Merck & Co. (MRK) 10-K 28 Feb 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Jan. 31, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	MRK
Entity Registrant Name	Merck & Co., Inc.
Entity Central Index Key	310,158
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		2,745,571,067
Entity Public Float			$ 159,263

Consolidated Statement of Incom

Consolidated Statement of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Sales	$ 39,807	$ 39,498	$ 42,237
Costs, Expenses and Other
Materials and production	13,891	14,934	16,768
Marketing and administrative	9,762	10,313	11,606
Research and development	10,124	6,704	7,180
Restructuring costs	651	619	1,013
Other (income) expense, net	720	1,527	(11,613)
Total Costs, Expenses and Other	35,148	34,097	24,954
Income Before Taxes	4,659	5,401	17,283
Taxes on Income	718	942	5,349
Net Income	3,941	4,459	11,934
Less: Net Income Attributable to Noncontrolling Interests	21	17	14
Net Income Attributable to Merck & Co., Inc.	$ 3,920	$ 4,442	$ 11,920
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.42	$ 1.58	$ 4.12
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.41	$ 1.56	$ 4.07

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 3,920	$ 4,442	$ 11,920
Other Comprehensive Income (Loss) Net of Taxes:
Net unrealized (loss) gain on derivatives, net of reclassifications	(66)	(126)	398
Net unrealized (loss) gain on investments, net of reclassifications	(44)	(70)	57
Benefit plan net (loss) gain and prior service (cost) credit, net of amortization	(799)	579	(2,077)
Cumulative translation adjustment	(169)	(208)	(504)
Other comprehensive income (loss), net of taxes	(1,078)	175	(2,126)
Comprehensive Income Attributable to Merck & Co., Inc.	$ 2,842	$ 4,617	$ 9,794

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents	$ 6,515	$ 8,524
Short-term investments	7,826	4,903
Accounts receivable (net of allowance for doubtful accounts of $195 in 2016 and $165 in 2015) (excludes accounts receivable of $10 in 2015 classified in Other assets)	7,018	6,484
Inventories (excludes inventories of $1,117 in 2016 and $1,569 in 2015 classified in Other assets - see Note 6)	4,866	4,700
Other current assets	4,389	5,140
Total current assets	30,614	29,751
Investments	11,416	13,039
Property, Plant and Equipment (at cost)
Land	412	490
Buildings	11,439	12,154
Machinery, equipment and office furnishings	14,053	14,261
Construction in progress	1,871	1,525
Property, plant and equipment (at cost)	27,775	28,430
Less: accumulated depreciation	15,749	15,923
Property, plant and equipment, net	12,026	12,507
Goodwill	18,162	17,723
Other Intangibles, Net	17,305	22,602
Other Assets	5,854	6,055
Total Assets	95,377	101,677
Current Liabilities
Loans payable and current portion of long-term debt	568	2,583
Trade accounts payable	2,807	2,533
Accrued and other current liabilities	10,274	11,216
Income taxes payable	2,239	1,560
Dividends payable	1,316	1,309
Total current liabilities	17,204	19,201
Long-Term Debt	24,274	23,829
Deferred Income Taxes	5,077	6,535
Other Noncurrent Liabilities	8,514	7,345
Merck & Co., Inc. Stockholders’ Equity
Common stock, $0.50 par value Authorized - 6,500,000,000 shares Issued - 3,577,103,522 shares in 2016 and 2015	1,788	1,788
Other paid-in capital	39,939	40,222
Retained earnings	44,133	45,348
Accumulated other comprehensive loss	(5,226)	(4,148)
Stockholders' equity before deduction for treasury stock	80,634	83,210
Less treasury stock, at cost: 828,372,200 shares in 2016 and 795,975,449 shares in 2015	40,546	38,534
Total Merck & Co., Inc. stockholders’ equity	40,088	44,676
Noncontrolling Interests	220	91
Total equity	40,308	44,767
Total Liabilities and Equity	$ 95,377	$ 101,677

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 195	$ 165
Accounts receivable classified in other assets	0	10
Inventories classified in other assets	$ 1,117	$ 1,569
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)	828,372,200	795,975,449

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, 2013	$ 52,326	$ 1,788	$ 40,508	$ 39,257	$ (2,197)	$ (29,591)	$ 2,561
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Merck & Co., Inc.	11,920			11,920
Other comprehensive income (loss), net of taxes	(2,126)				(2,126)
Cash dividends declared on common stock ($1.85 per share in 2016, $1.81 per share in 2015 and $1.77 per share in 2014)	(5,156)			(5,156)
Treasury stock shares purchased	(7,703)					(7,703)
AstraZeneca option exercise	(2,400)						(2,400)
Net income attributable to noncontrolling interests	14						14
Distributions attributable to noncontrolling interests	(77)						(77)
Share-based compensation plans and other	1,993		(85)			2,032	46
Ending Balance at Dec. 31, 2014	48,791	1,788	40,423	46,021	(4,323)	(35,262)	144
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Merck & Co., Inc.	4,442			4,442
Other comprehensive income (loss), net of taxes	175				175
Cash dividends declared on common stock ($1.85 per share in 2016, $1.81 per share in 2015 and $1.77 per share in 2014)	(5,115)			(5,115)
Treasury stock shares purchased	(4,186)					(4,186)
Changes in noncontrolling ownership interests	(75)		(20)				(55)
Net income attributable to noncontrolling interests	17						17
Distributions attributable to noncontrolling interests	(15)						(15)
Share-based compensation plans and other	733		(181)			914
Ending Balance at Dec. 31, 2015	44,767	1,788	40,222	45,348	(4,148)	(38,534)	91
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Merck & Co., Inc.	3,920			3,920
Other comprehensive income (loss), net of taxes	(1,078)				(1,078)
Cash dividends declared on common stock ($1.85 per share in 2016, $1.81 per share in 2015 and $1.77 per share in 2014)	(5,135)			(5,135)
Treasury stock shares purchased	(3,434)					(3,434)
Changes in noncontrolling ownership interests	124						124
Net income attributable to noncontrolling interests	21						21
Distributions attributable to noncontrolling interests	(16)						(16)
Share-based compensation plans and other	1,139		(283)			1,422
Ending Balance at Dec. 31, 2016	$ 40,308	$ 1,788	$ 39,939	$ 44,133	$ (5,226)	$ (40,546)	$ 220

Consolidated Statement of Equi7

Consolidated Statement of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Common stock, dividends declared (in dollars per share)	$ 1.85	$ 1.81	$ 1.77

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash Flows from Operating Activities
Net income	$ 3,941	$ 4,459	$ 11,934
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	5,441	6,375	6,691
Intangible asset impairment charges	3,948	162	1,222
Charge related to the settlement of worldwide Keytruda patent litigation	625	0	0
Foreign currency devaluation related to Venezuela	0	876	0
Net charge related to the settlement of Vioxx shareholder class action litigation	0	680	0
Gain on divestiture of Merck Consumer Care business	0	0	(11,209)
Gain on AstraZeneca option exercise	0	0	(741)
Loss on extinguishment of debt	0	0	628
Equity income from affiliates	(86)	(205)	(257)
Dividends and distributions from equity method affiliates	16	50	185
Deferred income taxes	(1,521)	(764)	(2,600)
Share-based compensation	300	299	278
Other	313	874	34
Net changes in assets and liabilities:
Accounts receivable	(619)	(480)	(554)
Inventories	206	805	79
Trade accounts payable	278	(37)	593
Accrued and other current liabilities	(2,018)	(8)	1,635
Income taxes payable	124	(266)	(21)
Noncurrent liabilities	(809)	(277)	190
Other	237	(5)	(98)
Net Cash Provided by Operating Activities	10,376	12,538	7,989
Cash Flows from Investing Activities
Capital expenditures	(1,614)	(1,283)	(1,317)
Purchases of securities and other investments	(15,651)	(16,681)	(24,944)
Proceeds from sales of securities and other investments	14,353	20,413	15,114
Divestiture of Merck Consumer Care business, net of cash divested	0	0	13,951
Dispositions of other businesses, net of cash divested	0	316	1,169
Proceeds from AstraZeneca option exercise	0	0	419
Acquisition of Cubist Pharmaceuticals, Inc., net of cash acquired	0	(7,598)	0
Acquisition of Idenix Pharmaceuticals, Inc., net of cash acquired	0	0	(3,700)
Acquisitions of other businesses, net of cash acquired	(780)	(146)	(181)
Acquisition of Bayer AG collaboration rights	0	0	(1,000)
Cash inflows from net investment hedges	29	139	195
Other	453	82	(80)
Net Cash Used in Investing Activities	(3,210)	(4,758)	(374)
Cash Flows from Financing Activities
Net change in short-term borrowings	0	(1,540)	(460)
Payments on debt	(2,386)	(2,906)	(6,617)
Proceeds from issuance of debt	1,079	7,938	3,146
Purchases of treasury stock	(3,434)	(4,186)	(7,703)
Dividends paid to stockholders	(5,124)	(5,117)	(5,170)
Other dividends paid	0	0	(77)
Proceeds from exercise of stock options	939	485	1,560
Other	(118)	(61)	79
Net Cash Used in Financing Activities	(9,044)	(5,387)	(15,242)
Effect of Exchange Rate Changes on Cash and Cash Equivalents	(131)	(1,310)	(553)
Net (Decrease) Increase in Cash and Cash Equivalents	(2,009)	1,083	(8,180)
Cash and Cash Equivalents at Beginning of Year	8,524	7,441	15,621
Cash and Cash Equivalents at End of Year	$ 6,515	$ 8,524	$ 7,441

Nature of Operations

Nature of Operations	12 Months Ended
	Dec. 31, 2016
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 segment is the only reportable segment. The Pharmaceutical segment includes human health pharmaceutical and vaccine products marketed either directly by the Company or through joint ventures. 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. 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. Sales of vaccines in most major European markets were marketed through the Company’s Sanofi Pasteur MSD (SPMSD) joint venture until its termination on December 31, 2016. Beginning in 2017, Merck will record vaccine sales in the European markets that were previously part of the joint venture. The Company also has animal health operations that discover, develop, manufacture and market animal health products, including vaccines, which the Company sells to veterinarians, distributors and animal producers. The Company’s 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. Merck’s Alliances segment primarily includes results from the Company’s relationship with AstraZeneca LP until the termination of that relationship on June 30, 2014 (see Note 8). On October 1, 2014, the Company divested its Consumer Care segment that developed, manufactured and marketed over-the-counter, foot care and sun care products (see Note 3).

Summary of Accounting Policies

Summary of Accounting Policies	12 Months Ended
	Dec. 31, 2016
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 recognized at fair value if fair value can reasonably be estimated. If the acquisition date fair value of an asset acquired or liability assumed that arises from a contingency 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. 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 market. The cost of a substantial majority of domestic 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 and equity securities classified as available-for-sale are reported at fair value. Fair values of the Company’s investments 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 ). For declines in the fair value of equity securities that are considered other-than-temporary, impairment losses are charged to Other (income) expense, net . The Company considers available evidence in evaluating potential impairments of its investments, including the duration and extent to which fair value is less than cost and, for equity securities, the Company’s ability and intent to hold the investments. For debt securities, an other-than-temporary impairment has occurred if the Company does not expect to recover the entire amortized cost basis of the 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 both debt and equity securities are included in Other (income) expense, net . Revenue Recognition — Revenues from sales of products are recognized when title and risk of loss passes to the customer, typically upon delivery. Recognition of revenue also requires reasonable assurance of collection of sales proceeds and completion of all performance obligations. Domestically, sales discounts are issued to customers as direct discounts at the point-of-sale, indirectly through an intermediary wholesaler, known as chargebacks, or indirectly 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. Accruals for chargebacks are reflected as a direct reduction to accounts receivable and accruals for rebates are recorded as current liabilities. The accrued balances relative to the provisions for chargebacks and rebates included in Accounts receivable and Accrued and other current liabilities were $196 million and $2.7 billion , respectively, at December 31, 2016 and $145 million and $2.7 billion , respectively, at December 31, 2015 . 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 . 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 $1.6 billion in 2016 , $1.6 billion in 2015 and $2.5 billion in 2014 . 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 $2.3 billion in 2016 , 2015 and 2014 , 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. Capitalized software costs are included in Property, plant and equipment and 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 $452 million and $421 million , net of accumulated amortization at December 31, 2016 and 2015 , 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. Acquired Intangibles — Acquired intangibles include products and product rights, tradenames and patents, which are recorded at fair value, assigned an estimated useful life, and are amortized primarily on a straight-line basis over their estimated useful lives ranging from 2 to 20 years (see Note 7). 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 through business combinations 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 tests IPR&D for impairment at least annually, 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 the IPR&D intangible asset is less than its carrying amount. If the Company concludes it is more likely than not that the fair value is less than the carrying amount, a quantitative test that compares the fair value of the IPR&D intangible asset with its carrying value is performed. 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 business 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. 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, the contingent consideration liability is remeasured at current fair value with changes (either expense or income) recorded in earnings. Changes in any of the inputs may result in a significantly different fair value adjustment. Research and Development — Research and development is expensed as incurred. Upfront and milestone payments due to third parties in connection with research and development collaborations prior to regulatory approval are expensed as incurred. Payments due to third parties upon or subsequent to regulatory approval are capitalized and amortized over the shorter of the remaining license or product patent life. Amounts due from collaborative partners related to development activities are generally reflected as a reduction of research and development expenses when the specific milestone has been achieved. 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 all periods. In addition, research and development expenses include expense or income related to changes in the estimated fair value measurement of liabilities for contingent consideration. 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. 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 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 the first quarter of 2016, the Company adopted accounting guidance issued by the Financial Accounting Standards Board (FASB) in April of 2015, which requires debt issuance costs to be presented as a direct deduction from the carrying amount of that debt on the balance sheet as opposed to being presented as a deferred charge. Approximately $100 million of debt issuance costs were reclassified in the first quarter of 2016 as a result of the adoption of the new standard. Prior period amounts have been recast to conform to the new presentation. In the second quarter of 2016, the Company elected to early adopt an accounting standards update issued by the FASB in March of 2016 intended to simplify the accounting and reporting for employee share-based payment transactions. Among other provisions, the new standard requires that excess tax benefits and deficiencies that arise upon vesting or exercise of share-based payments be recognized in the income statement (as opposed to previous guidance under which tax effects were recorded to Other paid-in-capital in certain instances). This aspect of the new guidance, which was required to be adopted prospectively, resulted in the recognition of $79 million of excess tax benefits in Taxes on income in 2016 arising from share-based payments. The new guidance also amended the presentation of certain share-based payment items in the statement of cash flows. Cash flows related to excess income tax benefits are now classified as an operating activity (formerly included as a financing activity). The Company elected to adopt this aspect of the new guidance prospectively. The standard also clarified that cash payments made to taxing authorities on the employees’ behalf for shares withheld should be presented as a financing activity. This aspect of the guidance was adopted retrospectively; accordingly, the Company reclassified $117 million and $129 million of such payments from operating activities to financing activities in the Consolidated Statement of Cash Flows for the years ended December 31, 2015 and 2014, respectively, to conform to the current presentation. The Company has elected to continue to estimate the impact of forfeitures when determining the amount of compensation cost to be recognized each period rather than account for them as they occur. In the fourth quarter of 2016, the Company elected to early adopt an accounting standards update issued by the FASB on January 5, 2017 intended to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. If substantially all of the fair value of gross assets included in a transaction is concentrated in a single asset (or a group of similar assets), the assets would not represent a business. To be considered a business, the assets in the transaction need to include an input and a substantive process that together significantly contribute to the ability to create outputs. Prior to the adoption of the new guidance, an acquisition or disposition would be considered a business if there were inputs, as well as processes that when applied to those inputs had the ability to create outputs. Entities are permitted to apply the updated guidance to transactions occurring before the guidance was issued as long as the applicable financial statements have not been issued. Accordingly, the Company elected to adopt this guidance prospectively as of October 1, 2016. Recently Issued Accounting Standards — In May 2014, the FASB issued amended accounting guidance on revenue recognition that will be applied to all contracts with customers. The objective of the new guidance is to improve comparability of revenue recognition practices across entities and to provide more useful information to users of financial statements through improved disclosure requirements. In August 2015, the FASB approved a one-year deferral of the effective date making this guidance effective for interim and annual periods beginning in 2018. The new standard permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of adopting the guidance being recognized at the date of initial application (modified retrospective method). The Company will adopt the new standard on January 1, 2018 and currently plans to use the modified retrospective method. The majority of the Company’s business is ship and bill and, on that primary revenue stream, Merck does not expect significant differences. However, the Company’s analysis is preliminary and subject to change. Merck has not completed its assessment of multiple element arrangements and certain discount and trade promotion programs. In January 2016, the FASB issued revised guidance for the accounting and reporting of financial instruments. The new guidance requires that equity investments with readily determinable fair values currently classified as available for sale be measured at fair value with changes in fair value recognized in net income. The new guidance also simplifies the impairment testing of equity investments without readily determinable fair values and changes certain disclosure requirements. This guidance is effective for interim and annual periods beginning in 2018. Early adoption is not permitted. The Company is currently assessing the impact of adoption on its consolidated financial statements. In February 2016, the FASB issued new accounting guidance for the accounting and reporting of leases. The new guidance requires that lessees recognize a right-of-use asset and a lease liability recorded on the balance sheet for each of its leases (other than leases that meet the definition of a short-term lease). Leases will be classified as either operating or finance. Operating leases will result in straight-line expense in the income statement (similar to current operating leases) while finance leases will result in more expense being recognized in the earlier years of the lease term (similar to current capital leases). The new guidance will be effective for interim and annual periods beginning in 2019. Early adoption is permitted. The Company is currently evaluating the impact of adoption on its consolidated financial statements. In June 2016, the FASB issued amended guidance on the accounting for credit losses on financial instruments within its scope. The 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 new guidance is effective for interim and annual periods beginning in 2020, with earlier application permitted in 2019. The Company is currently evaluating the impact of adoption on its consolidated financial statements. In August 2016, the FASB issued guidance on the classification of certain cash receipts and payments in the statement of cash flows intended to reduce diversity in practice. The guidance is effective for interim and annual periods beginning in 2018. Early adoption is permitted. The guidance is to be applied retrospectively to all periods presented but may be applied prospectively if retrospective application would be impracticable. The Company is currently evaluating the effect of the standard on its Consolidated Statement of Cash Flows. In October 2016, the FASB issued guidance on the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. Under existing guidance, the recognition of current and deferred income taxes for an intra-entity asset transfer is prohibited until the asset has been sold to a third party. The new guidance will require the recognition of the income tax consequences of an intra-entity transfer of an asset (with the exception of inventory) when the intra-entity transfer occurs. The guidance is effective for interim and annual periods beginning in 2018. Early adoption is permitted. The new guidance is to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings in the beginning of the period of adoption. The Company does not anticipate the adoption of the new guidance will have a material effect on its consolidated financial statements. In November 2016, the FASB issued guidance requiring that amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The guidance is effective for interim and annual periods beginning in 2018 and should be applied using a retrospective transition method to each period presented. Early adoption is permitted. The Company is currently evaluating the effect of the standard on its Consolidated Statement of Cash Flows. In January 2017, the FASB issued guidance that provides for the elimination of Step 2 from the goodwill impairment test. If impairment charges are recognized, the amount recorded will be the amount by which the carrying amount exceeds the reporting unit’s fair value with certain limitations. The new guidance is effective for interim and annual periods in 2021. The Company does not anticipate the adoption of the new guidance will have a material effect on its consolidated financial statements.

Restructuring

Restructuring	12 Months Ended
	Dec. 31, 2016
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring The Company incurs substantial costs for restructuring program activities related to Merck’s productivity and cost reduction initiatives, as well as in connection with the integration of certain acquired businesses. In 2010 and 2013, the Company commenced actions under global restructuring programs designed to streamline its cost structure. The actions under these programs include the elimination of positions in sales, administrative and headquarters organizations, as well as the sale or closure of certain manufacturing and research and development sites and the consolidation of office facilities. The Company also continues to reduce its global real estate footprint and improve the efficiency of its manufacturing and supply network. The non-facility related restructuring actions under these programs are substantially complete; the remaining activities primarily relate to ongoing facility rationalizations. The Company recorded total pretax costs of $1.1 billion in 2016 , $1.1 billion in 2015 and $2.0 billion in 2014 related to restructuring program activities. Since inception of the programs through December 31, 2016 , Merck has recorded total pretax accumulated costs of approximately $12.6 billion and eliminated approximately 40,900 positions comprised of employee separations, as well as the elimination of contractors and vacant positions. The Company expects to substantially complete the remaining actions under these programs by the end of 2017 and incur approximately $700 million of additional pretax costs. The Company estimates that approximately two-thirds of the cumulative pretax costs will result in cash outlays, primarily related to employee separation expense. Approximately one-third of the cumulative pretax costs are non-cash, relating primarily to the accelerated depreciation of facilities to be closed or divested. 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, 2016 Materials and production $ — $ 77 $ 104 $ 181 Marketing and administrative — 8 87 95 Research and development — 142 — 142 Restructuring costs 216 — 435 651 $ 216 $ 227 $ 626 $ 1,069 Year Ended December 31, 2015 Materials and production $ — $ 78 $ 283 $ 361 Marketing and administrative — 59 19 78 Research and development — 37 15 52 Restructuring costs 208 — 411 619 $ 208 $ 174 $ 728 $ 1,110 Year Ended December 31, 2014 Materials and production $ — $ 429 $ 53 $ 482 Marketing and administrative — 198 2 200 Research and development — 273 10 283 Restructuring costs 674 — 339 1,013 $ 674 $ 900 $ 404 $ 1,978 Separation costs are associated with actual headcount reductions, as well as those headcount reductions which were probable and could be reasonably estimated. Positions eliminated under restructuring program activities were approximately 2,625 in 2016 , 3,770 in 2015 and 6,085 in 2014 . These position eliminations were comprised of actual headcount reductions and the elimination of contractors and vacant positions. 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 of the sites have and will continue to operate up through the respective closure dates and, since future undiscounted cash flows were sufficient to recover the respective book values, Merck recorded accelerated depreciation 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 2016 , 2015 and 2014 includes $409 million , $550 million and $240 million , respectively, of asset abandonment, shut-down and other related costs. Additionally, other activity includes certain employee-related costs associated with pension and other postretirement benefit plans (see Note 13) and share-based compensation. Other activity also reflects net pretax losses resulting from sales of facilities and related assets of $151 million in 2016 , $117 million in 2015 and $133 million in 2014 . The following table summarizes the charges and spending relating to restructuring program activities: Separation Costs Accelerated Depreciation Other Total Restructuring reserves January 1, 2015 $ 1,031 $ — $ 20 $ 1,051 Expenses 208 174 728 1,110 (Payments) receipts, net (647 ) — (435 ) (1,082 ) Non-cash activity — (174 ) (260 ) (434 ) Restructuring reserves December 31, 2015 592 — 53 645 Expenses 216 227 626 1,069 (Payments) receipts, net (413 ) — (347 ) (760 ) Non-cash activity — (227 ) (186 ) (413 ) Restructuring reserves December 31, 2016 (1) $ 395 $ — $ 146 $ 541 (1) The remaining cash outlays are expected to be substantially completed by the end of 2017.

Acquisitions, Divestitures, Res

Acquisitions, Divestitures, Research Collaborations and License Agreements	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Acquisitions, Divestitures, Research Collaborations and License Agreements	Acquisitions, Divestitures, Research Collaborations and License Agreements The Company continues to acquire businesses and establish 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 payments, 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. 2016 Transactions In July 2016, Merck acquired Afferent Pharmaceuticals (Afferent), a privately held pharmaceutical company focused on the development of therapeutic candidates targeting the P2X3 receptor for the treatment of common, poorly-managed, neurogenic conditions. Afferent’s lead investigational candidate, MK-7264 (formerly AF-219), is a selective, non-narcotic, orally-administered P2X3 antagonist being evaluated in a Phase 2b clinical trial for the treatment of refractory, chronic cough as well as in a Phase 2 clinical trial in idiopathic pulmonary fibrosis with cough. Total consideration transferred of $510 million included cash paid for outstanding Afferent shares of $487 million , as well as share-based compensation payments to settle equity awards attributable to precombination service and cash paid for transaction costs on behalf of Afferent. In addition, former Afferent shareholders are eligible to receive a total of up to an additional $750 million contingent upon the attainment of certain clinical development and commercial milestones for multiple indications and candidates, including MK-7264. This transaction was accounted for as an acquisition of a business; accordingly, the assets acquired and liabilities assumed were recorded at their respective fair values as of the acquisition date. The Company determined the fair value of the contingent consideration was $223 million at the acquisition date utilizing a probability-weighted estimated cash flow stream adjusted for the expected timing of each payment using an appropriate discount rate dependent on the nature and timing of the milestone payment. Merck recognized an intangible asset for in-process research and development (IPR&D) of $832 million , net deferred tax liabilities of $258 million , and other net assets of $29 million (primarily consisting of cash acquired). The excess of the consideration transferred over the fair value of net assets acquired of $130 million was recorded as goodwill that was allocated to the Pharmaceutical segment and is not deductible for tax purposes. The fair value of the identifiable intangible asset related to IPR&D was determined using an income approach, through which fair value is estimated based upon the asset’s probability-adjusted future net cash flows, which reflects the stage of development of the project and the associated probability of successful completion. The net cash flows were then discounted to present value using a discount rate of 11.5% . Actual cash flows are likely to be different than those assumed. Also in July 2016, Merck, through its wholly owned subsidiary Healthcare Services & Solutions, LLC, acquired a majority ownership interest in The StayWell Company LLC (StayWell), a portfolio company of Vestar Capital Partners (Vestar). StayWell is a health engagement company that helps its clients engage and educate people to improve health and business results. Under the terms of the transaction, Merck paid $150 million for a majority ownership interest. Additionally, Merck provided StayWell with a $150 million intercompany loan to pay down preexisting third-party debt. Merck has an option to buy, and Vestar has an option to require Merck to buy, some or all of Vestar’s remaining ownership interest at fair value beginning three years from the acquisition date. This transaction was accounted for as an acquisition of a business. Merck recognized intangible assets of $238 million , deferred tax liabilities of $84 million , other net liabilities of $5 million and noncontrolling interest of $124 million . The excess of the consideration transferred over the fair value of net assets acquired of $275 million was recorded as goodwill and is largely attributable to anticipated synergies expected to arise after the acquisition. The goodwill was allocated to the Healthcare Services segment and is not deductible for tax purposes. The intangible assets recognized primarily relate to customer relationships, which are being amortized over a 10 -year useful life, and medical information and solutions content, which are being amortized over a five -year useful life. Additionally, in July 2016, Merck announced it had executed an agreement to acquire 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 will acquire approximately 93% of the shares of Vallée for approximately $400 million , based on exchange rates at the time of the announcement. This agreement is subject to regulatory review and certain closing conditions. In June 2016, Merck and Moderna Therapeutics (Moderna) entered into a strategic collaboration and license agreement to develop and commercialize novel messenger RNA (mRNA)-based personalized cancer vaccines. The development program will entail multiple studies in several types of cancer and include the evaluation of mRNA-based personalized cancer vaccines in combination with Merck’s Keytruda . Pursuant to the terms of the agreement, Merck made an upfront cash payment to Moderna of $200 million , which was recorded in Research and development expenses. Following human proof of concept studies, Merck has the right to elect to make an additional payment to Moderna. If Merck exercises this right, the two companies will then equally share cost and profits under a worldwide collaboration for the development of personalized cancer vaccines. Moderna will have the right to elect to co-promote the personalized cancer vaccines in the United States. The agreement entails exclusivity around combinations with Keytruda . Moderna and Merck will each have the ability to combine mRNA-based personalized cancer vaccines with other (non-PD-1) agents. In January 2016, Merck acquired IOmet Pharma Ltd (IOmet), a privately held UK-based drug discovery company focused on the development of innovative medicines for the treatment of cancer, with a particular emphasis on the fields of cancer immunotherapy and cancer metabolism. The acquisition provides Merck with IOmet’s preclinical pipeline of IDO (indoleamine-2,3-dioxygenase 1), TDO (tryptophan-2,3-dioxygenase), and dual-acting IDO/TDO inhibitors. The transaction was accounted for as an acquisition of a business. Total purchase consideration in the transaction included a cash payment of $150 million and future additional milestone payments of up to $250 million that are contingent upon certain clinical and regulatory milestones being achieved. The Company determined the fair value of the contingent consideration was $94 million at the acquisition date utilizing a probability-weighted estimated cash flow stream adjusted for the expected timing of each payment utilizing a discount rate of 10.5% . Merck recognized intangible assets for IPR&D of $155 million and net deferred tax assets of $32 million . The excess of the consideration transferred over the fair value of net assets acquired of $57 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. The assets’ probability-adjusted future net cash flows were then discounted to present value also using a discount rate of 10.5% . Actual cash flows are likely to be different than those assumed. 2015 Transactions In December 2015, the Company divested its remaining ophthalmics portfolio in international markets to Mundipharma Ophthalmology Products Limited. Merck received consideration of approximately $170 million and recognized a gain of $147 million recorded in Other (income) expense, net in 2015. In July 2015, Merck acquired cCAM Biotherapeutics Ltd. (cCAM), a privately held biopharmaceutical company focused on the discovery and development of novel cancer immunotherapies. Total purchase consideration in the transaction included an upfront payment of $96 million in cash and future additional payments of up to $510 million associated with the attainment of certain clinical development, regulatory and commercial milestones. The transaction was accounted for as an acquisition of a business. Merck recognized an intangible asset for IPR&D of $180 million related to CM-24, a monoclonal antibody, as well as a liability for contingent consideration of $105 million , goodwill of $14 million and other net assets of $7 million . During 2016, as a result of unfavorable efficacy data, the Company determined that it would discontinue development of the pipeline program. Accordingly, the Company recorded an IPR&D impairment charge of $180 million related to CM-24 and reversed the related liability for contingent consideration, which had a fair value of $116 million at the time of program discontinuation. Both the IPR&D impairment charge and the income related to the reduction in the liability for contingent consideration were recorded in Research and development expenses in 2016. Also in July 2015, Merck and Allergan plc (Allergan) entered into an agreement pursuant to which Allergan acquired the exclusive worldwide rights to MK-1602 and MK-8031, Merck’s investigational small molecule oral calcitonin gene-related peptide (CGRP) receptor antagonists, which are being developed for the treatment and prevention of migraine. Under the terms of the agreement, Allergan acquired these rights for upfront payments of $250 million , of which $125 million was paid in August 2015 upon closing of the transaction and the remaining $125 million was paid in April of 2016. The Company recorded a gain of $250 million within Other (income) expense, net in 2015 related to the transaction. Allergan is fully responsible for development of the CGRP programs, as well as manufacturing and commercialization upon approval and launch of the products. Under the agreement, Merck is entitled to receive potential development and commercial milestone payments and royalties at tiered double-digit rates based on commercialization of the programs. During 2016, Merck recognized gains of $100 million within Other (income) expense, net resulting from payments by Allergan for the achievement of research and development milestones. In February 2015, Merck and NGM Biopharmaceuticals, Inc. (NGM), a privately held biotechnology company, entered into a multi-year collaboration to research, discover, develop and commercialize novel biologic therapies across a wide range of therapeutic areas. Under the terms of the agreement, Merck made an upfront payment to NGM of $94 million , which was included in Research and development expenses, and purchased a 15% equity stake in NGM for $106 million . Merck committed up to $250 million to fund all of NGM’s efforts under the initial five -year term of the collaboration, with the potential for additional funding if certain conditions are met. Prior to Merck initiating a Phase 3 study for a licensed program, NGM may elect to either receive milestone and royalty payments or, in certain cases, to co-fund development and participate in a global cost and revenue share arrangement of up to 50% . The agreement also provides NGM with the option to participate in the co-promotion of any co-funded program in the United States. Merck has the option to extend the research agreement for two additional two -year terms. In January 2015, Merck acquired Cubist Pharmaceuticals, Inc. (Cubist), a leader in the development of therapies to treat serious infections caused by a broad range of bacteria. Total consideration transferred of $8.3 billion included cash paid for outstanding Cubist shares of $7.8 billion , as well as share-based compensation payments to settle equity awards attributable to precombination service and cash paid for transaction costs on behalf of Cubist. Share-based compensation payments to settle non-vested equity awards attributable to postcombination service were recognized as transaction expense in 2015. In addition, the Company assumed all of the outstanding convertible debt of Cubist, which had a fair value of approximately $1.9 billion at the acquisition date. Merck redeemed this debt in February 2015. The transaction was accounted for as an acquisition of a business. The estimated fair value of assets acquired and liabilities assumed from Cubist is as follows: Estimated fair value at January 21, 2015 Cash and cash equivalents $ 733 Accounts receivable 123 Inventories 216 Other current assets 55 Property, plant and equipment 151 Identifiable intangible assets: Products and product rights (11 year weighted-average useful life) 6,923 IPR&D 50 Other noncurrent assets 184 Current liabilities (1) (233 ) Deferred income tax liabilities (2,519 ) Long-term debt (1,900 ) Other noncurrent liabilities (1) (122 ) Total identifiable net assets 3,661 Goodwill (2) 4,670 Consideration transferred $ 8,331 (1) Included in current liabilities and other noncurrent liabilities is contingent consideration of $73 million and $50 million , respectively. (2) The goodwill recognized is largely attributable to anticipated synergies expected to arise after the acquisition and was allocated to the Pharmaceutical segment. The goodwill 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 through which fair value is estimated based on market participant expectations of each asset’s discounted projected net cash flows. The Company’s estimates of projected net cash flows considered historical and projected pricing, margins and expense levels; the performance of competing products where applicable; relevant industry and therapeutic area growth drivers and factors; current and expected trends in technology and product life cycles; the extent and timing of potential new product introductions by the Company’s competitors; and the life of each asset’s underlying patent. The net cash flows were then probability-adjusted where appropriate to consider the uncertainties associated with the underlying assumptions, as well as the risk profile of the net cash flows utilized in the valuation. The probability-adjusted future net cash flows of each product were then discounted to present value utilizing a discount rate of 8% . Actual cash flows are likely to be different than those assumed. The Company recorded the fair value of incomplete research project surotomycin (MK-4261) which, at the time of acquisition, had not reached technological feasibility and had no alternative future use. During the second quarter of 2015, the Company received unfavorable efficacy data from a clinical trial for surotomycin. The evaluation of this data, combined with an assessment of the commercial opportunity for surotomycin, resulted in the discontinuation of the program and an IPR&D impairment charge (see Note 7). In connection with the Cubist acquisition, liabilities were recorded for potential future consideration that is contingent upon the achievement of future sales-based milestones. The fair value of contingent consideration liabilities was 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 a risk-adjusted discount rate of 8% used to present value the probability-weighted cash flows. Changes in the inputs could result in a different fair value measurement. This transaction closed on January 21, 2015; accordingly, the results of operations of the acquired business have been included in the Company’s results of operations beginning after that date. During 2015, the Company incurred $324 million of transaction costs directly related to the acquisition of Cubist including share-based compensation costs, severance costs, and legal and advisory fees which are reflected in Marketing and administrative expenses. The following unaudited supplemental pro forma data presents consolidated information as if the acquisition of Cubist had been completed on January 1, 2014: Years Ended December 31 2015 2014 Sales $ 39,584 $ 43,437 Net income attributable to Merck & Co., Inc. 4,640 10,887 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders 1.65 3.76 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders 1.63 3.72 The unaudited supplemental pro forma data reflects the historical information of Merck and Cubist adjusted to include additional amortization expense based on the fair value of assets acquired, additional interest expense that would have been incurred on borrowings used to fund the acquisition, transaction costs associated with the acquisition, and the related tax effects of these adjustments. The pro forma data should not be considered indicative of the results that would have occurred if the acquisition had been consummated on January 1, 2014, nor are they indicative of future results. 2014 Transactions In December 2014, Merck acquired OncoEthix, a privately held biotechnology company specializing in oncology drug development. Total purchase consideration in the transaction included an upfront cash payment of $110 million and future additional milestone payments of up to $265 million that were contingent upon certain clinical and regulatory milestones being achieved. The transaction was accounted for as an acquisition of a business. Merck recognized an intangible asset for IPR&D of $143 million related to MK-8628 (formerly OTX015), an investigational, novel oral BET (bromodomain) inhibitor, as well as a liability for contingent consideration of $43 million and other net assets of $10 million . During 2016, as a result of unfavorable efficacy data, the Company determined that it would discontinue the development of MK-8628. Accordingly, the Company recorded an IPR&D impairment charge of $143 million related to MK-8628 and reversed the related liability for contingent consideration, which had a fair value of $40 million at the time of program discontinuation. Both the IPR&D impairment charge and the income related to the reduction in the liability for contingent consideration were recorded in Research and development expenses in 2016. On October 1, 2014, the Company completed the sale of its Merck Consumer Care (MCC) business to Bayer AG (Bayer) for $14.2 billion ( $14.0 billion net of cash divested), less customary closing adjustments as well as certain contingent amounts held back that were payable upon the manufacturing site transfer in Canada and regulatory approval in Korea. Under the terms of the agreement, Bayer acquired Merck’s existing over-the-counter business, including the global trademark and prescription rights for Claritin and Afrin. The Company recognized a pretax gain from the sale of MCC of $11.2 billion recorded in Other (income) expense, net in 2014. Also on October 1, 2014, the Company entered into a worldwide clinical development collaboration with Bayer AG (Bayer) to market and develop soluble guanylate cyclase (sGC) modulators including Bayer’s Adempas (riociguat), which is approved to treat pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. The two companies will equally share costs and profits from the collaboration and implement 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 at Bayer. Merck in turn made available its early-stage sGC compounds under similar terms. In return for these broad collaboration rights, Merck made an upfront payment to Bayer of $1.0 billion with the potential for additional milestone payments of up to $1.1 billion upon the achievement of agreed-upon sales goals. Under the agreement, Bayer will lead commercialization of Adempas in the Americas, while Merck will lead commercialization in the rest of the world. For vericiguat and other potential opt-in products, Bayer will lead 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. The Company determined that Merck’s payment to access Bayer’s compounds constituted an acquisition of an asset. Of the $1.0 billion consideration paid by Merck, $915 million of fair value related to Adempas and was capitalized as an intangible asset subject to amortization over its estimated useful life of 12 years , and the remaining $85 million of fair value related to the vericiguat compound in clinical development and was expensed within Research and development expenses. The fair values of Adempas and vericiguat were determined using an income approach. The probability-adjusted future net cash flows were then discounted to present value using a discount rate of 10.0% for Adempas and 10.5% for vericiguat. During the second quarter of 2016, the Company determined it was probable that, in 2017, Adempas sales would exceed the threshold triggering a $350 million milestone payment from Merck to Bayer. Accordingly, in the second quarter of 2016, the Company recorded a $350 million liability and a corresponding intangible asset and also recognized $50 million of cumulative amortization expense within Materials and production costs. The remaining intangible asset at June 30, 2016 of $300 million is being amortized over its then-remaining estimated useful life of 10.5 years as supported by projected future cash flows, subject to impairment testing. The remaining potential future milestone payments of $775 million have not yet been accrued as they are not deemed by the Company to be probable at this time. In August 2014, Merck completed the acquisition of Idenix Pharmaceuticals, Inc. (Idenix) for approximately $3.9 billion in cash ( $3.7 billion net of cash acquired). Idenix was a biopharmaceutical company engaged in the discovery and development of medicines for the treatment of human viral diseases, whose primary focus was on the development of next-generation oral antiviral therapeutics to treat hepatitis C virus (HCV) infection. The transaction was accounted for as an acquisition of a business. Merck recognized an intangible asset for IPR&D of $3.2 billion related to MK-3682 (formerly IDX21437), uprifosbuvir, as well as net deferred tax liabilities of $951 million and other net liabilities of $12 million . Uprifosbuvir is a nucleotide prodrug in clinical development being evaluated for the treatment of HCV infection. The excess of the consideration transferred over the fair value of net assets acquired of $1.5 billion was recorded as goodwill that was allocated to the Pharmaceutical segment and is not deductible for tax purposes. The fair value of the identifiable intangible asset related to IPR&D was determined using an income approach. The asset’s probability-adjusted future net cash flows were then discounted to present value using a discount rate of 11.5% . During 2016, the Company recorded a $ 2.9 billion IPR&D impairment charge related to uprifosbuvir that resulted from recent changes to the product profile taken together with changes to the Company’s expectations for pricing and the market opportunity (see Note 7). In May 2014, Merck entered into an agreement to sell certain ophthalmic products to Santen Pharmaceutical Co., Ltd. (Santen) in Japan and markets in Europe and Asia Pacific. The agreement provided for upfront payments from Santen and additional payments based on defined sales milestones. Santen will also purchase supply of ophthalmology products covered by the agreement for a two - to five -year period. The transaction closed in most markets on July 1, 2014 and in the remaining markets on October 1, 2014. The Company received $565 million of upfront payments from Santen, net of certain adjustments, and recognized gains of $480 million on the transactions in 2014 included in Other (income) expense, net . In March 2014, Merck sold its Sirna Therapeutics, Inc. (Sirna) subsidiary to Alnylam Pharmaceuticals, Inc. (Alnylam) for consideration of $25 million and 2,520,044 shares of Alnylam common stock. Merck is eligible to receive future payments associated with the achievement of certain regulatory and commercial milestones, as well as royalties on future sales. Merck recorded a gain of $204 million in Other (income) expense, net in 2014 related to this transaction. The excess of Merck’s tax basis in its investment in Sirna over the value received resulted in an approximate $300 million tax benefit recorded in 2014. In January 2014, Merck sold the U.S. marketing rights to Saphris , an antipsychotic indicated for the treatment of schizophrenia and bipolar I disorder in adults to Forest Laboratories, Inc. (Forest). Under the terms of the agreement, Forest made upfront payments of $232 million , which were recorded in Sales in 2014, and will make additional payments to Merck based on defined sales milestones. In addition, as part of this transaction, Merck agreed to supply product to Forest (subsequently acquired by Allergan) until patent expiry. 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 February 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.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2016
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 volatility 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 and Japanese yen. 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 foreign currency denominated 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 effective portion of the unrealized gains or losses on these contracts is recorded in AOCI and reclassified into Sales when the hedged anticipated revenue is recognized. The hedge relationship is highly effective and hedge ineffectiveness has been de minimis . 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 the local level in order to mitigate the effect 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 may also use forward exchange contracts to hedge 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 Company hedges a portion of the net investment in certain of its foreign operations and measures ineffectiveness based upon changes in spot foreign exchange rates that are recorded in Other (income) expense, net . The effective portion of the unrealized gains or losses on these contracts is recorded in foreign currency translation adjustment within OCI , and remains in AOCI until either the sale or complete or substantially complete liquidation of the subsidiary. 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 . Included in the cumulative translation adjustment are pretax gains of $193 million in 2016 , $304 million in 2015 and $294 million in 2014 from the euro-denominated notes. Interest Rate Risk Management The Company may use interest rate swap contracts on certain investing and borrowing transactions to manage its net exposure to interest rate changes and to reduce its overall cost of borrowing. The Company does not use leveraged swaps and, in general, does not leverage any of its investment activities that would put principal capital at risk. In May 2016, four interest rate swaps with notional amounts of $250 million each matured. These swaps effectively converted the Company’s $1.0 billion , 0.70% fixed-rate notes due 2016 to variable rate debt. At December 31, 2016 , the Company was a party to 26 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. 2016 Debt Instrument Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 1.30% notes due 2018 1,000 4 1,000 5.00% notes due 2019 1,250 3 550 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 and offset by the 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. 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: 2016 2015 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 $ 20 $ — $ 2,700 $ 42 $ — $ 2,700 Interest rate swap contracts Accrued and other current liabilities — — — — 1 1,000 Interest rate swap contracts Other noncurrent liabilities — 29 3,500 — 23 3,500 Foreign exchange contracts Other current assets 616 — 6,063 579 — 4,171 Foreign exchange contracts Other assets 129 — 2,075 386 — 4,136 Foreign exchange contracts Accrued and other current liabilities — 1 48 — 1 77 Foreign exchange contracts Other noncurrent liabilities — 1 12 — — — $ 765 $ 31 $ 14,398 $ 1,007 $ 25 $ 15,584 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts Other current assets $ 230 $ — $ 8,210 $ 212 $ — $ 8,783 Foreign exchange contracts Other assets — — — 18 — 179 Foreign exchange contracts Accrued and other current liabilities — 103 2,931 — 37 2,508 Foreign exchange contracts Other noncurrent liabilities — — — — 1 6 $ 230 $ 103 $ 11,141 $ 230 $ 38 $ 11,476 $ 995 $ 134 $ 25,539 $ 1,237 $ 63 $ 27,060 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: 2016 2015 Asset Liability Asset Liability Gross amounts recognized in the consolidated balance sheet $ 995 $ 134 $ 1,237 $ 63 Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet (131 ) (131 ) (59 ) (59 ) Cash collateral (received) posted (529 ) — (862 ) — Net amounts $ 335 $ 3 $ 316 $ 4 The table below provides information on the location and pretax gain or loss amounts for derivatives that are: (i) designated in a fair value hedging relationship, (ii) designated in a foreign currency cash flow hedging relationship, (iii) designated in a foreign currency net investment hedging relationship and (iv) not designated in a hedging relationship: Years Ended December 31 2016 2015 2014 Derivatives designated in a fair value hedging relationship Interest rate swap contracts Amount of loss (gain) recognized in Other (income) expense, net on derivatives (1) $ 28 $ (14 ) $ (17 ) Amount of (gain) loss recognized in Other (income) expense, net on hedged item (1) (29 ) 7 14 Derivatives designated in foreign currency cash flow hedging relationships Foreign exchange contracts Amount of gain reclassified from AOCI to Sales (311 ) (724 ) (143 ) Amount of gain recognized in OCI on derivatives (210 ) (526 ) (775 ) Derivatives designated in foreign currency net investment hedging relationships Foreign exchange contracts Amount of gain recognized in Other (income) expense, net on derivatives (2) (1 ) (4 ) (6 ) Amount of loss (gain) recognized in OCI on derivatives 2 (10 ) (192 ) Derivatives not designated in a hedging relationship Foreign exchange contracts Amount of loss (gain) recognized in Other (income) expense, net on derivatives (3) 132 (461 ) (516 ) Amount of (gain) loss recognized in Sales — (1 ) 15 (1) There was $1 million , $7 million and $3 million of ineffectiveness on the hedge during 2016 , 2015 and 2014 , respectively. (2) There was no ineffectiveness on the hedge. Represents the amount excluded from hedge effectiveness testing. (3) 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. At December 31, 2016 , the Company estimates $462 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: 2016 2015 Fair Value Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Gains Losses Gains Losses Corporate notes and bonds $ 10,577 $ 10,601 $ 15 $ (39 ) $ 10,259 $ 10,299 $ 7 $ (47 ) Commercial paper 4,330 4,330 — — 2,977 2,977 — — U.S. government and agency securities 2,232 2,244 1 (13 ) 1,761 1,767 — (6 ) Asset-backed securities 1,376 1,380 1 (5 ) 1,284 1,290 — (6 ) Mortgage-backed securities 796 801 1 (6 ) 694 697 1 (4 ) Foreign government bonds 519 521 — (2 ) 607 586 22 (1 ) Equity securities 349 281 71 (3 ) 534 409 125 — $ 20,179 $ 20,158 $ 89 $ (68 ) $ 18,116 $ 18,025 $ 155 $ (64 ) Available-for-sale debt securities included in Short-term investments totaled $7.8 billion at December 31, 2016 . Of the remaining debt securities, $10.2 billion mature within five years. At December 31, 2016 and 2015 , 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 Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total 2016 2015 Assets Investments Corporate notes and bonds $ — $ 10,389 $ — $ 10,389 $ — $ 10,259 $ — $ 10,259 Commercial paper — 4,330 — 4,330 — 2,977 — 2,977 U.S. government and agency securities 29 1,890 — 1,919 — 1,761 — 1,761 Asset-backed securities (1) — 1,257 — 1,257 — 1,284 — 1,284 Mortgage-backed securities (1) — 628 — 628 — 694 — 694 Foreign government bonds — 518 — 518 — 607 — 607 Equity securities 201 — — 201 360 — — 360 230 19,012 — 19,242 360 17,582 — 17,942 Other assets (2) U.S. government and agency securities — 313 — 313 — — — — Corporate notes and bonds — 188 — 188 — — — — Mortgage-backed securities (1) — 168 — 168 — — — — Asset-backed securities (1) — 119 — 119 — — — — Foreign government bonds — 1 — 1 — — — — Equity securities 148 — — 148 155 19 — 174 148 789 — 937 155 19 — 174 Derivative assets (3) Purchased currency options — 644 — 644 — 1,041 — 1,041 Forward exchange contracts — 331 — 331 — 154 — 154 Interest rate swaps — 20 — 20 — 42 — 42 — 995 — 995 — 1,237 — 1,237 Total assets $ 378 $ 20,796 $ — $ 21,174 $ 515 $ 18,838 $ — $ 19,353 Liabilities Other liabilities Contingent consideration $ — $ — $ 891 $ 891 $ — $ — $ 590 $ 590 Derivative liabilities (2) Forward exchange contracts — 93 — 93 — 38 — 38 Interest rate swaps — 29 — 29 — 24 — 24 Written currency options — 12 — 12 — 1 — 1 — 134 — 134 — 63 — 63 Total liabilities $ — $ 134 $ 891 $ 1,025 $ — $ 63 $ 590 $ 653 (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. Mortgage-backed securities represent AAA-rated securities issued or unconditionally guaranteed as to payment of principal and interest by U.S. government agencies. (2) The increase in investments included in Other assets reflects certain assets previously restricted for retiree benefits that became available to fund certain other health and welfare benefits during 2016 (see Note 13). (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. There were no transfers between Level 1 and Level 2 during 2016 . As of December 31, 2016 , Cash and cash equivalents of $6.5 billion included $5.4 billion of cash equivalents (considered Level 2 in the fair value hierarchy). Contingent Consideration Summarized information about the changes in liabilities for contingent consideration is as follows: 2016 2015 Fair value January 1 $ 590 $ 428 Changes in fair value (1) (407 ) (16 ) Additions 733 228 Payments (25 ) (50 ) Fair value December 31 $ 891 $ 590 (1) Recorded in Research and development expenses and Materials and production costs. The changes in fair value in 2016 were largely attributable to the reversal of liabilities related to programs obtained in connection with the acquisitions of cCAM, OncoEthix and SmartCells (see Note 7). The additions to contingent consideration in 2016 relate to the termination of the SPMSD joint venture (see Note 8) and the acquisitions of IOmet and Afferent (see Note 3). The additions to contingent consideration in 2015 relate to the acquisitions of Cubist and cCAM (see Note 3). The payments of contingent consideration in 2016 relate to the first commercial sale of Zerbaxa in the European Union and in 2015 relate to the first commercial sale of Zerbaxa in the United States. 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, 2016 , was $25.7 billion compared with a carrying value of $24.8 billion and at December 31, 2015 , was $27.0 billion compared with a carrying value of $26.4 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 and Europe 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 economic conditions, including the volatility associated with international sovereign economies, and associated impacts on the financial markets and its business, taking into consideration global economic conditions and the ongoing sovereign debt issues in certain European countries. As of December 31, 2016 , the Company’s total net accounts receivable outstanding for more than one year were approximately $140 million . The Company does not expect to have write-offs or adjustments to accounts receivable which would have a material adverse effect on its financial position, liquidity or results of operations. The Company’s customers with the largest accounts receivable balances are: McKesson Corporation, AmerisourceBergen Corporation, Cardinal Health, Inc., Zuellig Pharma Ltd. (Asia Pacific), and AAH Pharmaceuticals Ltd (UK) which represented, in aggregate, approximately 40% of total accounts receivable at December 31, 2016 . 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. 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. As of December 31, 2016 and 2015 , the Company had received cash collateral of $529 million and $862 million , respectively, from various counterparties and the obligation to return such collateral is recorded in Accrued and other current liabilities . The Company had not advanced any cash collateral to counterparties as of December 31, 2016 or 2015 .

Inventories

Inventories	12 Months Ended
	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories at December 31 consisted of: 2016 2015 Finished goods $ 1,304 $ 1,343 Raw materials and work in process 4,222 4,374 Supplies 155 168 Total (approximates current cost) 5,681 5,885 Increase to LIFO costs 302 384 $ 5,983 $ 6,269 Recognized as: Inventories $ 4,866 $ 4,700 Other assets 1,117 1,569 Inventories valued under the LIFO method comprised approximately $2.3 billion and $2.4 billion of inventories at December 31, 2016 and 2015 , respectively. Amounts recognized as Other assets are comprised almost entirely of raw materials and work in process inventories. At December 31, 2016 and 2015 , these amounts included $1.0 billion and $1.5 billion , respectively, of inventories not expected to be sold within one year. In addition, these amounts included $80 million and $63 million at December 31, 2016 and 2015 , respectively, of inventories produced in preparation for product launches.

Goodwill and Other Intangibles

Goodwill and Other Intangibles	12 Months Ended
	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles	Goodwill and Other Intangibles The following table summarizes goodwill activity by segment: Pharmaceutical All Other Total Balance January 1, 2015 $ 11,108 $ 1,884 $ 12,992 Acquisitions 4,684 29 4,713 Divestitures (18 ) — (18 ) Impairments — (47 ) (47 ) Other (1) 88 (5 ) 83 Balance December 31, 2015 (2) 15,862 1,861 17,723 Acquisitions 207 275 482 Impairments — (47 ) (47 ) Other (1) 6 (2 ) 4 Balance December 31, 2016 (2) $ 16,075 $ 2,087 $ 18,162 (1) Other includes cumulative translation adjustments on goodwill balances and certain other adjustments. (2) Accumulated goodwill impairment losses at December 31, 2016 and 2015 were $187 million and $140 million , respectively. In 2016, the additions to goodwill in the Pharmaceutical segment resulted primarily from the acquisitions of Afferent and IOmet (see Note 3), as well as from the termination of the SPMSD joint venture, which was treated as a step-acquisition for accounting purposes (see Note 8). The addition to goodwill within other non-reportable segments in 2016 relates to the acquisition of StayWell, which is part of the Healthcare Services segment (see Note 3). In 2015, the additions to goodwill in the Pharmaceutical segment resulted primarily from the acquisition of Cubist and the reductions resulted from the divestiture of the Company’s remaining ophthalmics business in international markets (see Note 3). The impairments of goodwill within other non-reportable segments in 2016 and 2015 relate to certain businesses within the Healthcare Services segment. Other intangibles at December 31 consisted of: 2016 2015 Gross Carrying Amount Accumulated Amortization Net Gross Carrying Amount Accumulated Amortization Net Products and product rights $ 46,269 $ 31,919 $ 14,350 $ 45,949 $ 28,514 $ 17,435 IPR&D 1,653 — 1,653 4,226 — 4,226 Tradenames 215 89 126 198 79 119 Other 1,947 771 1,176 1,418 596 822 $ 50,084 $ 32,779 $ 17,305 $ 51,791 $ 29,189 $ 22,602 Acquired intangibles include products and product rights, tradenames and patents, which are recorded at fair value, assigned an estimated useful life, and are amortized primarily on a straight-line basis over their estimated useful lives. The increase in intangible assets for products and product rights in 2016 primarily relates to the recognition of intangible assets in connection with the termination of the SPMSD joint venture (see Note 8). Some of the Company’s more significant acquired intangibles related to marketed products (included in product and product rights above) at December 31, 2016 include Zerbaxa , $3.3 billion ; Zetia , $1.5 billion ; Sivextro , $955 million ; Vytorin , $938 million ; Implanon/Nexplanon $587 million ; Dificid , $561 million ; Gardasil/Gardasil 9, $468 million ; NuvaRing , $319 million ; and Nasonex , $308 million . The Company recognized an intangible asset related to Adempas as a result of the formation of a collaboration with Bayer in 2014 (see Note 3) that had a carrying value of $872 million at December 31, 2016 reflected in “Other” in the table above. During 2016 , 2015 and 2014 , the Company recorded impairment charges related to marketed products and other intangibles of $347 million , $45 million and $1.1 billion , respectively, within Material and production costs. In 2016, the Company lowered its cash flow projections for Zontivity, a product for the reduction of thrombotic cardiovascular events in patients with a history of myocardial infarction or with peripheral arterial disease, following several business decisions that reduced sales expectations for Zontivity in the United States and Europe. The Company utilized market participant assumptions and considered several different scenarios to determine the fair value of the intangible asset related to Zontivity that, when compared with its related carrying value, resulted in an impairment charge of $252 million . Also during 2016, the Company wrote-off $95 million that had been capitalized in connection with in-licensed products Grastek and Ragwitek , allergy immunotherapy tablets that, for business reasons, the Company has determined it will return to the licensor. The charges in 2015 primarily relate to the impairment of customer relationship and tradename intangibles for certain businesses within in the Healthcare Services segment. Of the amount recorded in 2014, $793 million related to PegIntron, $244 million related to Victrelis and $35 million related to Rebetol , all of which are products for the treatment of chronic HCV infection. During 2014, developments in the competitive HCV treatment market led to market share losses that were greater than the Company had predicted causing changes in cash flow projections for PegIntron , Victrelis and Rebetol that indicated the intangible asset values were not recoverable on an undiscounted cash flows basis. The Company utilized market participant assumptions to determine its best estimate of the fair values of the intangible assets related to PegIntron , Victrelis and Rebetol that, when compared with their related carrying values, resulted in the impairment charges noted above. 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. During 2016 , 2015 and 2014 , $8 million , $280 million and $654 million , respectively, of IPR&D was reclassified to products and product rights upon receipt of marketing approval in a major market. During 2016, the Company recorded $3.6 billion of IPR&D impairment charges within Research and development expenses. Of this amount, $2.9 billion relates to the clinical development program for uprifosbuvir, a nucleotide prodrug in clinical development being evaluated for the treatment of HCV. The Company determined that recent changes to the product profile, as well as changes to Merck’s expectations for pricing and the market opportunity, taken together constituted a triggering event that required the Company to evaluate the uprifosbuvir intangible asset for impairment. Utilizing market participant assumptions, and considering different scenarios, the Company concluded that its best estimate of the current fair value of the intangible asset related to uprifosbuvir was $240 million , resulting in the recognition of the pretax impairment charge noted above. The IPR&D impairment charges in 2016 also include charges of $180 million and $143 million related to the discontinuation of programs obtained in connection with the acquisitions of cCAM and OncoEthix, respectively, resulting from unfavorable efficacy data. An additional $72 million relates to programs obtained in connection with the SmartCells acquisition following a decision to terminate the lead compound due to a lack of efficacy and to pursue a back-up compound which reduced projected future cash flows. The IPR&D impairment charges in 2016 also include $112 million related to an in-licensed program for house dust mite allergies that, for business reasons, will be returned to the licensor. The remaining IPR&D impairment charges for 2016 primarily relate to deprioritized pipeline programs that were deemed to have no alternative use during the period, including a $79 million impairment charge for an investigational candidate for contraception. The discontinuation or delay of certain of these clinical development programs resulted in a reduction of the related liabilities for contingent consideration (see Note 3). During 2015, the Company recorded $63 million of IPR&D impairment charges, of which $50 million related to the surotomycin clinical development program. During 2015, the Company received unfavorable efficacy data from a clinical trial for surotomycin. The evaluation of this data, combined with an assessment of the commercial opportunity for surotomycin, resulted in the discontinuation of the program and the IPR&D impairment charge noted above. During 2014, the Company recorded $49 million of IPR&D impairment charges primarily as a result of changes in cash flow assumptions for certain compounds obtained in connection with the Company’s joint venture with Supera Farma Laboratorios S.A. (Supera), as well as for the discontinuation of certain Animal Health programs. All of 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 primarily recorded within Materials and production costs was $3.8 billion in 2016 , $4.8 billion in 2015 and $4.2 billion in 2014 . The estimated aggregate amortization expense for each of the next five years is as follows: 2017 , $3.2 billion ; 2018 , $2.8 billion ; 2019 , $1.4 billion ; 2020 , $1.2 billion ; 2021 , $1.1 billion .

Joint Ventures and Other Equity

Joint Ventures and Other Equity Method Affiliates	12 Months Ended
	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Joint Ventures and Other Equity Method Affiliates	Joint Ventures and Other Equity Method Affiliates Equity income from affiliates reflects the performance of the Company’s joint ventures and other equity method affiliates including SPMSD (until termination on December 31, 2016), certain investment funds, as well as AZLP (until the termination of the Company’s relationship with AZLP on June 30, 2014). Equity income from affiliates was $86 million in 2016 , $205 million in 2015 and $257 million in 2014 and is included in Other (income) expense, net (see Note 14). Investments in affiliates accounted for using the equity method totaled $715 million at December 31, 2016 and $702 million at December 31, 2015 . These amounts are reported in Other assets . Amounts due from the above joint ventures included in Other current assets were $1 million at December 31, 2016 and $34 million at December 31, 2015 . Sanofi Pasteur MSD In 1994, Merck and Pasteur Mérieux Connaught (now Sanofi Pasteur S.A.) established an equally-owned joint venture (SPMSD) to market vaccines in Europe and to collaborate in the development of combination vaccines for distribution in Europe. Joint venture vaccine sales were $1.0 billion for 2016 , $923 million for 2015 and $1.1 billion for 2014 . On December 31, 2016, Merck and Sanofi Pasteur (Sanofi) terminated SPMSD and ended their joint vaccines operations in Europe. Under the terms of the termination, Merck acquired Sanofi’s 50% interest in SPMSD in exchange for consideration of $657 million comprised of cash, as well as future royalties of 11.5% on net sales of all Merck products through December 31, 2024, which the Company determined had a fair value of $416 million on the date of termination. The Company accounted for this transaction as a step acquisition, which required that Merck remeasure its ownership interest (previously accounted for as an equity method investment) to fair value at the acquisition date. Merck in turn sold to Sanofi its intellectual property rights held by SPMSD in exchange for consideration of $596 million comprised of cash and future royalties of 11.5% on net sales of all Sanofi products through December 31, 2024, which the Company determined had a fair value of $302 million on the date of termination. Excluded from this arrangement are potential future sales of Vaxelis (a jointly developed investigational pediatric hexavalent combination vaccine that was approved by the European Commission in February 2016). The European marketing rights for Vaxelis were transferred to a separate equally-owned joint venture between Sanofi and Merck (MCM). The net impact of the termination of the SPMSD joint venture is as follows: Products and product rights (8 year useful life) $ 936 Accounts receivable 133 Income taxes payable (221 ) Deferred income tax liabilities (175 ) Other, net 34 Goodwill (1) 20 Net assets acquired 727 Consideration payable to Sanofi, net (378 ) Derecognition of Merck’s previously held equity investment in SPMSD (183 ) Increase in net assets 166 Merck’s share of restructuring costs related to the termination (77 ) Net gain on termination of SPMSD joint venture (2) $ 89 (1) The goodwill was allocated to the Pharmaceutical segment and is not deductible for tax purposes. (2) Recorded in Other (income) expense, net . The estimated fair values of identifiable intangible assets related to products and product rights were determined using an income approach through which fair value is estimated based on market participant expectations of each asset’s projected net cash flows. The projected net cash flows were then discounted to present value utilizing a discount rate of 11.5% . Actual cash flows are likely to be different than those assumed. Of the amount recorded for products and product rights, $468 million relates to Gardasil/Gardasil 9. The fair value of liabilities for contingent consideration related to Merck’s future royalty payments to Sanofi of $416 million (reflected in the consideration payable to Sanofi, net, in the table above) was determined at the acquisition date using unobservable inputs. These inputs include the estimated amount and timing of projected cash flows and a risk-adjusted discount rate of 8% used to present value the cash flows. Changes in the inputs could result in a different fair value measurement. Based on an existing accounting policy election, Merck has not recorded the $302 million estimated fair value of contingent future royalties to be received from Sanofi on the sale of Sanofi products, but rather will recognize such amounts in future periods as sales occur and the royalties are earned. The Company incurred $24 million of transaction costs related to the termination of SPMSD included in Marketing and administrative expenses in 2016. Pro forma financial information for this transaction has not been presented as the results are not significant when compared with the Company’s financial results. AstraZeneca LP In 1982, Merck entered into an agreement with Astra AB (Astra) to develop and market Astra products under a royalty-bearing license. In 1993, Merck’s total sales of Astra products reached a level that triggered the first step in the establishment of a joint venture business carried on by Astra Merck Inc. (AMI), in which Merck and Astra each owned a 50% share. This joint venture, formed in 1994, developed and marketed most of Astra’s new prescription medicines in the United States. In 1998, Merck and Astra completed a restructuring of the ownership and operations of the joint venture whereby Merck acquired Astra’s interest in AMI, renamed KBI Inc. (KBI), and contributed KBI’s operating assets to a new U.S. limited partnership, Astra Pharmaceuticals L.P. (the Partnership), in exchange for a 1% limited partner interest. Astra contributed the net assets of its wholly owned subsidiary, Astra USA, Inc., to the Partnership in exchange for a 99% general partner interest. The Partnership, renamed AstraZeneca LP (AZLP) upon Astra’s 1999 merger with Zeneca Group Plc, became the exclusive distributor of the products for which KBI retained rights. In connection with the 1998 restructuring of AMI, Merck assumed $2.4 billion par value preferred stock with a dividend rate of 5% per annum, which was carried by KBI and included in Noncontrolling interests . Merck earned revenue based on sales of KBI products and such revenue was $463 million in 2014 primarily relating to sales of Nexium, as well as Prilosec. In addition, Merck earned certain Partnership returns from AZLP of $192 million in 2014, which were recorded in equity income from affiliates. On June 30, 2014, AstraZeneca exercised its option to purchase Merck’s interest in KBI for $419 million in cash. Of this amount, $327 million reflected an estimate of the fair value of Merck’s interest in Nexium and Prilosec. This portion of the exercise price, which is subject to a true-up in 2018 based on actual sales from closing in 2014 to June 2018, was deferred and recognized as income of $5 million , $182 million and $140 million , during 2016, 2015 and 2014, respectively, in Other (income) expense, net as the contingency was eliminated as sales occurred. Once the deferred income amount was fully amortized, in the first quarter of 2016, the Company began recognizing income and a corresponding receivable for amounts that will be due to Merck from AstraZeneca based on the sales performance of Nexium and Prilosec subject to the true-up in June 2018. The Company recognized $93 million of such income in 2016 included in Other (income) expense, net . The remaining exercise price of $91 million primarily represents a multiple of ten times Merck’s average 1% annual profit allocation in the partnership for the three years prior to exercise. Merck recognized the $91 million as a gain in 2014 within Other (income) expense, net . As a result of AstraZeneca’s option exercise, the Company’s remaining interest in AZLP was redeemed. Accordingly, the Company also recognized a non-cash gain of approximately $650 million in 2014 within Other (income) expense, net resulting from the retirement of the $2.4 billion of KBI preferred stock, the elimination of the Company’s $1.4 billion investment in AZLP and a $340 million reduction of goodwill. This transaction resulted in a net tax benefit of $517 million in 2014 primarily reflecting the reversal of deferred taxes on the AZLP investment balance. As a result of AstraZeneca exercising its option, as of July 1, 2014, the Company no longer records equity income from AZLP and supply sales to AZLP have terminated. Summarized financial information for AZLP is as follows: Year Ended December 31 2014 (1) Sales $ 2,205 Materials and production costs 1,044 Other expense, net 604 Income before taxes (2) 557 (1) Includes results through the June 30, 2014 termination date. (2) Merck’s partnership returns from AZLP were generally contractually determined as noted above and were not based on a percentage of income from AZLP, other than with respect to Merck’s 1% limited partnership interest.

Loans Payable, Long-Term Debt a

Loans Payable, Long-Term Debt and Other Commitments	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Loans Payable, Long-Term Debt and Other Commitments	Loans Payable, Long-Term Debt and Other Commitments Loans payable at December 31, 2016 included $300 million of notes due in 2017 and $267 million of long-dated notes that are subject to repayment at the option of the holder. Loans payable at December 31, 2015 included $2.3 billion of notes due in 2016 , $10 million of short-term foreign borrowings and $225 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 0.40% and 0.07% for the years ended December 31, 2016 and 2015 , respectively. Long-term debt at December 31 consisted of: 2016 2015 2.75% notes due 2025 $ 2,487 $ 2,485 3.70% notes due 2045 1,972 1,971 2.80% notes due 2023 1,743 1,742 5.00% notes due 2019 1,273 1,283 1.85% notes due 2020 1,238 1,239 4.15% notes due 2043 1,236 1,236 2.35% notes due 2022 1,228 1,233 3.875% notes due 2021 1,152 1,158 1.125% euro-denominated notes due 2021 1,035 1,091 1.875% euro-denominated notes due 2026 1,028 1,084 2.40% notes due 2022 1,003 1,011 Floating-rate borrowing due 2018 999 998 1.10% notes due 2018 999 998 1.30% notes due 2018 985 985 6.50% notes due 2033 806 809 Floating-rate notes due 2020 698 698 6.55% notes due 2037 594 596 0.50% euro-denominated notes due 2024 516 — 1.375% euro-denominated notes due 2036 512 — 2.50% euro-denominated notes due 2034 511 538 3.60% notes due 2042 489 489 5.85% notes due 2039 415 415 5.75% notes due 2036 369 369 5.95% debentures due 2028 355 354 6.40% debentures due 2028 325 325 6.30% debentures due 2026 152 152 Floating-rate notes due 2017 — 300 Other 154 270 $ 24,274 $ 23,829 Other (as presented in the table above) included $147 million and $223 million at December 31, 2016 and 2015 , respectively, of borrowings at variable rates that resulted in effective interest rates of 0.89% and zero for 2016 and 2015 , respectively. Other also included foreign borrowings of $43 million at December 31, 2015 at varying rates up to 4.75% . 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 November 2016, the Company issued €1.0 billion principal amount of senior unsecured notes consisting of €500 million principal amount of 0.50% notes due 2024 and €500 million principal amount of 1.375% notes due 2036. The Company intends to use the net proceeds of the offering of $1.1 billion for general corporate purposes, including without limitation, the repayment of outstanding commercial paper borrowings and other indebtedness with upcoming maturities. In October 2014, the Company issued €2.5 billion principal amount of senior unsecured notes. The net proceeds of the offering of $3.1 billion were used in part to repay debt that was validly tendered in connection with tender offers launched by the Company for certain outstanding notes and debentures. The Company paid $2.5 billion in aggregate consideration (applicable purchase price together with accrued interest) to redeem $1.8 billion principal amount of debt. In November 2014, Merck redeemed an additional $2.0 billion principal amount of senior unsecured notes. The Company recorded a pretax loss of $628 million in 2014 in connection with these transactions. 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 financial covenants including a requirement that the Total Debt to Capitalization Ratio (as defined in the applicable agreements) not exceed 60% . At December 31, 2016 , 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: 2017 , $301 million ; 2018 , $3.0 billion ; 2019 , $1.3 billion ; 2020 , $1.9 billion ; 2021 , $2.2 billion . In June 2016, the Company terminated its existing credit facility and entered into a new $6.0 billion , five -year credit facility that matures in June 2021. 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. Rental expense under operating leases, net of sublease income, was $292 million in 2016 , $303 million in 2015 and $350 million in 2014 . The minimum aggregate rental commitments under noncancellable leases are as follows: 2017 , $200 million ; 2018 , $141 million ; 2019 , $122 million ; 2020 , $88 million ; 2021 , $63 million and thereafter, $140 million . The Company has no significant capital leases.

Contingencies and Environmental

Contingencies and Environmental Liabilities	12 Months Ended
	Dec. 31, 2016
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 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 position, 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 effective August 1, 2004. Vioxx Litigation Product Liability Lawsuits As previously disclosed, Merck was a defendant in a number of putative class action lawsuits alleging economic injury as a result of the purchase of Vioxx , all but one of which have been settled. Under the settlement, Merck agreed to pay up to $23 million to resolve all properly documented claims submitted by class members, approved attorneys’ fees and expenses, and approved settlement notice costs and certain other administrative expenses. The claims review process has been completed with the Company paying approximately $700,000 . The amount of attorneys’ fees to be paid is yet to be determined. Merck is also a defendant in a lawsuit (together with the above-referenced lawsuits, the Vioxx Product Liability Lawsuits) brought by the Attorney General of Utah. The lawsuit is pending in Utah state court. Utah alleges that Merck misrepresented the safety of Vioxx and seeks damages and penalties under the Utah False Claims Act. No trial date has been set. Merck recently reached agreements with the Attorneys General in Alaska and Montana to settle their state consumer protection act cases against the Company for $15.25 million and $16.7 million , respectively. As a result, Alaska’s action was dismissed with prejudice on September 30, 2016, and Montana’s action was dismissed with prejudice on October 6, 2016. Shareholder Lawsuits As previously disclosed, in addition to the Vioxx Product Liability Lawsuits, various putative class actions and individual lawsuits were filed against Merck and certain former employees alleging that the defendants violated federal securities laws by making alleged material misstatements and omissions with respect to the cardiovascular safety of Vioxx ( Vioxx Securities Lawsuits). The Vioxx Securities Lawsuits were coordinated in a multidistrict litigation in the U.S. District Court for the District of New Jersey before Judge Stanley R. Chesler. As previously disclosed, Merck reached a resolution of the Vioxx securities class action for which a reserve was recorded in 2015 and under which Merck created a settlement fund in 2016 of $830 million (the Settlement Class Fund) and agreed to pay an additional amount for approved attorneys’ fees and expenses up to $232 million (the Fee/Expense Fund). On June 28, 2016, the court approved the settlement and awarded attorneys’ fees and expenses in the amount of $222 million ; the remaining amount of the Fee/Expense Fund will be added to the Settlement Class Fund. The Company paid the total settlement amount into escrow in April 2016. After available funds under certain insurance policies, Merck’s net cash payment for the settlement and fees was approximately $680 million . The settlement covers all claims relating to Vioxx by settlement class members who purchased Merck securities between May 21, 1999, and October 29, 2004. The settlement is not an admission of wrongdoing and, as part of the settlement agreement, defendants continue to deny the allegations. In addition, Merck reached a resolution of the above referenced individual securities lawsuits filed by foreign and domestic institutional investors, which were also consolidated with the Vioxx Securities Lawsuits. Insurance As a result of the previously disclosed insurance arbitration, the Company’s insurers paid insurance proceeds of approximately $380 million in connection with the settlement of the class action. The Company also has Directors and Officers insurance coverage applicable to the Vioxx Securities Lawsuits with remaining stated upper limits of approximately $145 million , which the Company has not received. There are disputes with the insurers about the availability of the Company’s Directors and Officers insurance coverage for these claims. The amounts actually recovered under the Directors and Officers policies discussed in this paragraph may be less than the stated upper limits. International Lawsuits As previously disclosed, in addition to the lawsuits discussed above, Merck has been named as a defendant in litigation relating to Vioxx in Brazil and Europe (collectively, the Vioxx International Lawsuits). The litigation in these jurisdictions is generally in procedural stages and Merck expects that the litigation may continue for a number of years. Reserves The Company has an immaterial reserve with respect to certain Vioxx Product Liability Lawsuits. The Company has established no other liability reserves for, and believes that it has meritorious defenses to, the remaining Vioxx Product Liability Lawsuits and Vioxx International Lawsuits and will defend against them. Other 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, 2016 , approximately 4,230 cases are filed and pending against Merck in either federal or state court. In approximately 20 of these actions, plaintiffs allege, among other things, that they have suffered osteonecrosis of the jaw (ONJ), generally subsequent to invasive dental procedures, such as tooth extraction or dental implants and/or delayed healing, in association with the use of Fosamax . In addition, plaintiffs in approximately 4,210 of these actions generally allege that they sustained femur fractures and/or other bone injuries (Femur Fractures) in association with the use of Fosamax . Cases Alleging ONJ and/or Other Jaw Related Injuries In August 2006, the Judicial Panel on Multidistrict Litigation (JPML) ordered that certain Fosamax product liability cases pending in federal courts nationwide should be transferred and consolidated into one multidistrict litigation ( Fosamax ONJ MDL) for coordinated pre-trial proceedings. In December 2013, Merck reached an agreement in principle with the Plaintiffs’ Steering Committee (PSC) in the Fosamax ONJ MDL to resolve pending ONJ cases not on appeal in the Fosamax ONJ MDL and in the state courts for an aggregate amount of $27.7 million . Merck and the PSC subsequently formalized the terms of this agreement in a Master Settlement Agreement (ONJ Master Settlement Agreement) that was executed in April 2014 and included over 1,200 plaintiffs. In July 2014, Merck elected to proceed with the ONJ Master Settlement Agreement at a reduced funding level of $27.3 million since the participation level was approximately 95% . Merck has fully funded the ONJ Master Settlement Agreement and the escrow agent under the agreement has been making settlement payments to qualifying plaintiffs. The ONJ Master Settlement Agreement has no effect on the cases alleging Femur Fractures discussed below. Discovery is currently ongoing in some of the approximately 20 remaining ONJ cases that are pending in various federal and state courts and the Company intends to defend against these lawsuits. Cases Alleging Femur Fractures In March 2011, Merck submitted a Motion to Transfer to the JPML seeking to have all federal cases alleging Femur Fractures consolidated into one multidistrict litigation for coordinated pre-trial proceedings. The Motion to Transfer was granted in May 2011, and all federal cases involving allegations of Femur Fracture 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 are appealing that decision to the U.S. Court of Appeals for the Third Circuit (Third Circuit). The Femur Fracture MDL court has since dismissed without prejudice another approximately 540 cases pending plaintiffs’ appeal of the preemption ruling to the Third Circuit. On June 30, 2016, the Third Circuit heard oral argument on plaintiffs’ appeal of the preemption ruling and the parties are awaiting the decision. In addition, in June 2014, the Femur Fracture MDL court granted Merck summary judgment in the Gaynor v. Merck case and found that Merck’s updates in January 2011 to the Fosamax label regarding atypical femur fractures were adequate as a matter of law and that Merck adequately communicated those changes. The plaintiffs in Gaynor have appealed the court’s decision to the Third Circuit. In August 2014, Merck filed a motion requesting that the court enter a further order requiring all plaintiffs in the Femur Fracture MDL who claim that the 2011 Fosamax label is inadequate and the proximate cause of their alleged injuries to show cause why their cases should not be dismissed based on the court’s preemption decision and its ruling in the Gaynor case. In November 2014, the court granted Merck’s motion and entered the requested show cause order. As of December 31, 2016 , seven cases were pending in the Femur Fracture MDL, excluding the 515 cases dismissed with prejudice on preemption grounds that are pending appeal and the 540 cases dismissed without prejudice that are also pending the aforementioned appeal. As of December 31, 2016 , approximately 2,860 cases alleging Femur Fractures have been filed in New Jersey state court and are pending before Judge Jessica Mayer in Middlesex County. The parties selected an initial group of 30 cases to be reviewed through fact discovery. Two additional groups of 50 cases each to be reviewed through fact discovery were selected in November 2013 and March 2014, respectively. A further group of 25 cases to be reviewed through fact discovery was selected by Merck in July 2015, and Merck has continued to select additional cases to be reviewed through fact discovery during 2016. As of December 31, 2016 , approximately 280 cases alleging Femur Fractures have been filed and are pending in California state court. A petition was filed seeking to coordinate all Femur Fracture cases filed in California state court before a single judge in Orange County, California. The petition was granted and Judge Thierry Colaw is currently presiding over the coordinated proceedings. In March 2014, the court directed that a group of 10 discovery pool cases be reviewed through fact discovery and subsequently scheduled the Galper v. Merck case, which plaintiffs selected, as the first trial. The Galper trial began in February 2015 and the jury returned a verdict in Merck’s favor in April 2015, and plaintiff has appealed that verdict to the California appellate court. Oral argument on plaintiff’s appeal in Galper was held on November 17, 2016 and the parties are awaiting a decision. The next Femur Fracture trial in California that was scheduled to begin in April 2016 was stayed at plaintiffs’ request and a new trial date has not been set. Additionally, there are five Femur Fracture cases pending in other state courts. Discovery is ongoing in the Femur Fracture MDL and in state courts where Femur Fracture cases are pending and the Company 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, 2016 , approximately 1,195 product user claims have been served on Merck alleging generally that use of Januvia and/or Janumet caused the development of pancreatic cancer and other injuries. These complaints were filed in several different state and federal courts. Most of the claims were filed in a consolidated multidistrict litigation proceeding in the U.S. District Court for the Southern District of California called “In re Incretin-Based Therapies Products Liability Litigation” (MDL). The MDL includes federal lawsuits alleging pancreatic cancer due to use of the following medicines: Januvia, Janumet , Byetta and Victoza, the latter two of which are products manufactured by other pharmaceutical companies. The majority of claims not filed in the MDL were filed in the Superior Court of California, County of Los Angeles (California State Court). As of December 31, 2016, eight product users have claims pending against Merck in state courts other than the California State Court. In November 2015, the MDL and California State Court - in separate opinions - granted summary judgment to defendants on grounds of preemption. Of the approximately 1,195 served product user claims, these rulings resulted in the dismissal of approximately 1,100 product user claims. Plaintiffs are appealing the MDL and California State Court preemption rulings. In addition to the claims noted above, the Company has agreed, as of December 31, 2016 , to toll the statute of limitations for approximately 50 additional claims. The Company intends to continue defending against these lawsuits. Propecia/Proscar As previously disclosed, Merck is a defendant in product liability lawsuits in the United States involving Propecia and/or Proscar . As of December 31, 2016 , approximately 1,330 lawsuits have been filed by plaintiffs who allege that they have experienced persistent sexual side effects following cessation of treatment with Propecia and/or Proscar . Approximately 50 of the plaintiffs also allege that Propecia or Proscar has caused or can cause prostate cancer, testicular cancer or male breast cancer. The lawsuits have been filed in various federal courts and in state court in New Jersey. The federal lawsuits have been consolidated for pretrial purposes in a federal multidistrict litigation before Judge Brian Cogan of the Eastern District of New York. The matters pending in state court in New Jersey have been consolidated before Judge Jessica Mayer in Middlesex County. In addition, there is one matter pending in state court in California, one matter pending in state court in New York, and one matter pending in state court in Ohio. The Company intends to defend against these lawsuits. Governmental Proceedings As previously disclosed, the Company has received a civil investigative demand from the U.S. Attorney’s Office for the Southern District of New York that requests information relating to the Company’s contracts with, services from and payments to pharmacy benefit managers with respect to Maxalt and Levitra from January 1, 2006 to the present. The Company is cooperating with the investigation. As previously disclosed, the Company has received a subpoena from the Office of Inspector General of the U.S. Department of Health and Human Services on behalf of the U.S. Attorney’s Office for the District of Maryland and the Civil Division of the U.S. Department of Justice (DOJ) that requests information relating to the Company’s marketing of Singulair and Dulera Inhalation Aerosol and certain of its other marketing activities from January 1, 2006 to the present. The Company is cooperating with the investigation. As previously disclosed, the Company had received a civil investigative demand from the U.S. Attorney’s Office, Eastern District of Pennsylvania that requested information relating to the Company’s contracting and pricing of Dulera Inhalation Aerosol with certain pharmacy benefit managers and Medicare Part D plans. The Company cooperated with the investigation and, in August 2016, the Company learned that the underlying qui tam complaint had been unsealed and voluntarily dismissed with prejudice as to the relator and without prejudice as to the government. The DOJ informed the Company that the matter is inactive and that there is no current investigation. As previously disclosed, the Company has received letters from the DOJ and the SEC that seek information about activities in a number of countries and reference the Foreign Corrupt Practices Act. The Company has cooperated with the agencies in their requests and believes that this inquiry is part of a broader review of pharmaceutical industry practices in foreign countries. As previously disclosed, the Company has been advised by the DOJ that, based on the information that it has received, it has closed its inquiry into this matter as it relates to the Company. The Company has also recently been advised by the SEC that it has closed its inquiry into this matter as it relates to the Company. 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. From time to time, the Company receives inquiries and is the subject of preliminary investigation activities from Competition Authorities in various markets outside the United States. Certain of these 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 K-DUR Antitrust Litigation As previously disclosed, in June 1997 and January 1998, Schering-Plough Corporation (Schering-Plough) settled patent litigation with Upsher-Smith, Inc. (Upsher-Smith) and ESI Lederle, Inc. (Lederle), respectively, relating to generic versions of Schering-Plough’s long-acting potassium chloride product supplement used by cardiac patients, for which Lederle and Upsher-Smith had filed Abbreviated New Drug Applications (ANDAs). Following the commencement of an administrative proceeding by the U.S. Federal Trade Commission in 2001 alleging anti-competitive effects from those settlements (which was resolved in Schering-Plough’s favor), putative class and non-class action suits were filed on behalf of direct and indirect purchasers of K-DUR against Schering-Plough, Upsher-Smith and Lederle and were consolidated in a multidistrict litigation in the U.S. District Court for the District of New Jersey. These suits claimed violations of federal and state antitrust laws, as well as other state statutory and common law causes of action, and sought unspecified damages. In April 2008, the indirect purchasers voluntarily dismissed their case. In February 2016, the District Court denied the Company’s motion for summary judgment relating to all of the direct purchasers’ claims concerning the settlement with Upsher-Smith and granted the Company’s motion for summary judgment relating to all of the direct purchasers’ claims concerning the settlement with Lederle. In anticipation of trial, the parties filed motions to exclude certain expert opinions and other evidence, and defendants filed a motion for summary judgment. In February 2017, Merck and Upsher-Smith reached a settlement in principle with the class of direct purchasers and the opt-outs to the class. Merck will contribute approximately $80 million in the aggregate towards the overall settlement. Formal settlement agreements with the class and the opt-outs have yet to be executed and the settlement with the class is subject to approval by the District Court. 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. Plaintiffs sought and were granted leave to file an amended complaint. In January 2014, plaintiffs filed an amended complaint adding four additional named plaintiffs. In October 2014, the court denied the Company’s motion to dismiss or strike the class claims as premature. In September 2015, plaintiffs filed additional motions, including a motion for conditional certification under the Equal Pay Act; a motion to amend the pleadings seeking to add ERISA and constructive discharge claims and a Company subsidiary as a named defendant; and a motion for equitable relief. Merck filed papers in opposition to the motions. On April 27, 2016, the court granted plaintiff’s motion for conditional certification but denied plaintiffs’ motions to extend the liability period for their Equal Pay Act claims back to June 2009. As a result, the liability period will date back to April 2012, at the earliest. On April 29, 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 have opted-in to this action; the opt-in period has closed. Qui Tam Litigation As previously disclosed, on June 21, 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. The Company intends to defend against these lawsuits. Merck KGaA Litigation 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), 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 United Kingdom (UK), Germany, Switzerland, Mexico, and India alleging breach of the parties’ co-existence agreement, unfair competition and/or trademark infringement. In December 2015, the Paris Court of First Instance issued a judgment finding that certain activities by the Company directed towards France did not constitute trademark infringement and unfair competition while other activities were found to infringe. The Company and KGaA have both appealed the decision, and the appeal is scheduled to be heard in May 2017. In January 2016, the UK High Court issued a judgment finding that the Company had breached the co-existence agreement and infringed KGaA’s trademark rights as a result of certain activities directed towards the UK based on use of the word MERCK on promotional and information activity. As noted in the UK decision, this finding was not based on the Company’s use of the sign MERCK in connection with the sale of products or any material pharmaceutical business transacted in the UK. The Company and KGaA have both appealed this decision, and the appeal is scheduled to be heard in June 2017. Patent Litigation From time to time, generic manufacturers of pharmaceutical products file ANDAs 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. Certain products of the Company (or products marketed via agreements with other companies) currently involved in such patent infringement litigation in the United States include: Cancidas , Invanz , Nasonex , Noxafil , and NuvaRing . 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. Cancidas — In February 2014, a patent infringement lawsuit was filed in the United States against Xellia Pharmaceuticals ApS (Xellia) with respect to Xellia’s application to the FDA seeking pre-patent expiry approval to market a generic version of Cancidas . In June 2015, the district court found that Xellia infringed the Company’s patent and ordered that Xellia’s application not be approved until the patent expires in September 2017 (including pediatric exclusivity). Xellia appealed this decision, and the appeal was heard in March 2016. In May 2016, the parties reached a settlement whereby Xellia can launch its generic version in August 2017, or earlier under certain conditions. In August 2014, a patent infringement lawsuit was filed in the United States against Fresenius Kabi USA, LLC (Fresenius) in respect of Fresenius’s application to the FDA seeking pre-patent expiry approval to market a generic version of Cancidas . In December 2016, the parties reached a settlement whereby Fresenius can launch its generic version in August 2017, or earlier under certain conditions. Invanz — In July 2014, a patent infringement lawsuit was filed in the United States against Hospira in respect of Hospira’s application to the FDA seeking pre-patent expiry approval to market a generic version of Invanz . The trial in this matter was held in April 2016 and, in October 2016, the district court ruled that the patent is valid and infringed. In August 2015, a patent infringement lawsuit was filed in the United States against Savior Lifetec Corporation (Savior) in respect of Savior’s application to the FDA seeking pre-patent expiry approval to market a generic version of Invanz . The lawsuit automatically stays FDA approval of Savior’s application until November 2017 or until an adverse court decision, if any, whichever may occur earlier. Nasonex — In July 2014, a patent infringement lawsuit was filed in the United States against Teva Pharmaceuticals USA, Inc. (Teva Pharma) in respect of Teva Pharma’s application to the FDA seeking pre-patent expiry approval to market a generic version of Nasonex . The trial in this matter was held in June 2016. In November 2016, the district court ruled that the patent was valid but not infringed. The Company has appealed this decision. In March 2015, a patent infringement lawsuit was filed in the United States against Amneal Pharmaceuticals LLC (Amneal) in respect of Amneal’s application to the FDA seeking pre-patent expiry approval to market a generic version of Nasonex . The trial in this matter was held in June 2016. In January 2017, the district court ruled that the patent was valid but not infringed. The Company has appealed this decision. A previous decision, issued in June 2013, held that the Merck patent in the Teva Pharma and Amneal lawsuits covering mometasone furoate monohydrate was valid, but that it was not infringed by Apotex Corp.’s proposed product. In April 2015, a patent infringement lawsuit was filed against Apotex Inc. and Apotex Corp. (Apotex) in respect of Apotex’s now-launched product that the Company believes differs from the generic version in the previous lawsuit. Noxafil — In August 2015, the Company filed a lawsuit against Actavis Laboratories Fl, Inc. (Actavis) in the United States in respect of that company’s application to the FDA seeking pre-patent expiry approval to sell a generic version of Noxafil . The lawsuit automatically stays FDA approval of Actavis’s application until December 2017 or until an adverse court decision, if any, whichever may occur earlier. The trial in this matter is currently scheduled to begin in July 2017. In March 2016, the Company filed a lawsuit against Roxane Laboratories, Inc. (Roxane) in the United States in respect of that company’s application to the FDA seeking pre-patent expiry approval to sell a generic version of Noxafil . The lawsuit automatically stays FDA approval of Roxane’s application until August 2018 or until an adverse court decision, if any, whichever may occur earlier. In February 2016, the Company filed a lawsuit against Par Sterile Products LLC, Par Pharmaceutical, Inc., Par Pharmaceutical Companies, Inc. and Par Pharmaceutical Holdings, Inc. (collectively, Par) in the United States in respect of that company’s application to the FDA seeking pre-patent expiry approval to sell a generic version of Noxafil . In October 2016, the parties reached a settlement whereby Par can launch its generic version in January 2023, or earlier under certain conditions. NuvaRing — In December 2013, the Company filed a lawsuit against a subsidiary of Allergan plc in the United States in respect of that company’s application to the FDA seeking pre-patent expiry approval to sell a generic version of NuvaRing . The trial in this matter was held in January 201

Equity

Equity	12 Months Ended
	Dec. 31, 2016
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: 2016 2015 2014 Common Stock Treasury Stock Common Stock Treasury Stock Common Stock Treasury Stock Balance January 1 3,577 796 3,577 739 3,577 650 Purchases of treasury stock — 60 — 75 — 134 Issuances (1) — (28 ) — (18 ) — (45 ) Balance December 31 3,577 828 3,577 796 3,577 739 (1) Issuances primarily reflect activity under share-based compensation plans.

Share-Based Compensation Plans

Share-Based Compensation Plans	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [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. The Company also issues RSUs to employees of certain of the Company’s equity method investees. 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, 2016 , 125 million shares collectively were authorized for future grants under the Company’s share-based compensation plans. These awards are settled primarily 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, generally three years, subject to the terms applicable to such awards. Total pretax share-based compensation cost recorded in 2016 , 2015 and 2014 was $300 million , $299 million and $278 million , respectively, with related income tax benefits of $92 million , $93 million and $86 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 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 2016 , 2015 and 2014 was $54.63 , $59.73 and $58.14 per option, respectively. The weighted average fair value of options granted in 2016 , 2015 and 2014 was $5.89 , $6.46 and $6.79 per option, respectively, and were determined using the following assumptions: Years Ended December 31 2016 2015 2014 Expected dividend yield 3.8 % 4.1 % 4.3 % Risk-free interest rate 1.4 % 1.7 % 2.0 % Expected volatility 19.6 % 19.9 % 22.0 % Expected life (years) 6.2 6.2 6.4 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, 2016 64,668 $ 41.64 Granted 6,220 54.63 Exercised (23,846 ) 39.39 Forfeited (1,951 ) 45.14 Outstanding December 31, 2016 45,091 $ 44.47 4.42 $ 654 Exercisable December 31, 2016 34,311 $ 40.87 3.12 $ 619 Additional information pertaining to stock option plans is provided in the table below: Years Ended December 31 2016 2015 2014 Total intrinsic value of stock options exercised $ 444 $ 332 $ 626 Fair value of stock options vested 28 30 35 Cash received from the exercise of stock options 939 485 1,560 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, 2016 13,400 $ 53.73 1,884 $ 55.33 Granted 5,617 54.67 733 57.38 Vested (4,956 ) 45.06 (786 ) 48.18 Forfeited (795 ) 56.65 (87 ) 58.82 Nonvested December 31, 2016 13,266 $ 57.19 1,744 $ 59.24 At December 31, 2016 , there was $443 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, 2016
Compensation and Retirement Disclosure [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 for pension and other postretirement benefit plans consisted of the following components: Pension Benefits U.S. International Other Postretirement Benefits Years Ended December 31 2016 2015 2014 2016 2015 2014 2016 2015 2014 Service cost $ 282 $ 307 $ 300 $ 238 $ 251 $ 266 $ 54 $ 80 $ 78 Interest cost 456 434 425 204 206 269 82 110 115 Expected return on plan assets (831 ) (819 ) (782 ) (382 ) (379 ) (416 ) (107 ) (143 ) (139 ) Net amortization 64 158 74 76 104 59 (103 ) (59 ) (71 ) Termination benefits 23 22 53 4 1 11 4 7 22 Curtailments 5 (12 ) (69 ) (1 ) (9 ) (4 ) (18 ) (19 ) (39 ) Settlements — 1 11 6 12 6 — — — Net periodic benefit (credit) cost $ (1 ) $ 91 $ 12 $ 145 $ 186 $ 191 $ (88 ) $ (24 ) $ (34 ) The changes in net periodic benefit (credit) cost year over year for pension plans are largely attributable to changes in the discount rate affecting net amortization. The decrease in net periodic benefit cost for other postretirement benefit plans in 2016 as compared with 2015 is largely attributable to changes in retiree medical benefits approved by the Company in December 2015. In connection with restructuring actions (see Note 4), termination charges were recorded in 2016 , 2015 and 2014 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. 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 2016 2015 2016 2015 2016 2015 Fair value of plan assets January 1 $ 9,266 $ 9,984 $ 7,204 $ 7,724 $ 1,913 $ 1,984 Actual return on plan assets 941 (226 ) 898 138 138 (34 ) Company contributions 63 66 424 163 68 63 Effects of exchange rate changes — — (546 ) (568 ) — (1 ) Benefits paid (504 ) (523 ) (193 ) (196 ) (108 ) (99 ) Settlements — (35 ) (21 ) (66 ) — — Assets no longer restricted to the payment of postretirement benefits (1) — — — — (992 ) — Other — — 28 9 — — Fair value of plan assets December 31 $ 9,766 $ 9,266 $ 7,794 $ 7,204 $ 1,019 $ 1,913 Benefit obligation January 1 $ 9,723 $ 10,632 $ 7,733 $ 8,331 $ 1,810 $ 2,638 Service cost 282 307 238 251 54 80 Interest cost 456 434 204 206 82 110 Actuarial losses (gains) (2) 854 (1,102 ) 938 (127 ) 77 (384 ) Benefits paid (504 ) (523 ) (193 ) (196 ) (108 ) (99 ) Effects of exchange rate changes — — (576 ) (647 ) 2 (11 ) Plan amendments (3) — — — (1 ) — (531 ) Curtailments 15 (14 ) (15 ) (15 ) 1 (3 ) Termination benefits 23 22 4 1 4 7 Settlements — (35 ) (21 ) (66 ) — — Other — 2 60 (4 ) — 3 Benefit obligation December 31 $ 10,849 $ 9,723 $ 8,372 $ 7,733 $ 1,922 $ 1,810 Funded status December 31 $ (1,083 ) $ (457 ) $ (578 ) $ (529 ) $ (903 ) $ 103 Recognized as: Other assets $ — $ 179 $ 451 $ 567 $ — $ 359 Accrued and other current liabilities (50 ) (48 ) (7 ) (7 ) (11 ) (10 ) Other noncurrent liabilities (1,033 ) (588 ) (1,022 ) (1,089 ) (892 ) (246 ) (1) As a result of certain allowable administrative actions that occurred in June 2016, $992 million of plan assets previously restricted for the payment of other postretirement benefits became available to fund certain other health and welfare benefits. (2) Actuarial losses in 2016 and actuarial gains in 2015 primarily reflect changes in discount rates. (3) The decline in other postretirement benefit obligations in 2015 resulting from plan amendments primarily reflects changes to Merck’s retiree medical benefits approved by the Company in December 2015. The changes provide that, beginning in 2017, Merck will provide access to retiree health insurance coverage that supplements government-sponsored Medicare through a private insurance marketplace. At December 31, 2016 and 2015 , the accumulated benefit obligation was $18.4 billion and $16.7 billion , respectively, for all pension plans, of which $10.5 billion and $9.4 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 2016 2015 2016 2015 Pension plans with a projected benefit obligation in excess of plan assets Projected benefit obligation $ 10,849 $ 1,310 $ 5,486 $ 5,093 Fair value of plan assets 9,766 674 4,457 3,996 Pension plans with an accumulated benefit obligation in excess of plan assets Accumulated benefit obligation $ 9,807 $ 611 $ 2,692 $ 4,812 Fair value of plan assets 9,057 — 1,898 3,964 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, 2016 and 2015 , $435 million and $423 million , respectively, or approximately 2% and 3% , 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 Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total 2016 2015 U.S. Pension Plans Assets Cash and cash equivalents $ 2 $ 2 $ — $ 4 $ — $ — $ — $ — Investment funds Developed markets equities 521 — — 521 566 — — 566 Emerging markets equities 104 — — 104 87 — — 87 Equity securities Developed markets 2,521 — — 2,521 2,444 — — 2,444 Fixed income securities Government and agency obligations — 475 — 475 — 391 — 391 Corporate obligations — 660 — 660 — 679 — 679 Mortgage and asset-backed securities — 239 — 239 — 236 — 236 Other investments — — 18 18 — — 23 23 Net assets in fair value hierarchy $ 3,148 $ 1,376 $ 18 $ 4,542 $ 3,097 $ 1,306 $ 23 $ 4,426 Investments measured at NAV practical expedient (1) 5,224 4,840 Plan assets at fair value $ 9,766 $ 9,266 International Pension Plans Assets Cash and cash equivalents $ 42 $ 11 $ — $ 53 $ 63 $ 4 $ — $ 67 Investment funds Developed markets equities 187 2,846 — 3,033 184 2,738 — 2,922 Emerging markets equities 24 148 — 172 21 137 — 158 Government and agency obligations 123 1,904 — 2,027 305 1,115 — 1,420 Corporate obligations 2 282 — 284 173 103 — 276 Fixed income obligations 6 3 — 9 8 3 — 11 Real estate (2) — 3 4 7 — 3 5 8 Equity securities Developed markets 565 — — 565 496 — — 496 Fixed income securities Government and agency obligations 2 235 — 237 2 465 — 467 Corporate obligations — 92 — 92 — 161 — 161 Mortgage and asset-backed securities — 50 — 50 — 68 — 68 Other investments Insurance contracts (3) — 59 412 471 — 57 393 450 Other 1 4 1 6 — 3 2 5 Net assets in fair value hierarchy $ 952 $ 5,637 $ 417 $ 7,006 $ 1,252 $ 4,857 $ 400 $ 6,509 Investments measured at NAV practical expedient (1) 788 695 Plan assets at fair value $ 7,794 $ 7,204 (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 fair value 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, 2016 and 2015. (2) The plans’ Level 3 investments in real estate funds are generally valued by market appraisals of the underlying investments in the funds. (3) 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: 2016 2015 Insurance Contracts Real Estate Other Total Insurance Contracts Real Estate Other Total U.S. Pension Plans Balance January 1 $ — $ — $ 23 $ 23 $ — $ — $ 28 $ 28 Actual return on plan assets: Relating to assets still held at December 31 — — (3 ) (3 ) — — (3 ) (3 ) Relating to assets sold during the year — — 4 4 — — 5 5 Purchases and sales, net — — (6 ) (6 ) — — (7 ) (7 ) Balance December 31 $ — $ — $ 18 $ 18 $ — $ — $ 23 $ 23 International Pension Plans Balance January 1 $ 393 $ 5 $ 2 $ 400 $ 394 $ 23 $ 2 $ 419 Actual return on plan assets: Relating to assets still held at December 31 (9 ) 1 — (8 ) (28 ) (2 ) — (30 ) Purchases and sales, net 2 (2 ) (1 ) (1 ) 2 (16 ) — (14 ) Transfers into Level 3 26 — — 26 25 — — 25 Balance December 31 $ 412 $ 4 $ 1 $ 417 $ 393 $ 5 $ 2 $ 400 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 Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total 2016 2015 Assets Cash and cash equivalents $ 125 $ — $ — $ 125 $ 65 $ — $ — $ 65 Investment funds Developed markets equities 48 — — 48 53 — — 53 Emerging markets equities 10 — — 10 29 — — 29 Government and agency obligations 1 — — 1 2 — — 2 Equity securities Developed markets 231 — — 231 229 — — 229 Fixed income securities Government and agency obligations — 43 — 43 — 339 — 339 Corporate obligations — 60 — 60 — 311 — 311 Mortgage and asset-backed securities — 22 — 22 — 218 — 218 Net assets in fair value hierarchy $ 415 $ 125 $ — $ 540 $ 378 $ 868 $ — $ 1,246 Investments measured at NAV practical expedient (1) 479 667 Plan assets at fair value $ 1,019 $ 1,913 (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 fair value 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, 2016 and 2015. 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 40% to 60% in U.S. equities, 20% to 40% in international equities, 15% to 25% 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 13% , 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 2017 are approximately $50 million for U.S. pension plans, approximately $160 million for international pension plans and approximately $25 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 2017 $ 561 $ 186 $ 101 2018 588 179 104 2019 629 195 106 2020 638 202 111 2021 655 201 115 2022 — 2026 3,596 1,168 641 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 2016 2015 2014 2016 2015 2014 2016 2015 2014 Net (loss) gain arising during the period $ (743 ) $ 73 $ (2,085 ) $ (380 ) $ (66 ) $ (779 ) $ (45 ) $ 209 $ (223 ) Prior service (cost) credit arising during the period (10 ) (13 ) (59 ) (2 ) (4 ) (8 ) (19 ) 511 (42 ) $ (753 ) $ 60 $ (2,144 ) $ (382 ) $ (70 ) $ (787 ) $ (64 ) $ 720 $ (265 ) Net loss amortization included in benefit cost $ 119 $ 214 $ 135 $ 87 $ 118 $ 74 $ 3 $ 5 $ 1 Prior service (credit) cost amortization included in benefit cost (55 ) (56 ) (61 ) (11 ) (14 ) (15 ) (106 ) (64 ) (72 ) $ 64 $ 158 $ 74 $ 76 $ 104 $ 59 $ (103 ) $ (59 ) $ (71 ) The estimated net loss (gain) and prior service cost (credit) amounts that will be amortized from AOCI into net periodic benefit cost during 2017 are $270 million and $(64) million , respectively, for pension plans (of which $178 million and $(53) million , respectively, relates to U.S. pension plans) and $1 million and $(99) million , respectively, for other postretirement benefit plans. 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 2016 2015 2014 2016 2015 2014 Net periodic benefit cost Discount rate 4.70 % 4.20 % 4.90 % 2.80 % 2.70 % 3.80 % Expected rate of return on plan assets 8.60 % 8.50 % 8.50 % 5.60 % 5.70 % 6.00 % Salary growth rate 4.30 % 4.40 % 4.50 % 2.90 % 2.90 % 3.10 % Benefit obligation Discount rate 4.30 % 4.80 % 4.20 % 2.20 % 2.80 % 2.70 % Salary growth rate 4.30 % 4.30 % 4.40 % 2.90 % 2.90 % 2.90 % 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. In developing the expected rate of return within each plan, long-term historical returns data are considered as well as actual returns on the plan assets and other capital markets experience. 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 2017 , the expected rate of return for the Company’s U.S. pension and other postretirement benefit plans will range from 8.00% to 8.75% , as compared to a range of 7.30% to 8.75% in 2016 . The health care cost trend rate assumptions for other postretirement benefit plans are as follows: December 31 2016 2015 Health care cost trend rate assumed for next year 7.4 % 6.8 % 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 2027 A one percentage point change in the health care cost trend rate would have had the following effects: One Percentage Point Increase Decrease Effect on total service and interest cost components $ 12 $ (12 ) Effect on benefit obligation 138 (114 ) 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 2016 , 2015 and 2014 were $126 million , $125 million and $124 million , respectively.

Other (Income) Expense, Net

Other (Income) Expense, Net	12 Months Ended
	Dec. 31, 2016
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (Income) Expense, Net Other (income) expense, net, consisted of: Years Ended December 31 2016 2015 2014 Interest income $ (328 ) $ (289 ) $ (266 ) Interest expense 693 672 732 Exchange losses 174 1,277 180 Equity income from affiliates (86 ) (205 ) (257 ) Other, net 267 72 (12,002 ) $ 720 $ 1,527 $ (11,613 ) The higher exchange losses in 2015 as compared with 2016 and 2014 were related primarily to the Venezuelan Bolívar. During the second quarter of 2015, upon evaluation of evolving economic conditions in Venezuela and volatility in the country, combined with a decline in transactions that were settled at the then official (CENCOEX) rate of 6.30 VEF (Bolívar Fuertes) per U.S. dollar, the Company determined it was unlikely that all outstanding net monetary assets would be settled at the CENCOEX rate. Accordingly, during the second quarter of 2015, the Company recorded a charge of $715 million to devalue its net monetary assets in Venezuela to an amount that represented the Company’s estimate of the U.S. dollar amount that would ultimately be collected. During the third quarter of 2015, the Company recorded additional exchange losses of $138 million in the aggregate reflecting the ongoing effect of translating transactions and net monetary assets consistent with the second quarter. In the fourth quarter of 2015, as a result of the further deterioration of economic conditions in Venezuela, and continued declines in transactions which were settled at the official rate, the Company began using the SIMADI rate to report its Venezuelan operations. The Company also revalued its remaining net monetary assets at the SIMADI rate (subsequently replaced with the DICOM rate), which resulted in an additional charge in the fourth quarter of 2015 of $161 million . Since January 2010, Venezuela has been designated hyperinflationary and, as a result, local foreign operations are remeasured in U.S. dollars with the impact recorded in results of operations. The decline in equity income from affiliates in 2016 as compared with 2015 was driven primarily by lower equity income from certain research investment funds. Other, net (as presented in the table above) in 2016 includes a charge of $625 million to settle worldwide patent litigation related to Keytruda (see Note 10), a gain of $117 million related to the settlement of other patent litigation (see Note 10), gains of $100 million resulting from the receipt of milestone payments for out-licensed migraine clinical development programs (see Note 3) and $98 million of income related to AstraZeneca’s option exercise (see Note 8). Other, net in 2015 includes a $680 million net charge related to the settlement of Vioxx shareholder class action litigation (see Note 10) and an expense of $78 million for a contribution of investments in equity securities to the Merck Foundation, partially offset by a $250 million gain on the sale of certain migraine clinical development programs (see Note 3), a $147 million gain on the divestiture of Merck’s remaining ophthalmics business in international markets (see Note 3), and the recognition of $182 million of deferred income related to AstraZeneca’s option exercise. Other, net in 2014 includes an $11.2 billion gain on the divestiture of MCC (see Note 3), a gain of $741 million related to AstraZeneca’s option exercise, a $480 million gain on the divestiture of certain ophthalmic products in several international markets (see Note 3), a gain of $204 million related to the sale of Sirna (see Note 3) and the recognition of $140 million of deferred income related to AstraZeneca’s option exercise, partially offset by a $628 million loss on extinguishment of debt (see Note 9) and a $93 million goodwill impairment charge related to the Company’s joint venture with Supera. Interest paid was $686 million in 2016 , $653 million in 2015 and $852 million in 2014 .

Taxes on Income

Taxes on Income	12 Months Ended
	Dec. 31, 2016
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: 2016 2015 2014 Amount Tax Rate Amount Tax Rate Amount Tax Rate U.S. statutory rate applied to income before taxes $ 1,631 35.0 % $ 1,890 35.0 % $ 6,049 35.0 % Differential arising from: Foreign earnings (1,593 ) (34.2 ) (2,105 ) (39.0 ) (1,367 ) (7.9 ) Unremitted foreign earnings (30 ) (0.6 ) 260 4.8 (209 ) (1.2 ) Tax settlements — — (417 ) (7.7 ) (89 ) (0.5 ) AstraZeneca option exercise — — — — (774 ) (4.5 ) Sale of Sirna Therapeutics, Inc. — — — — (357 ) (2.1 ) Impact of purchase accounting adjustments, including amortization 623 13.4 797 14.8 1,013 5.9 Foreign currency devaluation related to Venezuela — — 321 5.9 — — State taxes 173 3.7 159 2.9 7 — Restructuring 145 3.1 167 3.1 289 1.7 U.S. health care reform legislation 68 1.4 66 1.2 134 0.8 Divestiture of Merck Consumer Care — — — — 440 2.5 Other (1) (299 ) (6.4 ) (196 ) (3.6 ) 213 1.2 $ 718 15.4 % $ 942 17.4 % $ 5,349 30.9 % (1) Other includes the tax effect of contingency reserves, research credits, and miscellaneous items. 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, where the earnings have been indefinitely reinvested, thereby yielding a favorable impact on the effective tax rate as compared with the 35.0% U.S. statutory rate. 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 as compared to the 35.0% U.S. statutory rate. The Company’s 2015 effective tax rate reflects the impact of the Protecting Americans From Tax Hikes Act, which was signed into law on December 18, 2015, extending the research credit permanently and the controlled foreign corporation look-through provisions for five years. The Company’s 2014 effective tax rate reflects the impact of the Tax Increase Prevention Act, which was signed into law on December 19, 2014, extending the research credit and the controlled foreign corporation look-through provisions for one year only. Income before taxes consisted of: Years Ended December 31 2016 2015 2014 Domestic $ 518 $ 2,247 $ 15,730 Foreign 4,141 3,154 1,553 $ 4,659 $ 5,401 $ 17,283 Taxes on income consisted of: Years Ended December 31 2016 2015 2014 Current provision Federal $ 1,166 $ 732 $ 7,136 Foreign 916 844 438 State 157 130 375 2,239 1,706 7,949 Deferred provision Federal (1,255 ) (552 ) (2,162 ) Foreign (225 ) (163 ) (201 ) State (41 ) (49 ) (237 ) (1,521 ) (764 ) (2,600 ) $ 718 $ 942 $ 5,349 Deferred income taxes at December 31 consisted of: 2016 2015 Assets Liabilities Assets Liabilities Intangibles $ 86 $ 3,734 $ — $ 4,962 Inventory related 30 660 49 752 Accelerated depreciation 28 927 43 910 Unremitted foreign earnings — 2,044 — 2,124 Pensions and other postretirement benefits 727 109 435 131 Compensation related 438 — 535 — Unrecognized tax benefits 383 — 412 — Net operating losses and other tax credit carryforwards 437 — 565 — Other 1,128 46 1,217 — Subtotal 3,257 7,520 3,256 8,879 Valuation allowance (268 ) (304 ) Total deferred taxes $ 2,989 $ 7,520 $ 2,952 $ 8,879 Net deferred income taxes $ 4,531 $ 5,927 Recognized as: Other assets $ 546 $ 608 Deferred income taxes $ 5,077 $ 6,535 The Company has net operating loss (NOL) carryforwards in several jurisdictions. As of December 31, 2016 , $243 million of deferred taxes on NOL carryforwards relate to foreign jurisdictions, none of which are individually significant. Valuation allowances of $268 million have been established on these foreign NOL carryforwards and other foreign deferred tax assets. In addition, the Company has $194 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 2016 , 2015 and 2014 were $1.8 billion , $1.8 billion and $7.9 billion , respectively. Income taxes paid in 2014 reflects approximately $5.0 billion of taxes paid on the divestiture of MCC. Tax benefits relating to stock option exercises were $147 million in 2016 , $109 million in 2015 and $202 million in 2014 . A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2016 2015 2014 Balance January 1 $ 3,448 $ 3,534 $ 3,503 Additions related to current year positions 196 198 389 Additions related to prior year positions 75 53 23 Reductions for tax positions of prior years (1) (90 ) (59 ) (156 ) Settlements (1) (92 ) (184 ) (161 ) Lapse of statute of limitations (43 ) (94 ) (64 ) Balance December 31 $ 3,494 $ 3,448 $ 3,534 (1) Amounts reflect the settlements with the IRS as discussed below. If the Company were to recognize the unrecognized tax benefits of $3.5 billion at December 31, 2016 , the income tax provision would reflect a favorable net impact of $3.3 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, 2016 could decrease by up to $1.7 billion 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. However, there is one item that is currently under discussion with the Internal Revenue Service (IRS) relating to the 2006 through 2008 examination. The Company has concluded that its position should be sustained upon audit. However, if this item were to result in an unfavorable outcome or settlement, it could have a material adverse impact on the Company’s financial position, liquidity and results of operations. Expenses for interest and penalties associated with uncertain tax positions amounted to $134 million in 2016 , $102 million in 2015 and $9 million in 2014 . These amounts reflect the beneficial impacts of various tax settlements, including those discussed below. Liabilities for accrued interest and penalties were $886 million and $766 million as of December 31, 2016 and 2015 , respectively. The IRS is currently conducting examinations of the Company’s tax returns for the years 2006 through 2008, as well as 2010 and 2011. Although the IRS’s examination of the Company’s 2002-2005 federal tax returns was concluded prior to 2015, one issue relating to a refund claim remained open. During 2015, this issue was resolved and the Company received a refund of approximately $715 million , which exceeded the receivable previously recorded by the Company, resulting in a tax benefit of $410 million . In addition, various state and foreign tax examinations are in progress. For most of its other significant tax jurisdictions (both U.S. state and foreign), the Company’s income tax returns are open for examination for the period 2003 through 2016. At December 31, 2016 , foreign earnings of $63.1 billion have been retained indefinitely by subsidiary companies for reinvestment; therefore, no provision has been made for income taxes that would be payable upon the distribution of such earnings and it would not be practicable to determine the amount of the related unrecognized deferred income tax liability. In addition, the Company has subsidiaries operating in Puerto Rico and Singapore under tax incentive grants that begin to expire in 2022.

Earnings per Share

Earnings per Share	12 Months Ended
	Dec. 31, 2016
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 2016 2015 2014 Net income attributable to Merck & Co., Inc. $ 3,920 $ 4,442 $ 11,920 Average common shares outstanding 2,766 2,816 2,894 Common shares issuable (1) 21 25 34 Average common shares outstanding assuming dilution 2,787 2,841 2,928 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders $ 1.42 $ 1.58 $ 4.12 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders $ 1.41 $ 1.56 $ 4.07 (1) Issuable primarily under share-based compensation plans. In 2016 , 2015 and 2014 , 13 million , 9 million and 4 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, 2016
Other Comprehensive Income (Loss), Net of Tax [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, 2014, net of taxes $ 132 $ 54 $ (909 ) $ (1,474 ) $ (2,197 ) Other comprehensive income (loss) before reclassification adjustments, pretax 778 48 (3,196 ) (412 ) (2,782 ) Tax (285 ) (17 ) 1,067 (92 ) 673 Other comprehensive income (loss) before reclassification adjustments, net of taxes 493 31 (2,129 ) (504 ) (2,109 ) Reclassification adjustments, pretax (146 ) (1) 43 (2) 62 (3) — (41 ) Tax 51 (17 ) (10 ) — 24 Reclassification adjustments, net of taxes (95 ) 26 52 — (17 ) Other comprehensive income (loss), net of taxes 398 57 (2,077 ) (504 ) (2,126 ) Balance December 31, 2014, net of taxes 530 111 (2,986 ) (1,978 ) (4,323 ) Other comprehensive income (loss) before reclassification adjustments, pretax 526 (9 ) 710 (158 ) 1,069 Tax (177 ) (13 ) (272 ) (28 ) (490 ) Other comprehensive income (loss) before reclassification adjustments, net of taxes 349 (22 ) 438 (186 ) 579 Reclassification adjustments, pretax (731 ) (1) (73 ) (2) 203 (3) (22 ) (623 ) Tax 256 25 (62 ) — 219 Reclassification adjustments, net of taxes (475 ) (48 ) 141 (22 ) (404 ) Other comprehensive income (loss), net of taxes (126 ) (70 ) 579 (208 ) 175 Balance December 31, 2015, net of taxes 404 41 (2,407 ) (4) (2,186 ) (4,148 ) Other comprehensive income (loss) before reclassification adjustments, pretax 210 (38 ) (1,199 ) (150 ) (1,177 ) Tax (72 ) 16 363 (19 ) 288 Other comprehensive income (loss) before reclassification adjustments, net of taxes 138 (22 ) (836 ) (169 ) (889 ) Reclassification adjustments, pretax (314 ) (1) (31 ) (2) 37 (3) — (308 ) Tax 110 9 — — 119 Reclassification adjustments, net of taxes (204 ) (22 ) 37 — (189 ) Other comprehensive income (loss), net of taxes (66 ) (44 ) (799 ) (169 ) (1,078 ) Balance December 31, 2016, net of taxes $ 338 $ (3 ) $ (3,206 ) (4) $ (2,355 ) $ (5,226 ) (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 . (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 $ 3.9 billion and $3.3 billion at December 31, 2016 and 2015 , respectively, and other postretirement benefit plan net loss of $115 million and $86 million at December 31, 2016 and in 2015 , respectively, as well as pension plan prior service credit of $361 million and $414 million at December 31, 2016 and 2015 , respectively, and other postretirement benefit plan prior service credit of $466 million and $547 million at December 31, 2016 and 2015 , respectively.

Segment Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company’s operations are principally managed on a products basis and are comprised of four operating segments – Pharmaceutical, Animal Health, Healthcare Services and Alliances. The Animal Health, Healthcare Services and Alliances segments are not material for separate reporting. 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. 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. Sales of vaccines in most major European markets were marketed through the Company’s SPMSD joint venture until its termination on December 31, 2016 (see Note 8). The Company also has animal health operations that discover, develop, manufacture and market animal health products, including vaccines, which the Company sells to veterinarians, distributors and animal producers. During 2016, the Company made changes to the composition of the Animal Health segment that resulted in the inclusion of certain revenues and costs that were previously included in non-segment revenues and profits. Prior periods have been recast to reflect these changes on a comparable basis. The Company’s 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. Merck’s Alliances segment primarily includes results from the Company’s relationship with AZLP until the termination of that relationship on June 30, 2014 (see Note 8). On October 1, 2014, the Company divested its Consumer Care segment that developed, manufactured and marketed over-the-counter, foot care and sun care products (see Note 3). Sales of the Company’s products were as follows: Years Ended December 31 2016 2015 2014 Primary Care and Women’s Health Cardiovascular Zetia $ 2,560 $ 2,526 $ 2,650 Vytorin 1,141 1,251 1,516 Diabetes Januvia 3,908 3,863 3,931 Janumet 2,201 2,151 2,071 General Medicine and Women’s Health NuvaRing 777 732 723 Implanon/Nexplanon 606 588 502 Dulera 436 536 460 Follistim AQ 355 383 412 Hospital and Specialty Hepatitis Zepatier 555 — — HIV Isentress 1,387 1,511 1,673 Hospital Acute Care Cubicin (1) 1,087 1,127 25 Noxafil 595 487 402 Invanz 561 569 529 Cancidas 558 573 681 Bridion 482 353 340 Primaxin 297 313 329 Immunology Remicade 1,268 1,794 2,372 Simponi 766 690 689 Oncology Keytruda 1,402 566 55 Emend 549 535 553 Temodar 283 312 350 Diversified Brands Respiratory Singulair 915 931 1,092 Nasonex 537 858 1,099 Other Cozaar/Hyzaar 511 667 806 Arcoxia 450 471 519 Fosamax 284 359 470 Zocor 186 217 258 Vaccines (2) Gardasil/Gardasil 9 2,173 1,908 1,738 ProQuad/M-M-R II/Varivax 1,640 1,505 1,394 Zostavax 685 749 765 RotaTeq 652 610 659 Pneumovax 23 641 542 746 Other pharmaceutical (3) 4,703 5,105 6,233 Total Pharmaceutical segment sales 35,151 34,782 36,042 Other segment sales (4) 3,862 3,667 5,758 Total segment sales 39,013 38,449 41,800 Other (5) 794 1,049 437 $ 39,807 $ 39,498 $ 42,237 (1) Sales of Cubicin in 2015 represent sales subsequent to the Cubist acquisition date. Sales of Cubicin in 2014 reflect sales in Japan pursuant to a previously existing licensing agreement. (2) These amounts do not reflect sales of vaccines sold in most major European markets through the Company’s joint venture, SPMSD, the results of which are reflected in equity income from affiliates which is included in Other (income) expense, net . These amounts do, however, reflect supply sales to SPMSD. On December 31, 2016, Merck and Sanofi terminated the SPMSD joint venture (see Note 8). (3) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (4) Represents the non-reportable segments of Animal Health, Healthcare Services and Alliances, as well as Consumer Care until its divestiture on October 1, 2014 (see Note 3). The Alliances segment includes revenue from the Company’s relationship with AZLP until termination on June 30, 2014 (see Note 8). (5) Other is primarily comprised of miscellaneous corporate revenues, including revenue hedging activities, as well as third-party manufacturing sales. Other in 2016 and 2014 also includes approximately $170 million and $232 million , respectively, in connection with the sale of the marketing rights to certain products. Consolidated revenues by geographic area where derived are as follows: Years Ended December 31 2016 2015 2014 United States $ 18,478 $ 17,519 $ 17,071 Europe, Middle East and Africa 10,953 10,677 13,174 Asia Pacific 3,918 3,825 3,952 Japan 2,846 2,673 3,471 Latin America 2,155 2,825 3,151 Other 1,457 1,979 1,418 $ 39,807 $ 39,498 $ 42,237 A reconciliation of total segment profits to consolidated Income before taxes is as follows: Years Ended December 31 2016 2015 2014 Segment profits: Pharmaceutical segment $ 22,180 $ 21,658 $ 22,164 Other segments 1,507 1,573 2,386 Total segment profits 23,687 23,231 24,550 Other profits 481 810 627 Unallocated: Interest income 328 289 266 Interest expense (693 ) (672 ) (732 ) Equity income from affiliates (19 ) 135 59 Depreciation and amortization (1,585 ) (1,573 ) (2,452 ) Research and development (9,084 ) (5,871 ) (5,823 ) Amortization of purchase accounting adjustments (3,692 ) (4,816 ) (4,182 ) Restructuring costs (651 ) (619 ) (1,013 ) Gain on sale of certain migraine clinical development programs 100 250 — Charge related to the settlement of worldwide Keytruda patent litigation (625 ) — — Gain on divestiture of certain ophthalmic products — 147 480 Foreign currency devaluation related to Venezuela — (876 ) — Net charge related to the settlement of Vioxx shareholder class action litigation — (680 ) — Gain on divestiture of Merck Consumer Care — — 11,209 Gain on AstraZeneca option exercise — — 741 Loss on extinguishment of debt — — (628 ) Other unallocated, net (3,588 ) (4,354 ) (5,819 ) $ 4,659 $ 5,401 $ 17,283 Segment profits are comprised of segment sales less standard costs and certain operating expenses directly incurred by the segments. For internal management reporting presented to the chief operating decision maker, Merck does not allocate materials and production costs, other than standard costs, the majority of research and development expenses 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 contingent consideration, and other miscellaneous income or expense items. Equity income from affiliates and depreciation and amortization included in segment profits is as follows: Pharmaceutical All Other Total Year Ended December 31, 2016 Included in segment profits: Equity income from affiliates $ 105 $ — $ 105 Depreciation and amortization (160 ) (23 ) (183 ) Year Ended December 31, 2015 Included in segment profits: Equity income from affiliates $ 70 $ — $ 70 Depreciation and amortization (82 ) (18 ) (100 ) Year Ended December 31, 2014 Included in segment profits: Equity income from affiliates $ 90 $ 108 $ 198 Depreciation and amortization (39 ) (18 ) (57 ) Property, plant and equipment, net by geographic area where located is as follows: December 31 2016 2015 2014 United States $ 8,114 $ 8,467 $ 8,727 Europe, Middle East and Africa 2,732 2,844 3,120 Asia Pacific 775 842 897 Latin America 234 182 207 Japan 164 164 172 Other 7 8 13 $ 12,026 $ 12,507 $ 13,136 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, 2016
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 recognized at fair value if fair value can reasonably be estimated. If the acquisition date fair value of an asset acquired or liability assumed that arises from a contingency 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.
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 market. The cost of a substantial majority of domestic 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 and equity securities classified as available-for-sale are reported at fair value. Fair values of the Company’s investments 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 ). For declines in the fair value of equity securities that are considered other-than-temporary, impairment losses are charged to Other (income) expense, net . The Company considers available evidence in evaluating potential impairments of its investments, including the duration and extent to which fair value is less than cost and, for equity securities, the Company’s ability and intent to hold the investments. For debt securities, an other-than-temporary impairment has occurred if the Company does not expect to recover the entire amortized cost basis of the 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 both debt and equity securities are included in Other (income) expense, net .
Revenue Recognition	Revenue Recognition — Revenues from sales of products are recognized when title and risk of loss passes to the customer, typically upon delivery. Recognition of revenue also requires reasonable assurance of collection of sales proceeds and completion of all performance obligations. Domestically, sales discounts are issued to customers as direct discounts at the point-of-sale, indirectly through an intermediary wholesaler, known as chargebacks, or indirectly 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. Accruals for chargebacks are reflected as a direct reduction to accounts receivable and accruals for rebates are recorded as current liabilities. The accrued balances relative to the provisions for chargebacks and rebates included in Accounts receivable and Accrued and other current liabilities were $196 million and $2.7 billion , respectively, at December 31, 2016 and $145 million and $2.7 billion , respectively, at December 31, 2015 . 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 .
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 — Advertising and promotion costs are expensed as incurred.
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. Capitalized software costs are included in Property, plant and equipment and 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 $452 million and $421 million , net of accumulated amortization at December 31, 2016 and 2015 , 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.
Acquired Intangibles	Acquired Intangibles — Acquired intangibles include products and product rights, tradenames and patents, which are recorded at fair value, assigned an estimated useful life, and are amortized primarily on a straight-line basis over their estimated useful lives ranging from 2 to 20 years (see Note 7). 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 — Acquired in-process research and development (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. 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 tests IPR&D for impairment at least annually, 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 the IPR&D intangible asset is less than its carrying amount. If the Company concludes it is more likely than not that the fair value is less than the carrying amount, a quantitative test that compares the fair value of the IPR&D intangible asset with its carrying value is performed. 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 business 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. 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, the contingent consideration liability is remeasured at current fair value with changes (either expense or income) recorded in earnings. Changes in any of the inputs may result in a significantly different fair value adjustment.
Research and Development	Research and Development — Research and development is expensed as incurred. Upfront and milestone payments due to third parties in connection with research and development collaborations prior to regulatory approval are expensed as incurred. Payments due to third parties upon or subsequent to regulatory approval are capitalized and amortized over the shorter of the remaining license or product patent life. Amounts due from collaborative partners related to development activities are generally reflected as a reduction of research and development expenses when the specific milestone has been achieved. 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 all periods. In addition, research and development expenses include expense or income related to changes in the estimated fair value measurement of liabilities for contingent consideration.
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.
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 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.
New Accounting Standards	Recently Adopted Accounting Standards — In the first quarter of 2016, the Company adopted accounting guidance issued by the Financial Accounting Standards Board (FASB) in April of 2015, which requires debt issuance costs to be presented as a direct deduction from the carrying amount of that debt on the balance sheet as opposed to being presented as a deferred charge. Approximately $100 million of debt issuance costs were reclassified in the first quarter of 2016 as a result of the adoption of the new standard. Prior period amounts have been recast to conform to the new presentation. In the second quarter of 2016, the Company elected to early adopt an accounting standards update issued by the FASB in March of 2016 intended to simplify the accounting and reporting for employee share-based payment transactions. Among other provisions, the new standard requires that excess tax benefits and deficiencies that arise upon vesting or exercise of share-based payments be recognized in the income statement (as opposed to previous guidance under which tax effects were recorded to Other paid-in-capital in certain instances). This aspect of the new guidance, which was required to be adopted prospectively, resulted in the recognition of $79 million of excess tax benefits in Taxes on income in 2016 arising from share-based payments. The new guidance also amended the presentation of certain share-based payment items in the statement of cash flows. Cash flows related to excess income tax benefits are now classified as an operating activity (formerly included as a financing activity). The Company elected to adopt this aspect of the new guidance prospectively. The standard also clarified that cash payments made to taxing authorities on the employees’ behalf for shares withheld should be presented as a financing activity. This aspect of the guidance was adopted retrospectively; accordingly, the Company reclassified $117 million and $129 million of such payments from operating activities to financing activities in the Consolidated Statement of Cash Flows for the years ended December 31, 2015 and 2014, respectively, to conform to the current presentation. The Company has elected to continue to estimate the impact of forfeitures when determining the amount of compensation cost to be recognized each period rather than account for them as they occur. In the fourth quarter of 2016, the Company elected to early adopt an accounting standards update issued by the FASB on January 5, 2017 intended to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. If substantially all of the fair value of gross assets included in a transaction is concentrated in a single asset (or a group of similar assets), the assets would not represent a business. To be considered a business, the assets in the transaction need to include an input and a substantive process that together significantly contribute to the ability to create outputs. Prior to the adoption of the new guidance, an acquisition or disposition would be considered a business if there were inputs, as well as processes that when applied to those inputs had the ability to create outputs. Entities are permitted to apply the updated guidance to transactions occurring before the guidance was issued as long as the applicable financial statements have not been issued. Accordingly, the Company elected to adopt this guidance prospectively as of October 1, 2016. Recently Issued Accounting Standards — In May 2014, the FASB issued amended accounting guidance on revenue recognition that will be applied to all contracts with customers. The objective of the new guidance is to improve comparability of revenue recognition practices across entities and to provide more useful information to users of financial statements through improved disclosure requirements. In August 2015, the FASB approved a one-year deferral of the effective date making this guidance effective for interim and annual periods beginning in 2018. The new standard permits two methods of adoption: retrospectively to each prior reporting period presented (full retrospective method), or retrospectively with the cumulative effect of adopting the guidance being recognized at the date of initial application (modified retrospective method). The Company will adopt the new standard on January 1, 2018 and currently plans to use the modified retrospective method. The majority of the Company’s business is ship and bill and, on that primary revenue stream, Merck does not expect significant differences. However, the Company’s analysis is preliminary and subject to change. Merck has not completed its assessment of multiple element arrangements and certain discount and trade promotion programs. In January 2016, the FASB issued revised guidance for the accounting and reporting of financial instruments. The new guidance requires that equity investments with readily determinable fair values currently classified as available for sale be measured at fair value with changes in fair value recognized in net income. The new guidance also simplifies the impairment testing of equity investments without readily determinable fair values and changes certain disclosure requirements. This guidance is effective for interim and annual periods beginning in 2018. Early adoption is not permitted. The Company is currently assessing the impact of adoption on its consolidated financial statements. In February 2016, the FASB issued new accounting guidance for the accounting and reporting of leases. The new guidance requires that lessees recognize a right-of-use asset and a lease liability recorded on the balance sheet for each of its leases (other than leases that meet the definition of a short-term lease). Leases will be classified as either operating or finance. Operating leases will result in straight-line expense in the income statement (similar to current operating leases) while finance leases will result in more expense being recognized in the earlier years of the lease term (similar to current capital leases). The new guidance will be effective for interim and annual periods beginning in 2019. Early adoption is permitted. The Company is currently evaluating the impact of adoption on its consolidated financial statements. In June 2016, the FASB issued amended guidance on the accounting for credit losses on financial instruments within its scope. The 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 new guidance is effective for interim and annual periods beginning in 2020, with earlier application permitted in 2019. The Company is currently evaluating the impact of adoption on its consolidated financial statements. In August 2016, the FASB issued guidance on the classification of certain cash receipts and payments in the statement of cash flows intended to reduce diversity in practice. The guidance is effective for interim and annual periods beginning in 2018. Early adoption is permitted. The guidance is to be applied retrospectively to all periods presented but may be applied prospectively if retrospective application would be impracticable. The Company is currently evaluating the effect of the standard on its Consolidated Statement of Cash Flows. In October 2016, the FASB issued guidance on the accounting for the income tax consequences of intra-entity transfers of assets other than inventory. Under existing guidance, the recognition of current and deferred income taxes for an intra-entity asset transfer is prohibited until the asset has been sold to a third party. The new guidance will require the recognition of the income tax consequences of an intra-entity transfer of an asset (with the exception of inventory) when the intra-entity transfer occurs. The guidance is effective for interim and annual periods beginning in 2018. Early adoption is permitted. The new guidance is to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings in the beginning of the period of adoption. The Company does not anticipate the adoption of the new guidance will have a material effect on its consolidated financial statements. In November 2016, the FASB issued guidance requiring that amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. The guidance is effective for interim and annual periods beginning in 2018 and should be applied using a retrospective transition method to each period presented. Early adoption is permitted. The Company is currently evaluating the effect of the standard on its Consolidated Statement of Cash Flows. In January 2017, the FASB issued guidance that provides for the elimination of Step 2 from the goodwill impairment test. If impairment charges are recognized, the amount recorded will be the amount by which the carrying amount exceeds the reporting unit’s fair value with certain limitations. The new guidance is effective for interim and annual periods in 2021. The Company does not anticipate the adoption of the new guidance will have a material effect on its consolidated financial statements.

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Dec. 31, 2016
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, 2016 Materials and production $ — $ 77 $ 104 $ 181 Marketing and administrative — 8 87 95 Research and development — 142 — 142 Restructuring costs 216 — 435 651 $ 216 $ 227 $ 626 $ 1,069 Year Ended December 31, 2015 Materials and production $ — $ 78 $ 283 $ 361 Marketing and administrative — 59 19 78 Research and development — 37 15 52 Restructuring costs 208 — 411 619 $ 208 $ 174 $ 728 $ 1,110 Year Ended December 31, 2014 Materials and production $ — $ 429 $ 53 $ 482 Marketing and administrative — 198 2 200 Research and development — 273 10 283 Restructuring costs 674 — 339 1,013 $ 674 $ 900 $ 404 $ 1,978
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, 2015 $ 1,031 $ — $ 20 $ 1,051 Expenses 208 174 728 1,110 (Payments) receipts, net (647 ) — (435 ) (1,082 ) Non-cash activity — (174 ) (260 ) (434 ) Restructuring reserves December 31, 2015 592 — 53 645 Expenses 216 227 626 1,069 (Payments) receipts, net (413 ) — (347 ) (760 ) Non-cash activity — (227 ) (186 ) (413 ) Restructuring reserves December 31, 2016 (1) $ 395 $ — $ 146 $ 541 (1) The remaining cash outlays are expected to be substantially completed by the end of 2017.

Acquisitions, Divestitures, R29

Acquisitions, Divestitures, Research Collaborations and License Agreements (Tables)	12 Months Ended
	Dec. 31, 2016
Business Combinations [Abstract]
Schedule of Fair Value of Assets Acquired and Liabilities Assumed	The estimated fair value of assets acquired and liabilities assumed from Cubist is as follows: Estimated fair value at January 21, 2015 Cash and cash equivalents $ 733 Accounts receivable 123 Inventories 216 Other current assets 55 Property, plant and equipment 151 Identifiable intangible assets: Products and product rights (11 year weighted-average useful life) 6,923 IPR&D 50 Other noncurrent assets 184 Current liabilities (1) (233 ) Deferred income tax liabilities (2,519 ) Long-term debt (1,900 ) Other noncurrent liabilities (1) (122 ) Total identifiable net assets 3,661 Goodwill (2) 4,670 Consideration transferred $ 8,331 (1) Included in current liabilities and other noncurrent liabilities is contingent consideration of $73 million and $50 million , respectively. (2) The goodwill recognized is largely attributable to anticipated synergies expected to arise after the acquisition and was allocated to the Pharmaceutical segment. The goodwill is not deductible for tax purposes. The net impact of the termination of the SPMSD joint venture is as follows: Products and product rights (8 year useful life) $ 936 Accounts receivable 133 Income taxes payable (221 ) Deferred income tax liabilities (175 ) Other, net 34 Goodwill (1) 20 Net assets acquired 727 Consideration payable to Sanofi, net (378 ) Derecognition of Merck’s previously held equity investment in SPMSD (183 ) Increase in net assets 166 Merck’s share of restructuring costs related to the termination (77 ) Net gain on termination of SPMSD joint venture (2) $ 89 (1) The goodwill was allocated to the Pharmaceutical segment and is not deductible for tax purposes. (2) Recorded in Other (income) expense, net .
Unaudited Supplemental Pro Forma Data	The following unaudited supplemental pro forma data presents consolidated information as if the acquisition of Cubist had been completed on January 1, 2014: Years Ended December 31 2015 2014 Sales $ 39,584 $ 43,437 Net income attributable to Merck & Co., Inc. 4,640 10,887 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders 1.65 3.76 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders 1.63 3.72

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Interest Rate Derivatives	At December 31, 2016 , the Company was a party to 26 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. 2016 Debt Instrument Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 1.30% notes due 2018 1,000 4 1,000 5.00% notes due 2019 1,250 3 550 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
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: 2016 2015 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 $ 20 $ — $ 2,700 $ 42 $ — $ 2,700 Interest rate swap contracts Accrued and other current liabilities — — — — 1 1,000 Interest rate swap contracts Other noncurrent liabilities — 29 3,500 — 23 3,500 Foreign exchange contracts Other current assets 616 — 6,063 579 — 4,171 Foreign exchange contracts Other assets 129 — 2,075 386 — 4,136 Foreign exchange contracts Accrued and other current liabilities — 1 48 — 1 77 Foreign exchange contracts Other noncurrent liabilities — 1 12 — — — $ 765 $ 31 $ 14,398 $ 1,007 $ 25 $ 15,584 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts Other current assets $ 230 $ — $ 8,210 $ 212 $ — $ 8,783 Foreign exchange contracts Other assets — — — 18 — 179 Foreign exchange contracts Accrued and other current liabilities — 103 2,931 — 37 2,508 Foreign exchange contracts Other noncurrent liabilities — — — — 1 6 $ 230 $ 103 $ 11,141 $ 230 $ 38 $ 11,476 $ 995 $ 134 $ 25,539 $ 1,237 $ 63 $ 27,060
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: 2016 2015 Asset Liability Asset Liability Gross amounts recognized in the consolidated balance sheet $ 995 $ 134 $ 1,237 $ 63 Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet (131 ) (131 ) (59 ) (59 ) Cash collateral (received) posted (529 ) — (862 ) — Net amounts $ 335 $ 3 $ 316 $ 4
Location and Pretax Gain or Loss Amounts for Derivatives	The table below provides information on the location and pretax gain or loss amounts for derivatives that are: (i) designated in a fair value hedging relationship, (ii) designated in a foreign currency cash flow hedging relationship, (iii) designated in a foreign currency net investment hedging relationship and (iv) not designated in a hedging relationship: Years Ended December 31 2016 2015 2014 Derivatives designated in a fair value hedging relationship Interest rate swap contracts Amount of loss (gain) recognized in Other (income) expense, net on derivatives (1) $ 28 $ (14 ) $ (17 ) Amount of (gain) loss recognized in Other (income) expense, net on hedged item (1) (29 ) 7 14 Derivatives designated in foreign currency cash flow hedging relationships Foreign exchange contracts Amount of gain reclassified from AOCI to Sales (311 ) (724 ) (143 ) Amount of gain recognized in OCI on derivatives (210 ) (526 ) (775 ) Derivatives designated in foreign currency net investment hedging relationships Foreign exchange contracts Amount of gain recognized in Other (income) expense, net on derivatives (2) (1 ) (4 ) (6 ) Amount of loss (gain) recognized in OCI on derivatives 2 (10 ) (192 ) Derivatives not designated in a hedging relationship Foreign exchange contracts Amount of loss (gain) recognized in Other (income) expense, net on derivatives (3) 132 (461 ) (516 ) Amount of (gain) loss recognized in Sales — (1 ) 15 (1) There was $1 million , $7 million and $3 million of ineffectiveness on the hedge during 2016 , 2015 and 2014 , respectively. (2) There was no ineffectiveness on the hedge. Represents the amount excluded from hedge effectiveness testing. (3) 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.
Information on Available-for-Sale Investments	Information on investments in debt and equity securities at December 31 is as follows: 2016 2015 Fair Value Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Gains Losses Gains Losses Corporate notes and bonds $ 10,577 $ 10,601 $ 15 $ (39 ) $ 10,259 $ 10,299 $ 7 $ (47 ) Commercial paper 4,330 4,330 — — 2,977 2,977 — — U.S. government and agency securities 2,232 2,244 1 (13 ) 1,761 1,767 — (6 ) Asset-backed securities 1,376 1,380 1 (5 ) 1,284 1,290 — (6 ) Mortgage-backed securities 796 801 1 (6 ) 694 697 1 (4 ) Foreign government bonds 519 521 — (2 ) 607 586 22 (1 ) Equity securities 349 281 71 (3 ) 534 409 125 — $ 20,179 $ 20,158 $ 89 $ (68 ) $ 18,116 $ 18,025 $ 155 $ (64 )
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 Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total 2016 2015 Assets Investments Corporate notes and bonds $ — $ 10,389 $ — $ 10,389 $ — $ 10,259 $ — $ 10,259 Commercial paper — 4,330 — 4,330 — 2,977 — 2,977 U.S. government and agency securities 29 1,890 — 1,919 — 1,761 — 1,761 Asset-backed securities (1) — 1,257 — 1,257 — 1,284 — 1,284 Mortgage-backed securities (1) — 628 — 628 — 694 — 694 Foreign government bonds — 518 — 518 — 607 — 607 Equity securities 201 — — 201 360 — — 360 230 19,012 — 19,242 360 17,582 — 17,942 Other assets (2) U.S. government and agency securities — 313 — 313 — — — — Corporate notes and bonds — 188 — 188 — — — — Mortgage-backed securities (1) — 168 — 168 — — — — Asset-backed securities (1) — 119 — 119 — — — — Foreign government bonds — 1 — 1 — — — — Equity securities 148 — — 148 155 19 — 174 148 789 — 937 155 19 — 174 Derivative assets (3) Purchased currency options — 644 — 644 — 1,041 — 1,041 Forward exchange contracts — 331 — 331 — 154 — 154 Interest rate swaps — 20 — 20 — 42 — 42 — 995 — 995 — 1,237 — 1,237 Total assets $ 378 $ 20,796 $ — $ 21,174 $ 515 $ 18,838 $ — $ 19,353 Liabilities Other liabilities Contingent consideration $ — $ — $ 891 $ 891 $ — $ — $ 590 $ 590 Derivative liabilities (2) Forward exchange contracts — 93 — 93 — 38 — 38 Interest rate swaps — 29 — 29 — 24 — 24 Written currency options — 12 — 12 — 1 — 1 — 134 — 134 — 63 — 63 Total liabilities $ — $ 134 $ 891 $ 1,025 $ — $ 63 $ 590 $ 653 (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. Mortgage-backed securities represent AAA-rated securities issued or unconditionally guaranteed as to payment of principal and interest by U.S. government agencies. (2) The increase in investments included in Other assets reflects certain assets previously restricted for retiree benefits that became available to fund certain other health and welfare benefits during 2016 (see Note 13). (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 is as follows: 2016 2015 Fair value January 1 $ 590 $ 428 Changes in fair value (1) (407 ) (16 ) Additions 733 228 Payments (25 ) (50 ) Fair value December 31 $ 891 $ 590 (1) Recorded in Research and development expenses and Materials and production costs.

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2016
Inventory Disclosure [Abstract]
Inventories	Inventories at December 31 consisted of: 2016 2015 Finished goods $ 1,304 $ 1,343 Raw materials and work in process 4,222 4,374 Supplies 155 168 Total (approximates current cost) 5,681 5,885 Increase to LIFO costs 302 384 $ 5,983 $ 6,269 Recognized as: Inventories $ 4,866 $ 4,700 Other assets 1,117 1,569

Goodwill and Other Intangibles

Goodwill and Other Intangibles (Tables)	12 Months Ended
	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill Activity by Segment	The following table summarizes goodwill activity by segment: Pharmaceutical All Other Total Balance January 1, 2015 $ 11,108 $ 1,884 $ 12,992 Acquisitions 4,684 29 4,713 Divestitures (18 ) — (18 ) Impairments — (47 ) (47 ) Other (1) 88 (5 ) 83 Balance December 31, 2015 (2) 15,862 1,861 17,723 Acquisitions 207 275 482 Impairments — (47 ) (47 ) Other (1) 6 (2 ) 4 Balance December 31, 2016 (2) $ 16,075 $ 2,087 $ 18,162 (1) Other includes cumulative translation adjustments on goodwill balances and certain other adjustments. (2) Accumulated goodwill impairment losses at December 31, 2016 and 2015 were $187 million and $140 million , respectively.
Other Intangibles	Other intangibles at December 31 consisted of: 2016 2015 Gross Carrying Amount Accumulated Amortization Net Gross Carrying Amount Accumulated Amortization Net Products and product rights $ 46,269 $ 31,919 $ 14,350 $ 45,949 $ 28,514 $ 17,435 IPR&D 1,653 — 1,653 4,226 — 4,226 Tradenames 215 89 126 198 79 119 Other 1,947 771 1,176 1,418 596 822 $ 50,084 $ 32,779 $ 17,305 $ 51,791 $ 29,189 $ 22,602

Joint Ventures and Other Equi33

Joint Ventures and Other Equity Method Affiliates (Tables)	12 Months Ended
	Dec. 31, 2016
Equity Method Investments and Joint Ventures [Abstract]
Schedule of Fair Value of Assets Acquired and Liabilities Assumed	The estimated fair value of assets acquired and liabilities assumed from Cubist is as follows: Estimated fair value at January 21, 2015 Cash and cash equivalents $ 733 Accounts receivable 123 Inventories 216 Other current assets 55 Property, plant and equipment 151 Identifiable intangible assets: Products and product rights (11 year weighted-average useful life) 6,923 IPR&D 50 Other noncurrent assets 184 Current liabilities (1) (233 ) Deferred income tax liabilities (2,519 ) Long-term debt (1,900 ) Other noncurrent liabilities (1) (122 ) Total identifiable net assets 3,661 Goodwill (2) 4,670 Consideration transferred $ 8,331 (1) Included in current liabilities and other noncurrent liabilities is contingent consideration of $73 million and $50 million , respectively. (2) The goodwill recognized is largely attributable to anticipated synergies expected to arise after the acquisition and was allocated to the Pharmaceutical segment. The goodwill is not deductible for tax purposes. The net impact of the termination of the SPMSD joint venture is as follows: Products and product rights (8 year useful life) $ 936 Accounts receivable 133 Income taxes payable (221 ) Deferred income tax liabilities (175 ) Other, net 34 Goodwill (1) 20 Net assets acquired 727 Consideration payable to Sanofi, net (378 ) Derecognition of Merck’s previously held equity investment in SPMSD (183 ) Increase in net assets 166 Merck’s share of restructuring costs related to the termination (77 ) Net gain on termination of SPMSD joint venture (2) $ 89 (1) The goodwill was allocated to the Pharmaceutical segment and is not deductible for tax purposes. (2) Recorded in Other (income) expense, net .
Summarized Financial Information for AZLP	Summarized financial information for AZLP is as follows: Year Ended December 31 2014 (1) Sales $ 2,205 Materials and production costs 1,044 Other expense, net 604 Income before taxes (2) 557 (1) Includes results through the June 30, 2014 termination date. (2) Merck’s partnership returns from AZLP were generally contractually determined as noted above and were not based on a percentage of income from AZLP, other than with respect to Merck’s 1% limited partnership interest.

Loans Payable, Long-Term Debt34

Loans Payable, Long-Term Debt and Other Commitments (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Long-Term Debt	Long-term debt at December 31 consisted of: 2016 2015 2.75% notes due 2025 $ 2,487 $ 2,485 3.70% notes due 2045 1,972 1,971 2.80% notes due 2023 1,743 1,742 5.00% notes due 2019 1,273 1,283 1.85% notes due 2020 1,238 1,239 4.15% notes due 2043 1,236 1,236 2.35% notes due 2022 1,228 1,233 3.875% notes due 2021 1,152 1,158 1.125% euro-denominated notes due 2021 1,035 1,091 1.875% euro-denominated notes due 2026 1,028 1,084 2.40% notes due 2022 1,003 1,011 Floating-rate borrowing due 2018 999 998 1.10% notes due 2018 999 998 1.30% notes due 2018 985 985 6.50% notes due 2033 806 809 Floating-rate notes due 2020 698 698 6.55% notes due 2037 594 596 0.50% euro-denominated notes due 2024 516 — 1.375% euro-denominated notes due 2036 512 — 2.50% euro-denominated notes due 2034 511 538 3.60% notes due 2042 489 489 5.85% notes due 2039 415 415 5.75% notes due 2036 369 369 5.95% debentures due 2028 355 354 6.40% debentures due 2028 325 325 6.30% debentures due 2026 152 152 Floating-rate notes due 2017 — 300 Other 154 270 $ 24,274 $ 23,829

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2016
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: 2016 2015 2014 Common Stock Treasury Stock Common Stock Treasury Stock Common Stock Treasury Stock Balance January 1 3,577 796 3,577 739 3,577 650 Purchases of treasury stock — 60 — 75 — 134 Issuances (1) — (28 ) — (18 ) — (45 ) Balance December 31 3,577 828 3,577 796 3,577 739 (1) Issuances primarily reflect activity under share-based compensation plans.

Share-Based Compensation Plans

Share-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Assumptions Used to Determine Weighted-Average Fair Value of Options Granted	The weighted average fair value of options granted in 2016 , 2015 and 2014 was $5.89 , $6.46 and $6.79 per option, respectively, and were determined using the following assumptions: Years Ended December 31 2016 2015 2014 Expected dividend yield 3.8 % 4.1 % 4.3 % Risk-free interest rate 1.4 % 1.7 % 2.0 % Expected volatility 19.6 % 19.9 % 22.0 % Expected life (years) 6.2 6.2 6.4
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, 2016 64,668 $ 41.64 Granted 6,220 54.63 Exercised (23,846 ) 39.39 Forfeited (1,951 ) 45.14 Outstanding December 31, 2016 45,091 $ 44.47 4.42 $ 654 Exercisable December 31, 2016 34,311 $ 40.87 3.12 $ 619
Additional Information Pertaining to Stock Option Plans	Additional information pertaining to stock option plans is provided in the table below: Years Ended December 31 2016 2015 2014 Total intrinsic value of stock options exercised $ 444 $ 332 $ 626 Fair value of stock options vested 28 30 35 Cash received from the exercise of stock options 939 485 1,560
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, 2016 13,400 $ 53.73 1,884 $ 55.33 Granted 5,617 54.67 733 57.38 Vested (4,956 ) 45.06 (786 ) 48.18 Forfeited (795 ) 56.65 (87 ) 58.82 Nonvested December 31, 2016 13,266 $ 57.19 1,744 $ 59.24

Pension and Other Postretirem37

Pension and Other Postretirement Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Cost	The net periodic benefit cost for pension and other postretirement benefit plans consisted of the following components: Pension Benefits U.S. International Other Postretirement Benefits Years Ended December 31 2016 2015 2014 2016 2015 2014 2016 2015 2014 Service cost $ 282 $ 307 $ 300 $ 238 $ 251 $ 266 $ 54 $ 80 $ 78 Interest cost 456 434 425 204 206 269 82 110 115 Expected return on plan assets (831 ) (819 ) (782 ) (382 ) (379 ) (416 ) (107 ) (143 ) (139 ) Net amortization 64 158 74 76 104 59 (103 ) (59 ) (71 ) Termination benefits 23 22 53 4 1 11 4 7 22 Curtailments 5 (12 ) (69 ) (1 ) (9 ) (4 ) (18 ) (19 ) (39 ) Settlements — 1 11 6 12 6 — — — Net periodic benefit (credit) cost $ (1 ) $ 91 $ 12 $ 145 $ 186 $ 191 $ (88 ) $ (24 ) $ (34 )
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 2016 2015 2016 2015 2016 2015 Fair value of plan assets January 1 $ 9,266 $ 9,984 $ 7,204 $ 7,724 $ 1,913 $ 1,984 Actual return on plan assets 941 (226 ) 898 138 138 (34 ) Company contributions 63 66 424 163 68 63 Effects of exchange rate changes — — (546 ) (568 ) — (1 ) Benefits paid (504 ) (523 ) (193 ) (196 ) (108 ) (99 ) Settlements — (35 ) (21 ) (66 ) — — Assets no longer restricted to the payment of postretirement benefits (1) — — — — (992 ) — Other — — 28 9 — — Fair value of plan assets December 31 $ 9,766 $ 9,266 $ 7,794 $ 7,204 $ 1,019 $ 1,913 Benefit obligation January 1 $ 9,723 $ 10,632 $ 7,733 $ 8,331 $ 1,810 $ 2,638 Service cost 282 307 238 251 54 80 Interest cost 456 434 204 206 82 110 Actuarial losses (gains) (2) 854 (1,102 ) 938 (127 ) 77 (384 ) Benefits paid (504 ) (523 ) (193 ) (196 ) (108 ) (99 ) Effects of exchange rate changes — — (576 ) (647 ) 2 (11 ) Plan amendments (3) — — — (1 ) — (531 ) Curtailments 15 (14 ) (15 ) (15 ) 1 (3 ) Termination benefits 23 22 4 1 4 7 Settlements — (35 ) (21 ) (66 ) — — Other — 2 60 (4 ) — 3 Benefit obligation December 31 $ 10,849 $ 9,723 $ 8,372 $ 7,733 $ 1,922 $ 1,810 Funded status December 31 $ (1,083 ) $ (457 ) $ (578 ) $ (529 ) $ (903 ) $ 103 Recognized as: Other assets $ — $ 179 $ 451 $ 567 $ — $ 359 Accrued and other current liabilities (50 ) (48 ) (7 ) (7 ) (11 ) (10 ) Other noncurrent liabilities (1,033 ) (588 ) (1,022 ) (1,089 ) (892 ) (246 ) (1) As a result of certain allowable administrative actions that occurred in June 2016, $992 million of plan assets previously restricted for the payment of other postretirement benefits became available to fund certain other health and welfare benefits. (2) Actuarial losses in 2016 and actuarial gains in 2015 primarily reflect changes in discount rates. (3) The decline in other postretirement benefit obligations in 2015 resulting from plan amendments primarily reflects changes to Merck’s retiree medical benefits approved by the Company in December 2015. The changes provide that, beginning in 2017, Merck will provide access to retiree health insurance coverage that supplements government-sponsored Medicare through a private insurance marketplace.
Schedule of Accumulated and Projected Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]	Information related to the funded status of selected pension plans at December 31 is as follows: U.S. International 2016 2015 2016 2015 Pension plans with a projected benefit obligation in excess of plan assets Projected benefit obligation $ 10,849 $ 1,310 $ 5,486 $ 5,093 Fair value of plan assets 9,766 674 4,457 3,996 Pension plans with an accumulated benefit obligation in excess of plan assets Accumulated benefit obligation $ 9,807 $ 611 $ 2,692 $ 4,812 Fair value of plan assets 9,057 — 1,898 3,964
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
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: 2016 2015 Insurance Contracts Real Estate Other Total Insurance Contracts Real Estate Other Total U.S. Pension Plans Balance January 1 $ — $ — $ 23 $ 23 $ — $ — $ 28 $ 28 Actual return on plan assets: Relating to assets still held at December 31 — — (3 ) (3 ) — — (3 ) (3 ) Relating to assets sold during the year — — 4 4 — — 5 5 Purchases and sales, net — — (6 ) (6 ) — — (7 ) (7 ) Balance December 31 $ — $ — $ 18 $ 18 $ — $ — $ 23 $ 23 International Pension Plans Balance January 1 $ 393 $ 5 $ 2 $ 400 $ 394 $ 23 $ 2 $ 419 Actual return on plan assets: Relating to assets still held at December 31 (9 ) 1 — (8 ) (28 ) (2 ) — (30 ) Purchases and sales, net 2 (2 ) (1 ) (1 ) 2 (16 ) — (14 ) Transfers into Level 3 26 — — 26 25 — — 25 Balance December 31 $ 412 $ 4 $ 1 $ 417 $ 393 $ 5 $ 2 $ 400
Summary of Expected Benefit Payments	Expected benefit payments are as follows: U.S. Pension Benefits International Pension Benefits Other Postretirement Benefits 2017 $ 561 $ 186 $ 101 2018 588 179 104 2019 629 195 106 2020 638 202 111 2021 655 201 115 2022 — 2026 3,596 1,168 641
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 2016 2015 2014 2016 2015 2014 2016 2015 2014 Net (loss) gain arising during the period $ (743 ) $ 73 $ (2,085 ) $ (380 ) $ (66 ) $ (779 ) $ (45 ) $ 209 $ (223 ) Prior service (cost) credit arising during the period (10 ) (13 ) (59 ) (2 ) (4 ) (8 ) (19 ) 511 (42 ) $ (753 ) $ 60 $ (2,144 ) $ (382 ) $ (70 ) $ (787 ) $ (64 ) $ 720 $ (265 ) Net loss amortization included in benefit cost $ 119 $ 214 $ 135 $ 87 $ 118 $ 74 $ 3 $ 5 $ 1 Prior service (credit) cost amortization included in benefit cost (55 ) (56 ) (61 ) (11 ) (14 ) (15 ) (106 ) (64 ) (72 ) $ 64 $ 158 $ 74 $ 76 $ 104 $ 59 $ (103 ) $ (59 ) $ (71 )
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 2016 2015 2014 2016 2015 2014 Net periodic benefit cost Discount rate 4.70 % 4.20 % 4.90 % 2.80 % 2.70 % 3.80 % Expected rate of return on plan assets 8.60 % 8.50 % 8.50 % 5.60 % 5.70 % 6.00 % Salary growth rate 4.30 % 4.40 % 4.50 % 2.90 % 2.90 % 3.10 % Benefit obligation Discount rate 4.30 % 4.80 % 4.20 % 2.20 % 2.80 % 2.70 % Salary growth rate 4.30 % 4.30 % 4.40 % 2.90 % 2.90 % 2.90 %
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 2016 2015 Health care cost trend rate assumed for next year 7.4 % 6.8 % 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 2027
One Percentage Point Change in Health Care Cost Trend Rate	A one percentage point change in the health care cost trend rate would have had the following effects: One Percentage Point Increase Decrease Effect on total service and interest cost components $ 12 $ (12 ) Effect on benefit obligation 138 (114 )
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair Values of Pension Plan and Other Postretirement Benefit Plan Assets	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 Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total 2016 2015 U.S. Pension Plans Assets Cash and cash equivalents $ 2 $ 2 $ — $ 4 $ — $ — $ — $ — Investment funds Developed markets equities 521 — — 521 566 — — 566 Emerging markets equities 104 — — 104 87 — — 87 Equity securities Developed markets 2,521 — — 2,521 2,444 — — 2,444 Fixed income securities Government and agency obligations — 475 — 475 — 391 — 391 Corporate obligations — 660 — 660 — 679 — 679 Mortgage and asset-backed securities — 239 — 239 — 236 — 236 Other investments — — 18 18 — — 23 23 Net assets in fair value hierarchy $ 3,148 $ 1,376 $ 18 $ 4,542 $ 3,097 $ 1,306 $ 23 $ 4,426 Investments measured at NAV practical expedient (1) 5,224 4,840 Plan assets at fair value $ 9,766 $ 9,266 International Pension Plans Assets Cash and cash equivalents $ 42 $ 11 $ — $ 53 $ 63 $ 4 $ — $ 67 Investment funds Developed markets equities 187 2,846 — 3,033 184 2,738 — 2,922 Emerging markets equities 24 148 — 172 21 137 — 158 Government and agency obligations 123 1,904 — 2,027 305 1,115 — 1,420 Corporate obligations 2 282 — 284 173 103 — 276 Fixed income obligations 6 3 — 9 8 3 — 11 Real estate (2) — 3 4 7 — 3 5 8 Equity securities Developed markets 565 — — 565 496 — — 496 Fixed income securities Government and agency obligations 2 235 — 237 2 465 — 467 Corporate obligations — 92 — 92 — 161 — 161 Mortgage and asset-backed securities — 50 — 50 — 68 — 68 Other investments Insurance contracts (3) — 59 412 471 — 57 393 450 Other 1 4 1 6 — 3 2 5 Net assets in fair value hierarchy $ 952 $ 5,637 $ 417 $ 7,006 $ 1,252 $ 4,857 $ 400 $ 6,509 Investments measured at NAV practical expedient (1) 788 695 Plan assets at fair value $ 7,794 $ 7,204 (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 fair value 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, 2016 and 2015. (2) The plans’ Level 3 investments in real estate funds are generally valued by market appraisals of the underlying investments in the funds. (3) 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.
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair Values of Pension Plan and Other Postretirement Benefit 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 Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Quoted Prices In Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total 2016 2015 Assets Cash and cash equivalents $ 125 $ — $ — $ 125 $ 65 $ — $ — $ 65 Investment funds Developed markets equities 48 — — 48 53 — — 53 Emerging markets equities 10 — — 10 29 — — 29 Government and agency obligations 1 — — 1 2 — — 2 Equity securities Developed markets 231 — — 231 229 — — 229 Fixed income securities Government and agency obligations — 43 — 43 — 339 — 339 Corporate obligations — 60 — 60 — 311 — 311 Mortgage and asset-backed securities — 22 — 22 — 218 — 218 Net assets in fair value hierarchy $ 415 $ 125 $ — $ 540 $ 378 $ 868 $ — $ 1,246 Investments measured at NAV practical expedient (1) 479 667 Plan assets at fair value $ 1,019 $ 1,913 (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 fair value 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, 2016 and 2015.

Other (Income) Expense, Net (Ta

Other (Income) Expense, Net (Tables)	12 Months Ended
	Dec. 31, 2016
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (income) expense, net, consisted of: Years Ended December 31 2016 2015 2014 Interest income $ (328 ) $ (289 ) $ (266 ) Interest expense 693 672 732 Exchange losses 174 1,277 180 Equity income from affiliates (86 ) (205 ) (257 ) Other, net 267 72 (12,002 ) $ 720 $ 1,527 $ (11,613 )

Taxes on Income (Tables)

Taxes on Income (Tables)	12 Months Ended
	Dec. 31, 2016
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: 2016 2015 2014 Amount Tax Rate Amount Tax Rate Amount Tax Rate U.S. statutory rate applied to income before taxes $ 1,631 35.0 % $ 1,890 35.0 % $ 6,049 35.0 % Differential arising from: Foreign earnings (1,593 ) (34.2 ) (2,105 ) (39.0 ) (1,367 ) (7.9 ) Unremitted foreign earnings (30 ) (0.6 ) 260 4.8 (209 ) (1.2 ) Tax settlements — — (417 ) (7.7 ) (89 ) (0.5 ) AstraZeneca option exercise — — — — (774 ) (4.5 ) Sale of Sirna Therapeutics, Inc. — — — — (357 ) (2.1 ) Impact of purchase accounting adjustments, including amortization 623 13.4 797 14.8 1,013 5.9 Foreign currency devaluation related to Venezuela — — 321 5.9 — — State taxes 173 3.7 159 2.9 7 — Restructuring 145 3.1 167 3.1 289 1.7 U.S. health care reform legislation 68 1.4 66 1.2 134 0.8 Divestiture of Merck Consumer Care — — — — 440 2.5 Other (1) (299 ) (6.4 ) (196 ) (3.6 ) 213 1.2 $ 718 15.4 % $ 942 17.4 % $ 5,349 30.9 % (1) Other includes the tax effect of contingency reserves, research credits, and miscellaneous items.
Income Before Taxes	Income before taxes consisted of: Years Ended December 31 2016 2015 2014 Domestic $ 518 $ 2,247 $ 15,730 Foreign 4,141 3,154 1,553 $ 4,659 $ 5,401 $ 17,283
Taxes on Income	Taxes on income consisted of: Years Ended December 31 2016 2015 2014 Current provision Federal $ 1,166 $ 732 $ 7,136 Foreign 916 844 438 State 157 130 375 2,239 1,706 7,949 Deferred provision Federal (1,255 ) (552 ) (2,162 ) Foreign (225 ) (163 ) (201 ) State (41 ) (49 ) (237 ) (1,521 ) (764 ) (2,600 ) $ 718 $ 942 $ 5,349
Deferred Income Taxes	Deferred income taxes at December 31 consisted of: 2016 2015 Assets Liabilities Assets Liabilities Intangibles $ 86 $ 3,734 $ — $ 4,962 Inventory related 30 660 49 752 Accelerated depreciation 28 927 43 910 Unremitted foreign earnings — 2,044 — 2,124 Pensions and other postretirement benefits 727 109 435 131 Compensation related 438 — 535 — Unrecognized tax benefits 383 — 412 — Net operating losses and other tax credit carryforwards 437 — 565 — Other 1,128 46 1,217 — Subtotal 3,257 7,520 3,256 8,879 Valuation allowance (268 ) (304 ) Total deferred taxes $ 2,989 $ 7,520 $ 2,952 $ 8,879 Net deferred income taxes $ 4,531 $ 5,927 Recognized as: Other assets $ 546 $ 608 Deferred income taxes $ 5,077 $ 6,535
Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2016 2015 2014 Balance January 1 $ 3,448 $ 3,534 $ 3,503 Additions related to current year positions 196 198 389 Additions related to prior year positions 75 53 23 Reductions for tax positions of prior years (1) (90 ) (59 ) (156 ) Settlements (1) (92 ) (184 ) (161 ) Lapse of statute of limitations (43 ) (94 ) (64 ) Balance December 31 $ 3,494 $ 3,448 $ 3,534 (1) Amounts reflect the settlements with the IRS as discussed below.

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2016
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 2016 2015 2014 Net income attributable to Merck & Co., Inc. $ 3,920 $ 4,442 $ 11,920 Average common shares outstanding 2,766 2,816 2,894 Common shares issuable (1) 21 25 34 Average common shares outstanding assuming dilution 2,787 2,841 2,928 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders $ 1.42 $ 1.58 $ 4.12 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders $ 1.41 $ 1.56 $ 4.07 (1) Issuable primarily under share-based compensation plans.

Other Comprehensive Income (L41

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2016
Other Comprehensive Income (Loss), Net of Tax [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, 2014, net of taxes $ 132 $ 54 $ (909 ) $ (1,474 ) $ (2,197 ) Other comprehensive income (loss) before reclassification adjustments, pretax 778 48 (3,196 ) (412 ) (2,782 ) Tax (285 ) (17 ) 1,067 (92 ) 673 Other comprehensive income (loss) before reclassification adjustments, net of taxes 493 31 (2,129 ) (504 ) (2,109 ) Reclassification adjustments, pretax (146 ) (1) 43 (2) 62 (3) — (41 ) Tax 51 (17 ) (10 ) — 24 Reclassification adjustments, net of taxes (95 ) 26 52 — (17 ) Other comprehensive income (loss), net of taxes 398 57 (2,077 ) (504 ) (2,126 ) Balance December 31, 2014, net of taxes 530 111 (2,986 ) (1,978 ) (4,323 ) Other comprehensive income (loss) before reclassification adjustments, pretax 526 (9 ) 710 (158 ) 1,069 Tax (177 ) (13 ) (272 ) (28 ) (490 ) Other comprehensive income (loss) before reclassification adjustments, net of taxes 349 (22 ) 438 (186 ) 579 Reclassification adjustments, pretax (731 ) (1) (73 ) (2) 203 (3) (22 ) (623 ) Tax 256 25 (62 ) — 219 Reclassification adjustments, net of taxes (475 ) (48 ) 141 (22 ) (404 ) Other comprehensive income (loss), net of taxes (126 ) (70 ) 579 (208 ) 175 Balance December 31, 2015, net of taxes 404 41 (2,407 ) (4) (2,186 ) (4,148 ) Other comprehensive income (loss) before reclassification adjustments, pretax 210 (38 ) (1,199 ) (150 ) (1,177 ) Tax (72 ) 16 363 (19 ) 288 Other comprehensive income (loss) before reclassification adjustments, net of taxes 138 (22 ) (836 ) (169 ) (889 ) Reclassification adjustments, pretax (314 ) (1) (31 ) (2) 37 (3) — (308 ) Tax 110 9 — — 119 Reclassification adjustments, net of taxes (204 ) (22 ) 37 — (189 ) Other comprehensive income (loss), net of taxes (66 ) (44 ) (799 ) (169 ) (1,078 ) Balance December 31, 2016, net of taxes $ 338 $ (3 ) $ (3,206 ) (4) $ (2,355 ) $ (5,226 ) (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 . (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 $ 3.9 billion and $3.3 billion at December 31, 2016 and 2015 , respectively, and other postretirement benefit plan net loss of $115 million and $86 million at December 31, 2016 and in 2015 , respectively, as well as pension plan prior service credit of $361 million and $414 million at December 31, 2016 and 2015 , respectively, and other postretirement benefit plan prior service credit of $466 million and $547 million at December 31, 2016 and 2015 , respectively.

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Sales of Company's Products	Sales of the Company’s products were as follows: Years Ended December 31 2016 2015 2014 Primary Care and Women’s Health Cardiovascular Zetia $ 2,560 $ 2,526 $ 2,650 Vytorin 1,141 1,251 1,516 Diabetes Januvia 3,908 3,863 3,931 Janumet 2,201 2,151 2,071 General Medicine and Women’s Health NuvaRing 777 732 723 Implanon/Nexplanon 606 588 502 Dulera 436 536 460 Follistim AQ 355 383 412 Hospital and Specialty Hepatitis Zepatier 555 — — HIV Isentress 1,387 1,511 1,673 Hospital Acute Care Cubicin (1) 1,087 1,127 25 Noxafil 595 487 402 Invanz 561 569 529 Cancidas 558 573 681 Bridion 482 353 340 Primaxin 297 313 329 Immunology Remicade 1,268 1,794 2,372 Simponi 766 690 689 Oncology Keytruda 1,402 566 55 Emend 549 535 553 Temodar 283 312 350 Diversified Brands Respiratory Singulair 915 931 1,092 Nasonex 537 858 1,099 Other Cozaar/Hyzaar 511 667 806 Arcoxia 450 471 519 Fosamax 284 359 470 Zocor 186 217 258 Vaccines (2) Gardasil/Gardasil 9 2,173 1,908 1,738 ProQuad/M-M-R II/Varivax 1,640 1,505 1,394 Zostavax 685 749 765 RotaTeq 652 610 659 Pneumovax 23 641 542 746 Other pharmaceutical (3) 4,703 5,105 6,233 Total Pharmaceutical segment sales 35,151 34,782 36,042 Other segment sales (4) 3,862 3,667 5,758 Total segment sales 39,013 38,449 41,800 Other (5) 794 1,049 437 $ 39,807 $ 39,498 $ 42,237 (1) Sales of Cubicin in 2015 represent sales subsequent to the Cubist acquisition date. Sales of Cubicin in 2014 reflect sales in Japan pursuant to a previously existing licensing agreement. (2) These amounts do not reflect sales of vaccines sold in most major European markets through the Company’s joint venture, SPMSD, the results of which are reflected in equity income from affiliates which is included in Other (income) expense, net . These amounts do, however, reflect supply sales to SPMSD. On December 31, 2016, Merck and Sanofi terminated the SPMSD joint venture (see Note 8). (3) Other pharmaceutical primarily reflects sales of other human health pharmaceutical products, including products within the franchises not listed separately. (4) Represents the non-reportable segments of Animal Health, Healthcare Services and Alliances, as well as Consumer Care until its divestiture on October 1, 2014 (see Note 3). The Alliances segment includes revenue from the Company’s relationship with AZLP until termination on June 30, 2014 (see Note 8). (5) Other is primarily comprised of miscellaneous corporate revenues, including revenue hedging activities, as well as third-party manufacturing sales. Other in 2016 and 2014 also includes approximately $170 million and $232 million , respectively, in connection with the sale of the marketing rights to certain products.
Consolidated Revenues by Geographic Area	Consolidated revenues by geographic area where derived are as follows: Years Ended December 31 2016 2015 2014 United States $ 18,478 $ 17,519 $ 17,071 Europe, Middle East and Africa 10,953 10,677 13,174 Asia Pacific 3,918 3,825 3,952 Japan 2,846 2,673 3,471 Latin America 2,155 2,825 3,151 Other 1,457 1,979 1,418 $ 39,807 $ 39,498 $ 42,237
Reconciliation of Segment Profits to Income Before Taxes	A reconciliation of total segment profits to consolidated Income before taxes is as follows: Years Ended December 31 2016 2015 2014 Segment profits: Pharmaceutical segment $ 22,180 $ 21,658 $ 22,164 Other segments 1,507 1,573 2,386 Total segment profits 23,687 23,231 24,550 Other profits 481 810 627 Unallocated: Interest income 328 289 266 Interest expense (693 ) (672 ) (732 ) Equity income from affiliates (19 ) 135 59 Depreciation and amortization (1,585 ) (1,573 ) (2,452 ) Research and development (9,084 ) (5,871 ) (5,823 ) Amortization of purchase accounting adjustments (3,692 ) (4,816 ) (4,182 ) Restructuring costs (651 ) (619 ) (1,013 ) Gain on sale of certain migraine clinical development programs 100 250 — Charge related to the settlement of worldwide Keytruda patent litigation (625 ) — — Gain on divestiture of certain ophthalmic products — 147 480 Foreign currency devaluation related to Venezuela — (876 ) — Net charge related to the settlement of Vioxx shareholder class action litigation — (680 ) — Gain on divestiture of Merck Consumer Care — — 11,209 Gain on AstraZeneca option exercise — — 741 Loss on extinguishment of debt — — (628 ) Other unallocated, net (3,588 ) (4,354 ) (5,819 ) $ 4,659 $ 5,401 $ 17,283
Equity Income from Affiliates and Depreciation and Amortization Included in Segment Profits	Equity income from affiliates and depreciation and amortization included in segment profits is as follows: Pharmaceutical All Other Total Year Ended December 31, 2016 Included in segment profits: Equity income from affiliates $ 105 $ — $ 105 Depreciation and amortization (160 ) (23 ) (183 ) Year Ended December 31, 2015 Included in segment profits: Equity income from affiliates $ 70 $ — $ 70 Depreciation and amortization (82 ) (18 ) (100 ) Year Ended December 31, 2014 Included in segment profits: Equity income from affiliates $ 90 $ 108 $ 198 Depreciation and amortization (39 ) (18 ) (57 )
Property, Plant and Equipment, Net by Geographic Area	Property, plant and equipment, net by geographic area where located is as follows: December 31 2016 2015 2014 United States $ 8,114 $ 8,467 $ 8,727 Europe, Middle East and Africa 2,732 2,844 3,120 Asia Pacific 775 842 897 Latin America 234 182 207 Japan 164 164 172 Other 7 8 13 $ 12,026 $ 12,507 $ 13,136

Nature of Operations (Details)

Nature of Operations (Details)	12 Months Ended
	Dec. 31, 2016segment
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments	4

Summary of Accounting Policie44

Summary of Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary Of Significant Accounting Policies [Line Items]
Accrual for chargebacks reflected as direct reduction to Accounts receivable	$ 196	$ 145
Accrual for rebates included in Accrued and other current liabilities	2,700	2,700
Depreciation expense	1,600	1,600	$ 2,500
Advertising expenses	2,100	2,100	$ 2,300
Enterprise wide resource planning system
Summary Of Significant Accounting Policies [Line Items]
Unamortized capitalized software costs	$ 452	$ 421
Minimum
Summary Of Significant Accounting Policies [Line Items]
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 | Building
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property, plant and equipment	25 years
Minimum | Machinery and Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property, plant and equipment	3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets	20 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 | Building
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property, plant and equipment	45 years
Maximum | Machinery and Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of property, plant and equipment	15 years

Summary of Accounting Policie45

Summary of Accounting Policies - New Accounting Pronouncements Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense (benefit)	$ 718	$ 942	$ 5,349
Accounting Standards Update 2015-03
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance costs				$ 100
Adjustments for New Accounting Pronouncements
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax expense (benefit)	$ (79)
Share-based compensation tax payment		$ 117	$ 129

Restructuring - Narrative (Deta

Restructuring - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)position	Dec. 31, 2015USD ($)position	Dec. 31, 2014USD ($)position
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1,069	$ 1,110	$ 1,978
Cumulative restructuring costs incurred to date since program inception	$ 12,600
Number of positions elimination since inception of program | position	40,900
Expected remaining costs related to restructuring program activities	$ 700
Percentage estimate of cumulative pretax costs that will result in cash outlays (primarily from employee separation expense) (as percent)	66.67%
Percentage estimate of cumulative pretax costs that will be non-cash (primarily from accelerated depreciation of facilities) (as percent)	33.33%
Number of positions eliminated | position	2,625	3,770	6,085
Asset abandonment, shut-down and other related costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 409	$ 550	$ 240
Facility Closing
Restructuring Cost and Reserve [Line Items]
Pretax losses resulting from sales of facilities and related assets	$ 151	$ 117	$ 133

Restructuring - Charges Related

Restructuring - Charges Related to Restructuring Program Activities by Type of Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1,069	$ 1,110	$ 1,978
Materials and production
Restructuring Cost and Reserve [Line Items]
Restructuring costs	181	361	482
Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	95	78	200
Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring costs	142	52	283
Restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	651	619	1,013
Separation Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	216	208	674
Separation Costs | Materials and production
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	0	0
Separation Costs | Marketing 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	216	208	674
Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Restructuring costs	227	174	900
Accelerated Depreciation | Materials and production
Restructuring Cost and Reserve [Line Items]
Restructuring costs	77	78	429
Accelerated Depreciation | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	8	59	198
Accelerated Depreciation | Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring costs	142	37	273
Accelerated Depreciation | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	0	0
Other
Restructuring Cost and Reserve [Line Items]
Restructuring costs	626	728	404
Other | Materials and production
Restructuring Cost and Reserve [Line Items]
Restructuring costs	104	283	53
Other | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring costs	87	19	2
Other | Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	15	10
Other | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 435	$ 411	$ 339

Restructuring - Charges and Spe

Restructuring - Charges and Spending Relating to Restructuring Activities by Program (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	$ 645	$ 1,051
Expenses	1,069	1,110	$ 1,978
(Payments) receipts, net	(760)	(1,082)
Non-cash activity	(413)	(434)
Restructuring reserve, ending balance	541	645	1,051
Separation Costs
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	592	1,031
Expenses	216	208	674
(Payments) receipts, net	(413)	(647)
Non-cash activity	0	0
Restructuring reserve, ending balance	395	592	1,031
Accelerated Depreciation
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	0	0
Expenses	227	174	900
(Payments) receipts, net	0	0
Non-cash activity	(227)	(174)
Restructuring reserve, ending balance	0	0	0
Other
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	53	20
Expenses	626	728	404
(Payments) receipts, net	(347)	(435)
Non-cash activity	(186)	(260)
Restructuring reserve, ending balance	$ 146	$ 53	$ 20

Acquisitions, Divestitures, R49

Acquisitions, Divestitures, Research Collaborations and License Agreements - Narrative (Detail)	Dec. 31, 2016USD ($)	Jan. 21, 2015USD ($)	Oct. 01, 2014USD ($)	Jul. 31, 2016USD ($)	Jun. 30, 2016USD ($)	Jan. 31, 2016USD ($)	Jul. 31, 2015USD ($)	Feb. 28, 2015USD ($)renewal	Dec. 31, 2014USD ($)	Aug. 31, 2014USD ($)	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration	$ 891,000,000								$ 428,000,000			$ 891,000,000	$ 590,000,000	$ 428,000,000
Goodwill	$ 18,162,000,000								12,992,000,000			18,162,000,000	17,723,000,000	12,992,000,000
Discount rate (as percent)	11.50%
In-process research and development impairment charges												3,600,000,000	63,000,000	49,000,000
Changes in fair value												407,000,000	16,000,000
Agreement term								2 years
Payment to Bayer AG for collaboration rights												0	0	1,000,000,000
Payments to acquire business, net of cash acquired												780,000,000	146,000,000	181,000,000
Liability	$ 8,514,000,000											8,514,000,000	7,345,000,000
Amortization expense for intangible assets												3,800,000,000	4,800,000,000	4,200,000,000
monoclonal antibody (cCAM)
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
In-process research and development impairment charges												180,000,000
Changes in fair value												116,000,000
BET inhibitor (OncoEthix)
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
In-process research and development impairment charges												143,000,000
Changes in fair value												40,000,000
uprifosbuvir
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
In-process research and development impairment charges												2,900,000,000
Afferent Pharmaceuticals
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Consideration transferred in business combination				$ 510,000,000
Cash paid for acquisition of business				487,000,000
Potential future milestone payments, maximum				750,000,000
Contingent consideration				223,000,000
In-process research and development (IPR&D)				832,000,000
Deferred income tax liabilities				258,000,000
Other net assets				29,000,000
Goodwill				$ 130,000,000
Discount rate (as percent)				11.50%
StayWell Company
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Cash paid for acquisition of business				$ 150,000,000
Deferred income tax liabilities				84,000,000
Goodwill				275,000,000
Fair value of debt assumed in business combination				$ 150,000,000
Period before option becomes exercisable				3 years
Identifiable intangible assets				$ 238,000,000
Other net liabilities				5,000,000
Noncontrolling interest				$ 124,000,000
Estimated useful life of intangible assets, acquired				10 years
Estimated useful life of intangible assets				5 years
Vallee SA
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Voting rights acquired in acquisition (as percent)				93.00%
Estimated future payment to acquire business				$ 400,000,000
Moderna Therapeutics
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Upfront and milestone payments					$ 200,000,000
IOmet Pharma Ltd
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Cash paid for acquisition of business						$ 150,000,000
Potential future milestone payments, maximum						250,000,000
Contingent consideration						94,000,000
In-process research and development (IPR&D)						155,000,000
Goodwill						$ 57,000,000
Discount rate (as percent)						10.50%
Deferred tax assets						$ 32,000,000
cCAM Biotherapeutics
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Cash paid for acquisition of business							$ 96,000,000
Potential future milestone payments, maximum							510,000,000
Contingent consideration							105,000,000
In-process research and development (IPR&D)							180,000,000
Goodwill							14,000,000
Other net noncurrent assets							$ 7,000,000
NGM Biopharmaceuticals
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Upfront and milestone payments								$ 94,000,000
Cost Method Investment, ownership percentage								15.00%
Payments to acquire cost method investment								$ 106,000,000
Purchase commitment, maximum amount (up to)								$ 250,000,000
Agreement term								5 years
Revenue and cost allocation percentage (as percent) (up to)								50.00%
Number of extensions for research agreement | renewal								2
Cubist Pharmaceuticals Inc
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Consideration transferred in business combination		$ 8,300,000,000
Cash paid for acquisition of business		7,800,000,000
In-process research and development (IPR&D)		50,000,000
Deferred income tax liabilities		2,519,000,000
Other net assets		55,000,000
Goodwill		$ 4,670,000,000
Discount rate (as percent)		8.00%
Fair value of debt assumed in business combination		$ 1,900,000,000
Identifiable intangible assets		6,923,000,000
Other net liabilities		$ 122,000,000
Estimated useful life of intangible assets, acquired		11 years
Transaction costs													$ 324,000,000
Other net noncurrent assets		$ 184,000,000
Cubist Pharmaceuticals Inc | Other noncurrent liabilities
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration		$ 50,000,000
OncoEthix
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Cash paid for acquisition of business									110,000,000
Potential future milestone payments, maximum									265,000,000					265,000,000
Contingent consideration									43,000,000					43,000,000
In-process research and development (IPR&D)									143,000,000					143,000,000
Other net noncurrent assets									$ 10,000,000					$ 10,000,000
Bayer AG
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Identifiable intangible assets			$ 915,000,000
Estimated useful life of intangible assets											10 years 6 months
Payment to Bayer AG for collaboration rights			1,000,000,000
Potential future milestone payments	$ 775,000,000		1,100,000,000									$ 775,000,000
Fair value of IPR&D that was expensed			$ 85,000,000
Liability					350,000,000						$ 350,000,000
Amortization expense for intangible assets											50,000,000
Intangible assets, net					300,000,000						300,000,000
Bayer AG | Other noncurrent liabilities
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Potential future milestone payments					$ 350,000,000						$ 350,000,000
Bayer AG | Adempas
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Discount rate (as percent)			10.00%
Estimated useful life of intangible assets			12 years
Bayer AG | vericiguat
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Discount rate (as percent)			10.50%
Idenix Pharmaceuticals, Inc.
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Consideration transferred in business combination										$ 3,900,000,000
In-process research and development (IPR&D)										3,200,000,000
Deferred income tax liabilities										951,000,000
Goodwill										$ 1,500,000,000
Discount rate (as percent)										11.50%
Other net liabilities										$ 12,000,000
Payments to acquire business, net of cash acquired										$ 3,700,000,000

Acquisitions, Divestitures, R50

Acquisitions, Divestitures, Research Collaborations and License Agreements - Divestitures Narrative (Detail) - USD ($)	Oct. 01, 2014	Apr. 30, 2016	Aug. 31, 2015	Feb. 28, 2015	May 31, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jul. 31, 2015
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Agreement term				2 years
Divestiture of Merck Consumer Care business, net of cash divested							$ 0	$ 0	$ 13,951,000,000
Gain on divestiture of Merck Consumer Care							0	0	11,209,000,000
Income tax expense (benefit)							718,000,000	942,000,000	5,349,000,000
Proceeds from sale of intangible assets							170,000,000	232,000,000
Saphris
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Proceeds from sale of intangible assets									232,000,000
CGRP receptor antagonists
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Total consideration received for sale of clinical development programs										$ 250,000,000
Proceeds from collaborators		$ 125,000,000	$ 125,000,000
Gain (loss) on sale of clinical development programs							$ 100,000,000	250,000,000
Consumer Care
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Proceeds from divestiture of business	$ 14,200,000,000
Divestiture of Merck Consumer Care business, net of cash divested	$ 14,000,000,000
Gain on divestiture of Merck Consumer Care									11,200,000,000
Ophthalmic products
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Proceeds from divestiture of business								170,000,000	565,000,000
Gain on disposition of business								$ 147,000,000	480,000,000
Ophthalmic products | Minimum
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Agreement term					2 years
Ophthalmic products | Maximum
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Agreement term					5 years
Sirna Therapeutics Inc.
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Proceeds from sale of subsidiary						$ 25,000,000
Shares received in consideration for sale of asset						2,520,044
Gain on disposition of subsidiary									204,000,000
Income tax expense (benefit)									$ (300,000,000)

Acquisitions, Divestitures, R51

Acquisitions, Divestitures, Research Collaborations and License Agreements - Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Jan. 21, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Goodwill		$ 18,162	$ 17,723	$ 12,992
Contingent consideration		$ 891	$ 590	$ 428
Cubist Pharmaceuticals Inc
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Cash and cash equivalents	$ 733
Accounts receivable	123
Inventories	216
Other current assets	55
Property, plant and equipment	151
Products and product rights (11 year weighted-average useful life)	6,923
IPR&D	50
Other noncurrent assets	184
Current liabilities	(233)
Deferred income tax liabilities	(2,519)
Long-term debt	(1,900)
Other noncurrent liabilities	(122)
Total identifiable net assets	3,661
Goodwill	4,670
Consideration transferred	$ 8,331
Finite-lived intangible assets, useful life	11 years
Cubist Pharmaceuticals Inc | Other current liabilities
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration	$ 73
Cubist Pharmaceuticals Inc | Other noncurrent liabilities
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration	$ 50

Acquisitions, Divestitures, R52

Acquisitions, Divestitures, Research Collaborations and License Agreements - Pro Forma Financial Information (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Business Combinations [Abstract]
Sales	$ 39,584	$ 43,437
Net income attributable to Merck & Co., Inc.	$ 4,640	$ 10,887
Basic earnings per common share attributable to Merck & Co., Inc. common shareholders (in dollars per share)	$ 1.65	$ 3.76
Earnings per common share assuming dilution attributable to Merck & Co. Inc. common shareholders (in dollars per share)	$ 1.63	$ 3.72

Financial Instruments - Narrati

Financial Instruments - Narrative (Details)	12 Months Ended
	Dec. 31, 2016USD ($)interest_rate_swap	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Nov. 30, 2016EUR (€)	May 31, 2016USD ($)interest_rate_swap	Oct. 31, 2014EUR (€)	Dec. 31, 2013USD ($)
Derivative [Line Items]
Maximum planning cycle of third-party sales hedges (no more than)	2 years
Pretax gains (losses) from euro-denominated notes included in cumulative translation adjustments	$ 193,000,000	$ 304,000,000	$ 294,000,000
Number of interest rate swaps held | interest_rate_swap	26
Notional amount of derivative	$ 25,539,000,000	27,060,000,000
Par Value of Debt | €				€ 1,000,000,000		€ 2,500,000,000
Pre tax net unrealized gain (loss) on derivatives maturing within next 12 months estimated to be reclassified from AOCI to sales	462,000,000
Available-for-sale debt securities included in Short-term investments	7,800,000,000
Available-for-sale debt securities maturing after one year through five years	10,200,000,000
Cash and cash equivalents	6,515,000,000	8,524,000,000	$ 7,441,000,000				$ 15,621,000,000
Fair value of loans payable and long-term debt, including current portion	25,700,000,000	27,000,000,000
Carrying value of Loans payable and long-term debt, including current portion	24,800,000,000	26,400,000,000
Total accounts receivable outstanding in excess of one year	$ 140,000,000
Percentage of accounts receivable represented by customers with largest balances (as percent)	40.00%
Cash collateral received from counterparties	$ 529,000,000	$ 862,000,000
Significant Other Observable Inputs (Level 2)
Derivative [Line Items]
Cash and cash equivalents	6,500,000,000
Cash equivalents	$ 5,400,000,000
0.70% notes due 2016 | Interest Rate Swap
Derivative [Line Items]
Number of interest rate swaps held | interest_rate_swap					4
Notional amount of derivative					$ 250,000,000
Par Value of Debt					$ 1,000,000,000
Fixed-rate notes, stated interest rate (as percent)					0.70%

Financial Instruments - Informa

Financial Instruments - Information About Interest Rate Swaps (Details)	Dec. 31, 2016USD ($)interest_rate_swap	Nov. 30, 2016EUR (€)	Dec. 31, 2015USD ($)	Oct. 31, 2014EUR (€)
Derivative [Line Items]
Par Value of Debt | €		€ 1,000,000,000		€ 2,500,000,000
Number of Interest Rate Swaps Held | interest_rate_swap	26
U.S. Dollar Notional	$ 25,539,000,000		$ 27,060,000,000
1.30% notes due 2018 | 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)	1.30%
5.00% notes due 2019 | Interest Rate Swap
Derivative [Line Items]
Par Value of Debt	$ 1,250,000,000
Number of Interest Rate Swaps Held | interest_rate_swap	3
U.S. Dollar Notional	$ 550,000,000
Fixed-rate notes, stated interest rate (as percent)	5.00%
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 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, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	$ 995	$ 1,237
Fair Value of Derivative, Liability	134	63
U.S. Dollar Notional	25,539	27,060
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	765	1,007
Fair Value of Derivative, Liability	31	25
U.S. Dollar Notional	14,398	15,584
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	230	230
Fair Value of Derivative, Liability	103	38
U.S. Dollar Notional	11,141	11,476
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	20	42
U.S. Dollar Notional	2,700	2,700
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	0	1
U.S. Dollar Notional	0	1,000
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	29	23
U.S. Dollar Notional	3,500	3,500
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	129	386
Fair Value of Derivative, Liability
U.S. Dollar Notional	2,075	4,136
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1	1
U.S. Dollar Notional	48	77
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1	0
U.S. Dollar Notional	12	0
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	616	579
U.S. Dollar Notional	6,063	4,171
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	0	18
U.S. Dollar Notional	0	179
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	103	37
U.S. Dollar Notional	2,931	2,508
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	0	1
U.S. Dollar Notional	0	6
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	230	212
U.S. Dollar Notional	$ 8,210	$ 8,783

Financial Instruments - Infor56

Financial Instruments - Information on Derivative Positions Subject to Master Netting Arrangements as if they were Presented on a Net Basis (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross amounts recognized in the consolidated balance sheet, Asset	$ 995	$ 1,237
Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet, Asset	(131)	(59)
Cash collateral (received) posted, Asset	(529)	(862)
Net amounts, Asset	335	316
Gross amounts recognized in the consolidated balance sheet, Liability	134	63
Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet, Liability	(131)	(59)
Cash collateral (received) posted, Liability	0	0
Net amounts, Liability	$ 3	$ 4

Financial Instruments - Locatio

Financial Instruments - Location and Pretax Gain or Loss Amounts for Derivatives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Ineffectiveness on the hedged item	$ 1	$ 7	$ 3
Derivatives not designated in a hedging relationship | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (gain) loss recognized in Other (income) expense, net on derivatives	132	(461)	(516)
Amount of (gain) loss recognized in Sales	0	(1)	15
Derivatives designated in a fair value hedging relationship | Interest rate swap contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (gain) loss recognized in Other (income) expense, net on derivatives	28	(14)	(17)
Amount of loss (gain) recognized in Other (income) expense, net on hedged item	(29)	7	14
Derivatives designated in foreign currency cash flow hedging relationships | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain reclassified from AOCI to Sales	(311)	(724)	(143)
Amount of gain recognized in OCI on derivatives	(210)	(526)	(775)
Derivatives designated in foreign currency net investment hedging relationships | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain recognized in Other (income) expense, net on derivatives	(1)	(4)	(6)
Amount of gain recognized in OCI on derivatives	$ 2	$ (10)	$ (192)

Financial Instruments - Infor58

Financial Instruments - Information on Available-for-sale Investments (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 20,179	$ 18,116
Amortized Cost	20,158	18,025
Gross Unrealized Gains	89	155
Gross Unrealized Losses	(68)	(64)
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Fair Value	4,330	2,977
Amortized Cost	4,330	2,977
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Corporate notes and bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value	10,577	10,259
Amortized Cost	10,601	10,299
Gross Unrealized Gains	15	7
Gross Unrealized Losses	(39)	(47)
U.S. government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	2,232	1,761
Amortized Cost	2,244	1,767
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(13)	(6)
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	1,376	1,284
Amortized Cost	1,380	1,290
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(5)	(6)
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	796	694
Amortized Cost	801	697
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(6)	(4)
Foreign government bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value	519	607
Amortized Cost	521	586
Gross Unrealized Gains	0	22
Gross Unrealized Losses	(2)	(1)
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	349	534
Amortized Cost	281	409
Gross Unrealized Gains	71	125
Gross Unrealized Losses	$ (3)	$ 0

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, 2016	Dec. 31, 2015	Dec. 31, 2014
Assets
Investments	$ 20,179	$ 18,116
Derivative assets	995	1,237
Liabilities
Contingent consideration	891	590	$ 428
Derivative liabilities	134	63
Commercial paper
Assets
Investments	4,330	2,977
Corporate notes and bonds
Assets
Investments	10,577	10,259
U.S. government and agency securities
Assets
Investments	2,232	1,761
Asset-backed securities
Assets
Investments	$ 1,376	1,284
Liabilities
Primary weighted-average lives of investment collateral (or less)	5 years
Mortgage-backed securities
Assets
Investments	$ 796	694
Foreign government bonds
Assets
Investments	519	607
Equity securities
Assets
Investments	349	534
Fair Value, Measurements, Recurring
Assets
Investments	19,242	17,942
Other assets	937	174
Derivative assets	995	1,237
Total assets	21,174	19,353
Liabilities
Contingent consideration	891	590
Derivative liabilities	134	63
Total liabilities	1,025	653
Fair Value, Measurements, Recurring | Purchased currency options
Assets
Derivative assets	644	1,041
Liabilities
Derivative liabilities	12	1
Fair Value, Measurements, Recurring | Foreign exchange contracts
Assets
Derivative assets	331	154
Liabilities
Derivative liabilities	93	38
Fair Value, Measurements, Recurring | Interest rate swap contracts
Assets
Derivative assets	20	42
Liabilities
Derivative liabilities	29	24
Fair Value, Measurements, Recurring | Commercial paper
Assets
Investments	4,330	2,977
Fair Value, Measurements, Recurring | Corporate notes and bonds
Assets
Investments	10,389	10,259
Other assets	188	0
Fair Value, Measurements, Recurring | U.S. government and agency securities
Assets
Investments	1,919	1,761
Other assets	313	0
Fair Value, Measurements, Recurring | Asset-backed securities
Assets
Investments	1,257	1,284
Other assets	119	0
Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets
Investments	628	694
Other assets	168	0
Fair Value, Measurements, Recurring | Foreign government bonds
Assets
Investments	518	607
Other assets	1	0
Fair Value, Measurements, Recurring | Equity securities
Assets
Investments	201	360
Other assets	148	174
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	230	360
Other assets	148	155
Derivative assets	0	0
Total assets	378	515
Liabilities
Contingent consideration	0	0
Derivative liabilities	0	0
Total liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Purchased currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Foreign exchange contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Interest rate swap contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Commercial paper
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Corporate notes and bonds
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | U.S. government and agency securities
Assets
Investments	29	0
Other assets	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Asset-backed securities
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Mortgage-backed securities
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Foreign government bonds
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Equity securities
Assets
Investments	201	360
Other assets	148	155
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Investments	19,012	17,582
Other assets	789	19
Derivative assets	995	1,237
Total assets	20,796	18,838
Liabilities
Contingent consideration	0	0
Derivative liabilities	134	63
Total liabilities	134	63
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Purchased currency options
Assets
Derivative assets	644	1,041
Liabilities
Derivative liabilities	12	1
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Assets
Derivative assets	331	154
Liabilities
Derivative liabilities	93	38
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swap contracts
Assets
Derivative assets	20	42
Liabilities
Derivative liabilities	29	24
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets
Investments	4,330	2,977
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate notes and bonds
Assets
Investments	10,389	10,259
Other assets	188	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. government and agency securities
Assets
Investments	1,890	1,761
Other assets	313	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed securities
Assets
Investments	1,257	1,284
Other assets	119	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-backed securities
Assets
Investments	628	694
Other assets	168	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign government bonds
Assets
Investments	518	607
Other assets	1	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Equity securities
Assets
Investments	0	0
Other assets	0	19
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Investments	0	0
Other assets	0	0
Derivative assets	0	0
Total assets	0	0
Liabilities
Contingent consideration	891	590
Derivative liabilities	0	0
Total liabilities	891	590
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Purchased currency options
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign exchange contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Interest rate swap contracts
Assets
Derivative assets	0	0
Liabilities
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Commercial paper
Assets
Investments	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate notes and bonds
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | U.S. government and agency securities
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Asset-backed securities
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Mortgage-backed securities
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Foreign government bonds
Assets
Investments	0	0
Other assets	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Equity securities
Assets
Investments	0	0
Other assets	$ 0	$ 0

Financial Instruments - Summari

Financial Instruments - Summarized Information About Changes in Liabilities for Contingent Consideration (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration	$ 590	$ 428
Changes in fair value	(407)	(16)
Additions	733	228
Payments	(25)	(50)
Contingent consideration	$ 891	$ 590

Inventories - Inventories (Deta

Inventories - Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Finished goods	$ 1,304	$ 1,343
Raw materials and work in process	4,222	4,374
Supplies	155	168
Total (approximates current cost)	5,681	5,885
Increase to LIFO costs	302	384
Total current and noncurrent inventories	5,983	6,269
Recognized as:
Inventories	4,866	4,700
Other assets	$ 1,117	$ 1,569

Inventories - Narrative (Detail

Inventories - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Inventory [Line Items]
LIFO Inventory Amount	$ 2,300	$ 2,400
Inventories classified in other assets	1,117	1,569
Inventory Not Expected to be Sold Within One Year
Inventory [Line Items]
Inventories classified in other assets	1,000	1,500
Inventories Produced in Preparation for Product Launches
Inventory [Line Items]
Inventories classified in other assets	$ 80	$ 63

Goodwill and Other Intangible63

Goodwill and Other Intangibles - Goodwill Activity by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 17,723	$ 12,992
Acquisitions	482	4,713
Divestitures		(18)
Impairments	(47)	(47)
Other	4	83
Goodwill, Ending Balance	18,162	17,723
Accumulated goodwill impairment losses	187	140
Pharmaceutical
Goodwill [Roll Forward]
Goodwill, Beginning Balance	15,862	11,108
Acquisitions	207	4,684
Divestitures		(18)
Impairments	0	0
Other	6	88
Goodwill, Ending Balance	16,075	15,862
All Other
Goodwill [Roll Forward]
Goodwill, Beginning Balance	1,861	1,884
Acquisitions	275	29
Divestitures		0
Impairments	(47)	(47)
Other	(2)	(5)
Goodwill, Ending Balance	$ 2,087	$ 1,861

Goodwill and Other Intangible64

Goodwill and Other Intangibles - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	$ 17,305	$ 22,602
Intangible asset impairment charge related to marketed product	347	45	$ 1,100
IPR&D reclassified to products and product rights upon receipt of marketing approval	8	280	654
IPR&D impairment charges	3,600	63	49
Amortization expense for intangible assets	3,800	4,800	4,200
Estimated Future Amortization Expense, 2017	3,200
Estimated Future Amortization Expense, 2018	2,800
Estimated Future Amortization Expense, 2019	1,400
Estimated Future Amortization Expense, 2020	1,200
Estimated Future Amortization Expense, 2021	1,100
IPR&D
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	1,653	4,226
Zerbaxa
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	3,300
Zetia
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	1,500
Sivextro
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	955
Vytorin
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	938
Implanon/Nexplanon
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	587
Dificid
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	561
Gardasil/Gardasil 9
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	468
NuvaRing
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	319
Nasonex
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	308
Adempas
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	872
Zontivity
Intangible Assets Excluding Goodwill [Line Items]
Intangible asset impairment charge related to marketed product	252
Grastek/Ragwitek
Intangible Assets Excluding Goodwill [Line Items]
Intangible asset impairment charge related to marketed product	95
PegIntron
Intangible Assets Excluding Goodwill [Line Items]
Intangible asset impairment charge related to marketed product			793
Victrelis
Intangible Assets Excluding Goodwill [Line Items]
Intangible asset impairment charge related to marketed product			244
Rebetol
Intangible Assets Excluding Goodwill [Line Items]
Intangible asset impairment charge related to marketed product			$ 35
uprifosbuvir
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges	2,900
uprifosbuvir | IPR&D
Intangible Assets Excluding Goodwill [Line Items]
Other intangibles, net	240
monoclonal antibody (cCAM)
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges	180
BET inhibitor (OncoEthix)
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges	143
diabetes treatment
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges	72
House Dust Mite
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges	112
Next Generation Ring
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges	$ 79
surotomycin
Intangible Assets Excluding Goodwill [Line Items]
IPR&D impairment charges		$ 50

Goodwill and Other Intangible65

Goodwill and Other Intangibles - Other Intangibles (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	$ 50,084	$ 51,791
Accumulated Amortization	32,779	29,189
Net	17,305	22,602
Products and product rights
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	46,269	45,949
Accumulated Amortization	31,919	28,514
Net	14,350	17,435
IPR&D
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	1,653	4,226
Net	1,653	4,226
Tradenames
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	215	198
Accumulated Amortization	89	79
Net	126	119
Other
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	1,947	1,418
Accumulated Amortization	771	596
Net	$ 1,176	$ 822

Joint Ventures and Other Equi66

Joint Ventures and Other Equity Method Affiliates - Narrative (Details) $ in Millions	Dec. 31, 2016USD ($)	Jun. 30, 2014USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 1998USD ($)	Dec. 31, 1993
Equity Income from Affiliates [Line Items]
Equity income from affiliates			$ 86	$ 205	$ 257
Investments in affiliates accounted for using the equity method	$ 715		715	702
Amounts due from equity method affiliates	1		1	34
Contingent consideration	$ 891		891	590	428
Proceeds from sale of intangible assets			170	232
Discount rate (as percent)	11.50%
Other intangibles, net	$ 17,305		17,305	22,602
Proceeds from AstraZeneca option exercise			0	0	419
Non-cash gain			98
Decrease in noncontrolling interest as a result of AstraZeneca option exercise					2,400
Reduction of goodwill				18
Deferred income taxes			1,521	764	2,600
Gardasil/Gardasil 9
Equity Income from Affiliates [Line Items]
Other intangibles, net	468		468
Step Acquisition and Termination of SPMSD
Equity Income from Affiliates [Line Items]
Investments in affiliates accounted for using the equity method	$ 183		$ 183
Equity interest acquired (as percent)	50.00%		50.00%
Consideration transferred in business combination	$ 657
Royalty rate (as percent)	11.50%
Contingent consideration	$ 416		$ 416
Proceeds from sale of intangible assets	596
Fair value of future royalties	$ 302		302
Discount rate (as percent)	8.00%
Transaction costs	$ 24
Sanofi Pasteur MSD
Equity Income from Affiliates [Line Items]
Sales of products marketed by the joint venture			1,000	923	1,100
AstraZeneca LP
Equity Income from Affiliates [Line Items]
Equity income from affiliates					192
Sales of products marketed by the joint venture					2,205
Agreed-upon payment to be made by AstraZeneca at closing for exercise of option		$ 327
Ownership percentage (as percent)							50.00%
Limited partner interest in AZLP (as percent)						1.00%
General partner interest in AZLP (as percent)						99.00%
Par value of preferred stock obligation assumed in connection with 1998 restructuring of AMI						$ 2,400
Preferred stock dividend rate (as percent)						5.00%
Revenue from AZLP					463
Proceeds from AstraZeneca option exercise		419
Recognition of deferred income			5	$ 182	140
Other income			$ 93
Portion of exercise that represents multiple of annual profit allocation recognized as a gain		$ 91
Multiple of average annual profit allocation to be included in option exercise price		10
Years prior to option exercise to be included in average annual profit allocation portion of exercise price		3 years
Non-cash gain					650
Decrease in noncontrolling interest as a result of AstraZeneca option exercise					2,400
Amount of investment sold					1,400
Reduction of goodwill					340
Deferred income taxes					$ 517

Joint Ventures and Other Equi67

Joint Ventures and Other Equity Method Affiliates Joint Ventures and Other Equity Method Affiliates - Termination of SPMSD (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 18,162	$ 17,723	$ 12,992
Investments in affiliates accounted for using the equity method	(715)	(702)
Net loss on termination of SPMSD joint venture	0	$ 0	$ 11,209
Step Acquisition and Termination of SPMSD
Business Acquisition [Line Items]
Products and product rights	936
Accounts receivable	133
Current liabilities	(221)
Deferred income tax liabilities	(175)
Other current assets	34
Goodwill	20
Total identifiable net assets	727
Consideration payable to Sanofi, net	(378)
Investments in affiliates accounted for using the equity method	(183)
Increase in net assets	166
Merck's share of restructuring costs	(77)
Net loss on termination of SPMSD joint venture	$ 89

Joint Ventures and Other Equi68

Joint Ventures and Other Equity Method Affiliates - Summarized Financial Information for AZLP (Details) - AstraZeneca LP - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2014	Dec. 31, 1998
Equity Income from Affiliates [Line Items]
Sales	$ 2,205
Materials and production costs	1,044
Other expense, net	604
Income before taxes	$ 557
Limited partner interest in AZLP (as percent)		1.00%

Loans Payable, Long-Term Debt69

Loans Payable, Long-Term Debt and Other Commitments - Narrative (Details)	1 Months Ended			12 Months Ended
	Nov. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Oct. 31, 2014USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Nov. 30, 2016EUR (€)	Nov. 30, 2014USD ($)	Oct. 31, 2014EUR (€)
Debt Instrument [Line Items]
Long-term debt, current maturities				$ 300,000,000	$ 2,300,000,000
Loans payable and current portion of long-term debt				568,000,000	2,583,000,000
Long-term debt				24,274,000,000	23,829,000,000
Principal amount of debt | €							€ 1,000,000,000		€ 2,500,000,000
Net proceeds of debt offering	$ 1,100,000,000		$ 3,100,000,000
Repayments of Debt			2,500,000,000
Face amount of debt repurchased			$ 1,800,000,000					$ 2,000,000,000
Loss on extinguishment of debt				$ 0	0	$ 628,000,000
Maximum total debt to capitalization ratio allowable by financial covenants under certain borrowings (not to exceed) (as percent)				60.00%
Long-term debt, maturities, repayments of principal in 2017				$ 301,000,000
Long-term debt, maturities, repayments of principal in 2018				3,000,000,000
Long-term debt, maturities, repayments of principal in 2019				1,300,000,000
Long-term debt, maturities, repayments of principal in 2020				1,900,000,000
Long-term debt, maturities, repayments of principal in 2021				2,200,000,000
Available borrowing capacity under credit facility		$ 6,000,000,000
Term of debt		5 years
Rental expense under operating leases net of sublease income				292,000,000	303,000,000	$ 350,000,000
Minimum aggregate rental commitments under noncancellable leases in 2017				200,000,000
Minimum aggregate rental commitments under noncancellable leases in 2018				141,000,000
Minimum aggregate rental commitments under noncancellable leases in 2019				122,000,000
Minimum aggregate rental commitments under noncancellable leases in 2020				88,000,000
Minimum aggregate rental commitments under noncancellable leases in 2021				63,000,000
Minimum aggregate rental commitments under noncancellable leases thereafter				140,000,000
Other Variable Rate Debt
Debt Instrument [Line Items]
Long-term debt				$ 147,000,000	$ 223,000,000
Effective interest rate (as percent)				0.89%	0.00%
Other Foreign Debt
Debt Instrument [Line Items]
Long-term debt					$ 43,000,000
Stated interest rate (as percent)					4.75%
6.30% debentures due 2026
Debt Instrument [Line Items]
Long-term debt				$ 152,000,000	$ 152,000,000
Stated interest rate (as percent)				6.30%
0.50% euro-denominated notes due 2024
Debt Instrument [Line Items]
Long-term debt				$ 516,000,000	0
Stated interest rate (as percent)				0.50%			0.50%
Principal amount of debt | €							€ 500,000,000
1.375% euro-denominated notes due 2036
Debt Instrument [Line Items]
Long-term debt				$ 512,000,000	0
Stated interest rate (as percent)				1.375%			1.375%
Principal amount of debt | €							€ 500,000,000
Notes Subject To Repayment At Option Of Holder
Debt Instrument [Line Items]
Loans payable and current portion of long-term debt				$ 267,000,000	225,000,000
Short Term Foreign Borrowings
Debt Instrument [Line Items]
Loans payable and current portion of long-term debt					$ 10,000,000
Commercial paper
Debt Instrument [Line Items]
Weighted-average interest rate of commercial paper (as percent)				0.40%	0.07%

Loans Payable, Long-Term Debt70

Loans Payable, Long-Term Debt and Other Commitments - Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2016	Nov. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term debt	$ 24,274		$ 23,829
2.75% notes due 2025
Debt Instrument [Line Items]
Long-term debt	$ 2,487		2,485
Stated interest rate (as percent)	2.75%
3.70% notes due 2045
Debt Instrument [Line Items]
Long-term debt	$ 1,972		1,971
Stated interest rate (as percent)	3.70%
2.80% notes due 2023
Debt Instrument [Line Items]
Long-term debt	$ 1,743		1,742
Stated interest rate (as percent)	2.80%
5.00% notes due 2019
Debt Instrument [Line Items]
Long-term debt	$ 1,273		1,283
Stated interest rate (as percent)	5.00%
1.85% notes due 2020
Debt Instrument [Line Items]
Long-term debt	$ 1,238		1,239
Stated interest rate (as percent)	1.85%
4.15% notes due 2043
Debt Instrument [Line Items]
Long-term debt	$ 1,236		1,236
Stated interest rate (as percent)	4.15%
2.35% notes due 2022
Debt Instrument [Line Items]
Long-term debt	$ 1,228		1,233
Stated interest rate (as percent)	2.35%
3.875% notes due 2021
Debt Instrument [Line Items]
Long-term debt	$ 1,152		1,158
Stated interest rate (as percent)	3.875%
1.125% euro-denominated notes due 2021
Debt Instrument [Line Items]
Long-term debt	$ 1,035		1,091
Stated interest rate (as percent)	1.125%
1.875% euro-denominated notes due 2026
Debt Instrument [Line Items]
Long-term debt	$ 1,028		1,084
Stated interest rate (as percent)	1.875%
2.40% notes due 2022
Debt Instrument [Line Items]
Long-term debt	$ 1,003		1,011
Stated interest rate (as percent)	2.40%
Floating-rate borrowing due 2018
Debt Instrument [Line Items]
Long-term debt	$ 999		998
1.10% notes due 2018
Debt Instrument [Line Items]
Long-term debt	$ 999		998
Stated interest rate (as percent)	1.10%
1.30% notes due 2018
Debt Instrument [Line Items]
Long-term debt	$ 985		985
Stated interest rate (as percent)	1.30%
6.50% notes due 2033
Debt Instrument [Line Items]
Long-term debt	$ 806		809
Stated interest rate (as percent)	6.50%
Floating-rate notes due 2020
Debt Instrument [Line Items]
Long-term debt	$ 698		698
6.55% notes due 2037
Debt Instrument [Line Items]
Long-term debt	$ 594		596
Stated interest rate (as percent)	6.55%
0.50% euro-denominated notes due 2024
Debt Instrument [Line Items]
Long-term debt	$ 516		0
Stated interest rate (as percent)	0.50%	0.50%
1.375% euro-denominated notes due 2036
Debt Instrument [Line Items]
Long-term debt	$ 512		0
Stated interest rate (as percent)	1.375%	1.375%
2.50% euro-denominated notes due 2034
Debt Instrument [Line Items]
Long-term debt	$ 511		538
Stated interest rate (as percent)	2.50%
3.60% notes due 2042
Debt Instrument [Line Items]
Long-term debt	$ 489		489
Stated interest rate (as percent)	3.60%
5.85% notes due 2039
Debt Instrument [Line Items]
Long-term debt	$ 415		415
Stated interest rate (as percent)	5.85%
5.75% notes due 2036
Debt Instrument [Line Items]
Long-term debt	$ 369		369
Stated interest rate (as percent)	5.75%
5.95% debentures due 2028
Debt Instrument [Line Items]
Long-term debt	$ 355		354
Stated interest rate (as percent)	5.95%
6.40% debentures due 2028
Debt Instrument [Line Items]
Long-term debt	$ 325		325
Stated interest rate (as percent)	6.40%
6.30% debentures due 2026
Debt Instrument [Line Items]
Long-term debt	$ 152		152
Stated interest rate (as percent)	6.30%
Floating-rate notes due 2017
Debt Instrument [Line Items]
Long-term debt	$ 0		300
Other
Debt Instrument [Line Items]
Long-term debt	$ 154		$ 270

Contingencies and Environment71

Contingencies and Environmental Liabilities - Vioxx Litigation - Narrative (Details)	Jun. 28, 2016USD ($)	Dec. 31, 2016USD ($)legalmatter	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)legalmatter	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Loss Contingencies [Line Items]
Litigation settlement or judgment amount for (against) the company		$ 2,540,000,000	$ 200,000,000
Net charge related to the settlement of Vioxx shareholder class action litigation				$ 0	$ 680,000,000	$ 0
Vioxx Cases Brought by State Attorneys General | ALASKA
Loss Contingencies [Line Items]
Litigation settlement or judgment amount for (against) the company				(15,250,000)
Vioxx Cases Brought by State Attorneys General | MONTANA
Loss Contingencies [Line Items]
Litigation settlement or judgment amount for (against) the company				(16,700,000)
Vioxx Securities Lawsuits
Loss Contingencies [Line Items]
Insurance proceeds related to legal settlement				380,000,000
Upper limit of Directors and Officers insurance coverage		$ 145,000,000		$ 145,000,000
Vioxx | Cases alleging economic loss
Loss Contingencies [Line Items]
Loss contingency, pending claims number | legalmatter		1		1
Litigation settlement or judgment amount for (against) the company				$ (23,000,000)
Payments for legal settlements				700,000
Vioxx | Vioxx Securities Lawsuit Settlement Class Fund
Loss Contingencies [Line Items]
Litigation settlement or judgment amount for (against) the company					(830,000,000)
Vioxx | Vioxx Securities Lawsuit Fee/Expense Settlement Fund
Loss Contingencies [Line Items]
Litigation settlement or judgment amount for (against) the company	$ (222,000,000)			$ (232,000,000)
Vioxx | Vioxx Securities Lawsuits
Loss Contingencies [Line Items]
Net charge related to the settlement of Vioxx shareholder class action litigation					$ 680,000,000

Contingencies and Environment72

Contingencies and Environmental Liabilities - Fosamax Product Liability Litigation - Narrative (Details) $ in Millions	1 Months Ended						12 Months Ended
	Dec. 31, 2016USD ($)legalmatter	Mar. 31, 2016USD ($)	Jun. 30, 2015legalmatter	Jul. 31, 2014USD ($)	Mar. 31, 2014legalmatter	Dec. 31, 2013USD ($)legalmatter	Dec. 31, 2016legalmatter	Jul. 31, 2015legalmatter	Nov. 30, 2013legalmatter
Loss Contingencies [Line Items]
Litigation settlement or judgment amount for (against) the company | $	$ 2,540	$ 200
Fosamax
Loss Contingencies [Line Items]
Loss contingency, pending claims number	4,230						4,230
Fosamax | New Jersey
Loss Contingencies [Line Items]
Loss contingency, pending claims number	2,860						2,860
Initial number of cases selected for review	30						30
Subsequent number of cases selected for review					50			25	50
Fosamax | California State Court
Loss Contingencies [Line Items]
Loss contingency, pending claims number	280						280
Initial number of cases selected for review					10
Fosamax | Femur Fracture Litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims number	4,210						4,210
Fosamax | Femur Fracture Litigation | Other State Court
Loss Contingencies [Line Items]
Loss contingency, pending claims number	5						5
Fosamax | ONJ Litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims number	20						20
Litigation settlement or judgment amount for (against) the company | $				$ (27.3)		$ (27.7)
Number of plaintiffs						1,200
Percentage of participation in litigation settlement (as percent)				95.00%
Fosamax | Federal
Loss Contingencies [Line Items]
Loss contingency, pending claims number	7						7
Loss contingency, claims dismissed number			540		650		540
Loss contingency, claims on appeal, number	515						515

Contingencies and Environment73

Contingencies and Environmental Liabilities - Januvia/Janumet Litigation - Narrative (Details) - Januvia - legalmatter	Nov. 30, 2015	Dec. 31, 2016
Loss Contingencies [Line Items]
Loss contingency, pending claims number		1,195
Loss contingency, claims dismissed number	1,100
Cases Company Agreed ToToll 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		8

Contingencies and Environment74

Contingencies and Environmental Liabilities - Propecia/Proscar Litigation - Narrative (Details)	12 Months Ended
	Dec. 31, 2016Plaintifflegalmatter
Propecia
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1,330
Propecia | Cases alleging cancer
Loss Contingencies [Line Items]
Number of plaintiff groups | Plaintiff	50
Propecia/Proscar | Other State Court | California
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1
Propecia/Proscar | Other State Court | New York
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1
Propecia/Proscar | Other State Court | Ohio
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1

Contingencies and Environment75

Contingencies and Environmental Liabilities - Commercial and Other Litigation- Narrative (Details) $ in Millions	Apr. 29, 2016legalmatter	Feb. 28, 2017USD ($)	Jan. 31, 2014legalmatter	Dec. 31, 2016USD ($)legalmatter	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Loss Contingencies [Line Items]
Gain (charge) related to settlement | $				$ (625)	$ 0	$ 0
Commercial Litigation
Loss Contingencies [Line Items]
Additional claims filed	1		4
Loss contingency, pending claims number				700
Number of plaintiffs				2
Loss contingency, claims on appeal, number				2
Subsequent Event
Loss Contingencies [Line Items]
Gain (charge) related to settlement | $		$ (80)

Contingencies and Environment76

Contingencies and Environmental Liabilities Contingencies and Environmental Liabilities - Patent Litigation (Details) - USD ($) $ in Millions	1 Months Ended		12 Months Ended			36 Months Ended	84 Months Ended
	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2026	Dec. 31, 2023
Loss Contingencies [Line Items]
Gain (charge) related to settlement			$ (625)	$ 0	$ 0
Litigation settlement or judgment amount for (against) the company	$ 2,540	$ 200
Percentage of settlement to be paid to third-party (as percent)			20.00%
Scenario, Forecast
Loss Contingencies [Line Items]
Royalty rate (as percent)						2.50%	6.50%
Patent litigation
Loss Contingencies [Line Items]
Gain (charge) related to settlement			$ 117

Contingencies and Environment77

Contingencies and Environmental Liabilities - Legal Defense Reserves - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Legal Defense Costs
Loss Contingencies [Line Items]
Legal defense costs reserve	$ 185	$ 245

Contingencies and Environment78

Contingencies and Environmental Liabilities - Environmental Litigation and Matters - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Site Contingency [Line Items]
Accrued liabilities for environmental matters	$ 83,000	$ 109,000
Term for paying off environmental liabilities	15 years
Aggregate possible expenditure on environmental matters in excess of amounts accrued	$ 64,000
Oss Netherlands
Site Contingency [Line Items]
Environmental remediation expense	$ 235

Equity - Narrative (Details)

Equity - Narrative (Details) - shares	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Common stock, shares authorized	6,500,000,000	6,500,000,000
Preferred stock, shares authorized	20,000,000

Equity - Shareholders' Equity (

Equity - Shareholders' Equity (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Common Stock and Treasury Stock [Roll Forward]
Balance January 1	3,577,103,522
Balance December 31	3,577,103,522	3,577,103,522
Common Stock
Movement in Common Stock and Treasury Stock [Roll Forward]
Balance January 1	3,577,000,000	3,577,000,000	3,577,000,000
Purchases of treasury stock	0	0	0
Issuances	0	0	0
Balance December 31	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	796,000,000	739,000,000	650,000,000
Purchases of treasury stock	60,000,000	75,000,000	134,000,000
Issuances	(28,000,000)	(18,000,000)	(45,000,000)
Balance December 31	828,000,000	796,000,000	739,000,000

Share-Based Compensation Plan81

Share-Based Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares collectively authorized for future grants under share-based compensation plans (in shares)	125,000,000
Quantity of stock options that vest per year (as percent)	33.33%
Period over which awards under employee stock option are vested	3 years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax share-based compensation cost	$ 300	$ 299	$ 278
Income tax benefits related to share-based compensation	$ 92	$ 93	$ 86
Weighted average exercise price of options granted (in dollars per share)	$ 54.63	$ 59.73	$ 58.14
Weighted average fair value of options granted (in dollars per share)	$ 5.89	$ 6.46	$ 6.79
Total pre tax unrecognized compensation expense related to nonvested stock options, RSU and PSU awards	$ 443
Weighted average period in years of recognition for nonvested stock options, RSU and PSU awards	1 year 10 months 21 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 Plan82

Share-Based Compensation Plans - Assumptions Used to Determine Weighted-Average Fair Value of Options Granted (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected dividend yield	3.80%	4.10%	4.30%
Risk-free interest rate	1.40%	1.70%	2.00%
Expected volatility	19.60%	19.90%	22.00%
Expected life (years)	6 years 2 months 12 days	6 years 2 months 12 days	6 years 4 months 24 days

Share-Based Compensation Plan83

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, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Options, Outstanding, January 1 (in shares)	64,668
Number of Options, Granted (in shares)	6,220
Number of Options, Exercised (in shares)	(23,846)
Number of Options, Forfeited (in shares)	(1,951)
Number of Options, Outstanding, December 31 (in shares)	45,091	64,668
Number of Options, Exercisable (in shares)	34,311
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)	$ 41.64
Weighted Average Exercise Price, Granted (in dollars per share)	54.63	$ 59.73	$ 58.14
Weighted Average Exercise Price, Exercised (in dollars per share)	39.39
Weighted Average Exercise Price, Forfeited (in dollars per share)	45.14
Weighted Average Exercise Price, Options Outstanding, December 31 (in dollars per share)	44.47	$ 41.64
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 40.87
Weighted Average Remaining Contractual Term, Outstanding	4 years 5 months 1 day
Weighted Average Remaining Contractual Term, Exercisable	3 years 1 month 13 days
Aggregate Intrinsic Value, Outstanding	$ 654
Aggregate Intrinsic Value, Exercisable	$ 619

Share-Based Compensation Plan84

Share-Based Compensation Plans - Additional Information Pertaining to Stock Option Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total intrinsic value of stock options exercised	$ 444	$ 332	$ 626
Fair value of stock options vested	28	30	35
Cash received from the exercise of stock options	$ 939	$ 485	$ 1,560

Share-Based Compensation Plan85

Share-Based Compensation Plans - Summary of Nonvested RSU and PSU Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2016$ / 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	13,400
Number of Shares, Granted | shares	5,617
Number of Shares, Vested | shares	(4,956)
Number of Shares, Forfeited | shares	(795)
Number of Shares, Nonvested December 31 | shares	13,266
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	$ 53.73
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	54.67
Weighted Average Grant Date Fair Value, Vested (in dollars per share) | $ / shares	45.06
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	56.65
Weighted Average Grant Date Fair Value, Nonvested December 31 (in dollars per share) | $ / shares	$ 57.19
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	1,884
Number of Shares, Granted | shares	733
Number of Shares, Vested | shares	(786)
Number of Shares, Forfeited | shares	(87)
Number of Shares, Nonvested December 31 | shares	1,744
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	$ 55.33
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	57.38
Weighted Average Grant Date Fair Value, Vested (in dollars per share) | $ / shares	48.18
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	58.82
Weighted Average Grant Date Fair Value, Nonvested December 31 (in dollars per share) | $ / shares	$ 59.24

Pension and Other Postretirem86

Pension and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits, U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 282	$ 307	$ 300
Interest cost	456	434	425
Expected return on plan assets	(831)	(819)	(782)
Net amortization	64	158	74
Termination benefits	23	22	53
Curtailments	5	(12)	(69)
Settlements	0	1	11
Net periodic benefit (credit) cost	(1)	91	12
Pension Benefits, International
Defined Benefit Plan Disclosure [Line Items]
Service cost	238	251	266
Interest cost	204	206	269
Expected return on plan assets	(382)	(379)	(416)
Net amortization	76	104	59
Termination benefits	4	1	11
Curtailments	(1)	(9)	(4)
Settlements	6	12	6
Net periodic benefit (credit) cost	145	186	191
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	54	80	78
Interest cost	82	110	115
Expected return on plan assets	(107)	(143)	(139)
Net amortization	(103)	(59)	(71)
Termination benefits	4	7	22
Curtailments	(18)	(19)	(39)
Settlements	0	0	0
Net periodic benefit (credit) cost	$ (88)	$ (24)	$ (34)

Pension and Other Postretirem87

Pension and Other Postretirement Benefit Plans - Obligation and Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits, U.S.
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	$ 9,266	$ 9,984
Actual return on plan assets	941	(226)
Company contributions	63	66
Effects of exchange rate changes	0	0
Benefits paid	(504)	(523)
Settlements	0	(35)
Assets no longer restricted to the payment of postretirement benefits	0	0
Other	0	0
Fair value of plan assets December 31	9,766	9,266	$ 9,984
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation January 1	9,723	10,632
Service cost	282	307	300
Interest cost	456	434	425
Actuarial losses (gains)	854	(1,102)
Benefits paid	(504)	(523)
Effects of exchange rate changes	0	0
Plan amendments	0	0
Curtailments	15	(14)
Termination benefits	23	22	53
Settlements	0	(35)
Other	0	2
Benefit obligation December 31	10,849	9,723	10,632
Funded status December 31	(1,083)	(457)
Recognized as:
Other assets	0	179
Accrued and other current liabilities	(50)	(48)
Other noncurrent liabilities	(1,033)	(588)
Pension Benefits, International
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	7,204	7,724
Actual return on plan assets	898	138
Company contributions	424	163
Effects of exchange rate changes	(546)	(568)
Benefits paid	(193)	(196)
Settlements	(21)	(66)
Assets no longer restricted to the payment of postretirement benefits	0	0
Other	28	9
Fair value of plan assets December 31	7,794	7,204	7,724
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation January 1	7,733	8,331
Service cost	238	251	266
Interest cost	204	206	269
Actuarial losses (gains)	938	(127)
Benefits paid	(193)	(196)
Effects of exchange rate changes	(576)	(647)
Plan amendments	0	(1)
Curtailments	(15)	(15)
Termination benefits	4	1	11
Settlements	(21)	(66)
Other	60	(4)
Benefit obligation December 31	8,372	7,733	8,331
Funded status December 31	(578)	(529)
Recognized as:
Other assets	451	567
Accrued and other current liabilities	(7)	(7)
Other noncurrent liabilities	(1,022)	(1,089)
Other Postretirement Benefits
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	1,913	1,984
Actual return on plan assets	138	(34)
Company contributions	68	63
Effects of exchange rate changes	0	(1)
Benefits paid	(108)	(99)
Settlements	0	0
Assets no longer restricted to the payment of postretirement benefits	(992)	0
Other	0	0
Fair value of plan assets December 31	1,019	1,913	1,984
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation January 1	1,810	2,638
Service cost	54	80	78
Interest cost	82	110	115
Actuarial losses (gains)	77	(384)
Benefits paid	(108)	(99)
Effects of exchange rate changes	2	(11)
Plan amendments	0	(531)
Curtailments	1	(3)
Termination benefits	4	7	22
Settlements	0	0
Other	0	3
Benefit obligation December 31	1,922	1,810	$ 2,638
Funded status December 31	(903)	103
Recognized as:
Other assets	0	359
Accrued and other current liabilities	(11)	(10)
Other noncurrent liabilities	$ (892)	$ (246)

Pension and Other Postretirem88

Pension and Other Postretirement Benefit Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation		$ 18,400	$ 16,700
Percentage of Company's pension investments categorized as Level 3 assets (as percent)		2.00%	3.00%
Employer contributions to defined contribution savings plans		$ 126	$ 125	$ 124
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)		13.00%
Expected rate of return on plan assets (as percent)		8.60%	8.50%	8.50%
United States | Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets (as percent)		7.30%
United States | Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets (as percent)		8.75%
Scenario, Forecast | United States | Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets (as percent)	8.00%
Scenario, Forecast | United States | Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets (as percent)	8.75%
U.S. Equity Securities | United States
Defined Benefit Plan Disclosure [Line Items]
Minimum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans (as percent)		40.00%
Maximum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans (as percent)		60.00%
International Securities | United States
Defined Benefit Plan Disclosure [Line Items]
Minimum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans (as percent)		20.00%
Maximum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans (as percent)		40.00%
Fixed Income Investments | United States
Defined Benefit Plan Disclosure [Line Items]
Minimum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans (as percent)		15.00%
Maximum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans (as percent)		25.00%
Cash And Other Investments | United States
Defined Benefit Plan Disclosure [Line Items]
Maximum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans (as percent)		5.00%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Assets no longer restricted to the payment of postretirement benefits		$ 992	$ 0
Fair value of plan assets		1,019	1,913	$ 1,984
Expected contributions to the pension plans and other postretirement benefit plans during next fiscal year		25
Estimated net loss (gain) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during next fiscal year		1
Estimated prior service cost (credit) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during next fiscal year		(99)
Pension Benefits, U.S.
Defined Benefit Plan Disclosure [Line Items]
Assets no longer restricted to the payment of postretirement benefits		0	0
Accumulated benefit obligation		10,500	9,400
Fair value of plan assets		9,766	9,266	9,984
Expected contributions to the pension plans and other postretirement benefit plans during next fiscal year		50
Estimated net loss (gain) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during next fiscal year		178
Estimated prior service cost (credit) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during next fiscal year		(53)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Estimated net loss (gain) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during next fiscal year		270
Estimated prior service cost (credit) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during next fiscal year		(64)
Pension Plan | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		435	423
Pension Benefits, International
Defined Benefit Plan Disclosure [Line Items]
Assets no longer restricted to the payment of postretirement benefits		0	0
Fair value of plan assets		7,794	$ 7,204	$ 7,724
Expected contributions to the pension plans and other postretirement benefit plans during next fiscal year		$ 160
Expected rate of return on plan assets (as percent)		5.60%	5.70%	6.00%

Pension and Other Postretirem89

Pension and Other Postretirement Benefit Plans - Accumulated and Projected Benefit Obligation in Excess of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits, U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Projected benefit obligation	$ 10,849	$ 1,310
Fair value of plan assets	9,766	674
Accumulated benefit obligation	9,807	611
Fair value of plan assets	9,057	0
Pension Benefits, International
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Projected benefit obligation	5,486	5,093
Fair value of plan assets	4,457	3,996
Accumulated benefit obligation	2,692	4,812
Fair value of plan assets	$ 1,898	$ 3,964

Pension and Other Postretirem90

Pension and Other Postretirement Benefit Plans - Fair Values of Pension Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits, U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 9,766	$ 9,266	$ 9,984
Fair Value of Plan Assets Excluding Net Asset Value Investments	4,542	4,426
Investments measured at NAV practical expedient	5,224	4,840
Pension Benefits, U.S. | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	0
Pension Benefits, U.S. | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	521	566
Pension Benefits, U.S. | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	104	87
Pension Benefits, U.S. | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,521	2,444
Pension Benefits, U.S. | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	475	391
Pension Benefits, U.S. | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	660	679
Pension Benefits, U.S. | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	239	236
Pension Benefits, U.S. | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	23
Pension Benefits, U.S. | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Net Asset Value Investments	3,148	3,097
Pension Benefits, U.S. | Quoted Prices In Active Markets for Identical Assets (Level 1) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	0
Pension Benefits, U.S. | Quoted Prices In Active Markets for Identical Assets (Level 1) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	521	566
Pension Benefits, U.S. | Quoted Prices In Active Markets for Identical Assets (Level 1) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	104	87
Pension Benefits, U.S. | Quoted Prices In Active Markets for Identical Assets (Level 1) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,521	2,444
Pension Benefits, U.S. | Quoted Prices In Active Markets for Identical Assets (Level 1) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Quoted Prices In Active Markets for Identical Assets (Level 1) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Quoted Prices In Active Markets for Identical Assets (Level 1) | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Quoted Prices In Active Markets for Identical Assets (Level 1) | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Net Asset Value Investments	1,376	1,306
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	0
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	475	391
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	660	679
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	239	236
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Net Asset Value Investments	18	23	28
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Net Asset Value Investments	0	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18	23
Pension Benefits, International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7,794	7,204	7,724
Fair Value of Plan Assets Excluding Net Asset Value Investments	7,006	6,509
Investments measured at NAV practical expedient	788	695
Pension Benefits, International | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	53	67
Pension Benefits, International | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3,033	2,922
Pension Benefits, International | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	172	158
Pension Benefits, International | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,027	1,420
Pension Benefits, International | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	284	276
Pension Benefits, International | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9	11
Pension Benefits, International | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	8
Pension Benefits, International | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	565	496
Pension Benefits, International | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	237	467
Pension Benefits, International | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	92	161
Pension Benefits, International | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50	68
Pension Benefits, International | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	471	450
Pension Benefits, International | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	5
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Net Asset Value Investments	952	1,252
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	42	63
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	187	184
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24	21
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	123	305
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	173
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6	8
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	565	496
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1) | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	0
Pension Benefits, International | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Net Asset Value Investments	5,637	4,857
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	4
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2,846	2,738
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	148	137
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,904	1,115
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	282	103
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	3
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	3
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	235	465
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	92	161
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	50	68
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	59	57
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	3
Pension Benefits, International | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets Excluding Net Asset Value Investments	417	400	419
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4	5
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	412	393
Fair Value of Plan Assets Excluding Net Asset Value Investments	412	393	$ 394
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1	$ 2

Pension and Other Postretirem91

Pension and Other Postretirement Benefit Plans - Summary of Changes in Fair Value of Company's Level 3 Pension Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
U.S. Pension Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance January 1	$ 4,426
Actual return on plan assets:
Balance December 31	4,542	$ 4,426
U.S. Pension Plans | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance January 1	23	28
Actual return on plan assets:
Relating to assets still held at December 31	(3)	(3)
Relating to assets sold during the year	4	5
Purchases and sales, net	(6)	(7)
Balance December 31	18	23
U.S. Pension Plans | Significant Unobservable Inputs (Level 3) | Insurance Contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance 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
Balance December 31	0	0
U.S. Pension Plans | Significant Unobservable Inputs (Level 3) | Real Estate
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance 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
Balance December 31	0	0
U.S. Pension Plans | Significant Unobservable Inputs (Level 3) | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance January 1	23	28
Actual return on plan assets:
Relating to assets still held at December 31	(3)	(3)
Relating to assets sold during the year	4	5
Purchases and sales, net	(6)	(7)
Balance December 31	18	23
International Pension Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance January 1	6,509
Actual return on plan assets:
Balance December 31	7,006	6,509
International Pension Plans | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance January 1	400	419
Actual return on plan assets:
Relating to assets still held at December 31	(8)	(30)
Purchases and sales, net	(1)	(14)
Transfers into Level 3	26	25
Balance December 31	417	400
International Pension Plans | Significant Unobservable Inputs (Level 3) | Insurance Contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance January 1	393	394
Actual return on plan assets:
Relating to assets still held at December 31	(9)	(28)
Purchases and sales, net	2	2
Transfers into Level 3	26	25
Balance December 31	412	393
International Pension Plans | Significant Unobservable Inputs (Level 3) | Real Estate
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance January 1	5	23
Actual return on plan assets:
Relating to assets still held at December 31	1	(2)
Purchases and sales, net	(2)	(16)
Transfers into Level 3	0	0
Balance December 31	4	5
International Pension Plans | Significant Unobservable Inputs (Level 3) | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Balance January 1	2	2
Actual return on plan assets:
Relating to assets still held at December 31	0	0
Purchases and sales, net	(1)	0
Transfers into Level 3	0	0
Balance December 31	$ 1	$ 2

Pension and Other Postretirem92

Pension and Other Postretirement Benefit Plans - Fair Values of Other Postretirement Benefit Plan Assets (Details) - Other Postretirement Benefits - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net assets in fair value hierarchy	$ 540	$ 1,246
Investments measured at NAV practical expedient	479	667
Plan assets at fair value	1,019	1,913	$ 1,984
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	125	65
Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	48	53
Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	10	29
Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	2
Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	231	229
Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	43	339
Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	60	311
Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	22	218
Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Net assets in fair value hierarchy	415	378
Quoted Prices In Active Markets for Identical Assets (Level 1) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	125	65
Quoted Prices In Active Markets for Identical Assets (Level 1) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	48	53
Quoted Prices In Active Markets for Identical Assets (Level 1) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	10	29
Quoted Prices In Active Markets for Identical Assets (Level 1) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	2
Quoted Prices In Active Markets for Identical Assets (Level 1) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	231	229
Quoted Prices In Active Markets for Identical Assets (Level 1) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Quoted Prices In Active Markets for Identical Assets (Level 1) | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Net assets in fair value hierarchy	125	868
Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Other Observable Inputs (Level 2) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Other Observable Inputs (Level 2) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Other Observable Inputs (Level 2) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Other Observable Inputs (Level 2) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Other Observable Inputs (Level 2) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	43	339
Significant Other Observable Inputs (Level 2) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	60	311
Significant Other Observable Inputs (Level 2) | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	22	218
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Net assets in fair value hierarchy	0	0
Significant Unobservable Inputs (Level 3) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Unobservable Inputs (Level 3) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Unobservable Inputs (Level 3) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Unobservable Inputs (Level 3) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Unobservable Inputs (Level 3) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Unobservable Inputs (Level 3) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Unobservable Inputs (Level 3) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Significant Unobservable Inputs (Level 3) | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 0	$ 0

Pension and Other Postretirem93

Pension and Other Postretirement Benefit Plans - Summary of Expected Benefit Payments (Details) $ in Millions	Dec. 31, 2016USD ($)
U.S. Pension Plans
Defined Benefit Plan Disclosure [Line Items]
2,017	$ 561
2,018	588
2,019	629
2,020	638
2,021	655
2022 — 2026	3,596
International Pension Plans
Defined Benefit Plan Disclosure [Line Items]
2,017	186
2,018	179
2,019	195
2,020	202
2,021	201
2022 — 2026	1,168
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
2,017	101
2,018	104
2,019	106
2,020	111
2,021	115
2022 — 2026	$ 641

Pension and Other Postretirem94

Pension and Other Postretirement Benefit Plans - Components of Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits, U.S.
Defined Benefit Plan Disclosure [Line Items]
Total	$ (753)	$ 60	$ (2,144)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	119	214	135
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	(55)	(56)	(61)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Arising During Period, before Tax	(10)	(13)	(59)
Net loss amortization included in benefit cost	(743)	73	(2,085)
Total	64	158	74
Pension Benefits, International
Defined Benefit Plan Disclosure [Line Items]
Total	(382)	(70)	(787)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	87	118	74
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	(11)	(14)	(15)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Arising During Period, before Tax	(2)	(4)	(8)
Net loss amortization included in benefit cost	(380)	(66)	(779)
Total	76	104	59
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Total	(64)	720	(265)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	3	5	1
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	(106)	(64)	(72)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Arising During Period, before Tax	(19)	511	(42)
Net loss amortization included in benefit cost	(45)	209	(223)
Total	$ (103)	$ (59)	$ (71)

Pension and Other Postretirem95

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, 2016	Dec. 31, 2015	Dec. 31, 2014
International Pension Plans
Net periodic benefit cost
Discount rate	2.80%	2.70%	3.80%
Expected rate of return on plan assets	5.60%	5.70%	6.00%
Salary growth rate	2.90%	2.90%	3.10%
Benefit obligation
Discount rate	2.20%	2.80%	2.70%
Salary growth rate	2.90%	2.90%	2.90%
United States
Net periodic benefit cost
Discount rate	4.70%	4.20%	4.90%
Expected rate of return on plan assets	8.60%	8.50%	8.50%
Salary growth rate	4.30%	4.40%	4.50%
Benefit obligation
Discount rate	4.30%	4.80%	4.20%
Salary growth rate	4.30%	4.30%	4.40%

Pension and Other Postretirem96

Pension and Other Postretirement Benefit Plans - Summary of Health Care Cost Trend Rate Assumptions for Other Postretirement Benefit Plans (Details) - Other Postretirement Benefits	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	7.40%	6.80%
Rate to which the cost trend rate is assumed to decline	4.50%	4.50%

Pension and Other Postretirem97

Pension and Other Postretirement Benefit Plans - One Percentage Point Change in Health Care Cost Trend Rate (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Compensation and Retirement Disclosure [Abstract]
Effect on total service and interest cost components, Increase	$ 12
Effect on benefit obligation, Increase	138
Effect on total service and interest cost components, Decrease	(12)
Effect on benefit obligation, Decrease	$ (114)

Other (Income) Expense, Net (De

Other (Income) Expense, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Income and Expenses [Abstract]
Interest income	$ (328)	$ (289)	$ (266)
Interest expense	693	672	732
Exchange losses	174	1,277	180
Equity income from affiliates	(86)	(205)	(257)
Other, net	267	72	(12,002)
Other (income) expense, net	$ 720	$ 1,527	$ (11,613)

Other (Income) Expense, Net - N

Other (Income) Expense, Net - Narrative (Details) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)VEF / $	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Component of Other Income / Expense of Nonoperating [Line Items]
Foreign exchange losses related to Venezuela				$ 0	$ 876	$ 0
Gain (charge) related to settlement				(625)	0	0
Other income				98
Net charge related to the settlement of Vioxx shareholder class action litigation				0	680	0
Contribution expense					78
Gain on divestiture of Merck Consumer Care				0	0	11,209
Gain on AstraZeneca option exercise				0	0	741
Loss on extinguishment of debt				0	0	628
Goodwill impairment charge				47	47
Interest paid				686	653	852
AstraZeneca LP
Component of Other Income / Expense of Nonoperating [Line Items]
Other income						650
Recognition of deferred income				5	182	140
Supera
Component of Other Income / Expense of Nonoperating [Line Items]
Goodwill impairment charge						93
CGRP receptor antagonists
Component of Other Income / Expense of Nonoperating [Line Items]
Gain (loss) on sale of clinical development programs				100	250
Consumer Care
Component of Other Income / Expense of Nonoperating [Line Items]
Gain on divestiture of Merck Consumer Care						11,200
Ophthalmic products
Component of Other Income / Expense of Nonoperating [Line Items]
Gain on disposition of business					147	480
Sirna Therapeutics Inc.
Component of Other Income / Expense of Nonoperating [Line Items]
Gain on disposition of subsidiary						$ 204
Patent litigation
Component of Other Income / Expense of Nonoperating [Line Items]
Gain (charge) related to settlement				$ 117
Vioxx Securities Lawsuits | Vioxx
Component of Other Income / Expense of Nonoperating [Line Items]
Net charge related to the settlement of Vioxx shareholder class action litigation					$ 680
Venezuela
Component of Other Income / Expense of Nonoperating [Line Items]
Foreign currency exchange rate | VEF / $			6.30
Foreign exchange losses related to Venezuela	$ 161	$ 138	$ 715

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, 2016	Dec. 31, 2015	Dec. 31, 2014
Amount
U.S. statutory rate applied to income before taxes	$ 1,631	$ 1,890	$ 6,049
Differential arising from:
Foreign earnings	(1,593)	(2,105)	(1,367)
Unremitted foreign earnings	(30)	260	(209)
Tax settlements	0	(417)	(89)
AstraZeneca option exercise	0	0	(774)
Sale of Sirna Therapeutics, Inc.	0	0	(357)
Impact of purchase accounting adjustments, including amortization	623	797	1,013
Foreign currency devaluation related to Venezuela	0	321	0
State taxes	173	159	7
Restructuring	145	167	289
U.S. health care reform legislation	68	66	134
Divestiture of Merck Consumer Care	0	0	440
Other	(299)	(196)	213
Taxes on income	$ 718	$ 942	$ 5,349
Tax Rate
U.S. statutory rate applied to income before taxes	35.00%	35.00%	35.00%
Differential arising from:
Foreign earnings	(34.20%)	(39.00%)	(7.90%)
Unremitted foreign earnings	(0.60%)	4.80%	(1.20%)
Tax settlements	0.00%	(7.70%)	(0.50%)
AstraZeneca option exercise	0.00%	0.00%	(4.50%)
Sale of Sirna Therapeutics, Inc.	0.00%	0.00%	(2.10%)
Impact of purchase accounting adjustments, including amortization	13.40%	14.80%	5.90%
Foreign currency devaluation related to Venezuela	0.00%	5.90%	0.00%
State taxes	3.70%	2.90%	0.00%
Restructuring	3.10%	3.10%	1.70%
U.S. health care reform legislation	1.40%	1.20%	0.80%
Divestiture of Merck Consumer Care	0.00%	0.00%	2.50%
Other	(6.40%)	(3.60%)	1.20%
Total, Tax Rate	15.40%	17.40%	30.90%

Taxes on Income - Narrative (De

Taxes on Income - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
U.S. statutory rate applied to income before taxes (as percent)	35.00%	35.00%	35.00%
Income Tax [Line Items]
Deferred tax assets on NOL carryforwards relating to foreign jurisdictions	$ 243
Deferred tax assets relating to various U.S. tax credit carryforwards and NOL carryforwards	194
Income taxes paid	1,800	$ 1,800	$ 7,900
Tax benefits relating to stock option exercises	147	109	202
Unrecognized tax benefits	3,494	3,448	3,534	$ 3,503
Favorable net impact to income tax provision if unrecognized tax benefits were recognized	3,300
Reasonably possible amount that liability for unrecognized tax benefits could decline up to in next 12 months (up to)	1,700
Interest and penalties associated with uncertain tax positions, expense (benefit)	134	102	9
Liabilities for accrued interest and penalties	886	766
Proceeds from refunds		715
Income tax expense (benefit)	718	942	5,349
Foreign earnings retained indefinitely by subsidiary companies for reinvestments	63,100
Consumer Care
Income Tax [Line Items]
Income taxes paid			$ 5,000
Foreign Jurisdiction
Income Tax [Line Items]
Valuation allowance on foreign NOL carryforwards	$ 268
IRS
Income Tax [Line Items]
Income tax expense (benefit)		$ (410)

Taxes on Income - Income Before

Taxes on Income - Income Before Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Domestic	$ 518	$ 2,247	$ 15,730
Foreign	4,141	3,154	1,553
Income Before Taxes	$ 4,659	$ 5,401	$ 17,283

Taxes on Income - Taxes on Inco

Taxes on Income - Taxes on Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current provision
Federal	$ 1,166	$ 732	$ 7,136
Foreign	916	844	438
State	157	130	375
Total current provision	2,239	1,706	7,949
Deferred provision
Federal	(1,255)	(552)	(2,162)
Foreign	(225)	(163)	(201)
State	(41)	(49)	(237)
Total deferred provision	(1,521)	(764)	(2,600)
Taxes on income	$ 718	$ 942	$ 5,349

Taxes on Income - Deferred Inco

Taxes on Income - Deferred Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Intangibles, Assets	$ 86	$ 0
Inventory related, Assets	30	49
Accelerated depreciation, Assets	28	43
Pensions and other postretirement benefits, Assets	727	435
Compensation related, Assets	438	535
Unrecognized tax benefits, Assets	383	412
Net operating losses and other tax credit carryforwards, Assets	437	565
Other, Assets	1,128	1,217
Subtotal, Assets	3,257	3,256
Valuation allowance, Assets	(268)	(304)
Deferred Tax Assets	2,989	2,952
Intangibles, Liabilities	3,734	4,962
Inventory related, Liabilities	660	752
Accelerated depreciation, Liabilities	927	910
Unremitted foreign earnings, Liabilities	2,044	2,124
Pensions and other postretirement benefits, Liabilities	109	131
Other, Liabilities	46	0
Subtotal, Liabilities	7,520	8,879
Deferred income taxes, Liabilities	4,531	5,927
Deferred Income Taxes	5,077	6,535
Other assets
Income Tax [Line Items]
Deferred Tax Assets	$ 546	$ 608

Taxes on Income - Unrecognized

Taxes on Income - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance January 1	$ 3,448	$ 3,534	$ 3,503
Additions related to current year positions	196	198	389
Additions related to prior year positions	75	53	23
Reductions for tax positions of prior years	(90)	(59)	(156)
Settlements	(92)	(184)	(161)
Lapse of statute of limitations	(43)	(94)	(64)
Balance December 31	$ 3,494	$ 3,448	$ 3,534

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
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	13	9	4

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, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 3,920	$ 4,442	$ 11,920
Average common shares outstanding, in shares	2,766	2,816	2,894
Common shares issuable, in shares	21	25	34
Average common shares outstanding assuming dilution, in shares	2,787	2,841	2,928
Basic earnings per common share attributable to Merck & Co., Inc. common shareholders, in dollars per share	$ 1.42	$ 1.58	$ 4.12
Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders, in dollars per share	$ 1.41	$ 1.56	$ 4.07

Other Comprehensive Income (108

Other Comprehensive Income (Loss) - Changes in AOCI by Component (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 44,767	$ 48,791	$ 52,326
Accumulated Other Comprehensive Income (Loss), ending balance	(5,226)	(4,148)
Ending Balance	40,308	44,767	48,791
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	404	530	132
Other comprehensive income (loss) before reclassification adjustments, pretax	210	526	778
Tax	(72)	(177)	(285)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	138	349	493
Reclassification adjustments, pretax	(314)	(731)	(146)
Tax	110	256	51
Reclassification adjustments, net of taxes	(204)	(475)	(95)
Other comprehensive income (loss), net of taxes	(66)	(126)	398
Ending Balance	338	404	530
Investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	41	111	54
Other comprehensive income (loss) before reclassification adjustments, pretax	(38)	(9)	48
Tax	16	(13)	(17)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(22)	(22)	31
Reclassification adjustments, pretax	(31)	(73)	43
Tax	9	25	(17)
Reclassification adjustments, net of taxes	(22)	(48)	26
Other comprehensive income (loss), net of taxes	(44)	(70)	57
Ending Balance	(3)	41	111
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(2,407)	(2,986)	(909)
Other comprehensive income (loss) before reclassification adjustments, pretax	(1,199)	710	(3,196)
Tax	363	(272)	1,067
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(836)	438	(2,129)
Reclassification adjustments, pretax	37	203	62
Tax	0	(62)	(10)
Reclassification adjustments, net of taxes	37	141	52
Other comprehensive income (loss), net of taxes	(799)	579	(2,077)
Ending Balance	(3,206)	(2,407)	(2,986)
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	3,900	3,300
Other Postretirement Benefit 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	115	86
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	361	414
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	466	547
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(2,186)	(1,978)	(1,474)
Other comprehensive income (loss) before reclassification adjustments, pretax	(150)	(158)	(412)
Tax	(19)	(28)	(92)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(169)	(186)	(504)
Reclassification adjustments, pretax	0	(22)	0
Tax	0	0	0
Reclassification adjustments, net of taxes	0	(22)	0
Other comprehensive income (loss), net of taxes	(169)	(208)	(504)
Ending Balance	(2,355)	(2,186)	(1,978)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(4,148)	(4,323)	(2,197)
Other comprehensive income (loss) before reclassification adjustments, pretax	(1,177)	1,069	(2,782)
Tax	288	(490)	673
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(889)	579	(2,109)
Reclassification adjustments, pretax	(308)	(623)	(41)
Tax	119	219	24
Reclassification adjustments, net of taxes	(189)	(404)	(17)
Other comprehensive income (loss), net of taxes	(1,078)	175	(2,126)
Ending Balance	$ (5,226)	$ (4,148)	$ (4,323)

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details)	12 Months Ended
	Dec. 31, 2016segment
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, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Sales	$ 39,807	$ 39,498	$ 42,237
Proceeds from sale of intangible assets	170	232
Operating Segments
Segment Reporting Information [Line Items]
Sales	39,013	38,449	41,800
Operating Segments | Pharmaceutical segment
Segment Reporting Information [Line Items]
Sales	35,151	34,782	36,042
Operating Segments | Pharmaceutical segment | Zetia
Segment Reporting Information [Line Items]
Sales	2,560	2,526	2,650
Operating Segments | Pharmaceutical segment | Vytorin
Segment Reporting Information [Line Items]
Sales	1,141	1,251	1,516
Operating Segments | Pharmaceutical segment | Januvia
Segment Reporting Information [Line Items]
Sales	3,908	3,863	3,931
Operating Segments | Pharmaceutical segment | Janumet
Segment Reporting Information [Line Items]
Sales	2,201	2,151	2,071
Operating Segments | Pharmaceutical segment | NuvaRing
Segment Reporting Information [Line Items]
Sales	777	732	723
Operating Segments | Pharmaceutical segment | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	606	588	502
Operating Segments | Pharmaceutical segment | Dulera
Segment Reporting Information [Line Items]
Sales	436	536	460
Operating Segments | Pharmaceutical segment | Follistim AQ
Segment Reporting Information [Line Items]
Sales	355	383	412
Operating Segments | Pharmaceutical segment | Zepatier
Segment Reporting Information [Line Items]
Sales	555	0	0
Operating Segments | Pharmaceutical segment | Isentress
Segment Reporting Information [Line Items]
Sales	1,387	1,511	1,673
Operating Segments | Pharmaceutical segment | Cubicin
Segment Reporting Information [Line Items]
Sales	1,087	1,127	25
Operating Segments | Pharmaceutical segment | Noxafil
Segment Reporting Information [Line Items]
Sales	595	487	402
Operating Segments | Pharmaceutical segment | Invanz
Segment Reporting Information [Line Items]
Sales	561	569	529
Operating Segments | Pharmaceutical segment | Cancidas
Segment Reporting Information [Line Items]
Sales	558	573	681
Operating Segments | Pharmaceutical segment | Bridion
Segment Reporting Information [Line Items]
Sales	482	353	340
Operating Segments | Pharmaceutical segment | Primaxin
Segment Reporting Information [Line Items]
Sales	297	313	329
Operating Segments | Pharmaceutical segment | Remicade
Segment Reporting Information [Line Items]
Sales	1,268	1,794	2,372
Operating Segments | Pharmaceutical segment | Simponi
Segment Reporting Information [Line Items]
Sales	766	690	689
Operating Segments | Pharmaceutical segment | Keytruda
Segment Reporting Information [Line Items]
Sales	1,402	566	55
Operating Segments | Pharmaceutical segment | Emend
Segment Reporting Information [Line Items]
Sales	549	535	553
Operating Segments | Pharmaceutical segment | Temodar
Segment Reporting Information [Line Items]
Sales	283	312	350
Operating Segments | Pharmaceutical segment | Singulair
Segment Reporting Information [Line Items]
Sales	915	931	1,092
Operating Segments | Pharmaceutical segment | Nasonex
Segment Reporting Information [Line Items]
Sales	537	858	1,099
Operating Segments | Pharmaceutical segment | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	511	667	806
Operating Segments | Pharmaceutical segment | Arcoxia
Segment Reporting Information [Line Items]
Sales	450	471	519
Operating Segments | Pharmaceutical segment | Fosamax
Segment Reporting Information [Line Items]
Sales	284	359	470
Operating Segments | Pharmaceutical segment | Zocor
Segment Reporting Information [Line Items]
Sales	186	217	258
Operating Segments | Pharmaceutical segment | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	2,173	1,908	1,738
Operating Segments | Pharmaceutical segment | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	1,640	1,505	1,394
Operating Segments | Pharmaceutical segment | Zostavax
Segment Reporting Information [Line Items]
Sales	685	749	765
Operating Segments | Pharmaceutical segment | RotaTeq
Segment Reporting Information [Line Items]
Sales	652	610	659
Operating Segments | Pharmaceutical segment | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	641	542	746
Operating Segments | Pharmaceutical segment | Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	4,703	5,105	6,233
Operating Segments | Other segments
Segment Reporting Information [Line Items]
Sales	3,862	3,667	5,758
Other
Segment Reporting Information [Line Items]
Sales	$ 794	$ 1,049	$ 437

Segment Reporting - Consolidate

Segment Reporting - Consolidated Revenues by Geographic Area (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 39,807	$ 39,498	$ 42,237
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	18,478	17,519	17,071
Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	10,953	10,677	13,174
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	3,918	3,825	3,952
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	2,846	2,673	3,471
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	2,155	2,825	3,151
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 1,457	$ 1,979	$ 1,418

Segment Reporting - Reconciliat

Segment Reporting - Reconciliation of Segment Profits to Income Before Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Interest income	$ 328	$ 289	$ 266
Interest expense	(693)	(672)	(732)
Equity income from affiliates	86	205	257
Depreciation and amortization	(5,441)	(6,375)	(6,691)
Research and development	(10,124)	(6,704)	(7,180)
Restructuring costs	(651)	(619)	(1,013)
Charge related to the settlement of worldwide Keytruda patent litigation	(625)	0	0
Foreign currency devaluation related to Venezuela	0	(876)	0
Net charge related to the settlement of Vioxx shareholder class action litigation	0	680	0
Gain on divestiture of Merck Consumer Care	0	0	11,209
Gain on AstraZeneca option exercise	0	0	741
Loss on extinguishment of debt	0	0	(628)
Income Before Taxes	4,659	5,401	17,283
Total segment profits
Segment Reporting Information [Line Items]
Equity income from affiliates	105	70	198
Depreciation and amortization	(183)	(100)	(57)
Income Before Taxes	23,687	23,231	24,550
Total segment profits | Pharmaceutical segment
Segment Reporting Information [Line Items]
Equity income from affiliates	105	70	90
Depreciation and amortization	(160)	(82)	(39)
Income Before Taxes	22,180	21,658	22,164
Total segment profits | Other segments
Segment Reporting Information [Line Items]
Equity income from affiliates	0	0	108
Depreciation and amortization	(23)	(18)	(18)
Income Before Taxes	1,507	1,573	2,386
Other profits
Segment Reporting Information [Line Items]
Income Before Taxes	481	810	627
Unallocated
Segment Reporting Information [Line Items]
Interest income	328	289	266
Interest expense	(693)	(672)	(732)
Equity income from affiliates	(19)	135	59
Depreciation and amortization	(1,585)	(1,573)	(2,452)
Research and development	(9,084)	(5,871)	(5,823)
Amortization of purchase accounting adjustments	(3,692)	(4,816)	(4,182)
Restructuring costs	(651)	(619)	(1,013)
Gain on sale of certain migraine clinical development programs	100	250	0
Charge related to the settlement of worldwide Keytruda patent litigation	(625)	0	0
Gain on divestiture of certain ophthalmic products	0	147	480
Foreign currency devaluation related to Venezuela	0	(876)	0
Net charge related to the settlement of Vioxx shareholder class action litigation	0	(680)	0
Gain on divestiture of Merck Consumer Care	0	0	11,209
Gain on AstraZeneca option exercise	0	0	741
Loss on extinguishment of debt	0	0	(628)
Other unallocated, net	$ (3,588)	$ (4,354)	$ (5,819)

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, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Equity income from affiliates	$ 86	$ 205	$ 257
Depreciation and amortization	(5,441)	(6,375)	(6,691)
Operating Segments
Segment Reporting Information [Line Items]
Equity income from affiliates	105	70	198
Depreciation and amortization	(183)	(100)	(57)
Operating Segments | Pharmaceutical
Segment Reporting Information [Line Items]
Equity income from affiliates	105	70	90
Depreciation and amortization	(160)	(82)	(39)
Operating Segments | All Other
Segment Reporting Information [Line Items]
Equity income from affiliates	0	0	108
Depreciation and amortization	$ (23)	$ (18)	$ (18)

Segment Reporting - Property, P

Segment Reporting - Property, Plant and Equipment, Net by Geographic Area (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 12,026	$ 12,507	$ 13,136
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	8,114	8,467	8,727
Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	2,732	2,844	3,120
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	775	842	897
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	234	182	207
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	164	164	172
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 7	$ 8	$ 13