outstanding, January 1 (in shares)	23,807
Number of Options, Granted (in shares)	2,796
Number of Options, Exercised (in shares)	(8,119)
Number of Options, Forfeited (in shares)	(616)
Number of Options, Outstanding, December 31 (in shares)	17,868	23,807
Number of Options, Exercisable (in shares)	11,837
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Options Outstanding, January 1 (in dollars per share)	$ 51.89
Weighted Average Exercise Price, Granted (in dollars per share)	80.05	$ 58.15	$ 63.88
Weighted Average Exercise Price, Exercised (in dollars per share)	44.48
Weighted Average Exercise Price, Forfeited (in dollars per share)	45.48
Weighted Average Exercise Price, Options Outstanding, December 31 (in dollars per share)	59.88	$ 51.89
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 55.40
Weighted Average Remaining Contractual Term, Outstanding	6 years 5 months 23 days
Weighted Average Remaining Contractual Term, Exercisable	5 years 5 months 12 days
Aggregate Intrinsic Value, Outstanding	$ 555
Aggregate Intrinsic Value, Exercisable	$ 421

Share-Based Compensation Plan_5

Share-Based Compensation Plans - Additional Information Pertaining to Stock Option Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Total intrinsic value of stock options exercised	$ 295	$ 348	$ 236
Fair value of stock options vested	27	29	30
Cash received from the exercise of stock options	$ 361	$ 591	$ 499

Share-Based Compensation Plan_6

Share-Based Compensation Plans - Summary of Nonvested RSU and PSU Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2019$ / sharesshares
RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of Shares, Nonvested January 1 | shares	16,128
Number of Shares, Granted | shares	4,811
Number of Shares, Vested | shares	(6,594)
Number of Shares, Forfeited | shares	(818)
Number of Shares, Nonvested December 31 | shares	13,527
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted Average Grant Date Fair Value, Nonvested January 1 (in dollars per share) | $ / shares	$ 58.85
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	80.08
Weighted Average Grant Date Fair Value, Vested (in dollars per share) | $ / shares	55.70
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	64.75
Weighted Average Grant Date Fair Value, Nonvested December 31 (in dollars per share) | $ / shares	$ 67.58
PSUs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of Shares, Nonvested January 1 | shares	2,039
Number of Shares, Granted | shares	763
Number of Shares, Vested | shares	(748)
Number of Shares, Forfeited | shares	(82)
Number of Shares, Nonvested December 31 | shares	1,972
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted Average Grant Date Fair Value, Nonvested January 1 (in dollars per share) | $ / shares	$ 59.42
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	83.90
Weighted Average Grant Date Fair Value, Vested (in dollars per share) | $ / shares	57.87
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	66.68
Weighted Average Grant Date Fair Value, Nonvested December 31 (in dollars per share) | $ / shares	$ 69.18

Pension and Other Postretirem_3

Pension and Other Postretirement Benefit Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation		$ 22,800	$ 19,000
Employer contributions to defined contribution savings plans		$ 149	$ 136	$ 131
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Percentage of Company's pension investments categorized as Level 3 assets (as percent)		4.00%	5.00%
Pension Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 860	$ 826
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		1,102	968	$ 1,114
Expected contributions to the pension plans and other postretirement benefit plans during next fiscal year		15
Other Postretirement Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 0	$ 0
United States
Defined Benefit Plan Disclosure [Line Items]
Expected annual standard deviation in returns of the target portfolio which reflects both the equity allocation and the diversification benefits among the asset classes in which the portfolio invests (as percent)		10.00%
Expected rate of return on plan assets (as percent)		8.10%	8.20%	8.70%
United States | Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets (as percent)		7.70%
United States | Minimum | Forecast
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets (as percent)	7.00%
United States | Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets (as percent)		8.10%
United States | Maximum | Forecast
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets (as percent)	7.30%
United States | U.S. equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target allocation (as percent)		30.00%
United States | U.S. equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target allocation (as percent)		45.00%
United States | International equities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target allocation (as percent)		15.00%
United States | International equities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target allocation (as percent)		30.00%
United States | Fixed Income Investments | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target allocation (as percent)		35.00%
United States | Fixed Income Investments | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target allocation (as percent)		45.00%
United States | Cash And Other Investments | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target allocation (as percent)		5.00%
United States | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation		$ 12,800	$ 10,400
Fair value of plan assets		11,361	9,648	$ 10,896
Expected contributions to the pension plans and other postretirement benefit plans during next fiscal year		100
United States | Pension Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		9	13	15
International | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		10,163	$ 8,580	$ 9,339
Expected contributions to the pension plans and other postretirement benefit plans during next fiscal year		$ 150
Expected rate of return on plan assets (as percent)		4.90%	5.10%	5.10%
International | Pension Benefits | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		$ 851	$ 813	$ 473

Pension and Other Postretirem_4

Pension and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 48	$ 57	$ 57
Interest cost	69	69	81
Expected return on plan assets	(72)	(83)	(78)
Amortization of unrecognized prior service cost	(78)	(84)	(98)
Net loss amortization	(10)	1	1
Termination benefits	5	3	8
Curtailments	(11)	(8)	(31)
Settlements	0	0	0
Net periodic benefit cost (credit)	(49)	(45)	(60)
United States | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	293	326	312
Interest cost	458	432	454
Expected return on plan assets	(817)	(851)	(862)
Amortization of unrecognized prior service cost	(49)	(50)	(53)
Net loss amortization	151	232	180
Termination benefits	31	19	44
Curtailments	14	10	3
Settlements	0	5	0
Net periodic benefit cost (credit)	81	123	78
International | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	238	238	252
Interest cost	177	178	172
Expected return on plan assets	(426)	(431)	(393)
Amortization of unrecognized prior service cost	(12)	(13)	(11)
Net loss amortization	64	84	98
Termination benefits	8	2	4
Curtailments	6	1	(4)
Settlements	1	13	5
Net periodic benefit cost (credit)	$ 56	$ 72	$ 123

Pension and Other Postretirem_5

Pension and Other Postretirement Benefit Plans - Obligation and Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Postretirement Benefits
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	$ 968	$ 1,114
Actual return on plan assets	203	(72)
Company contributions	14	6
Effects of exchange rate changes	0	0
Benefits paid	(104)	(80)
Settlements	0	0
Other	21	0
Fair value of plan assets December 31	1,102	968	$ 1,114
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation January 1	1,615	1,922
Service cost	48	57	57
Interest cost	69	69	81
Actuarial (gains) losses	21	(341)
Benefits paid	(104)	(80)
Effects of exchange rate changes	1	(6)
Plan amendments	0	(9)
Curtailments	0	0
Termination benefits	5	3	8
Settlements	0	0
Other	18	0
Benefit obligation December 31	1,673	1,615	1,922
Funded status December 31	(571)	(647)
Recognized as:
Other Assets	0	0
Accrued and other current liabilities	(10)	(10)
Other Noncurrent Liabilities	(561)	(637)
United States | Pension Benefits
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	9,648	10,896
Actual return on plan assets	2,165	(810)
Company contributions	130	378
Effects of exchange rate changes	0	0
Benefits paid	(582)	(772)
Settlements	0	(44)
Other	0	0
Fair value of plan assets December 31	11,361	9,648	10,896
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation January 1	10,620	11,904
Service cost	293	326	312
Interest cost	458	432	454
Actuarial (gains) losses	2,165	(1,258)
Benefits paid	(582)	(772)
Effects of exchange rate changes	0	0
Plan amendments	0	0
Curtailments	18	13
Termination benefits	31	19	44
Settlements	0	(44)
Other	0	0
Benefit obligation December 31	13,003	10,620	11,904
Funded status December 31	(1,642)	(972)
Recognized as:
Other Assets	0	0
Accrued and other current liabilities	(92)	(47)
Other Noncurrent Liabilities	(1,550)	(925)
International | Pension Benefits
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	8,580	9,339
Actual return on plan assets	1,505	(289)
Company contributions	262	167
Effects of exchange rate changes	31	(352)
Benefits paid	(230)	(202)
Settlements	(12)	(106)
Other	27	23
Fair value of plan assets December 31	10,163	8,580	9,339
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation January 1	9,083	9,483
Service cost	238	238	252
Interest cost	177	178	172
Actuarial (gains) losses	1,313	(154)
Benefits paid	(230)	(202)
Effects of exchange rate changes	4	(387)
Plan amendments	1	10
Curtailments	3	(2)
Termination benefits	8	2	4
Settlements	(12)	(106)
Other	27	23
Benefit obligation December 31	10,612	9,083	$ 9,483
Funded status December 31	(449)	(503)
Recognized as:
Other Assets	837	659
Accrued and other current liabilities	(18)	(14)
Other Noncurrent Liabilities	$ (1,268)	$ (1,148)

Pension and Other Postretirem_6

Pension and Other Postretirement Benefit Plans - Accumulated and Projected Benefit Obligation in Excess of Plan Assets (Details) - Pension Benefits - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
United States
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plans with a projected benefit obligation in excess of plan assets, projected benefit obligation	$ 13,003	$ 10,620
Pension plans with a projected benefit obligation in excess of plan assets, fair value of plan assets	11,361	9,648
Pension plans with an accumulated benefit obligation in excess of plan assets, accumulated benefit obligation	12,009	9,702
Pension plans with an accumulated benefit obligation in excess of plan assets, fair value of plan assets	10,484	8,966
International
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension plans with a projected benefit obligation in excess of plan assets, projected benefit obligation	7,421	6,251
Pension plans with a projected benefit obligation in excess of plan assets, fair value of plan assets	6,135	5,089
Pension plans with an accumulated benefit obligation in excess of plan assets, accumulated benefit obligation	2,476	5,936
Pension plans with an accumulated benefit obligation in excess of plan assets, fair value of plan assets	$ 1,501	$ 5,071

Pension and Other Postretirem_7

Pension and Other Postretirement Benefit Plans - Fair Values of Pension Plan Assets (Details) - Pension Benefits - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 860	$ 826
United States
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11,361	9,648	$ 10,896
United States | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	239	222
United States | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,747	3,190
United States | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	888	841
United States | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	173	161
United States | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	32
United States | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,451	2,172
United States | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,094	1,509
United States | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,582	1,246
United States | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	178	262
United States | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	13
United States | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,824	2,502
United States | Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	40
United States | Level 1 | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	205	169
United States | Level 1 | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	165	121
United States | Level 1 | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 1 | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 1 | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,451	2,172
United States | Level 1 | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 1 | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 1 | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 1 | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,854	3,017
United States | Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 2 | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 2 | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 2 | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 2 | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 2 | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 2 | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,094	1,509
United States | Level 2 | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,582	1,246
United States | Level 2 | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	178	262
United States | Level 2 | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	13	15
United States | Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3 | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3 | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3 | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3 | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3 | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0	0
United States | Level 3 | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3 | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3 | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3 | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Level 3 | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0	0
United States | Level 3 | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	13	15
United States | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,674	4,116
United States | NAV | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	236	182
United States | NAV | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,542	3,021
United States | NAV | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	723	720
United States | NAV | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	173	161
United States | NAV | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	32
United States | NAV | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | NAV | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | NAV | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | NAV | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | NAV | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10,163	8,580	9,339
International | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	86	69
International | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,403	3,607
International | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	252	251
International | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,203	2,634
International | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	125	105
International | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	11
International | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	2
International | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	565	544
International | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	379	293
International | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	136	114
International | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61	55
International | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	916	877
International | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	21	18
International | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,727	1,497
International | Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	70	50
International | Level 1 | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	546	461
International | Level 1 | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	66	56
International | Level 1 | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	462	372
International | Level 1 | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	4
International | Level 1 | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	7
International | Level 1 | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 1 | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	565	544
International | Level 1 | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	2
International | Level 1 | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
International | Level 1 | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 1 | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 1 | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,052	5,809
International | Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	3
International | Level 2 | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,761	3,071
International | Level 2 | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	96	112
International | Level 2 | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,534	2,082
International | Level 2 | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	7
International | Level 2 | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	4
International | Level 2 | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
International | Level 2 | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 2 | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	376	291
International | Level 2 | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	135	113
International | Level 2 | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	61	55
International | Level 2 | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	65	66
International | Level 2 | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5	4
International | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	851	813	473
International | Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1	2
International | Level 3 | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | Level 3 | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	851	811	470
International | Level 3 | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	1	$ 1
International | NAV
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	533	461
International | NAV | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	16
International | NAV | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	96	75
International | NAV | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	90	83
International | NAV | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	207	180
International | NAV | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	109	94
International | NAV | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | NAV | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | NAV | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | NAV | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | NAV | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | NAV | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | NAV | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International | NAV | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 16	$ 13

Pension and Other Postretirem_8

Pension and Other Postretirement Benefit Plans - Summary of Changes in Fair Value of Company's Level 3 Pension Plan Assets (Details) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	$ 826
Actual return on plan assets:
Fair value of plan assets December 31	860	$ 826
United States
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	9,648	10,896
Actual return on plan assets:
Fair value of plan assets December 31	11,361	9,648
United States | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	13
Actual return on plan assets:
Fair value of plan assets December 31	9	13
United States | Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	13	15
Actual return on plan assets:
Relating to assets still held at December 31	(8)	(3)
Relating to assets sold during the year	8	4
Purchases and sales, net	(4)	(3)
Fair value of plan assets December 31	9	13
United States | Level 3 | Insurance Contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	0	0
Actual return on plan assets:
Relating to assets still held at December 31	0	0
Relating to assets sold during the year	0	0
Purchases and sales, net	0	0
Fair value of plan assets December 31	0	0
United States | Level 3 | Real Estate
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	0	0
Actual return on plan assets:
Relating to assets still held at December 31	0	0
Relating to assets sold during the year	0	0
Purchases and sales, net	0	0
Fair value of plan assets December 31	0	0
United States | Level 3 | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	13	15
Actual return on plan assets:
Relating to assets still held at December 31	(8)	(3)
Relating to assets sold during the year	8	4
Purchases and sales, net	(4)	(3)
Fair value of plan assets December 31	9	13
International
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	8,580	9,339
Actual return on plan assets:
Fair value of plan assets December 31	10,163	8,580
International | Insurance Contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	877
Actual return on plan assets:
Fair value of plan assets December 31	916	877
International | Real Estate
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	2
Actual return on plan assets:
Fair value of plan assets December 31	1	2
International | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	18
Actual return on plan assets:
Fair value of plan assets December 31	21	18
International | Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	813	473
Actual return on plan assets:
Relating to assets still held at December 31	54	(32)
Purchases and sales, net	(16)	379
Transfers out of Level 3	0	(7)
Fair value of plan assets December 31	851	813
International | Level 3 | Insurance Contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	811	470
Actual return on plan assets:
Relating to assets still held at December 31	54	(32)
Purchases and sales, net	(14)	380
Transfers out of Level 3	0	(7)
Fair value of plan assets December 31	851	811
International | Level 3 | Real Estate
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	1	2
Actual return on plan assets:
Relating to assets still held at December 31	0	0
Purchases and sales, net	(1)	(1)
Transfers out of Level 3	0	0
Fair value of plan assets December 31	0	1
International | Level 3 | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	1	1
Actual return on plan assets:
Relating to assets still held at December 31	0	0
Purchases and sales, net	(1)	0
Transfers out of Level 3	0	0
Fair value of plan assets December 31	$ 0	$ 1

Pension and Other Postretirem_9

Pension and Other Postretirement Benefit Plans - Fair Values of Other Postretirement Benefit Plan Assets (Details) - Other Postretirement Benefits - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 1,102	$ 968	$ 1,114
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	74	94
Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	343	295
Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	81	79
Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	17	16
Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	3
Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	225	200
Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	196	141
Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	149	116
Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	17	24
Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	312	307
Level 1 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	52	78
Level 1 | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	19	16
Level 1 | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	15	12
Level 1 | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	1
Level 1 | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	225	200
Level 1 | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	362	281
Level 2 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	196	141
Level 2 | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	149	116
Level 2 | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	17	24
Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 3 | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
NAV
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	428	380
NAV | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	22	16
NAV | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	324	279
NAV | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	66	67
NAV | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	16	15
NAV | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	3
NAV | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
NAV | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
NAV | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
NAV | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 0	$ 0

Pension and Other Postretire_10

Pension and Other Postretirement Benefit Plans - Summary of Expected Benefit Payments (Details) $ in Millions	Dec. 31, 2019USD ($)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
2020	$ 88
2021	92
2022	94
2023	98
2024	100
2025 — 2029	540
United States | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
2020	747
2021	717
2022	710
2023	718
2024	708
2025 — 2029	3,943
International | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
2020	242
2021	225
2022	243
2023	250
2024	250
2025 — 2029	$ 1,417

Pension and Other Postretire_11

Pension and Other Postretirement Benefit Plans - Components of Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net loss amortization included in benefit cost	$ 112	$ 186	$ 170
Prior service (cost) credit arising during the period	(11)	2	(31)
Total	101	188	139
Net loss amortization included in benefit cost	(10)	1	1
Prior service credit amortization included in benefit cost	(78)	(84)	(98)
Total	(88)	(83)	(97)
United States | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net loss amortization included in benefit cost	(816)	(397)	(19)
Prior service (cost) credit arising during the period	(4)	(4)	(13)
Total	(820)	(401)	(32)
Net loss amortization included in benefit cost	151	232	180
Prior service credit amortization included in benefit cost	(49)	(50)	(53)
Total	102	182	127
International | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net loss amortization included in benefit cost	(227)	(505)	309
Prior service (cost) credit arising during the period	(1)	(10)	22
Total	(228)	(515)	331
Net loss amortization included in benefit cost	64	84	98
Prior service credit amortization included in benefit cost	(12)	(13)	(11)
Total	$ 52	$ 71	$ 87

Pension and Other Postretire_12

Pension and Other Postretirement Benefit Plans - Summary of Weighted Average Assumptions Used in Determining Pension Plan and U.S. Pension and Other Postretirement Benefit Plan Information (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
United States
Net periodic benefit cost
Discount rate	4.40%	3.70%	4.30%
Expected rate of return on plan assets	8.10%	8.20%	8.70%
Salary growth rate	4.30%	4.30%	4.30%
Interest crediting rate	3.40%	3.30%	3.30%
Benefit obligation
Discount rate	3.40%	4.40%	3.70%
Salary growth rate	4.20%	4.30%	4.30%
Interest crediting rate	4.90%	3.40%	3.30%
International | Pension Benefits
Net periodic benefit cost
Discount rate	2.20%	2.10%	2.20%
Expected rate of return on plan assets	4.90%	5.10%	5.10%
Salary growth rate	2.80%	2.90%	2.90%
Interest crediting rate	2.90%	2.80%	3.00%
Benefit obligation
Discount rate	1.50%	2.20%	2.10%
Salary growth rate	2.80%	2.80%	2.90%
Interest crediting rate	2.80%	2.90%	2.80%

Pension and Other Postretire_13

Pension and Other Postretirement Benefit Plans - Summary of Health Care Cost Trend Rate Assumptions for Other Postretirement Benefit Plans (Details) - Other Postretirement Benefits	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	6.80%	7.00%
Rate to which the cost trend rate is assumed to decline	4.50%	4.50%

Other (Income) Expense, Net - N

Other (Income) Expense, Net - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Component of Other Income / Expense of Nonoperating [Line Items]
Goodwill impairment charges	$ 162	$ 144
Write-down of assets held for sale		41
Loss on extinguishment of debt			$ 191
Interest paid	841	777	723
Healthcare Services
Component of Other Income / Expense of Nonoperating [Line Items]
Goodwill impairment charges	$ 162	144
CGRP receptor antagonists
Component of Other Income / Expense of Nonoperating [Line Items]
Gain (loss) on sale of clinical development programs		85
AstraZeneca LP
Component of Other Income / Expense of Nonoperating [Line Items]
Other income		99	$ 232
Patent litigation
Component of Other Income / Expense of Nonoperating [Line Items]
Litigation settlement, gain (loss)		$ 115

Other (Income) Expense, Net (De

Other (Income) Expense, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Income and Expenses [Abstract]
Interest income	$ (274)	$ (343)	$ (385)
Interest expense	893	772	754
Exchange losses (gains)	187	145	(11)
Income on investments in equity securities, net	(170)	(324)	(352)
Net periodic defined benefit plan (credit) cost other than service cost	(545)	(512)	(512)
Other, net	48	(140)	6
Other (income) expense, net	$ 139	$ (402)	$ (500)

Taxes on Income - Narrative (De

Taxes on Income - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax [Line Items]
Transition tax	$ 117
Decrease in deferred tax liability			$ 2,000
Measurement period adjustment		$ 124
Transition tax for accumulated foreign earnings		5,500
Transition tax for accumulated foreign earnings, liability	3,400		5,300
Provisional income tax benefit			779
Income tax benefit		32
Deferred tax assets on NOL carryforwards relating to foreign jurisdictions	762
Deferred tax assets relating to various U.S. tax credit carryforwards and NOL carryforwards	135
Income taxes paid	4,500	1,500	4,900
Tax benefits relating to stock option exercises	65	77	73
Unrecognized tax benefits	1,225	1,893	1,723	$ 3,494
Favorable net impact to income tax provision if unrecognized tax benefits were recognized	1,100
Reasonably possible amount that liability for unrecognized tax benefits could decline up to in next 12 months (up to)	40
Interest and penalties associated with uncertain tax positions, expense (benefit)	(101)	51	183
Liabilities for accrued interest and penalties	243	372
Unrecognized tax benefits from adjustments related to examination	356	$ 91	1,388
Foreign Jurisdiction
Income Tax [Line Items]
Valuation allowance on foreign NOL carryforwards	1,100
Federal | Internal Revenue Service (IRS)
Income Tax [Line Items]
Income taxes paid	107		2,800
Unrecognized tax benefits from adjustments related to examination	364		$ 234
Income Taxes Payable
Income Tax [Line Items]
Transition tax liability, current	390
Other Noncurrent Liabilities
Income Tax [Line Items]
Transition tax liability, noncurrent	$ 3,000

Taxes on Income - Reconciliatio

Taxes on Income - Reconciliation Between Effective Tax Rate and US Statutory Rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amount
U.S. statutory rate applied to income before taxes	$ 2,408	$ 1,827	$ 2,282
Differential arising from:
Foreign earnings	(1,020)	(245)	(1,654)
GILTI and the foreign-derived intangible income deduction	336	(25)	0
Tax settlements	(403)	(22)	(356)
R&D tax credit	(118)	(96)	(71)
State taxes	(2)	201	77
Acquisition of Peloton	209	0	0
TCJA	117	289	2,625
Valuation allowances	113	269	632
Acquisition-related costs, including amortization	95	267	713
Restructuring	39	56	142
Other	(87)	(13)	(287)
Taxes on income	$ 1,687	$ 2,508	$ 4,103
Tax Rate
U.S. statutory rate applied to income before taxes	21.00%	21.00%	35.00%
Differential arising from:
Foreign earnings	(8.90%)	(2.80%)	(25.40%)
GILTI and the foreign-derived intangible income deduction	2.90%	(0.30%)	0.00%
Tax settlements	(3.50%)	(0.30%)	(5.50%)
R&D tax credit	(1.00%)	(1.10%)	(1.10%)
State taxes	0.00%	2.30%	1.20%
Acquisition of Peloton	1.80%	0.00%	0.00%
TCJA	0.010	0.033	0.403
Valuation allowances	1.00%	3.10%	9.70%
Acquisition-related costs, including amortization	0.80%	3.10%	10.90%
Restructuring	0.30%	0.60%	2.20%
Other	(0.70%)	(0.10%)	(4.40%)
Total, Tax Rate	14.70%	28.80%	62.90%

Taxes on Income - Income Before

Taxes on Income - Income Before Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Domestic	$ 439	$ 3,717	$ 3,483
Foreign	11,025	4,984	3,038
Income Before Taxes	$ 11,464	$ 8,701	$ 6,521

Taxes on Income - Taxes on Inco

Taxes on Income - Taxes on Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current provision
Federal	$ 514	$ 536	$ 5,585
Foreign	1,806	2,281	1,229
State	(77)	200	(90)
Total current provision	2,243	3,017	6,724
Deferred provision
Federal	(330)	(402)	(2,958)
Foreign	(240)	(64)	75
State	14	(43)	262
Total deferred provision	(556)	(509)	(2,621)
Taxes on income	$ 1,687	$ 2,508	$ 4,103

Taxes on Income - Deferred Inco

Taxes on Income - Deferred Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Income Tax [Line Items]
Product intangibles and licenses, Assets	$ 442	$ 720
Inventory related, Assets	32	32
Accelerated depreciation, Assets	0	0
Pensions and other postretirement benefits, Assets	785	565
Compensation related, Assets	322	291
Unrecognized tax benefits, Assets	109	174
Net operating losses and other tax credit carryforwards, Assets	897	715
Other, Assets	764	621
Subtotal, Assets	3,351	3,118
Valuation allowance, Assets	(1,100)	(1,348)
Deferred Tax Assets	2,251	1,770
Product intangibles and licenses, Liabilities	1,778	1,640
Inventory related, Liabilities	354	377
Accelerated depreciation, Liabilities	594	582
Pensions and other postretirement benefits, Liabilities	191	151
Other, Liabilities	84	66
Subtotal, Liabilities	3,001	2,816
Deferred income taxes, Liabilities	750	1,046
Deferred income taxes	1,470	1,702
Other Assets
Income Tax [Line Items]
Deferred Tax Assets	$ 719	$ 656

Taxes on Income - Unrecognized

Taxes on Income - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Unrecognized tax benefits, reduction resulting from divestiture of Merck's consumer care business	$ (103)	$ (29)	$ (11)
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance January 1	1,893	1,723	3,494
Additions related to current year positions	199	221	146
Additions related to prior year positions	46	142	520
Reductions for tax positions of prior years	(454)	(73)	(1,038)
Settlements	(356)	(91)	(1,388)
Lapse of statute of limitations (2)	(103)	(29)	(11)
Balance December 31	1,225	$ 1,893	$ 1,723
consumer care business
Income Tax Contingency [Line Items]
Unrecognized tax benefits, reduction resulting from divestiture of Merck's consumer care business	(78)
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Lapse of statute of limitations (2)	$ (78)

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Common shares issuable under share-based compensation plans excluded from diluted earnings per common share because the effect would have been antidilutive	2	6	5

Earnings Per Share - Calculatio

Earnings Per Share - Calculations of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income attributable to Merck & Co., Inc.	$ 9,843	$ 6,220	$ 2,394
Average common shares outstanding (in shares)	2,565	2,664	2,730
Common shares issuable (in shares)	15	15	18
Average common shares outstanding assuming dilution (in shares)	2,580	2,679	2,748
Basic earnings per common share attributable to Merck & Co., Inc. common shareholders (in dollars per share)	$ 3.84	$ 2.34	$ 0.88
Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders (in dollars per share)	$ 3.81	$ 2.32	$ 0.87

Other Comprehensive Income (L_3

Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 26,882	$ 34,569	$ 40,308
Other comprehensive income (loss) before reclassification adjustments, pretax	(610)	(692)	324
Tax	161	(24)	232
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(449)	(716)	556
Reclassification adjustments, pretax	(239)	424	(315)
Tax	40	(69)	75
Reclassification adjustments, net of taxes	(199)	355	(240)
Other comprehensive income (loss), net of taxes	(648)	(361)	316
Adoption of ASU 2018-02		(266)
Adoption of new accounting standards			48
Ending Balance	26,001	26,882	34,569
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	166	(108)	338
Other comprehensive income (loss) before reclassification adjustments, pretax	86	228	(561)
Tax	(15)	(55)	207
Other comprehensive income (loss) before reclassification adjustments, net of taxes	71	173	(354)
Reclassification adjustments, pretax	(261)	157	(141)
Tax	55	(33)	49
Reclassification adjustments, net of taxes	(206)	124	(92)
Other comprehensive income (loss), net of taxes	(135)	297	(446)
Adoption of ASU 2018-02		(23)
Adoption of new accounting standards				$ 0
Ending Balance	31	166	(108)
Investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(78)	(61)	(3)
Other comprehensive income (loss) before reclassification adjustments, pretax	140	(108)	212
Tax	0	1	(35)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	140	(107)	177
Reclassification adjustments, pretax	(44)	97	(291)
Tax	0	0	56
Reclassification adjustments, net of taxes	(44)	97	(235)
Other comprehensive income (loss), net of taxes	96	(10)	(58)
Adoption of ASU 2018-02		1
Adoption of new accounting standards				(8)
Ending Balance	18	(78)	(61)
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(3,556)	(2,787)	(3,206)
Other comprehensive income (loss) before reclassification adjustments, pretax	(948)	(728)	438
Tax	192	169	(106)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(756)	(559)	332
Reclassification adjustments, pretax	66	170	117
Tax	(15)	(36)	(30)
Reclassification adjustments, net of taxes	51	134	87
Other comprehensive income (loss), net of taxes	(705)	(425)	419
Adoption of ASU 2018-02		(344)
Adoption of new accounting standards				0
Ending Balance	(4,261)	(3,556)	(2,787)
Pension Plan Net Loss
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Pension and other postretirement benefit plans, net loss and prior service (credit) included in AOCI	5,100	4,400
Other Postretirement Benefit Plan Net Gain
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Pension and other postretirement benefit plans, net loss and prior service (credit) included in AOCI	(247)	(170)
Pension Plan Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Pension and other postretirement benefit plans, net loss and prior service (credit) included in AOCI	(263)	(314)
Other Postretirement Benefit Plan Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Pension and other postretirement benefit plans, net loss and prior service (credit) included in AOCI	(305)	(375)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(2,077)	(1,954)	(2,355)
Other comprehensive income (loss) before reclassification adjustments, pretax	112	(84)	235
Tax	(16)	(139)	166
Other comprehensive income (loss) before reclassification adjustments, net of taxes	96	(223)	401
Reclassification adjustments, pretax	0	0	0
Tax	0	0	0
Reclassification adjustments, net of taxes	0	0	0
Other comprehensive income (loss), net of taxes	96	(223)	401
Adoption of ASU 2018-02		100
Adoption of new accounting standards				0
Ending Balance	(1,981)	(2,077)	(1,954)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(5,545)	(4,910)	(5,226)
Adoption of new accounting standards			(274)	$ (8)
Ending Balance	$ (6,193)	$ (5,545)	$ (4,910)

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details)	12 Months Ended
	Dec. 31, 2019segment
Segment Reporting [Abstract]
Number of operating segments	4

Segment Reporting - Sales of Co

Segment Reporting - Sales of Company's Products (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Sales	$ 46,840	$ 42,294	$ 40,122
Proceeds from sale of intangible assets	80	95	85
Operating Segments
Segment Reporting Information [Line Items]
Sales	46,319	42,151	39,662
Operating Segments | Pharmaceutical segment
Segment Reporting Information [Line Items]
Sales	41,751	37,689	35,390
Operating Segments | Pharmaceutical segment | Keytruda
Segment Reporting Information [Line Items]
Sales	11,084	7,171	3,809
Operating Segments | Pharmaceutical segment | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	444	187	20
Operating Segments | Pharmaceutical segment | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	404	149	0
Operating Segments | Pharmaceutical segment | Emend
Segment Reporting Information [Line Items]
Sales	388	522	556
Operating Segments | Pharmaceutical segment | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	3,737	3,151	2,308
Operating Segments | Pharmaceutical segment | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	2,275	1,798	1,676
Operating Segments | Pharmaceutical segment | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	926	907	821
Operating Segments | Pharmaceutical segment | RotaTeq
Segment Reporting Information [Line Items]
Sales	791	728	686
Operating Segments | Pharmaceutical segment | Vaqta
Segment Reporting Information [Line Items]
Sales	238	239	218
Operating Segments | Pharmaceutical segment | Bridion
Segment Reporting Information [Line Items]
Sales	1,131	917	704
Operating Segments | Pharmaceutical segment | Noxafil
Segment Reporting Information [Line Items]
Sales	662	742	636
Operating Segments | Pharmaceutical segment | Primaxin
Segment Reporting Information [Line Items]
Sales	273	265	280
Operating Segments | Pharmaceutical segment | Invanz
Segment Reporting Information [Line Items]
Sales	263	496	602
Operating Segments | Pharmaceutical segment | Cubicin
Segment Reporting Information [Line Items]
Sales	257	367	382
Operating Segments | Pharmaceutical segment | Cancidas
Segment Reporting Information [Line Items]
Sales	249	326	422
Operating Segments | Pharmaceutical segment | Simponi
Segment Reporting Information [Line Items]
Sales	830	893	819
Operating Segments | Pharmaceutical segment | Remicade
Segment Reporting Information [Line Items]
Sales	411	582	837
Operating Segments | Pharmaceutical segment | Belsomra
Segment Reporting Information [Line Items]
Sales	306	260	210
Operating Segments | Pharmaceutical segment | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	975	1,140	1,204
Operating Segments | Pharmaceutical segment | Zepatier
Segment Reporting Information [Line Items]
Sales	370	455	1,660
Operating Segments | Pharmaceutical segment | Zetia
Segment Reporting Information [Line Items]
Sales	590	857	1,344
Operating Segments | Pharmaceutical segment | Vytorin
Segment Reporting Information [Line Items]
Sales	285	497	751
Operating Segments | Pharmaceutical segment | Atozet
Segment Reporting Information [Line Items]
Sales	391	347	225
Operating Segments | Pharmaceutical segment | Adempas
Segment Reporting Information [Line Items]
Sales	419	329	300
Operating Segments | Pharmaceutical segment | Januvia
Segment Reporting Information [Line Items]
Sales	3,482	3,686	3,737
Operating Segments | Pharmaceutical segment | Janumet
Segment Reporting Information [Line Items]
Sales	2,041	2,228	2,158
Operating Segments | Pharmaceutical segment | NuvaRing
Segment Reporting Information [Line Items]
Sales	879	902	761
Operating Segments | Pharmaceutical segment | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	787	703	686
Operating Segments | Pharmaceutical segment | Singulair
Segment Reporting Information [Line Items]
Sales	698	708	732
Operating Segments | Pharmaceutical segment | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	442	453	484
Operating Segments | Pharmaceutical segment | Nasonex
Segment Reporting Information [Line Items]
Sales	293	376	387
Operating Segments | Pharmaceutical segment | Arcoxia
Segment Reporting Information [Line Items]
Sales	288	335	363
Operating Segments | Pharmaceutical segment | Follistim AQ
Segment Reporting Information [Line Items]
Sales	241	268	298
Operating Segments | Pharmaceutical segment | Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	4,901	4,705	5,314
Operating Segments | Animal Health
Segment Reporting Information [Line Items]
Sales	4,393	4,212	3,875
Operating Segments | Animal Health | Livestock
Segment Reporting Information [Line Items]
Sales	2,784	2,630	2,484
Operating Segments | Animal Health | Companion Animals
Segment Reporting Information [Line Items]
Sales	1,609	1,582	1,391
Operating Segments | Other segments
Segment Reporting Information [Line Items]
Sales	175	250	397
Other
Segment Reporting Information [Line Items]
Sales	521	143	460
United States
Segment Reporting Information [Line Items]
Sales	20,325	18,212	17,424
United States | Operating Segments
Segment Reporting Information [Line Items]
Sales	20,239	18,094	17,340
United States | Operating Segments | Pharmaceutical segment
Segment Reporting Information [Line Items]
Sales	18,759	16,608	15,854
United States | Operating Segments | Pharmaceutical segment | Keytruda
Segment Reporting Information [Line Items]
Sales	6,305	4,150	2,309
United States | Operating Segments | Pharmaceutical segment | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	269	127	0
United States | Operating Segments | Pharmaceutical segment | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	239	95	0
United States | Operating Segments | Pharmaceutical segment | Emend
Segment Reporting Information [Line Items]
Sales	183	312	342
United States | Operating Segments | Pharmaceutical segment | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	1,831	1,873	1,565
United States | Operating Segments | Pharmaceutical segment | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	1,683	1,430	1,374
United States | Operating Segments | Pharmaceutical segment | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	679	627	581
United States | Operating Segments | Pharmaceutical segment | RotaTeq
Segment Reporting Information [Line Items]
Sales	506	496	481
United States | Operating Segments | Pharmaceutical segment | Vaqta
Segment Reporting Information [Line Items]
Sales	130	127	94
United States | Operating Segments | Pharmaceutical segment | Bridion
Segment Reporting Information [Line Items]
Sales	533	386	239
United States | Operating Segments | Pharmaceutical segment | Noxafil
Segment Reporting Information [Line Items]
Sales	282	353	309
United States | Operating Segments | Pharmaceutical segment | Primaxin
Segment Reporting Information [Line Items]
Sales	2	7	10
United States | Operating Segments | Pharmaceutical segment | Invanz
Segment Reporting Information [Line Items]
Sales	30	253	361
United States | Operating Segments | Pharmaceutical segment | Cubicin
Segment Reporting Information [Line Items]
Sales	92	191	189
United States | Operating Segments | Pharmaceutical segment | Cancidas
Segment Reporting Information [Line Items]
Sales	6	12	20
United States | Operating Segments | Pharmaceutical segment | Simponi
Segment Reporting Information [Line Items]
Sales	0	0	0
United States | Operating Segments | Pharmaceutical segment | Remicade
Segment Reporting Information [Line Items]
Sales	0	0	0
United States | Operating Segments | Pharmaceutical segment | Belsomra
Segment Reporting Information [Line Items]
Sales	92	96	98
United States | Operating Segments | Pharmaceutical segment | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	398	513	565
United States | Operating Segments | Pharmaceutical segment | Zepatier
Segment Reporting Information [Line Items]
Sales	118	8	771
United States | Operating Segments | Pharmaceutical segment | Zetia
Segment Reporting Information [Line Items]
Sales	14	45	352
United States | Operating Segments | Pharmaceutical segment | Vytorin
Segment Reporting Information [Line Items]
Sales	16	10	124
United States | Operating Segments | Pharmaceutical segment | Atozet
Segment Reporting Information [Line Items]
Sales	0	0	0
United States | Operating Segments | Pharmaceutical segment | Adempas
Segment Reporting Information [Line Items]
Sales	0	0	0
United States | Operating Segments | Pharmaceutical segment | Januvia
Segment Reporting Information [Line Items]
Sales	1,724	1,969	2,153
United States | Operating Segments | Pharmaceutical segment | Janumet
Segment Reporting Information [Line Items]
Sales	589	811	863
United States | Operating Segments | Pharmaceutical segment | NuvaRing
Segment Reporting Information [Line Items]
Sales	742	722	564
United States | Operating Segments | Pharmaceutical segment | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	568	495	496
United States | Operating Segments | Pharmaceutical segment | Singulair
Segment Reporting Information [Line Items]
Sales	29	20	40
United States | Operating Segments | Pharmaceutical segment | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	24	23	18
United States | Operating Segments | Pharmaceutical segment | Nasonex
Segment Reporting Information [Line Items]
Sales	9	23	54
United States | Operating Segments | Pharmaceutical segment | Arcoxia
Segment Reporting Information [Line Items]
Sales	0	0	0
United States | Operating Segments | Pharmaceutical segment | Follistim AQ
Segment Reporting Information [Line Items]
Sales	103	115	123
United States | Operating Segments | Pharmaceutical segment | Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	1,563	1,319	1,759
United States | Operating Segments | Animal Health
Segment Reporting Information [Line Items]
Sales	1,306	1,238	1,090
United States | Operating Segments | Animal Health | Livestock
Segment Reporting Information [Line Items]
Sales	582	528	471
United States | Operating Segments | Animal Health | Companion Animals
Segment Reporting Information [Line Items]
Sales	724	710	619
United States | Operating Segments | Other segments
Segment Reporting Information [Line Items]
Sales	174	248	396
United States | Other
Segment Reporting Information [Line Items]
Sales	86	118	84
Int’l
Segment Reporting Information [Line Items]
Sales	26,515	24,083	22,698
Int’l | Operating Segments
Segment Reporting Information [Line Items]
Sales	26,079	24,057	22,322
Int’l | Operating Segments | Pharmaceutical segment
Segment Reporting Information [Line Items]
Sales	22,992	21,081	19,536
Int’l | Operating Segments | Pharmaceutical segment | Keytruda
Segment Reporting Information [Line Items]
Sales	4,779	3,021	1,500
Int’l | Operating Segments | Pharmaceutical segment | Alliance revenue - Lynparza (1)
Segment Reporting Information [Line Items]
Sales	176	61	20
Int’l | Operating Segments | Pharmaceutical segment | Alliance revenue - Lenvima (1)
Segment Reporting Information [Line Items]
Sales	165	54	0
Int’l | Operating Segments | Pharmaceutical segment | Emend
Segment Reporting Information [Line Items]
Sales	205	210	213
Int’l | Operating Segments | Pharmaceutical segment | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	1,905	1,279	743
Int’l | Operating Segments | Pharmaceutical segment | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	592	368	303
Int’l | Operating Segments | Pharmaceutical segment | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	247	281	240
Int’l | Operating Segments | Pharmaceutical segment | RotaTeq
Segment Reporting Information [Line Items]
Sales	284	232	204
Int’l | Operating Segments | Pharmaceutical segment | Vaqta
Segment Reporting Information [Line Items]
Sales	108	112	124
Int’l | Operating Segments | Pharmaceutical segment | Bridion
Segment Reporting Information [Line Items]
Sales	598	531	465
Int’l | Operating Segments | Pharmaceutical segment | Noxafil
Segment Reporting Information [Line Items]
Sales	380	389	327
Int’l | Operating Segments | Pharmaceutical segment | Primaxin
Segment Reporting Information [Line Items]
Sales	271	258	270
Int’l | Operating Segments | Pharmaceutical segment | Invanz
Segment Reporting Information [Line Items]
Sales	233	243	241
Int’l | Operating Segments | Pharmaceutical segment | Cubicin
Segment Reporting Information [Line Items]
Sales	165	176	193
Int’l | Operating Segments | Pharmaceutical segment | Cancidas
Segment Reporting Information [Line Items]
Sales	242	314	402
Int’l | Operating Segments | Pharmaceutical segment | Simponi
Segment Reporting Information [Line Items]
Sales	830	893	819
Int’l | Operating Segments | Pharmaceutical segment | Remicade
Segment Reporting Information [Line Items]
Sales	411	582	837
Int’l | Operating Segments | Pharmaceutical segment | Belsomra
Segment Reporting Information [Line Items]
Sales	214	164	112
Int’l | Operating Segments | Pharmaceutical segment | Isentress/Isentress HD
Segment Reporting Information [Line Items]
Sales	576	627	639
Int’l | Operating Segments | Pharmaceutical segment | Zepatier
Segment Reporting Information [Line Items]
Sales	252	447	888
Int’l | Operating Segments | Pharmaceutical segment | Zetia
Segment Reporting Information [Line Items]
Sales	575	813	992
Int’l | Operating Segments | Pharmaceutical segment | Vytorin
Segment Reporting Information [Line Items]
Sales	269	487	627
Int’l | Operating Segments | Pharmaceutical segment | Atozet
Segment Reporting Information [Line Items]
Sales	391	347	225
Int’l | Operating Segments | Pharmaceutical segment | Adempas
Segment Reporting Information [Line Items]
Sales	419	329	300
Int’l | Operating Segments | Pharmaceutical segment | Januvia
Segment Reporting Information [Line Items]
Sales	1,758	1,718	1,584
Int’l | Operating Segments | Pharmaceutical segment | Janumet
Segment Reporting Information [Line Items]
Sales	1,452	1,417	1,296
Int’l | Operating Segments | Pharmaceutical segment | NuvaRing
Segment Reporting Information [Line Items]
Sales	136	180	197
Int’l | Operating Segments | Pharmaceutical segment | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	219	208	191
Int’l | Operating Segments | Pharmaceutical segment | Singulair
Segment Reporting Information [Line Items]
Sales	669	688	692
Int’l | Operating Segments | Pharmaceutical segment | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	418	431	466
Int’l | Operating Segments | Pharmaceutical segment | Nasonex
Segment Reporting Information [Line Items]
Sales	284	353	333
Int’l | Operating Segments | Pharmaceutical segment | Arcoxia
Segment Reporting Information [Line Items]
Sales	288	335	363
Int’l | Operating Segments | Pharmaceutical segment | Follistim AQ
Segment Reporting Information [Line Items]
Sales	138	153	174
Int’l | Operating Segments | Pharmaceutical segment | Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	3,343	3,380	3,556
Int’l | Operating Segments | Animal Health
Segment Reporting Information [Line Items]
Sales	3,086	2,974	2,785
Int’l | Operating Segments | Animal Health | Livestock
Segment Reporting Information [Line Items]
Sales	2,201	2,102	2,013
Int’l | Operating Segments | Animal Health | Companion Animals
Segment Reporting Information [Line Items]
Sales	885	872	772
Int’l | Operating Segments | Other segments
Segment Reporting Information [Line Items]
Sales	1	2	1
Int’l | Other
Segment Reporting Information [Line Items]
Sales	$ 436	$ 26	$ 376

Segment Reporting - Consolidate

Segment Reporting - Consolidated Revenues by Geographic Area (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 46,840	$ 42,294	$ 40,122
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	20,325	18,212	17,424
Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	12,707	12,213	11,478
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	3,583	3,212	3,122
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	3,207	2,184	1,586
Asia Pacific (other than Japan and China)
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	2,943	2,909	2,751
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	2,469	2,415	2,339
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 1,606	$ 1,149	$ 1,422

Segment Reporting - Reconciliat

Segment Reporting - Reconciliation of Segment Profits to Income Before Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Interest income	$ 274	$ 343	$ 385
Interest expense	(893)	(772)	(754)
Depreciation and amortization	(3,652)	(4,519)	(4,676)
Research and development	(9,872)	(9,752)	(10,339)
Restructuring costs	(638)	(632)	(776)
Loss on extinguishment of debt			(191)
Income Before Taxes	11,464	8,701	6,521
Total segment profits
Segment Reporting Information [Line Items]
Depreciation and amortization	(256)	(335)	(212)
Income Before Taxes	29,926	26,633	24,845
Total segment profits | Pharmaceutical segment
Segment Reporting Information [Line Items]
Depreciation and amortization	(137)	(243)	(125)
Income Before Taxes	28,324	24,871	23,018
Total segment profits | Animal Health
Segment Reporting Information [Line Items]
Depreciation and amortization	(109)	(82)	(75)
Income Before Taxes	1,609	1,659	1,552
Total segment profits | Other segments
Segment Reporting Information [Line Items]
Depreciation and amortization	(10)	(10)	(12)
Income Before Taxes	(7)	103	275
Other profits
Segment Reporting Information [Line Items]
Income Before Taxes	363	6	26
Unallocated
Segment Reporting Information [Line Items]
Interest income	274	343	385
Interest expense	(893)	(772)	(754)
Depreciation and amortization	(1,573)	(1,334)	(1,378)
Research and development	(9,499)	(9,432)	(10,004)
Amortization of purchase accounting adjustments	(1,419)	(2,664)	(3,056)
Restructuring costs	(638)	(632)	(776)
Charge related to the termination of a collaboration with Samsung	0	(423)	0
Loss on extinguishment of debt	0	0	(191)
Other unallocated, net	$ (5,077)	$ (3,024)	$ (2,576)

Segment Reporting - Schedule of

Segment Reporting - Schedule of Equity Income from Affiliates and Depreciation and Amortization Included in Segment Profits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Depreciation and amortization	$ 3,652	$ 4,519	$ 4,676
Operating Segments
Segment Reporting Information [Line Items]
Equity (income) loss from affiliates	0	4	7
Depreciation and amortization	256	335	212
Operating Segments | Pharmaceutical
Segment Reporting Information [Line Items]
Equity (income) loss from affiliates	0	4	7
Depreciation and amortization	137	243	125
Operating Segments | Animal Health
Segment Reporting Information [Line Items]
Equity (income) loss from affiliates	0	0	0
Depreciation and amortization	109	82	75
Operating Segments | All Other
Segment Reporting Information [Line Items]
Equity (income) loss from affiliates	0	0	0
Depreciation and amortization	$ 10	$ 10	$ 12

Segment Reporting - Property, P

Segment Reporting - Property, Plant and Equipment, Net by Geographic Area (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 15,053	$ 13,291	$ 12,439
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	8,974	8,306	8,070
Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	4,767	3,706	3,151
Asia Pacific (other than Japan and China)
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	714	684	632
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	266	264	271
China
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	174	167	150
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	152	159	158
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 6	$ 5	$ 7