Merck & Co. (MRK) 10-K 26 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Jan. 31, 2016	Jun. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
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		2,775,258,591
Entity Public Float			$ 160,710,000,000

Consolidated Statement of Incom

Consolidated Statement of Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Sales	$ 39,498	$ 42,237	$ 44,033
Costs, Expenses and Other
Materials and production	14,934	16,768	16,954
Marketing and administrative	10,313	11,606	11,911
Research and development	6,704	7,180	7,503
Restructuring costs	619	1,013	1,709
Other (income) expense, net	1,527	(11,613)	411
Total Costs, Expenses and Other	34,097	24,954	38,488
Income Before Taxes	5,401	17,283	5,545
Taxes on Income	942	5,349	1,028
Net Income	4,459	11,934	4,517
Less: Net Income Attributable to Noncontrolling Interests	17	14	113
Net Income Attributable to Merck & Co., Inc.	$ 4,442	$ 11,920	$ 4,404
Basic Earnings per Common Share Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.58	$ 4.12	$ 1.49
Earnings per Common Share Assuming Dilution Attributable to Merck & Co., Inc. Common Shareholders (in dollars per share)	$ 1.56	$ 4.07	$ 1.47

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 4,442	$ 11,920	$ 4,404
Other Comprehensive Income (Loss) Net of Taxes:
Net unrealized (loss) gain on derivatives, net of reclassifications	(126)	398	229
Net unrealized (loss) gain on investments, net of reclassifications	(70)	57	(19)
Benefit plan net gain (loss) and prior service credit (cost), net of amortization	579	(2,077)	2,758
Cumulative translation adjustment	(208)	(504)	(483)
Other comprehensive income (loss), net of taxes	175	(2,126)	2,485
Comprehensive Income Attributable to Merck & Co., Inc.	$ 4,617	$ 9,794	$ 6,889

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents	$ 8,524	$ 7,441
Short-term investments	4,903	8,278
Accounts receivable (net of allowance for doubtful accounts of $165 in 2015 and $153 in 2014) (excludes accounts receivable of $10 in 2015 and $80 in 2014 classified in Other assets - see Note 5)	6,484	6,626
Inventories (excludes inventories of $1,569 in 2015 and $1,664 in 2014 classified in Other assets - see Note 6)	4,700	5,571
Other current assets	5,153	4,689
Total current assets	29,764	32,605
Investments	13,039	13,515
Property, Plant and Equipment (at cost)
Land	490	541
Buildings	12,154	13,101
Machinery, equipment and office furnishings	14,261	16,050
Construction in progress	1,525	1,448
Property, Plant and Equipment, Gross	28,430	31,140
Less: accumulated depreciation	15,923	18,004
Property, Plant and Equipment, Net, Total	12,507	13,136
Goodwill	17,723	12,992
Other Intangibles, Net	22,602	20,386
Other Assets	6,144	5,533
Total Assets	101,779	98,167
Current Liabilities
Loans payable and current portion of long-term debt	2,585	2,704
Trade accounts payable	2,533	2,625
Accrued and other current liabilities	11,216	10,523
Income taxes payable	1,560	1,237
Dividends payable	1,309	1,308
Total current liabilities	19,203	18,397
Long-Term Debt	23,929	18,699
Deferred Income Taxes	6,535	4,467
Other Noncurrent Liabilities	7,345	7,813
Merck & Co., Inc. Stockholders’ Equity
Common stock, $0.50 par value Authorized - 6,500,000,000 shares Issued - 3,577,103,522 shares in 2015 and 2014	1,788	1,788
Other paid-in capital	40,222	40,423
Retained earnings	45,348	46,021
Accumulated other comprehensive loss	(4,148)	(4,323)
Stockholders' equity before deduction for treasury stock	83,210	83,909
Less treasury stock, at cost: 795,975,449 shares in 2015 and 738,963,326 shares in 2014	38,534	35,262
Total Merck & Co., Inc. stockholders’ equity	44,676	48,647
Noncontrolling Interests	91	144
Total equity	44,767	48,791
Total Liabilities and Equity	$ 101,779	$ 98,167

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 165	$ 153
Accounts receivable classified in other assets	10	80
Inventories classified in other assets	$ 1,569	$ 1,664
Common stock, par value (in dollars per share)	$ 0.50	$ 0.50
Common stock, shares authorized	6,500,000,000	6,500,000,000
Common stock, shares issued	3,577,103,522	3,577,103,522
Treasury stock, shares	795,975,449	738,963,326

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, 2012	$ 55,463	$ 1,788	$ 40,646	$ 39,985	$ (4,682)	$ (24,717)	$ 2,443
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income Attributable to Merck & Co., Inc.	4,404			4,404
Other comprehensive income (loss), net of taxes	2,485				2,485
Cash dividends declared on common stock ($1.81 per share in 2015, $1.77 per share in 2014, and $1.73 per share in 2013)	(5,132)			(5,132)
Treasury stock shares purchased	(6,516)					(6,516)
Supera joint venture formation	228		116				112
Net income attributable to noncontrolling interests	113						113
Distributions attributable to noncontrolling interests	(120)						(120)
Share-based compensation plans and other	1,401		(254)			1,642	13
Ending 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 ($1.81 per share in 2015, $1.77 per share in 2014, and $1.73 per share in 2013)	(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 ($1.81 per share in 2015, $1.77 per share in 2014, and $1.73 per share in 2013)	(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

Consolidated Statement of Equi7

Consolidated Statement of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Stockholders' Equity [Abstract]
Common stock, dividends declared (in dollars per share)	$ 1.81	$ 1.77	$ 1.73

Consolidated Statement of Cash

Consolidated Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flows from Operating Activities
Net income	$ 4,459	$ 11,934	$ 4,517
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,375	6,691	6,988
Intangible asset impairment charges	162	1,222	765
Foreign currency devaluation related to Venezuela	876	0	140
Net charge related to the settlement of Vioxx shareholder class action litigation	680	0	0
Gain on divestiture of Merck Consumer Care business	0	(11,209)	0
Gain on AstraZeneca option exercise	0	(741)	0
Loss on extinguishment of debt	0	628	0
Equity income from affiliates	(205)	(257)	(404)
Dividends and distributions from equity method affiliates	50	185	237
Deferred income taxes	(764)	(2,600)	(330)
Share-based compensation	299	278	276
Other	757	(95)	259
Net changes in assets and liabilities:
Accounts receivable	(480)	(554)	436
Inventories	805	79	(365)
Trade accounts payable	(37)	593	522
Accrued and other current liabilities	(8)	1,635	(397)
Income taxes payable	(266)	(21)	(1,421)
Noncurrent liabilities	(277)	190	(132)
Other	(5)	(98)	563
Net Cash Provided by Operating Activities	12,421	7,860	11,654
Cash Flows from Investing Activities
Capital expenditures	(1,283)	(1,317)	(1,548)
Purchases of securities and other investments	(16,681)	(24,944)	(17,991)
Proceeds from sales of securities and other investments	20,413	15,114	16,298
Divestiture of Merck Consumer Care business, net of cash divested	0	13,951	0
Dispositions of other businesses, net of cash divested	316	1,169	46
Proceeds from AstraZeneca option exercise	0	419	0
Acquisition of Cubist Pharmaceuticals, Inc., net of cash acquired	(7,598)	0	0
Acquisition of Idenix Pharmaceuticals, Inc., net of cash acquired	0	(3,700)	0
Acquisitions of other businesses, net of cash acquired	(146)	(181)	(246)
Acquisition of Bayer AG collaboration rights	0	(1,000)	0
Cash inflows from net investment hedges	139	195	350
Other	82	(80)	(57)
Net Cash Used in Investing Activities	(4,758)	(374)	(3,148)
Cash Flows from Financing Activities
Net change in short-term borrowings	(1,540)	(460)	(159)
Payments on debt	(2,906)	(6,617)	(1,775)
Proceeds from issuance of debt	7,938	3,146	6,467
Purchases of treasury stock	(4,186)	(7,703)	(6,516)
Dividends paid to stockholders	(5,117)	(5,170)	(5,157)
Other dividends paid	0	(77)	(120)
Proceeds from exercise of stock options	485	1,560	1,210
Other	56	208	60
Net Cash Used in Financing Activities	(5,270)	(15,113)	(5,990)
Effect of Exchange Rate Changes on Cash and Cash Equivalents	(1,310)	(553)	(346)
Net Increase (Decrease) in Cash and Cash Equivalents	1,083	(8,180)	2,170
Cash and Cash Equivalents at Beginning of Year	7,441	15,621	13,451
Cash and Cash Equivalents at End of Year	$ 8,524	$ 7,441	$ 15,621

Nature of Operations

Nature of Operations	12 Months Ended
	Dec. 31, 2015
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, which it markets directly and through its joint ventures. The Company’s operations are principally managed on a products basis and are comprised of four operating segments, the Pharmaceutical, Animal Health, Alliances and Healthcare Services 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. 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. 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. 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. On January 21, 2015, the Company acquired Cubist Pharmaceuticals, Inc. (Cubist) and, on July 31, 2015, Merck acquired cCAM Biotherapeutics Ltd. (cCAM). The results of Cubist’s and cCAM’s businesses have been included in Merck’s financial statements subsequent to their respective acquisition dates (see Note 4). 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 4).

Summary of Accounting Policies

Summary of Accounting Policies	12 Months Ended
	Dec. 31, 2015
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 $145 million and $2.7 billion , respectively, at December 31, 2015 and $112 million and $2.0 billion , respectively, at December 31, 2014 . 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 2015 , $2.5 billion in 2014 and $2.2 billion in 2013 . Advertising and Promotion Costs — Advertising and promotion costs are expensed as incurred. The Company recorded advertising and promotion expenses of $2.1 billion , $2.3 billion and $2.5 billion in 2015 , 2014 and 2013 , 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 $421 million and $505 million , net of accumulated amortization at December 31, 2015 and 2014 , 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 1 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 November 2015, the Financial Accounting Standards Board (FASB) issued accounting guidance on the balance sheet classification of deferred taxes as part of its simplification initiative aimed at reducing complexity in accounting standards. The new guidance requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. The Company elected to early adopt the new guidance in the fourth quarter of 2015 (see Note 15). 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. Reporting entities may choose to adopt the standard as of the original effective date. The Company is currently assessing the impact of adoption on its consolidated financial statements. In April 2015, the FASB issued accounting guidance 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. The new guidance is effective for interim and annual periods beginning in 2016. As of December 31, 2015, the Company had debt issuance costs recorded as deferred charges of approximately $100 million . 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.

Restructuring

Restructuring	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring	Restructuring 2013 Restructuring Program In 2013, the Company initiated actions under a global restructuring program (the 2013 Restructuring Program) as part of a global initiative to sharpen its commercial and research and development focus. The actions under this program primarily include the elimination of positions in sales, administrative and headquarters organizations, as well as research and development. Additionally, these actions include the reduction of the Company’s global real estate footprint and improvements in the efficiency of its manufacturing and supply network. The Company recorded total pretax costs of $527 million in 2015 and $1.2 billion in both 2014 and 2013 related to this restructuring program. Since inception of the 2013 Restructuring Program through December 31, 2015 , Merck has recorded total pretax accumulated costs of approximately $3.0 billion and eliminated approximately 8,630 positions comprised of employee separations, as well as the elimination of contractors and vacant positions. The actions under the 2013 Restructuring Program were substantially completed by the end of 2015. Accordingly, as of January 1, 2016, the remaining accrued liability for future separations under the 2013 Restructuring Program was combined with the remaining accrued liability for the Merger Restructuring Program (see below) and any remaining activities under both programs will be accounted for in the aggregate prospectively. Merger Restructuring Program In 2010, subsequent to the Merck and Schering-Plough Corporation (Schering-Plough) merger, the Company commenced actions under a global restructuring program (the Merger Restructuring Program) designed to streamline the cost structure of the combined company. Further actions under this program were initiated in 2011. The actions under this program primarily 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 recorded total pretax costs of $583 million in 2015 , $730 million in 2014 and $1.1 billion in 2013 related to this restructuring program. Since inception of the Merger Restructuring Program through December 31, 2015 , Merck has recorded total pretax accumulated costs of approximately $8.5 billion and eliminated approximately 29,645 positions comprised of employee separations, as well as the elimination of contractors and vacant positions. The non-facility related restructuring actions under the Merger Restructuring Program are substantially complete. Accordingly, as noted above, as of January 1, 2016, the remaining accrued liability for future separations under the 2013 Restructuring Program was combined with the remaining accrued liability for the Merger Restructuring Program and any remaining activities under both programs, which primarily relate to ongoing facility rationalizations, will be accounted for in the aggregate prospectively. The Company expects to complete such actions by the end of 2017 and incur approximately $1.5 billion of additional pretax costs. The Company estimates that approximately two-thirds of the cumulative pretax costs relate to 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. On October 1, 2013, the Company sold its active pharmaceutical ingredient (API) manufacturing business, including the related manufacturing facility, in the Netherlands to Aspen Holdings (Aspen) as part of planned manufacturing facility rationalizations under the Merger Restructuring Program. In connection with the sale, Aspen acquired certain branded products from Merck, which transferred to Aspen effective December 31, 2013. Consideration for the transaction included cash of $705 million and notes receivable with a present value of $198 million at the time of disposition. Of the cash portion of the consideration, the Company received $172 million in the fourth quarter of 2013. The remaining $533 million was received by the Company in January 2014. 2008 Restructuring Program In 2008, Merck announced a global restructuring program (the 2008 Restructuring Program) to reduce its cost structure, increase efficiency, and enhance competitiveness. Pretax costs of $54 million were recorded in 2013 related to the 2008 Restructuring Program. For segment reporting, restructuring charges are unallocated expenses. The following table summarizes the charges related to restructuring program activities by type of cost: Year Ended December 31, 2015 Separation Costs Accelerated Depreciation Other Total 2013 Restructuring Program Materials and production $ — $ 41 $ 2 $ 43 Marketing and administrative — 52 18 70 Research and development — 36 15 51 Restructuring costs 199 — 164 363 199 129 199 527 Merger Restructuring Program Materials and production — 37 281 318 Marketing and administrative — 7 1 8 Research and development — 1 — 1 Restructuring costs 9 — 247 256 9 45 529 583 $ 208 $ 174 $ 728 $ 1,110 Year Ended December 31, 2014 2013 Restructuring Program Materials and production $ — $ 204 $ 23 $ 227 Marketing and administrative — 142 3 145 Research and development — 273 9 282 Restructuring costs 566 — 28 594 566 619 63 1,248 Merger Restructuring Program Materials and production — 225 30 255 Marketing and administrative — 56 (1 ) 55 Research and development — — 1 1 Restructuring costs 108 — 311 419 108 281 341 730 $ 674 $ 900 $ 404 $ 1,978 Year Ended December 31, 2013 2013 Restructuring Program Materials and production $ — $ 186 $ 7 $ 193 Marketing and administrative — 72 3 75 Research and development — 76 (1 ) 75 Restructuring costs 866 — 32 898 866 334 41 1,241 Merger Restructuring Program Materials and production — 151 98 249 Marketing and administrative — 63 3 66 Research and development — 27 (1 ) 26 Restructuring costs 481 — 284 765 481 241 384 1,106 2008 Restructuring Program Materials and production — (2 ) 6 4 Marketing and administrative — 4 — 4 Restructuring costs 34 — 12 46 34 2 18 54 $ 1,381 $ 577 $ 443 $ 2,401 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 the 2013 Restructuring Program were approximately 2,535 in 2015 , 4,555 in 2014 and 1,540 in 2013 . Positions eliminated under the Merger Restructuring Program were approximately 1,235 in 2015 , 1,530 in 2014 and 4,475 in 2013 . 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 site, based upon the anticipated date the site will be closed or divested, 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 was required to accelerate depreciation of the site assets rather than record an impairment charge. 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 2015 , 2014 and 2013 includes $550 million , $240 million and $259 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 $117 million in 2015 , $133 million in 2014 and $64 million in 2013 (primarily reflecting a loss on the transaction with Aspen discussed above). Adjustments to previously recorded amounts were not material in any period. The following table summarizes the charges and spending relating to restructuring activities by program: Separation Costs Accelerated Depreciation Other Total 2013 Restructuring Program Restructuring reserves January 1, 2014 $ 745 $ — $ 23 $ 768 Expenses 566 619 63 1,248 (Payments) receipts, net (816 ) — (124 ) (940 ) Non-cash activity — (619 ) 52 (567 ) Restructuring reserves December 31, 2014 495 — 14 509 Expenses 199 129 199 527 (Payments) receipts, net (425 ) — (212 ) (637 ) Non-cash activity — (129 ) 1 (128 ) Restructuring reserves December 31, 2015 (1) $ 269 $ — $ 2 $ 271 Merger Restructuring Program Restructuring reserves January 1, 2014 $ 725 $ — $ 12 $ 737 Expenses 108 281 341 730 (Payments) receipts, net (297 ) — (232 ) (529 ) Non-cash activity — (281 ) (115 ) (396 ) Restructuring reserves December 31, 2014 536 — 6 542 Expenses 9 45 529 583 (Payments) receipts, net (222 ) — (223 ) (445 ) Non-cash activity — (45 ) (261 ) (306 ) Restructuring reserves December 31, 2015 (1) $ 323 $ — $ 51 $ 374 (1) The non-facility related cash outlays associated with both the 2013 Restructuring Program and the Merger Restructuring Program were substantially completed by the end of 2015; 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, 2015
Business Combinations [Abstract]
Acquisitions, Divestitures, Research Collaborations and License Agreements	Acquisitions, Divestitures, Research Collaborations and License Agreements The Company continues its strategy of establishing external alliances to complement its internal research capabilities, including research collaborations, licensing preclinical and clinical compounds to drive both near- and long-term growth. The Company supplements its internal research with a licensing and external alliance strategy focused on the entire spectrum of collaborations from early research to late-stage compounds, as well as access to new technologies. 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 pipeline to examine candidates which may provide more value through out-licensing and, as part of its portfolio assessment process, may also divest certain products. Acquisition of Cubist Pharmaceuticals, Inc. In January 2015, Merck acquired Cubist, a leader in the development of therapies to treat serious infections caused by a broad range of bacteria. The acquisition complements Merck’s existing hospital acute care business. Total consideration transferred of $8.3 billion includes 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; accordingly, the assets acquired and liabilities assumed were recorded at their respective fair values as of the acquisition date. The fair value of assets acquired and liabilities assumed from Cubist is as follows: 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 most significant intangible assets relate to Zerbaxa , Cubicin and Sivextro (see Note 7). 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. The amount was capitalized and accounted for as an indefinite-lived intangible asset, subject to impairment testing until completion or abandonment of the project. The fair value of surotomycin was determined by using an income approach, through which fair value is estimated based on 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 9% . 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. Cubist contributed sales of $1.3 billion in 2015 to Merck’s revenues. The Company is no longer able to provide the results of operations attributable to Cubist during 2015 as the operations of Cubist have been largely integrated. 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. Other 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, a privately held biopharmaceutical company focused on the discovery and development of novel cancer immunotherapies. The acquisition provides Merck with cCAM’s lead pipeline candidate, CM-24, a novel monoclonal antibody targeting the immune checkpoint protein CEACAM1 that is being evaluated in a Phase 1 study for the treatment of advanced or recurrent malignancies, including melanoma, non-small-cell lung, bladder, gastric, colorectal, and ovarian cancers. Total purchase consideration in the transaction of $201 million 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, which the Company determined had a fair value of $105 million at the acquisition date. The 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. Merck recognized an intangible asset for IPR&D of $180 million and other net assets of $7 million . The excess of the consideration transferred over the fair value of net assets acquired of $14 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. The asset’s probability-adjusted future net cash flows were then discounted to present value using a discount rate of 10.5% . The fair value of the contingent consideration was determined utilizing a probability-weighted estimated cash flow stream adjusted for the expected timing of each payment also utilizing a discount rate of 10.5% . Actual cash flows are likely to be different than those assumed. This transaction closed on July 31, 2015; accordingly, the results of operations of the acquired business have been included in the Company’s results of operations beginning after that date. Pro forma financial information has not been included because cCAM’s historical financial results are not significant when compared with the Company’s financial results. 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 , $125 million of which was paid in August 2015 upon closing of the transaction and $125 million of which is payable in April of 2016. Merck will additionally be entitled to receive potential development and commercial milestone payments and tiered double-digit royalties based on commercialization of the programs. Allergan will be fully responsible for development of the CGRP programs, as well as manufacturing and commercialization upon approval and launch of the products. The Company recorded a gain of $250 million within Other (income) expense, net in 2015 related to the transaction. 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. The collaboration includes multiple drug candidates currently in preclinical development at NGM, including NP201, which is being evaluated for the treatment of diabetes, obesity and nonalcoholic steatohepatitis. NGM will lead the research and development of the existing preclinical candidates and have the autonomy to identify and pursue other discovery stage programs at its discretion. Merck will have the option to license all resulting NGM programs following human proof of concept trials. If Merck exercises this option, Merck will lead global product development and commercialization for the resulting products, if approved. Under the terms of the agreement, Merck made an upfront payment to NGM of $94 million , which is 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 will have the option to extend the research agreement for two additional two -year terms. Each party has certain termination rights under the agreement in the event of an uncured material breach by the other party. Additionally, Merck has certain termination rights in the event of the occurrence of certain defined conditions. Upon a termination event, depending on the circumstances, the parties have varying rights and obligations with respect to the continued development and commercialization of compounds discovered under the agreement and certain related payment obligations. In December 2014, Merck acquired OncoEthix, a privately held biotechnology company specializing in oncology drug development. Total purchase consideration in the transaction of $153 million included an upfront cash payment of $110 million and future additional milestone payments of up to $265 million that are contingent upon certain clinical and regulatory milestones being achieved, which the Company determined had a fair value of $43 million at the acquisition date. The 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. Merck recognized an intangible asset for IPR&D of $143 million related to MK-8628 (formerly OTX015), an investigational, novel oral BET (bromodomain) inhibitor currently in Phase 2 studies for the treatment of hematological malignancies and advanced solid tumors, as well as a liability for contingent consideration of $43 million and other net assets of $10 million . 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% . The fair value of the contingent consideration was determined utilizing a probability-weighted estimated cash flow stream adjusted for the expected timing of each payment also utilizing a discount rate of 11.5% . Actual cash flows are likely to be different than those assumed. This transaction closed on December 18, 2014; accordingly, the results of operations of the acquired business have been included in the Company’s results of operations beginning after that date. Pro forma financial information has not been included because OncoEthix’s historical financial results are not significant when compared with the Company’s financial results. 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 in 2014. Also on October 1, 2014, the Company entered into a worldwide clinical development collaboration with Bayer to market and develop its portfolio of soluble guanylate cyclase (sGC) modulators. This includes Bayer’s Adempas (riociguat), the first member of this novel class of compounds. Adempas is approved to treat pulmonary arterial hypertension (PAH) and is approved for patients with chronic thromboembolic pulmonary hypertension (CTEPH). Adempas is marketed in the United States and Europe for both PAH and CTEPH and in Japan for CTEPH. 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 currently in Phase 2 trials for worsening heart failure, as well as opt-in rights for other early-stage sGC compounds in development at Bayer. Merck will in turn make 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. For Adempas, Bayer will continue to lead commercialization 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, through which fair value is estimated based upon probability-adjusted future net cash flows, and for vericiguat also for 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 10.0% for Adempas and 10.5% for vericiguat. Future sales based milestones will be accrued when probable of being achieved; the related intangible asset will be recognized and amortized to Materials and production costs over its applicable useful life. The Company and Bayer each have the right to terminate the agreement for cause on a product-by-product basis for all products being developed and commercialized under the agreement (other than Adempas for which Bayer has no termination rights) in the event of the other party’s material, uncured breach related to any such product. In September 2014, Merck and Sun Pharmaceutical Industries Ltd. (Sun Pharma) entered into an exclusive worldwide licensing agreement for Merck’s investigational therapeutic antibody candidate, MK-3222, tildrakizumab, for the treatment of chronic plaque psoriasis, a skin ailment. Under terms of the agreement, Sun Pharma acquired worldwide rights to tildrakizumab for use in all human indications from Merck in exchange for an upfront payment of $80 million . Merck will continue all clinical development and regulatory activities, which will be funded by Sun Pharma. Upon product approval, Sun Pharma will be responsible for regulatory activities, including subsequent submissions, pharmacovigilance, post approval studies, manufacturing and commercialization of the approved product. Merck is also eligible to receive future payments associated with regulatory (including product approval) and sales milestones, as well as tiered royalties ranging from mid-single digit through teen percentage rates on sales. Merck recorded a loss of $47 million in 2014 on the transaction included in Other (income) expense, net . 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; accordingly, the assets acquired and liabilities assumed were recorded at their respective fair values as of the acquisition date. Merck recognized an intangible asset for IPR&D of $3.2 billion related to MK-3682 (formerly IDX21437), net deferred tax liabilities of $951 million and other net liabilities of $12 million . MK-3682 is a nucleotide prodrug in Phase 2 clinical development being evaluated for potential inclusion in the development of all oral, pan-genotypic fixed-dose combination regimens. 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% . Actual cash flows are likely to be different than those assumed. This transaction closed on August 5, 2014; accordingly, the results of operations of the acquired business have been included in the Company’s results of operations beginning after that date. Pro forma financial information has not been included because Idenix’s historical financial results are not significant when compared with the Company’s financial results. 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 divested 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. In February 2013, Merck and Supera Farma Laboratorios S.A. (Supera), a Brazilian pharmaceutical company co-owned by Cristália and Eurofarma, established a joint venture that markets, distributes and sells a portfolio of pharmaceutical and branded generic products from Merck, Cristália and Eurofarma in Brazil. Merck owns 51% of the joint venture, and Cristália and Eurofarma collectively own 49% . The transaction was accounted for as an acquisition of a business; accordingly, the assets acquired and liabilities assumed were recorded at their respective fair values. This resulted in Merck recognizing intangible assets for currently marketed products of $89 million , IPR&D of $100 million , goodwill of $103 million , and deferred tax liabilities of $64 million . The Company also recorded increases to Noncontrolling interests and Other paid-in capital in the amounts of $112 million and $116 million , respectively. This transaction closed on February 1, 2013; accordingly, the results of operations of the acquired business have been included in the Company’s results of operations beginning after that date. The Company has recorded certain intangible asset impairments charges related to the Supera joint venture (see Note 7). 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. In 2007, Schering-Plough and Centocor revised their distribution agreement regarding the development, commercialization and distribution of both Remicade and Simponi , extending the Company’s rights to exclusively market Remicade to match the duration of the Company’s exclusive marketing rights for Simponi . In addition, Schering-Plough and Centocor agreed to share certain development costs relating to Simponi ’s auto-injector delivery system. In 2009, the European Commission approved Simponi as a treatment for rheumatoid arthritis and other immune system disorders in two presentations — a novel auto-injector and a prefilled syringe. As a result, the Company’s marketing rights for both products extend for 15 years from the first commercial sale of Simponi in the European Union (EU) following the receipt of pricing and reimbursement approval within the EU. 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, 2015
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 primary objective of the revenue hedging program is to reduce the potential for longer-term unfavorable changes in foreign exchange rates to decrease 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 that are expected to occur over its planning cycle, typically no more than three years into the future. The Company will layer in hedges over time, increasing the portion of third-party and intercompany distributor entity sales hedged as it gets closer to the expected date of the forecasted foreign currency denominated sales. The portion of 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 hedged anticipated sales are a specified component of a portfolio of similarly denominated foreign currency-based sales transactions, each of which responds to the hedged currency risk in the same manner. The Company manages its anticipated transaction exposure principally with purchased local currency put options, which provide the Company with a right, but not an obligation, to sell foreign currencies in the future at a predetermined price. If the U.S. dollar strengthens relative to the currency of the hedged anticipated sales, total changes in the options’ cash flows offset the decline in the expected future U.S. dollar equivalent cash flows of the hedged foreign currency sales. Conversely, if the U.S. dollar weakens, the options’ value reduces to zero, but the Company benefits from the increase in the U.S. dollar equivalent value of the anticipated foreign currency cash flows. In connection with the Company’s revenue hedging program, a purchased collar option strategy may be utilized. With a purchased collar option strategy, the Company writes a local currency call option and purchases a local currency put option. As compared to a purchased put option strategy alone, a purchased collar strategy reduces the upfront costs associated with purchasing puts through the collection of premiums by writing call options. If the U.S. dollar weakens relative to the currency of the hedged anticipated sales, the purchased put option value of the collar strategy reduces to zero and the Company benefits from the increase in the U.S. dollar equivalent value of its anticipated foreign currency cash flows; however, this benefit would be capped at the strike level of the written call. If the U.S. dollar strengthens relative to the currency of the hedged anticipated sales, the written call option value of the collar strategy reduces to zero and the changes in the purchased put cash flows of the collar strategy would offset the decline in the expected future U.S. dollar equivalent cash flows of the hedged foreign currency sales. The Company may also utilize forward contracts in its revenue hedging program. If the U.S. dollar strengthens relative to the currency of the hedged anticipated sales, the increase in the fair value of the forward contracts offsets the decrease in the expected future U.S. dollar cash flows of the hedged foreign currency sales. Conversely, if the U.S. dollar weakens, the decrease in the fair value of the forward contracts offsets the increase in the value of the anticipated foreign currency cash flows. 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 primary objective of the balance sheet risk management program is 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, which enable the Company to buy and sell foreign currencies in the future at fixed exchange rates and economically offset the consequences of changes in foreign exchange from the monetary assets. Merck routinely enters into 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 Company will also minimize the effect of exchange on monetary assets and liabilities by managing operating activities and net asset positions at the local level. The cash flows from these contracts are reported as operating activities in the Consolidated Statement of Cash Flows. Monetary assets and liabilities denominated in a currency other than the functional currency of a given subsidiary are remeasured at spot rates in effect on the balance sheet date with the effects of changes in spot rates reported in Other (income) expense, net . The forward contracts are not designated as hedges and are marked to market through Other (income) expense, net . Accordingly, fair value changes in the forward contracts help mitigate the changes in the value of the remeasured assets and liabilities attributable to changes in foreign currency exchange rates, except to the extent of the spot-forward differences. These differences are not significant due to the short-term nature of the contracts, which typically have average maturities at inception of less than one year. The Company also uses forward exchange contracts to hedge 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. 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 $304 million in 2015 and $294 million in 2014 and pretax losses of $84 million in 2013 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. At December 31, 2015 , the Company was a party to 30 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. 2015 Debt Instrument Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 0.70% notes due 2016 $ 1,000 4 $ 1,000 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: 2015 2014 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 (noncurrent) Other assets $ 42 $ — $ 2,700 $ 19 $ — $ 1,950 Interest rate swap contracts (current) Accrued and other current liabilities — 1 1,000 — — — Interest rate swap contracts (noncurrent) Other noncurrent liabilities — 23 3,500 — 15 2,000 Foreign exchange contracts (current) Other current assets 579 — 4,171 772 — 5,513 Foreign exchange contracts (noncurrent) Other assets 386 — 4,136 691 — 6,253 Foreign exchange contracts (current) Accrued and other current liabilities — 1 77 — — — $ 1,007 $ 25 $ 15,584 $ 1,482 $ 15 $ 15,716 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts (current) Other current assets $ 212 $ — $ 8,783 $ 365 $ — $ 6,966 Foreign exchange contracts (noncurrent) Other assets 18 — 179 — — — Foreign exchange contracts (current) Accrued and other current liabilities — 37 2,508 — 88 3,386 Foreign exchange contracts (noncurrent) Other noncurrent liabilities — 1 6 — — — $ 230 $ 38 $ 11,476 $ 365 $ 88 $ 10,352 $ 1,237 $ 63 $ 27,060 $ 1,847 $ 103 $ 26,068 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: 2015 2014 Asset Liability Asset Liability Gross amounts recognized in the consolidated balance sheet $ 1,237 $ 63 $ 1,847 $ 103 Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet (59 ) (59 ) (97 ) (97 ) Cash collateral (received) posted (862 ) — (1,410 ) — Net amounts $ 316 $ 4 $ 340 $ 6 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 2015 2014 2013 Derivatives designated in a fair value hedging relationship Interest rate swap contracts Amount of (gain) loss recognized in Other (income) expense, net on derivatives (1) $ (14 ) $ (17 ) $ 12 Amount of loss (gain) recognized in Other (income) expense, net on hedged item (1) 7 14 (14 ) Derivatives designated in foreign currency cash flow hedging relationships Foreign exchange contracts Amount of (gain) loss reclassified from AOCI to Sales (724 ) (143 ) 45 Amount of gain recognized in OCI on derivatives (526 ) (775 ) (306 ) Derivatives designated in foreign currency net investment hedging relationships Foreign exchange contracts Amount of gain recognized in Other (income) expense, net on derivatives (2) (4 ) (6 ) (10 ) Amount of gain recognized in OCI on derivatives (10 ) (192 ) (363 ) Derivatives not designated in a hedging relationship Foreign exchange contracts Amount of (gain) loss recognized in Other (income) expense, net on derivatives (3) (461 ) (516 ) 183 Amount of (gain) loss recognized in Sales (1 ) 15 8 (1) There was $7 million , $3 million and $2 million of ineffectiveness on the hedge during 2015 , 2014 and 2013 , 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, 2015 , the Company estimates $429 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 available-for-sale investments at December 31 is as follows: 2015 2014 Fair Value Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Gains Losses Gains Losses Corporate notes and bonds $ 10,259 $ 10,299 $ 7 $ (47 ) $ 10,107 $ 10,102 $ 22 $ (17 ) Commercial paper 2,977 2,977 — — 6,970 6,970 — — U.S. government and agency securities 1,761 1,767 — (6 ) 1,774 1,775 1 (2 ) Asset-backed securities 1,284 1,290 — (6 ) 1,460 1,462 1 (3 ) Mortgage-backed securities 694 697 1 (4 ) 602 604 2 (4 ) Foreign government bonds 607 586 22 (1 ) 385 385 — — Equity securities 534 409 125 — 730 557 173 — $ 18,116 $ 18,025 $ 155 $ (64 ) $ 22,028 $ 21,855 $ 199 $ (26 ) Available-for-sale debt securities included in Short-term investments totaled $4.8 billion at December 31, 2015 . Of the remaining debt securities, $11.8 billion mature within five years. At December 31, 2015 and 2014 , 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 2015 2014 Assets Investments Corporate notes and bonds $ — $ 10,259 $ — $ 10,259 $ — $ 10,107 $ — $ 10,107 Commercial paper — 2,977 — 2,977 — 6,970 — 6,970 U.S. government and agency securities — 1,761 — 1,761 — 1,774 — 1,774 Asset-backed securities (1) — 1,284 — 1,284 — 1,460 — 1,460 Mortgage-backed securities (1) — 694 — 694 — 602 — 602 Foreign government bonds — 607 — 607 — 385 — 385 Equity securities 360 — — 360 495 — — 495 360 17,582 — 17,942 495 21,298 — 21,793 Other assets Securities held for employee compensation 155 19 — 174 181 54 — 235 Derivative assets (2) Purchased currency options — 1,041 — 1,041 — 1,252 — 1,252 Forward exchange contracts — 154 — 154 — 576 — 576 Interest rate swaps — 42 — 42 — 19 — 19 — 1,237 — 1,237 — 1,847 — 1,847 Total assets $ 515 $ 18,838 $ — $ 19,353 $ 676 $ 23,199 $ — $ 23,875 Liabilities Other liabilities Contingent consideration $ — $ — $ 590 $ 590 $ — $ — $ 428 $ 428 Derivative liabilities (2) Forward exchange contracts — 38 — 38 — 46 — 46 Written currency options — 1 — 1 — 42 — 42 Interest rate swaps — 24 — 24 — 15 — 15 — 63 — 63 — 103 — 103 Total liabilities $ — $ 63 $ 590 $ 653 $ — $ 103 $ 428 $ 531 (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 credit card, auto loan, and home equity 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 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 2015 . As of December 31, 2015 , Cash and cash equivalents of $8.5 billion included $7.7 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: 2015 2014 Fair value January 1 $ 428 $ 69 Changes in fair value (1) (16 ) 316 Additions 228 43 Payments (50 ) — Fair value December 31 $ 590 $ 428 (1) Recorded in Research and development expenses and Materials and production costs. During 2015, the Company recognized liabilities for contingent consideration of $123 million related to the acquisition of Cubist and $105 million related to the acquisition of cCAM (see Note 4). In addition, in 2015, the Company paid $50 million of contingent consideration related to the first commercial sale of Zerbaxa in the United States. During 2014, the fair value of a liability for contingent consideration related to an acquisition that occurred in 2010 increased by $316 million resulting from the progression of the program from preclinical to Phase 1. The increase resulted from a higher fair value of future regulatory milestone and royalty payments due to an increased probability of success of the program given its progression into Phase 1. In addition, during 2014, the Company recognized a liability of $43 million for contingent consideration related to the acquisition of OncoEthix in 2014 (see Note 4). 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, 2015 , was $27.0 billion compared with a carrying value of $26.5 billion and at December 31, 2014 , was $22.5 billion compared with a carrying value of $21.4 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. At December 31, 2015 and 2014 , Other assets included $10 million and $80 million , respectively, of accounts receivable not expected to be collected within one year. As of December 31, 2015 , the Company’s total net accounts receivable outstanding for more than one year were approximately $125 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: AmerisourceBergen Corporation, Cardinal Health, Inc., McKesson Corporation, Zuellig Pharma Ltd. (Asia Pacific), and AAH Pharmaceuticals Ltd (UK) which represented, in aggregate, approximately one-third of total accounts receivable at December 31, 2015 . 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, 2015 and 2014 , the Company had received cash collateral of $862 million and $1.4 billion , 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, 2015 or 2014 .

Inventories

Inventories	12 Months Ended
	Dec. 31, 2015
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories at December 31 consisted of: 2015 2014 Finished goods $ 1,343 $ 1,588 Raw materials and work in process 4,374 5,141 Supplies 168 197 Total (approximates current cost) 5,885 6,926 Increase to LIFO costs 384 309 $ 6,269 $ 7,235 Recognized as: Inventories $ 4,700 $ 5,571 Other assets 1,569 1,664 Inventories valued under the LIFO method comprised approximately $2.4 billion and $2.6 billion of inventories at December 31, 2015 and 2014 , respectively. Amounts recognized as Other assets are comprised almost entirely of raw materials and work in process inventories. At December 31, 2015 and 2014 , these amounts included $1.5 billion and $1.6 billion , respectively, of inventories not expected to be sold within one year. In addition, these amounts included $63 million and $74 million at December 31, 2015 and 2014 , respectively, of inventories produced in preparation for product launches.

Goodwill and Other Intangibles

Goodwill and Other Intangibles	12 Months Ended
	Dec. 31, 2015
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, 2014 $ 10,065 $ 2,236 $ 12,301 Acquisitions 1,369 38 1,407 Divestitures (200 ) (362 ) (562 ) Impairments (93 ) — (93 ) Other (1) (33 ) (28 ) (61 ) Balance December 31, 2014 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 (1) Other includes cumulative translation adjustments on goodwill balances and certain other adjustments. (2) Accumulated goodwill impairment losses at December 31, 2015 and 2014 were $140 million and $93 million , respectively. In 2015, the additions to goodwill in the Pharmaceutical segment resulted primarily from the acquisition of Cubist (see Note 4). The reductions to Pharmaceutical segment goodwill resulted from the divestiture of the Company’s remaining ophthalmics business in international markets (see Note 4). The impairments of goodwill within other non-reportable segments relates primarily to certain businesses within the Healthcare Services segment. In 2014, the additions to goodwill in the Pharmaceutical segment primarily resulted from the acquisition of Idenix and the reductions resulted both from the sale of MCC and the divestiture of certain ophthalmic products in several international markets (see Note 4). The reductions to goodwill in other segments during 2014 resulted from the termination of the Company’s relationship with AstraZeneca LP (AZLP) (see Note 8) and the divestiture of MCC. Also, during the third quarter of 2014, the Company recorded an impairment charge on the goodwill related to the Supera joint venture as a result of changes in cash flow assumptions for certain compounds and currently marketed products. Other intangibles at December 31 consisted of: 2015 2014 Gross Carrying Amount Accumulated Amortization Net Gross Carrying Amount Accumulated Amortization Net Products and product rights $ 45,949 $ 28,514 $ 17,435 $ 38,714 $ 23,830 $ 14,884 In-process research and development 4,226 — 4,226 4,345 — 4,345 Tradenames 198 79 119 198 71 127 Other 1,418 596 822 1,527 497 1,030 $ 51,791 $ 29,189 $ 22,602 $ 44,784 $ 24,398 $ 20,386 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 2015 primarily relates to the acquisition of Cubist (see Note 4). Some of the Company’s more significant acquired intangibles related to marketed products (included in product and product rights above) at December 31, 2015 include Zerbaxa , $3.5 billion ; Zetia , $2.4 billion ; Vytorin , $1.5 billion ; Sivextro , $1.0 billion ; Implanon/Nexplanon $645 million ; Dificid , $644 million ; NuvaRing , $502 million ; Nasonex , $431 million and Cubicin, $418 million . During 2014, the Company recognized an intangible asset related to Adempas as a result of the formation of a collaboration with Bayer (see Note 4) that had a carrying value of $706 million at December 31, 2015 reflected in “Other” in the table above. During 2015 , 2014 and 2013 , the Company recorded impairment charges related to marketed products and other intangibles of $45 million , $1.1 billion and $486 million , respectively, within Material and production costs. 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 marketed by the Company for the treatment of chronic HCV infection. During 2014, sales of these products were adversely affected by loss of market share or patient treatment delays in markets anticipating the availability of newer therapeutic options. In 2014, these trends accelerated more rapidly than previously anticipated by the Company. In addition, developments in the competitive HCV treatment market led to market share losses that were greater than the Company had predicted. These factors caused 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. Of the impairment charges recorded in 2013, $330 million resulted from lower cash flow projections for Saphris/Sycrest, due to reduced expectations in international markets and in the United States. These revisions to cash flows indicated that the Saphris/Sycrest intangible asset value was not recoverable on an undiscounted cash flows basis. The Company utilized market participant assumptions and considered several different scenarios to determine its best estimate of the fair value of the intangible asset related to Saphris/Sycrest that, when compared with its related carrying value, resulted in the impairment charge noted above. The remaining $156 million of impairment charges in 2013 resulted from lower cash flow projections for Rebetol due to reduced expectations in Japan and Europe. These revisions to cash flows indicated that the Rebetol intangible asset value was not recoverable on an undiscounted cash flows basis. The Company utilized market participant assumptions to determine its best estimate of the fair value of the intangible asset related to Rebetol that, when compared with its related carrying value, resulted in the impairment charge 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 assets and begin amortization. During 2015 , 2014 and 2013 , $280 million , $654 million and $346 million , respectively, of IPR&D was reclassified to products and product rights upon receipt of marketing approval in a major market. During 2015, the Company recorded $63 million of IPR&D impairment charges within Research and development expenses. Of this amount, $50 million relates to the surotomycin clinical development program obtained in connection with the acquisition of Cubist. 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 Supera joint venture, as well as for the discontinuation of certain Animal Health programs. During 2013, the Company recorded $279 million of IPR&D impairment charges. Of this amount, $181 million related to the write-off of the intangible asset associated with preladenant as a result of the discontinuation of the clinical development program for this compound. In addition, the Company recorded impairment charges resulting from changes in cash flow assumptions for certain compounds, as well as for pipeline programs that had previously been deprioritized and were subsequently deemed to have no alternative use in the period. 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 $4.8 billion in 2015 , $4.2 billion in 2014 and $4.8 billion in 2013 . The estimated aggregate amortization expense for each of the next five years is as follows: 2016 , $4.0 billion ; 2017 , $3.5 billion ; 2018 , $2.0 billion ; 2019 , $1.2 billion ; 2020 , $1.0 billion .

Joint Ventures and Other Equity

Joint Ventures and Other Equity Method Affiliates	12 Months Ended
	Dec. 31, 2015
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 Sanofi Pasteur MSD, certain investments funds, as well as AZLP until the termination of the Company’s relationship with AZLP on June 30, 2014 as discussed below. Equity income from affiliates was $205 million in 2015 , $257 million in 2014 and $404 million in 2013 and is included in Other (income) expense, net (see Note 14). Investments in affiliates accounted for using the equity method, including the below joint ventures, totaled $702 million at December 31, 2015 and $337 million at December 31, 2014 . These amounts are reported in Other assets . Amounts due from the above joint ventures included in Other current assets were $34 million at December 31, 2015 and $45 million at December 31, 2014 . 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 the 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. Merck earned revenue based on sales of KBI products and such revenue was $463 million in 2014 and $920 million in 2013 primarily relating to sales of Nexium, as well as Prilosec. In addition, Merck earned certain Partnership returns from AZLP of $192 million in 2014 and $352 million in 2013, 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 reflects 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 is being recognized over time in Other (income) expense, net as the contingency is eliminated as sales occur. During 2015 and 2014, $182 million and $140 million , respectively, of the deferred income was recognized bringing cumulative deferred income recognized through December 31, 2015 to $322 million . 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 $2.4 billion of KBI preferred stock (see Note 11), 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: Years Ended December 31 2014 (1) 2013 Sales $ 2,205 $ 4,611 Materials and production costs 1,044 2,222 Other expense, net 604 1,175 Income before taxes (2) 557 1,214 (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. Sanofi Pasteur MSD In 1994, Merck and Pasteur Mérieux Connaught (now Sanofi Pasteur S.A.) established an equally-owned joint venture to market vaccines in Europe and to collaborate in the development of combination vaccines for distribution in Europe. Joint venture vaccine sales were $923 million for 2015 , $1.1 billion for 2014 and $1.2 billion for 2013 .

Loans Payable, Long-Term Debt a

Loans Payable, Long-Term Debt and Other Commitments	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Loans Payable, Long-Term Debt and Other Commitments	Loans Payable, Long-Term Debt and Other Commitments Loans payable at December 31, 2015 included $2.3 billion of notes due in 2016 , $10 million of short-term foreign borrowings and $226 million of long-dated notes that are subject to repayment at the option of the holder. Loans payable at December 31, 2014 included $1.0 billion of notes due in 2015 , $1.5 billion of commercial paper, $55 million of short-term foreign borrowings and $143 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 0.07% and 0.15% for the years ended December 31, 2015 and 2014 , respectively. Long-term debt at December 31 consisted of: 2015 2014 2.75% notes due 2025 $ 2,496 $ — 3.70% notes due 2045 1,989 — 2.80% notes due 2023 1,749 1,749 5.00% notes due 2019 1,285 1,291 4.15% notes due 2043 1,247 1,246 1.85% notes due 2020 1,243 — 2.35% notes due 2022 1,237 — 3.875% notes due 2021 1,161 1,150 1.125% euro-denominated notes due 2021 1,096 1,218 1.875% euro-denominated notes due 2026 1,090 1,210 2.40% notes due 2022 1,014 1,000 Floating-rate borrowing due 2018 1,000 1,000 1.10% notes due 2018 999 999 1.30% notes due 2018 987 984 6.50% notes due 2033 809 812 Floating-rate notes due 2020 700 — 6.55% notes due 2037 596 597 2.50% euro-denominated notes due 2034 543 603 3.60% notes due 2042 493 493 5.85% notes due 2039 418 418 5.75% notes due 2036 371 371 5.95% debentures due 2028 356 356 6.40% debentures due 2028 326 326 Floating-rate notes due 2017 300 — 6.30% debentures due 2026 152 152 0.70% notes due 2016 — 998 2.25% notes due 2016 — 858 Floating-rate borrowing due 2016 — 500 Other 272 368 $ 23,929 $ 18,699 Other (as presented in the table above) included $225 million and $309 million at December 31, 2015 and 2014 , respectively, of borrowings at variable rates that resulted in effective interest rates of zero for 2015 and 2014 . Other also included foreign borrowings of $43 million and $53 million at December 31, 2015 and 2014 , respectively, at varying rates up to 4.75% and 6.25% , respectively. With the exception of the 6.30% debentures due 2026, the notes listed in the table above are redeemable in whole or in part, at Merck’s option at any time, at varying redemption prices. In February 2015, Merck issued $8.0 billion aggregate principal amount of senior unsecured notes consisting of $300 million principal amount of floating rate notes due 2017, $700 million principal amount of floating rate notes due 2020, $1.25 billion principal amount of 1.85% notes due 2020, $1.25 billion aggregate principal amount of 2.35% notes due 2022, $2.5 billion aggregate principal amount of 2.75% notes due 2025 and $2.0 billion aggregate principal amount of 3.70% notes due 2045. The Company used a portion of the net proceeds of the offering of $7.9 billion to repay commercial paper issued to substantially finance the Company’s acquisition of Cubist. The remaining net proceeds were used for general corporate purposes, including for repurchases of the Company’s common stock, and the repayment of outstanding commercial paper borrowings and debt maturities. Also, in February 2015, the Company redeemed $1.9 billion of legacy Cubist debt acquired in the acquisition (see Note 4). 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, 2015 , 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: 2016 , $2.4 billion ; 2017 , $317 million ; 2018 , $3.0 billion ; 2019 , $1.3 billion ; 2020 , $2.0 billion . In August 2014, the Company terminated its existing credit facility and entered into a $6.0 billion , five -year credit facility that matures in August 2019. 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 $303 million in 2015 , $350 million in 2014 and $367 million in 2013 . The minimum aggregate rental commitments under noncancellable leases are as follows: 2016 , $213 million ; 2017 , $136 million ; 2018 , $114 million ; 2019 , $97 million ; 2020 , $69 million and thereafter, $160 million . The Company has no significant capital leases.

Contingencies and Environmental

Contingencies and Environmental Liabilities	12 Months Ended
	Dec. 31, 2015
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 is a defendant in approximately 10 active federal and state lawsuits ( Vioxx Product Liability Lawsuits) alleging personal injury as a result of the use of Vioxx . Most of these cases are coordinated in a multidistrict litigation in the U.S. District Court for the Eastern District of Louisiana ( Vioxx MDL) before Judge Eldon E. Fallon. As previously disclosed, Merck is also a defendant in approximately 30 putative class action lawsuits alleging economic injury as a result of the purchase of Vioxx . All but one of those cases are in the Vioxx MDL. Merck has reached a resolution, approved by Judge Fallon, of these class actions in the Vioxx MDL. Under the settlement, Merck will 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 court entered an order approving the settlement in January 2014 and the claims review process was recently completed. Merck is also a defendant in lawsuits brought by state Attorneys General of three states — Alaska, Montana and Utah. The lawsuits are pending in state courts. These actions allege that Merck misrepresented the safety of Vioxx and seek recovery for expenditures on Vioxx by government-funded health care programs, such as Medicaid, and/or penalties for alleged Consumer Fraud Act violations. Trial has been scheduled in the Montana case for September 12, 2016, and trial has been set in the Alaska case for January 9, 2017. Motions for judgment on the pleadings in the Alaska and Montana cases are currently pending, and a motion to dismiss was recently filed in the Utah case. Shareholder Lawsuits As previously disclosed, in addition to the Vioxx Product Liability Lawsuits, various putative class actions and individual lawsuits have been 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 are coordinated in a multidistrict litigation in the U.S. District Court for the District of New Jersey before Judge Stanley R. Chesler, and have been consolidated for all purposes. In August 2011, Judge Chesler granted in part and denied in part Merck’s motion to dismiss the Fifth Amended Class Action Complaint in the consolidated securities class action. Among other things, the court dismissed certain defendants from the case, and also dismissed claims based on statements made on or after the voluntary withdrawal of Vioxx on September 30, 2004. In October 2011, the remaining defendants answered the Fifth Amended Class Action Complaint. In April 2012, plaintiffs filed a motion for class certification for the period from May 21, 1999, through September 29, 2004, which the court granted in January 2013. In March 2013, plaintiffs filed a motion for leave to amend their complaint to add certain allegations to expand the class period. In May 2013, the court denied plaintiffs’ motion for leave to amend their complaint to expand the class period, but granted plaintiffs’ leave to amend their complaint to add certain allegations within the existing class period. In June 2013, plaintiffs filed their Sixth Amended Class Action Complaint (the Class Action). In July 2013, defendants answered the Class Action. Discovery has been completed and is now closed. On May 13, 2015, the court granted in part and denied in part defendants’ motions for summary judgment; the court granted judgment in defendants’ favor on five of the alleged misstatements, including all statements prior to March 27, 2000, but denied the motion with respect to the remaining statements. On January 15, 2016, the Company announced that it had reached an agreement with plaintiffs to settle the Class Action for $830 million , plus an additional amount for attorneys’ fees and expenses, in exchange for, among other things, a dismissal with prejudice of the Class Action and full releases of all claims against defendants. After available funds under certain insurance policies, Merck’s net cash payment for the settlement and fees will be approximately $680 million . The proposed 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. The proposed settlement, including any award of attorneys’ fees and expenses, is subject to final court approval. On February 8, 2016, the parties filed the stipulation of settlement, which the court preliminarily approved on February 11, 2016. The court has set a final approval hearing for June 28, 2016. The proposed settlement does not resolve the individual securities lawsuits discussed below. As previously disclosed, 13 individual securities lawsuits filed by foreign and domestic institutional investors also are consolidated with the Vioxx Securities Lawsuits. The allegations in the individual securities lawsuits are substantially similar to the allegations in the Vioxx Securities Lawsuits. Discovery has been completed in those actions. The proposed settlement in the Class Action, discussed above, does not resolve the individual securities lawsuits, although each individual plaintiff has the right, at its option, to join the settlement class at no additional cost to Merck. In light of the proposed settlement in the Class Action, the court adjourned the previously-scheduled trial date of March 1, 2016, for all cases in the consolidated action. The court has scheduled a conference on February 26, 2016, to discuss a pretrial schedule for any parties in the individual lawsuits for whom no settlement has been reached. Insurance As a result of the previously disclosed insurance arbitration, the Company will receive 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 . There are disputes with the insurers about the availability of some or all 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). As previously disclosed, in January 2012, the Company entered into an agreement to resolve all claims related to Vioxx in Canada and, in April 2013, the Company paid approximately $21 million into a settlement fund. The agreement was approved by courts in Canada’s provinces and, during December 2015, the claims administrator finalized claimant eligibility determinations and the Company made a final payment of approximately $5 million into the settlement fund. Reserves In connection with the settlement of the Class Action, which remains subject to final court approval, the Company established a net reserve of $680 million in the fourth quarter of 2015. The Company believes that it has meritorious defenses to the remaining Vioxx Product Liability Lawsuits, Vioxx Securities Lawsuits and Vioxx International Lawsuits (collectively, the Remaining Vioxx Litigation) and will vigorously defend against them. In view of the inherent difficulty of predicting the outcome of litigation, particularly where there are many claimants and the claimants seek indeterminate damages, the Company is unable to predict the outcome of these matters and, at this time, cannot reasonably estimate the possible loss or range of loss with respect to the Remaining Vioxx Litigation. The Company has established a reserve with respect to certain Vioxx Product Liability Lawsuits. The Company also has an immaterial remaining reserve relating to the previously disclosed Vioxx investigation for the non-participating states with which litigation is continuing. The Company has established no other liability reserves with respect to the Remaining Vioxx Litigation. 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, 2015 , approximately 4,675 cases had been filed and were pending against Merck in either federal or state court, including one case which seeks class action certification, as well as damages and/or medical monitoring. In approximately 210 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 ; however, a large majority of those actions are subject to the settlement discussed below. In addition, plaintiffs in approximately 4,460 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. As a condition to the settlement, 100% of the state and federal ONJ plaintiffs had to agree to participate in the settlement plan or Merck could either terminate the ONJ Master Settlement Agreement, or waive the 100% participation requirement and agree to a lesser funding amount for the settlement fund. On July 14, 2014, Merck elected to proceed with the ONJ Master Settlement Agreement at a reduced funding level since the participation level was approximately 95% . Merck has fully funded the ONJ Master Settlement Agreement and the escrow agent under the agreement has begun making settlement payments to qualifying plaintiffs. Approximately 40 non-participants’ cases will remain once the settlement is complete. The ONJ Master Settlement Agreement has no effect on the cases alleging Femur Fractures discussed below. 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 (the Femur Fracture MDL). Judge Pisano presided over the Femur Fracture MDL until March 10, 2015, at which time the Femur Fracture MDL was reassigned from Judge Pisano to Judge Freda L. Wolfson following Judge Pisano’s retirement. 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, on June 27, 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, on March 26, 2014, the Femur Fracture MDL court dismissed with prejudice approximately 650 cases on preemption grounds. Plaintiffs in approximately 500 of those cases are appealing that decision to the U.S. Court of Appeals for the Third Circuit. In June 2015, the Femur Fracture MDL court dismissed without prejudice another approximately 520 cases pending plaintiffs’ appeal of the preemption ruling to the Third Circuit. On June 17, 2014, Judge Pisano 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 Judge Pisano’s decision to the Third Circuit. In August 2014, Merck filed a motion requesting that Judge Pisano 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, 2015, approximately 30 cases were pending in the Femur Fracture MDL, excluding the 500 cases dismissed with prejudice on preemption grounds that are pending appeal and the 520 cases dismissed without prejudice that are also pending the aforementioned appeal. As of December 31, 2015 , approximately 3,100 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. As of December 31, 2015 , approximately 305 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 on February 17, 2015 and the jury returned a verdict in Merck’s favor on April 3, 2015, and plaintiff has appealed that verdict to the California appellate court. The next Femur Fracture trial in California is scheduled to be held on April 11, 2016, and is currently set to include several plaintiffs. Additionally, there are six 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, 2015 , approximately 785 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). There are 13 cases pending against Merck in state courts other than the California State Court. On November 9, 2015, the MDL granted summary judgment on the grounds of preemption as to all claims alleging injury due to pancreatic cancer. Based on that ruling, on November 30, 2015, the MDL entered final judgment resulting in the dismissal of the pancreatic cancer claims against Merck relating to approximately 665 product users. On November 16, 2015, the California State Court likewise granted summary judgment on preemption grounds as to claims alleging injury due to pancreatic cancer, which will result in the dismissal of the pancreatic cancer claims against Merck relating to approximately 350 product users. Plaintiffs are appealing the MDL preemption ruling, and are expected to do likewise with respect to the California State Court ruling once that court enters final judgment. In addition to the claims noted above, the Company has agreed, as of December 31, 2015 , to toll the statute of limitations for approximately 20 additional claims. The Company intends to continue defending against these lawsuits. NuvaRing As previously disclosed, beginning in May 2007, a number of product liability complaints were filed in various jurisdictions asserting claims against the Company and its subsidiaries relating to NuvaRing , a combined hormonal contraceptive vaginal ring. The plaintiffs contended the Company, among other things, failed to adequately design and manufacture NuvaRing and failed to adequately warn of the alleged increased risk of venous thromboembolism (VTE) posed by NuvaRing , and/or downplayed the risk of VTE. The plaintiffs sought damages for injuries allegedly sustained from their product use, including some alleged deaths, heart attacks and strokes. The majority of the cases were pending in a federal multidistrict litigation venued in Missouri. Pursuant to a settlement agreement between Merck and negotiating plaintiffs’ counsel, which became effective as of June 4, 2014, Merck paid a lump total settlement of $100 million to resolve more than 95% of the cases filed and under retainer by counsel as of February 7, 2014. Plaintiffs in approximately 3,700 cases joined the settlement program. Each filed case is to be dismissed with prejudice once the settlement administration process is completed. Those dismissals began in the second quarter and continued on a rolling basis throughout 2015. The Company has certain insurance coverage available to it, which is currently being used to partially fund the Company’s legal fees. This insurance coverage was also used to fund the settlement. As of December 31, 2015, there were 16 cases pending outside of the settlement program, inclusive of cases filed after the settlement program closed. Of these cases, 15 are pending in the multidistrict litigation and are subject to individual case management orders requiring plaintiffs to meet various discovery and evidentiary requirements. As of December 31, 2015, these 15 plaintiffs were meeting those requirements and continuing to prosecute their cases. 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, 2015 , approximately 1,400 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 60 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 John Gleeson 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 Massachusetts and one matter pending in state court in New York. The Company intends to defend against these lawsuits. Governmental Proceedings 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 (the DOJ) which 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 government. As previously disclosed, the Company has received a civil investigative demand from the U.S. Attorney’s Office, Eastern District of Pennsylvania which requests 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 is cooperating with the 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. In the future, the Company may receive additional requests for information from either or both of the DOJ and the SEC. 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. Commercial and Other Litigation K-DUR Antitrust Litigation As previously disclosed, in June 1997 and January 1998, Schering-Plough settled patent litigation with Upsher-Smith, Inc. (Upsher-Smith) and ESI Lederle, Inc. (Lederle), respectively, relating to generic versions of K‑DUR, 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 (the FTC) in 2001 alleging anti-competitive effects from those settlements (which has been 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 March 2010, the District Court granted summary judgment to the defendants on the remaining lawsuits and dismissed the matter in its entirety. In July 2012, the Third Circuit Court of Appeals reversed the District Court’s grant of summary judgment and remanded the case for further proceedings. At the same time, the Third Circuit upheld a December 2008 decision by the District Court certifying certain direct purchaser plaintiffs’ claims as a class action. In August 2012, the Company filed a petition for certiorari with the U.S. Supreme Court seeking review of the Third Circuit’s decision. In June 2013, the Supreme Court granted that petition, vacated the judgment of the Third Circuit, and remanded the case for further consideration in light of its decision in FTC v. Actavis, Inc. That decision held that whether a so-called “reverse payment” — i.e., a payment from the holder of a pharmaceutical patent to a party challenging the patent made in connection with a settlement of their dispute — violates the antitrust laws should be determined on the basis of a “rule of reason” analysis. In September 2013, the Third Circuit returned the case to the District Court for further proceedings in accordance with the Actavis standard. In April 2015, the Company filed motions for summary judgment. On February 25, 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. No trial date has yet been set. Sales Force Litigation As previously disclosed, in May 2013, Ms. Kelli Smith filed a complaint against the Company in the United States District Court for the District of New Jersey on behalf of herself and a putative class of female sales representatives and a putative sub-class of female sales representatives with children, claiming (a) discriminatory policies and practices in selection, promotion and advancement, (b) disparate pay, (c) differential treatment, (d) hostile work environment and (e) retaliation under federal and state discrimination laws. In November 2013, the Company filed a motion to dismiss the class claims. Plaintiffs sought and were granted leave to file an amended complaint. In January 2014, plaintiffs filed an amended complaint adding four additional named plaintiffs. On October 8, 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, which are currently pending before the court. 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, 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. On September 4, 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) and Germany 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. To date, KGaA has not taken steps to appeal the decision. 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. This decision reflects one step in a litigation process taking place in a number of countries and will be appealed. 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

Equity

Equity	12 Months Ended
	Dec. 31, 2015
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: 2015 2014 2013 Common Stock Treasury Stock Common Stock Treasury Stock Common Stock Treasury Stock Balance January 1 3,577 739 3,577 650 3,577 550 Purchases of treasury stock — 75 — 134 — 139 Issuances (1) — (18 ) — (45 ) — (39 ) Balance December 31 3,577 796 3,577 739 3,577 650 (1) Issuances primarily reflect activity under share-based compensation plans. Noncontrolling Interests 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 . In 2014, AstraZeneca exercised its option to acquire Merck’s interest in AZLP (see Note 8) and this preferred stock obligation was retired.

Share-Based Compensation Plans

Share-Based Compensation Plans	12 Months Ended
	Dec. 31, 2015
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, 2015 , 134 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 certain PSUs granted before December 31, 2009 employees participate in dividends on the same basis as common shares and such dividends are nonforfeitable by the holder. For RSUs and PSUs issued on or after January 1, 2010, 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 2015 , 2014 and 2013 was $299 million , $278 million and $276 million , respectively, with related income tax benefits of $93 million , $86 million and $84 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 2015 , 2014 and 2013 was $59.73 , $58.14 and $45.01 per option, respectively. The weighted average fair value of options granted in 2015 , 2014 and 2013 was $6.46 , $6.79 and $6.21 per option, respectively, and were determined using the following assumptions: Years Ended December 31 2015 2014 2013 Expected dividend yield 4.1 % 4.3 % 4.2 % Risk-free interest rate 1.7 % 2.0 % 1.2 % Expected volatility 19.9 % 22.0 % 25.0 % Expected life (years) 6.2 6.4 7.0 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, 2015 76,135 $ 39.05 Granted 5,565 59.73 Exercised (13,779 ) 35.23 Forfeited (3,253 ) 39.10 Outstanding December 31, 2015 64,668 $ 41.64 3.71 $ 785 Exercisable December 31, 2015 54,990 $ 39.12 2.87 $ 765 Additional information pertaining to stock option plans is provided in the table below: Years Ended December 31 2015 2014 2013 Total intrinsic value of stock options exercised $ 332 $ 626 $ 374 Fair value of stock options vested 30 35 42 Cash received from the exercise of stock options 485 1,560 1,210 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, 2015 15,634 $ 46.66 1,882 $ 52.81 Granted 4,562 59.66 909 51.84 Vested (5,774 ) 39.45 (743 ) 44.58 Forfeited (1,022 ) 52.64 (164 ) 55.66 Nonvested December 31, 2015 13,400 $ 53.73 1,884 $ 55.33 At December 31, 2015 , there was $407 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, 2015
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. Beginning on January 1, 2013, active participants in Merck’s primary U.S. defined benefit pension plans are accruing pension benefits using cash balance formulas based on age, service, pay and interest. However, during a transition period from January 1, 2013 through December 31, 2019, participants will earn the greater of the benefit as calculated under the employee’s legacy final average pay formula or their cash balance formula. For all years of service after December 31, 2019, participants will earn future benefits under only the cash balance formula. 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 2015 2014 2013 2015 2014 2013 2015 2014 2013 Service cost $ 307 $ 300 $ 386 $ 251 $ 266 $ 296 $ 80 $ 78 $ 102 Interest cost 434 425 402 206 269 263 110 115 107 Expected return on plan assets (819 ) (782 ) (721 ) (379 ) (416 ) (376 ) (143 ) (139 ) (126 ) Net amortization 158 74 251 104 59 85 (59 ) (71 ) (50 ) Termination benefits 22 53 51 1 11 7 7 22 50 Curtailments (12 ) (69 ) (22 ) (9 ) (4 ) (1 ) (19 ) (39 ) (11 ) Settlements 1 11 1 12 6 22 — — — Net periodic benefit cost (credit) $ 91 $ 12 $ 348 $ 186 $ 191 $ 296 $ (24 ) $ (34 ) $ 72 The changes in net periodic benefit cost for pension and other postretirement benefit plans year over year are largely attributable to changes in the discount rate affecting net amortization. In connection with restructuring actions (see Note 3), termination charges were recorded in 2015 , 2014 and 2013 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 in 2015 , 2014 and 2013 on pension and other postretirement benefit plans. In addition, settlements were recorded in 2015 , 2014 and 2013 on certain U.S. and international pension plans. 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 2015 2014 2015 2014 2015 2014 Fair value of plan assets January 1 $ 9,984 $ 10,007 $ 7,724 $ 7,428 $ 1,984 $ 1,913 Actual return on plan assets (226 ) 484 138 1,099 (34 ) 114 Company contributions 66 92 163 276 63 67 Effects of exchange rate changes — — (568 ) (816 ) (1 ) — Benefits paid (523 ) (535 ) (196 ) (245 ) (99 ) (110 ) Settlements (35 ) (64 ) (66 ) (31 ) — — Other — — 9 13 — — Fair value of plan assets December 31 $ 9,266 $ 9,984 $ 7,204 $ 7,724 $ 1,913 $ 1,984 Benefit obligation January 1 $ 10,632 $ 8,666 $ 8,331 $ 7,389 $ 2,638 $ 2,329 Service cost 307 300 251 266 80 78 Interest cost 434 425 206 269 110 115 Actuarial (gains) losses (1,102 ) 1,857 (127 ) 1,605 (384 ) 212 Benefits paid (523 ) (535 ) (196 ) (245 ) (99 ) (110 ) Effects of exchange rate changes — — (647 ) (864 ) (11 ) (6 ) Plan amendments — — (1 ) (4 ) (531 ) — Curtailments (14 ) (70 ) (15 ) (76 ) (3 ) 3 Termination benefits 22 53 1 11 7 22 Settlements (35 ) (64 ) (66 ) (31 ) — — Other 2 — (4 ) 11 3 (5 ) Benefit obligation December 31 $ 9,723 $ 10,632 $ 7,733 $ 8,331 $ 1,810 $ 2,638 Funded status December 31 $ (457 ) $ (648 ) $ (529 ) $ (607 ) $ 103 $ (654 ) Recognized as: Other assets $ 179 $ 68 $ 567 $ 565 $ 359 $ 1 Accrued and other current liabilities (48 ) (41 ) (7 ) (11 ) (10 ) (11 ) Other noncurrent liabilities (588 ) (675 ) (1,089 ) (1,161 ) (246 ) (644 ) At December 31, 2015 and 2014 , the accumulated benefit obligation was $16.7 billion and $17.9 billion , respectively, for all pension plans, of which $9.4 billion and $10.1 billion , respectively, related to U.S. pension plans. Actuarial gains in 2015 reflect a change in the discount rate. Actuarial losses in 2014 reflect a change in the discount rate and, for U.S. plans, also reflect an impact for the Company’s adoption of new retirement plan mortality assumptions issued by the Society of Actuaries in October 2014. The decline in the benefit obligation for other postretirement benefits 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. This new approach will allow Medicare-eligible retirees to choose insurance with the terms, cost and coverage that best fits their needs, while still receiving financial support as determined by Merck. The Company’s subsidy for these retirees for medical coverage in 2017 is expected to be comparable to 2016. Future changes in support, if any, will be based on a number of factors such as business conditions, government actions, marketplace changes and the general consumer inflation rate. Information related to the funded status of selected pension plans at December 31 is as follows: U.S. International 2015 2014 2015 2014 Pension plans with a projected benefit obligation in excess of plan assets Projected benefit obligation $ 1,310 $ 3,963 $ 5,093 $ 5,513 Fair value of plan assets 674 3,247 3,996 4,341 Pension plans with an accumulated benefit obligation in excess of plan assets Accumulated benefit obligation $ 611 $ 810 $ 4,812 $ 2,749 Fair value of plan assets — 138 3,964 1,870 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, 2015 and 2014 , $516 million and $580 million , respectively, or approximately 3% of the Company’s pension investments at each year end, 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 2015 2014 U.S. Pension Plans Assets Cash and cash equivalents $ — $ 189 $ — $ 189 $ 2 $ 234 $ — $ 236 Investment funds Developed markets equities 566 3,704 — 4,270 540 4,518 — 5,058 Emerging markets equities 87 632 — 719 107 718 — 825 Government and agency obligations — 181 — 181 — 31 — 31 Fixed income obligations — 134 — 134 — 132 — 132 Equity securities Developed markets 2,444 — — 2,444 2,169 — — 2,169 Fixed income securities Government and agency obligations — 391 — 391 — 516 — 516 Corporate obligations — 679 — 679 — 722 — 722 Mortgage and asset-backed securities — 236 — 236 — 245 — 245 Other investments Derivatives — — — — 1 31 — 32 Other — — 23 23 — — 28 28 Liabilities Derivatives — — — — — 10 — 10 $ 3,097 $ 6,146 $ 23 $ 9,266 $ 2,819 $ 7,137 $ 28 $ 9,984 International Pension Plans Assets Cash and cash equivalents $ 63 $ 9 $ — $ 72 $ 208 $ 13 $ — $ 221 Investment funds Developed markets equities 184 3,024 — 3,208 217 2,991 — 3,208 Emerging markets equities 21 228 — 249 31 256 — 287 Government and agency obligations 305 1,269 — 1,574 317 1,410 — 1,727 Corporate obligations 173 159 — 332 183 170 — 353 Fixed income obligations 8 10 — 18 9 16 — 25 Real estate (1) — 3 10 13 — 8 29 37 Equity securities Developed markets 496 — — 496 509 — — 509 Fixed income securities Government and agency obligations 2 465 — 467 28 448 — 476 Corporate obligations — 161 — 161 2 190 1 193 Mortgage and asset-backed securities — 68 — 68 — 90 — 90 Other investments Insurance contracts (2) — 60 481 541 — 69 521 590 Other — 3 2 5 3 4 1 8 $ 1,252 $ 5,459 $ 493 $ 7,204 $ 1,507 $ 5,665 $ 552 $ 7,724 (1) The plans’ Level 3 investments in real estate funds are generally valued by market appraisals of the underlying investments in the funds. (2) The plans’ Level 3 investments in insurance contracts are generally valued using a crediting rate that approximates market returns and invest in underlying securities whose market values are unobservable and determined using pricing models, discounted cash flow methodologies, or similar techniques. The table below provides a summary of the changes in fair value, including transfers in and/or out, of all financial assets measured at fair value using significant unobservable inputs (Level 3) for the Company’s pension plan assets: 2015 2014 Insurance Contracts Real Estate Other Total Insurance Contracts Real Estate Other Total U.S. Pension Plans Balance January 1 $ — $ — $ 28 $ 28 $ — $ — $ 31 $ 31 Actual return on plan assets: Relating to assets still held at December 31 — — (3 ) (3 ) — — 1 1 Relating to assets sold during the year — — 5 5 — — 4 4 Purchases — — 1 1 — — 1 1 Sales — — (8 ) (8 ) — — (9 ) (9 ) Balance December 31 $ — $ — $ 23 $ 23 $ — $ — $ 28 $ 28 International Pension Plans Balance January 1 $ 521 $ 29 $ 2 $ 552 $ 540 $ 49 $ 2 $ 591 Actual return on plan assets: Relating to assets still held at December 31 (23 ) (3 ) — (26 ) (35 ) (4 ) — (39 ) Relating to assets sold during the year — — — — — — — — Purchases 20 — — 20 22 — — 22 Sales (31 ) (16 ) — (47 ) (3 ) (10 ) — (13 ) Transfers out of Level 3 (6 ) — — (6 ) (3 ) (6 ) — (9 ) Balance December 31 $ 481 $ 10 $ 2 $ 493 $ 521 $ 29 $ 2 $ 552 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 2015 2014 Assets Cash and cash equivalents $ 65 $ 17 $ — $ 82 $ 60 $ 20 $ — $ 80 Investment funds Developed markets equities 53 540 — 593 51 613 — 664 Emerging markets equities 29 82 — 111 36 93 — 129 Government and agency obligations 2 16 — 18 3 2 — 5 Fixed income obligations — 12 — 12 — 12 — 12 Equity securities Developed markets 229 — — 229 204 — — 204 Fixed income securities Government and agency obligations — 339 — 339 — 333 — 333 Corporate obligations — 311 — 311 — 336 — 336 Mortgage and asset-backed securities — 218 — 218 — 219 — 219 Other investments Derivatives — — — — — 2 — 2 $ 378 $ 1,535 $ — $ 1,913 $ 354 $ 1,630 $ — $ 1,984 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 2016 are approximately $50 million for U.S. pension plans, approximately $150 million for international pension plans and approximately $60 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 2016 $ 528 $ 206 $ 101 2017 532 188 100 2018 555 198 104 2019 596 201 108 2020 610 211 111 2021 — 2025 3,414 1,179 624 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 pension and other postretirement 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 2015 2014 2013 2015 2014 2013 2015 2014 2013 Net gain (loss) arising during the period $ 73 $ (2,085 ) $ 2,676 $ (66 ) $ (779 ) $ 513 $ 209 $ (223 ) $ 499 Prior service (cost) credit arising during the period (13 ) (59 ) (23 ) (4 ) (8 ) 226 511 (42 ) 26 $ 60 $ (2,144 ) $ 2,653 $ (70 ) $ (787 ) $ 739 $ 720 $ (265 ) $ 525 Net loss amortization included in benefit cost $ 214 $ 135 $ 318 $ 118 $ 74 $ 89 $ 5 $ 1 $ 23 Prior service (credit) cost amortization included in benefit cost (56 ) (61 ) (67 ) (14 ) (15 ) (4 ) (64 ) (72 ) (73 ) $ 158 $ 74 $ 251 $ 104 $ 59 $ 85 $ (59 ) $ (71 ) $ (50 ) The estimated net loss (gain) and prior service cost (credit) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during 2016 are $202 million and $(67) million , respectively, for pension plans (of which $115 million and $(55) million , respectively, relates to U.S. pension plans). The estimated prior service cost (credit) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during 2016 for other postretirement benefit plans is $(106) million . 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 2015 2014 2013 2015 2014 2013 Net periodic benefit cost Discount rate 4.20 % 4.90 % 4.10 % 2.70 % 3.80 % 3.60 % Expected rate of return on plan assets 8.50 % 8.50 % 8.50 % 5.70 % 6.00 % 5.80 % Salary growth rate 4.40 % 4.50 % 4.50 % 2.90 % 3.10 % 3.30 % Benefit obligation Discount rate 4.80 % 4.20 % 5.10 % 2.80 % 2.70 % 3.80 % Salary growth rate 4.30 % 4.40 % 4.50 % 2.90 % 2.90 % 3.10 % 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 2016 , the Company’s expected rate of return will range from 7.30% to 8.75% , the same range as in 2015 for its U.S. pension and other postretirement benefit plans. The health care cost trend rate assumptions for other postretirement benefit plans are as follows: December 31 2015 2014 Health care cost trend rate assumed for next year 6.8 % 6.9 % Rate to which the cost trend rate is assumed to decline 4.5 % 4.6 % Year that the trend rate reaches the ultimate trend rate 2027 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 $ 34 $ (27 ) Effect on benefit obligation 75 (64 ) 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 2015 , 2014 and 2013 were $125 million , $124 million and $138 million , respectively.

Other (Income) Expense, Net

Other (Income) Expense, Net	12 Months Ended
	Dec. 31, 2015
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (Income) Expense, Net Other (income) expense, net, consisted of: Years Ended December 31 2015 2014 2013 Interest income $ (289 ) $ (266 ) $ (264 ) Interest expense 672 732 801 Exchange losses 1,277 180 290 Equity income from affiliates (205 ) (257 ) (404 ) Other, net 72 (12,002 ) (12 ) $ 1,527 $ (11,613 ) $ 411 The increase in exchange losses in 2015 was driven by Venezuela. During the second quarter of 2015, upon evaluation of evolving economic conditions in Venezuela and volatility in the country, the Company determined it was unlikely that all outstanding net monetary assets would be settled at the official rate of 6.30 VEF (Bolívar Fuertes) per U.S. dollar. 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 included 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, which resulted in an additional charge in the fourth quarter of 2015 of $161 million . Exchange losses in 2013 reflect $140 million of losses due to a Venezuelan currency devaluation. In February 2013, the Venezuelan government devalued its currency from 4.30 VEF per U.S. dollar to 6.30 VEF per U.S. dollar. The Company recognized losses due to exchange of approximately $140 million in 2013 resulting from the remeasurement of the local monetary assets and liabilities at the new rate. 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 2015 and 2014 as compared with 2013 was driven primarily by the termination of the Company’s relationship with AZLP on June 30, 2014 (see Note 8). In 2015, the lower equity income from AZLP was partially offset by higher equity income from certain research investment funds. Other, net (as presented in the table above) 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 4), a $147 million gain on the divestiture of Merck’s remaining ophthalmics business in international markets (see Note 4), and the recognition of $182 million of deferred income related to AstraZeneca’s option exercise (see Note 8). Other, net in 2014 includes an $11.2 billion gain on the divestiture of MCC (see Note 4), a gain of $741 million related to AstraZeneca’s option exercise (see Note 8), a $480 million gain on the divestiture of certain ophthalmic products in several international markets (see Note 4), a gain of $204 million related to the divestiture of Sirna (see Note 4) 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 (see Note 7). Interest paid was $653 million in 2015 , $852 million in 2014 and $922 million in 2013 .

Taxes on Income

Taxes on Income	12 Months Ended
	Dec. 31, 2015
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: 2015 2014 2013 Amount Tax Rate Amount Tax Rate Amount Tax Rate U.S. statutory rate applied to income before taxes $ 1,890 35.0 % $ 6,049 35.0 % $ 1,941 35.0 % Differential arising from: Foreign earnings (2,105 ) (39.0 ) (1,367 ) (7.9 ) (1,296 ) (23.4 ) Tax settlements (417 ) (7.7 ) (89 ) (0.5 ) (497 ) (9.0 ) AstraZeneca option exercise — — (774 ) (4.5 ) — — Sale of Sirna Therapeutics, Inc. — — (357 ) (2.1 ) — — The American Taxpayer Relief Act of 2012 — — — — (269 ) (4.8 ) Impact of purchase accounting adjustments, including amortization 797 14.8 1,013 5.9 990 17.8 Foreign currency devaluation related to Venezuela 321 5.9 — — 27 0.5 Unremitted foreign earnings 260 4.8 (209 ) (1.2 ) (81 ) (1.5 ) Restructuring 167 3.1 289 1.7 224 4.0 State taxes 159 2.9 7 — 44 0.8 U.S. health care reform legislation 66 1.2 134 0.8 65 1.2 Divestiture of Merck Consumer Care — — 440 2.5 — — Other (1) (196 ) (3.6 ) 213 1.2 (120 ) (2.1 ) $ 942 17.4 % $ 5,349 30.9 % $ 1,028 18.5 % (1) Other includes the tax effect of contingency reserves, research credits, tax rate changes 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. The American Taxpayer Relief Act of 2012 was signed into law on January 2, 2013, extending the research credit and the controlled foreign corporation look-through provisions for two years retroactively from January 1, 2012 through December 31, 2013. The Company recorded the entire 2012 benefit of $269 million in 2013, the financial statement period that included the date of enactment. Income before taxes consisted of: Years Ended December 31 2015 2014 2013 Domestic $ 2,247 $ 15,730 $ 3,513 Foreign 3,154 1,553 2,032 $ 5,401 $ 17,283 $ 5,545 Taxes on income consisted of: Years Ended December 31 2015 2014 2013 Current provision Federal $ 732 $ 7,136 $ 568 Foreign 844 438 923 State 130 375 (133 ) 1,706 7,949 1,358 Deferred provision Federal (552 ) (2,162 ) 30 Foreign (163 ) (201 ) (398 ) State (49 ) (237 ) 38 (764 ) (2,600 ) (330 ) $ 942 $ 5,349 $ 1,028 Deferred income taxes at December 31 consisted of: 2015 2014 Assets Liabilities Assets Liabilities Intangibles $ — $ 4,962 $ — $ 3,358 Inventory related 49 752 56 699 Accelerated depreciation 43 910 58 892 Unremitted foreign earnings — 2,124 — 2,016 Pensions and other postretirement benefits 435 131 778 156 Compensation related 535 — 578 — Unrecognized tax benefits 412 — 401 — Net operating losses and other tax credit carryforwards 565 — 379 — Other 1,217 — 1,535 65 Subtotal 3,256 8,879 3,785 7,186 Valuation allowance (304 ) (265 ) Total deferred taxes $ 2,952 $ 8,879 $ 3,520 $ 7,186 Net deferred income taxes $ 5,927 $ 3,666 Recognized as: Other assets $ 608 $ 801 Deferred income taxes $ 6,535 $ 4,467 As discussed in Note 2, the Company elected to retrospectively early adopt new accounting guidance that requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. The adoption of this standard had the following impact on the 2014 Consolidated Balance Sheet amounts as previously reported: Other current assets reduced by $568 million , Other assets increased by $400 million , Accrued and other current liabilities reduced by $369 million , Deferred income taxes increased by $201 million . Total assets and total liabilities as previously reported at December 31, 2014 were each reduced by $168 million . The Company has net operating loss (NOL) carryforwards in several jurisdictions. As of December 31, 2015 , $257 million of deferred taxes on NOL carryforwards relate to foreign jurisdictions, none of which are individually significant. Valuation allowances of $304 million have been established on these foreign NOL carryforwards and other foreign deferred tax assets. In addition, the Company has $308 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 2015 , 2014 and 2013 were $1.8 billion , $7.9 billion and $2.3 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 $109 million in 2015 , $202 million in 2014 and $70 million in 2013 . A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2015 2014 2013 Balance January 1 $ 3,534 $ 3,503 $ 4,425 Additions related to current year positions 198 389 320 Additions related to prior year positions 53 23 177 Reductions for tax positions of prior years (1) (59 ) (156 ) (747 ) Settlements (1) (184 ) (161 ) (603 ) Lapse of statute of limitations (94 ) (64 ) (69 ) Balance December 31 $ 3,448 $ 3,534 $ 3,503 (1) Amounts reflect the settlements with the IRS as discussed below. If the Company were to recognize the unrecognized tax benefits of $3.4 billion at December 31, 2015 , the income tax provision would reflect a favorable net impact of $3.2 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, 2015 could decrease by up to $1.2 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. Interest and penalties associated with uncertain tax positions amounted to an expense of $102 million in 2015 and $9 million in 2014 and a benefit of $319 million in 2013 . These amounts reflect the beneficial impacts of various tax settlements, including those discussed below. Liabilities for accrued interest and penalties were $766 million and $659 million as of December 31, 2015 and 2014 , 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 2015. In 2013, IRS finalized its examination of Schering-Plough’s 2007-2009 tax years. The Company’s unrecognized tax benefits for the years under examination exceeded the adjustments related to this examination period and therefore the Company recorded a net $165 million tax provision benefit in 2013. In 2013, the Company recorded an out-of-period net tax benefit of $160 million related to an open issue originally raised during the 2003-2006 IRS examination. That issue was settled in the fourth quarter of 2012, with final resolution relating to interest owed being reached in the first quarter of 2013. The Company’s unrecognized tax benefits related to this issue exceeded the settlement amount. Management concluded that the exclusion of this benefit was not material to prior year financial statements. At December 31, 2015 , foreign earnings of $59.2 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, 2015
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 2015 2014 2013 Net income attributable to Merck & Co., Inc. $ 4,442 $ 11,920 $ 4,404 Average common shares outstanding 2,816 2,894 2,963 Common shares issuable (1) 25 34 33 Average common shares outstanding assuming dilution 2,841 2,928 2,996 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders $ 1.58 $ 4.12 $ 1.49 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders $ 1.56 $ 4.07 $ 1.47 (1) Issuable primarily under share-based compensation plans. In 2015 , 2014 and 2013 , 9 million , 4 million and 25 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, 2015
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, 2013, net of taxes $ (97 ) $ 73 $ (3,667 ) $ (991 ) $ (4,682 ) Other comprehensive income (loss) before reclassification adjustments, pretax 335 33 3,917 (383 ) 3,902 Tax (132 ) (23 ) (1,365 ) (100 ) (1,620 ) Other comprehensive income (loss) before reclassification adjustments, net of taxes 203 10 2,552 (483 ) 2,282 Reclassification adjustments, pretax 42 (1) (39 ) (2) 286 (3) — 289 Tax (16 ) 10 (80 ) — (86 ) Reclassification adjustments, net of taxes 26 (29 ) 206 — 203 Other comprehensive income (loss), net of taxes 229 (19 ) 2,758 (483 ) 2,485 Balance December 31, 2013, 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 ) (4) (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 ) (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 $ 3.3 billion and $3.5 billion at December 31, 2015 and 2014 , respectively, and other postretirement benefit plan net loss of $86 million and $228 million at December 31, 2015 and in 2014 , respectively, as well as pension plan prior service credit of $414 million and $473 million at December 31, 2015 and 2014 , respectively, and other postretirement benefit plan prior service credit of $547 million and $257 million at December 31, 2015 and 2014 .

Segment Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2015
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, Alliances and Healthcare Services. The Animal Health, Alliances and Healthcare Services segments are not material for separate reporting and are included in all other in the table below. 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. A large component of pediatric and adolescent vaccines is sold to the U.S. Centers for Disease Control and Prevention Vaccines for Children program, which is funded by the U.S. government. Additionally, the Company sells vaccines to the Federal government for placement into vaccine stockpiles. The 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. 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. 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. On October 1, 2014, the Company divested its Consumer Care segment (see Note 4) that developed, manufactured and marketed over-the-counter, foot care and sun care products. The accounting policies for the segments described above are the same as those described in Note 2. Sales of the Company’s products were as follows: Years Ended December 31 2015 2014 2013 Primary Care and Women’s Health Cardiovascular Zetia $ 2,526 $ 2,650 $ 2,658 Vytorin 1,251 1,516 1,643 Diabetes Januvia 3,863 3,931 4,004 Janumet 2,151 2,071 1,829 General Medicine and Women’s Health NuvaRing 732 723 686 Implanon/Nexplanon 588 502 403 Dulera 536 460 324 Follistim AQ 383 412 481 Hospital and Specialty Hepatitis PegIntron 182 381 496 HIV Isentress 1,511 1,673 1,643 Hospital Acute Care Cubicin (1) 1,127 25 24 Cancidas 573 681 660 Invanz 569 529 488 Noxafil 487 402 309 Bridion 353 340 288 Primaxin 313 329 335 Immunology Remicade 1,794 2,372 2,271 Simponi 690 689 500 Oncology Keytruda 566 55 — Emend 535 553 507 Temodar 312 350 708 Diversified Brands Respiratory Singulair 931 1,092 1,196 Nasonex 858 1,099 1,335 Clarinex 187 232 235 Other Cozaar/Hyzaar 667 806 1,006 Arcoxia 471 519 484 Fosamax 359 470 560 Zocor 217 258 301 Propecia 183 264 283 Vaccines (2) Gardasil/Gardasil 9 1,908 1,738 1,831 ProQuad/M-M-R II/Varivax 1,505 1,394 1,306 Zostavax 749 765 758 RotaTeq 610 659 636 Pneumovax 23 542 746 653 Other pharmaceutical (3) 4,553 5,356 6,596 Total Pharmaceutical segment sales 34,782 36,042 37,437 Other segment sales (4) 3,659 5,758 6,397 Total segment sales 38,441 41,800 43,834 Other (5) 1,057 437 199 $ 39,498 $ 42,237 $ 44,033 (1) Sales of Cubicin in 2015 represent sales subsequent to the Cubist acquisition date. Sales of Cubicin in 2014 and 2013 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, Sanofi Pasteur MSD, 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 Sanofi Pasteur MSD. (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, Alliances and Healthcare Services, as well as Consumer Care until its divestiture on October 1, 2014 (see Note 4). The Alliances segment includes revenue from the Company’s relationship with AZLP until termination on June 30, 2014 (see Note 8). (5) Other revenues are primarily comprised of miscellaneous corporate revenues, including revenue hedging activities, as well as third-party manufacturing sales. Other revenues in 2014 also include $232 million received by Merck in connection with the sale of the U.S. marketing rights to Saphris (see Note 4). Other revenues in 2013 reflect $50 million of revenue for the out-license of a pipeline compound. Consolidated revenues by geographic area where derived are as follows: Years Ended December 31 2015 2014 2013 United States $ 17,519 $ 17,071 $ 18,246 Europe, Middle East and Africa 10,677 13,174 13,140 Asia Pacific 3,820 3,951 3,845 Japan 2,673 3,471 4,044 Latin America 2,823 3,151 3,203 Other 1,986 1,419 1,555 $ 39,498 $ 42,237 $ 44,033 A reconciliation of total segment profits to consolidated Income before taxes is as follows: Years Ended December 31 2015 2014 2013 Segment profits: Pharmaceutical segment $ 21,658 $ 22,164 $ 22,983 Other segments 1,659 2,458 3,049 Total segment profits 23,317 24,622 26,032 Other profits 810 627 63 Unallocated: Interest income 289 266 264 Interest expense (672 ) (732 ) (801 ) Equity income from affiliates 135 59 (159 ) Depreciation and amortization (1,573 ) (2,452 ) (2,250 ) Research and development (5,871 ) (5,823 ) (6,381 ) Amortization of purchase accounting adjustments (4,856 ) (4,182 ) (4,690 ) Restructuring costs (619 ) (1,013 ) (1,709 ) Gain on sale of certain migraine clinical development programs 250 — — Gain on the divestiture of certain ophthalmic products 147 480 — Foreign currency devaluation related to Venezuela (876 ) — (140 ) 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 (4,400 ) (5,891 ) (4,684 ) $ 5,401 $ 17,283 $ 5,545 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 product intangible asset impairment charges, gains or losses on sales of businesses 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, 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 ) Year Ended December 31, 2013 Included in segment profits: Equity income from affiliates $ 88 $ 475 $ 563 Depreciation and amortization (27 ) (22 ) (49 ) Property, plant and equipment, net by geographic area where located is as follows: December 31 2015 2014 2013 United States $ 8,467 $ 8,727 $ 10,076 Europe, Middle East and Africa 2,844 3,120 3,346 Asia Pacific 842 897 1,001 Latin America 182 207 242 Japan 164 172 211 Other 8 13 97 $ 12,507 $ 13,136 $ 14,973 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, 2015
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 $145 million and $2.7 billion , respectively, at December 31, 2015 and $112 million and $2.0 billion , respectively, at December 31, 2014 . 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 $421 million and $505 million , net of accumulated amortization at December 31, 2015 and 2014 , 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 1 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 November 2015, the Financial Accounting Standards Board (FASB) issued accounting guidance on the balance sheet classification of deferred taxes as part of its simplification initiative aimed at reducing complexity in accounting standards. The new guidance requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. The Company elected to early adopt the new guidance in the fourth quarter of 2015 (see Note 15). 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. Reporting entities may choose to adopt the standard as of the original effective date. The Company is currently assessing the impact of adoption on its consolidated financial statements. In April 2015, the FASB issued accounting guidance 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. The new guidance is effective for interim and annual periods beginning in 2016. As of December 31, 2015, the Company had debt issuance costs recorded as deferred charges of approximately $100 million . 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.

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Dec. 31, 2015
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: Year Ended December 31, 2015 Separation Costs Accelerated Depreciation Other Total 2013 Restructuring Program Materials and production $ — $ 41 $ 2 $ 43 Marketing and administrative — 52 18 70 Research and development — 36 15 51 Restructuring costs 199 — 164 363 199 129 199 527 Merger Restructuring Program Materials and production — 37 281 318 Marketing and administrative — 7 1 8 Research and development — 1 — 1 Restructuring costs 9 — 247 256 9 45 529 583 $ 208 $ 174 $ 728 $ 1,110 Year Ended December 31, 2014 2013 Restructuring Program Materials and production $ — $ 204 $ 23 $ 227 Marketing and administrative — 142 3 145 Research and development — 273 9 282 Restructuring costs 566 — 28 594 566 619 63 1,248 Merger Restructuring Program Materials and production — 225 30 255 Marketing and administrative — 56 (1 ) 55 Research and development — — 1 1 Restructuring costs 108 — 311 419 108 281 341 730 $ 674 $ 900 $ 404 $ 1,978 Year Ended December 31, 2013 2013 Restructuring Program Materials and production $ — $ 186 $ 7 $ 193 Marketing and administrative — 72 3 75 Research and development — 76 (1 ) 75 Restructuring costs 866 — 32 898 866 334 41 1,241 Merger Restructuring Program Materials and production — 151 98 249 Marketing and administrative — 63 3 66 Research and development — 27 (1 ) 26 Restructuring costs 481 — 284 765 481 241 384 1,106 2008 Restructuring Program Materials and production — (2 ) 6 4 Marketing and administrative — 4 — 4 Restructuring costs 34 — 12 46 34 2 18 54 $ 1,381 $ 577 $ 443 $ 2,401
Charges and Spending Relating to Restructuring Activities by Program	The following table summarizes the charges and spending relating to restructuring activities by program: Separation Costs Accelerated Depreciation Other Total 2013 Restructuring Program Restructuring reserves January 1, 2014 $ 745 $ — $ 23 $ 768 Expenses 566 619 63 1,248 (Payments) receipts, net (816 ) — (124 ) (940 ) Non-cash activity — (619 ) 52 (567 ) Restructuring reserves December 31, 2014 495 — 14 509 Expenses 199 129 199 527 (Payments) receipts, net (425 ) — (212 ) (637 ) Non-cash activity — (129 ) 1 (128 ) Restructuring reserves December 31, 2015 (1) $ 269 $ — $ 2 $ 271 Merger Restructuring Program Restructuring reserves January 1, 2014 $ 725 $ — $ 12 $ 737 Expenses 108 281 341 730 (Payments) receipts, net (297 ) — (232 ) (529 ) Non-cash activity — (281 ) (115 ) (396 ) Restructuring reserves December 31, 2014 536 — 6 542 Expenses 9 45 529 583 (Payments) receipts, net (222 ) — (223 ) (445 ) Non-cash activity — (45 ) (261 ) (306 ) Restructuring reserves December 31, 2015 (1) $ 323 $ — $ 51 $ 374 (1) The non-facility related cash outlays associated with both the 2013 Restructuring Program and the Merger Restructuring Program were substantially completed by the end of 2015; 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, 2015
Business Combinations [Abstract]
Schedule of Fair Value of Assets Acquired and Liabilities Assumed	The fair value of assets acquired and liabilities assumed from Cubist is as follows: 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.
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, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Interest Rate Derivatives	At December 31, 2015 , the Company was a party to 30 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. 2015 Debt Instrument Par Value of Debt Number of Interest Rate Swaps Held Total Swap Notional Amount 0.70% notes due 2016 $ 1,000 4 $ 1,000 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: 2015 2014 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 (noncurrent) Other assets $ 42 $ — $ 2,700 $ 19 $ — $ 1,950 Interest rate swap contracts (current) Accrued and other current liabilities — 1 1,000 — — — Interest rate swap contracts (noncurrent) Other noncurrent liabilities — 23 3,500 — 15 2,000 Foreign exchange contracts (current) Other current assets 579 — 4,171 772 — 5,513 Foreign exchange contracts (noncurrent) Other assets 386 — 4,136 691 — 6,253 Foreign exchange contracts (current) Accrued and other current liabilities — 1 77 — — — $ 1,007 $ 25 $ 15,584 $ 1,482 $ 15 $ 15,716 Derivatives Not Designated as Hedging Instruments Foreign exchange contracts (current) Other current assets $ 212 $ — $ 8,783 $ 365 $ — $ 6,966 Foreign exchange contracts (noncurrent) Other assets 18 — 179 — — — Foreign exchange contracts (current) Accrued and other current liabilities — 37 2,508 — 88 3,386 Foreign exchange contracts (noncurrent) Other noncurrent liabilities — 1 6 — — — $ 230 $ 38 $ 11,476 $ 365 $ 88 $ 10,352 $ 1,237 $ 63 $ 27,060 $ 1,847 $ 103 $ 26,068
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: 2015 2014 Asset Liability Asset Liability Gross amounts recognized in the consolidated balance sheet $ 1,237 $ 63 $ 1,847 $ 103 Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet (59 ) (59 ) (97 ) (97 ) Cash collateral (received) posted (862 ) — (1,410 ) — Net amounts $ 316 $ 4 $ 340 $ 6
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 2015 2014 2013 Derivatives designated in a fair value hedging relationship Interest rate swap contracts Amount of (gain) loss recognized in Other (income) expense, net on derivatives (1) $ (14 ) $ (17 ) $ 12 Amount of loss (gain) recognized in Other (income) expense, net on hedged item (1) 7 14 (14 ) Derivatives designated in foreign currency cash flow hedging relationships Foreign exchange contracts Amount of (gain) loss reclassified from AOCI to Sales (724 ) (143 ) 45 Amount of gain recognized in OCI on derivatives (526 ) (775 ) (306 ) Derivatives designated in foreign currency net investment hedging relationships Foreign exchange contracts Amount of gain recognized in Other (income) expense, net on derivatives (2) (4 ) (6 ) (10 ) Amount of gain recognized in OCI on derivatives (10 ) (192 ) (363 ) Derivatives not designated in a hedging relationship Foreign exchange contracts Amount of (gain) loss recognized in Other (income) expense, net on derivatives (3) (461 ) (516 ) 183 Amount of (gain) loss recognized in Sales (1 ) 15 8 (1) There was $7 million , $3 million and $2 million of ineffectiveness on the hedge during 2015 , 2014 and 2013 , 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 available-for-sale investments at December 31 is as follows: 2015 2014 Fair Value Amortized Cost Gross Unrealized Fair Value Amortized Cost Gross Unrealized Gains Losses Gains Losses Corporate notes and bonds $ 10,259 $ 10,299 $ 7 $ (47 ) $ 10,107 $ 10,102 $ 22 $ (17 ) Commercial paper 2,977 2,977 — — 6,970 6,970 — — U.S. government and agency securities 1,761 1,767 — (6 ) 1,774 1,775 1 (2 ) Asset-backed securities 1,284 1,290 — (6 ) 1,460 1,462 1 (3 ) Mortgage-backed securities 694 697 1 (4 ) 602 604 2 (4 ) Foreign government bonds 607 586 22 (1 ) 385 385 — — Equity securities 534 409 125 — 730 557 173 — $ 18,116 $ 18,025 $ 155 $ (64 ) $ 22,028 $ 21,855 $ 199 $ (26 )
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 2015 2014 Assets Investments Corporate notes and bonds $ — $ 10,259 $ — $ 10,259 $ — $ 10,107 $ — $ 10,107 Commercial paper — 2,977 — 2,977 — 6,970 — 6,970 U.S. government and agency securities — 1,761 — 1,761 — 1,774 — 1,774 Asset-backed securities (1) — 1,284 — 1,284 — 1,460 — 1,460 Mortgage-backed securities (1) — 694 — 694 — 602 — 602 Foreign government bonds — 607 — 607 — 385 — 385 Equity securities 360 — — 360 495 — — 495 360 17,582 — 17,942 495 21,298 — 21,793 Other assets Securities held for employee compensation 155 19 — 174 181 54 — 235 Derivative assets (2) Purchased currency options — 1,041 — 1,041 — 1,252 — 1,252 Forward exchange contracts — 154 — 154 — 576 — 576 Interest rate swaps — 42 — 42 — 19 — 19 — 1,237 — 1,237 — 1,847 — 1,847 Total assets $ 515 $ 18,838 $ — $ 19,353 $ 676 $ 23,199 $ — $ 23,875 Liabilities Other liabilities Contingent consideration $ — $ — $ 590 $ 590 $ — $ — $ 428 $ 428 Derivative liabilities (2) Forward exchange contracts — 38 — 38 — 46 — 46 Written currency options — 1 — 1 — 42 — 42 Interest rate swaps — 24 — 24 — 15 — 15 — 63 — 63 — 103 — 103 Total liabilities $ — $ 63 $ 590 $ 653 $ — $ 103 $ 428 $ 531 (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 credit card, auto loan, and home equity 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 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: 2015 2014 Fair value January 1 $ 428 $ 69 Changes in fair value (1) (16 ) 316 Additions 228 43 Payments (50 ) — Fair value December 31 $ 590 $ 428 (1) Recorded in Research and development expenses and Materials and production costs.

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2015
Inventory Disclosure [Abstract]
Inventories	Inventories at December 31 consisted of: 2015 2014 Finished goods $ 1,343 $ 1,588 Raw materials and work in process 4,374 5,141 Supplies 168 197 Total (approximates current cost) 5,885 6,926 Increase to LIFO costs 384 309 $ 6,269 $ 7,235 Recognized as: Inventories $ 4,700 $ 5,571 Other assets 1,569 1,664

Goodwill and Other Intangibles

Goodwill and Other Intangibles (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2014 $ 10,065 $ 2,236 $ 12,301 Acquisitions 1,369 38 1,407 Divestitures (200 ) (362 ) (562 ) Impairments (93 ) — (93 ) Other (1) (33 ) (28 ) (61 ) Balance December 31, 2014 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 (1) Other includes cumulative translation adjustments on goodwill balances and certain other adjustments. (2) Accumulated goodwill impairment losses at December 31, 2015 and 2014 were $140 million and $93 million , respectively.
Other Intangibles	Other intangibles at December 31 consisted of: 2015 2014 Gross Carrying Amount Accumulated Amortization Net Gross Carrying Amount Accumulated Amortization Net Products and product rights $ 45,949 $ 28,514 $ 17,435 $ 38,714 $ 23,830 $ 14,884 In-process research and development 4,226 — 4,226 4,345 — 4,345 Tradenames 198 79 119 198 71 127 Other 1,418 596 822 1,527 497 1,030 $ 51,791 $ 29,189 $ 22,602 $ 44,784 $ 24,398 $ 20,386

Joint Ventures and Other Equi33

Joint Ventures and Other Equity Method Affiliates (Tables)	12 Months Ended
	Dec. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Summarized Financial Information for AZLP	Summarized financial information for AZLP is as follows: Years Ended December 31 2014 (1) 2013 Sales $ 2,205 $ 4,611 Materials and production costs 1,044 2,222 Other expense, net 604 1,175 Income before taxes (2) 557 1,214 (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, 2015
Debt Disclosure [Abstract]
Long-Term Debt	Long-term debt at December 31 consisted of: 2015 2014 2.75% notes due 2025 $ 2,496 $ — 3.70% notes due 2045 1,989 — 2.80% notes due 2023 1,749 1,749 5.00% notes due 2019 1,285 1,291 4.15% notes due 2043 1,247 1,246 1.85% notes due 2020 1,243 — 2.35% notes due 2022 1,237 — 3.875% notes due 2021 1,161 1,150 1.125% euro-denominated notes due 2021 1,096 1,218 1.875% euro-denominated notes due 2026 1,090 1,210 2.40% notes due 2022 1,014 1,000 Floating-rate borrowing due 2018 1,000 1,000 1.10% notes due 2018 999 999 1.30% notes due 2018 987 984 6.50% notes due 2033 809 812 Floating-rate notes due 2020 700 — 6.55% notes due 2037 596 597 2.50% euro-denominated notes due 2034 543 603 3.60% notes due 2042 493 493 5.85% notes due 2039 418 418 5.75% notes due 2036 371 371 5.95% debentures due 2028 356 356 6.40% debentures due 2028 326 326 Floating-rate notes due 2017 300 — 6.30% debentures due 2026 152 152 0.70% notes due 2016 — 998 2.25% notes due 2016 — 858 Floating-rate borrowing due 2016 — 500 Other 272 368 $ 23,929 $ 18,699

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2015
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: 2015 2014 2013 Common Stock Treasury Stock Common Stock Treasury Stock Common Stock Treasury Stock Balance January 1 3,577 739 3,577 650 3,577 550 Purchases of treasury stock — 75 — 134 — 139 Issuances (1) — (18 ) — (45 ) — (39 ) Balance December 31 3,577 796 3,577 739 3,577 650 (1) Issuances primarily reflect activity under share-based compensation plans.

Share-Based Compensation Plans

Share-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2015
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 2015 , 2014 and 2013 was $6.46 , $6.79 and $6.21 per option, respectively, and were determined using the following assumptions: Years Ended December 31 2015 2014 2013 Expected dividend yield 4.1 % 4.3 % 4.2 % Risk-free interest rate 1.7 % 2.0 % 1.2 % Expected volatility 19.9 % 22.0 % 25.0 % Expected life (years) 6.2 6.4 7.0
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, 2015 76,135 $ 39.05 Granted 5,565 59.73 Exercised (13,779 ) 35.23 Forfeited (3,253 ) 39.10 Outstanding December 31, 2015 64,668 $ 41.64 3.71 $ 785 Exercisable December 31, 2015 54,990 $ 39.12 2.87 $ 765
Additional Information Pertaining to Stock Option Plans	Additional information pertaining to stock option plans is provided in the table below: Years Ended December 31 2015 2014 2013 Total intrinsic value of stock options exercised $ 332 $ 626 $ 374 Fair value of stock options vested 30 35 42 Cash received from the exercise of stock options 485 1,560 1,210
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, 2015 15,634 $ 46.66 1,882 $ 52.81 Granted 4,562 59.66 909 51.84 Vested (5,774 ) 39.45 (743 ) 44.58 Forfeited (1,022 ) 52.64 (164 ) 55.66 Nonvested December 31, 2015 13,400 $ 53.73 1,884 $ 55.33

Pension and Other Postretirem37

Pension and Other Postretirement Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2015
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 2015 2014 2013 2015 2014 2013 2015 2014 2013 Service cost $ 307 $ 300 $ 386 $ 251 $ 266 $ 296 $ 80 $ 78 $ 102 Interest cost 434 425 402 206 269 263 110 115 107 Expected return on plan assets (819 ) (782 ) (721 ) (379 ) (416 ) (376 ) (143 ) (139 ) (126 ) Net amortization 158 74 251 104 59 85 (59 ) (71 ) (50 ) Termination benefits 22 53 51 1 11 7 7 22 50 Curtailments (12 ) (69 ) (22 ) (9 ) (4 ) (1 ) (19 ) (39 ) (11 ) Settlements 1 11 1 12 6 22 — — — Net periodic benefit cost (credit) $ 91 $ 12 $ 348 $ 186 $ 191 $ 296 $ (24 ) $ (34 ) $ 72
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 2015 2014 2015 2014 2015 2014 Fair value of plan assets January 1 $ 9,984 $ 10,007 $ 7,724 $ 7,428 $ 1,984 $ 1,913 Actual return on plan assets (226 ) 484 138 1,099 (34 ) 114 Company contributions 66 92 163 276 63 67 Effects of exchange rate changes — — (568 ) (816 ) (1 ) — Benefits paid (523 ) (535 ) (196 ) (245 ) (99 ) (110 ) Settlements (35 ) (64 ) (66 ) (31 ) — — Other — — 9 13 — — Fair value of plan assets December 31 $ 9,266 $ 9,984 $ 7,204 $ 7,724 $ 1,913 $ 1,984 Benefit obligation January 1 $ 10,632 $ 8,666 $ 8,331 $ 7,389 $ 2,638 $ 2,329 Service cost 307 300 251 266 80 78 Interest cost 434 425 206 269 110 115 Actuarial (gains) losses (1,102 ) 1,857 (127 ) 1,605 (384 ) 212 Benefits paid (523 ) (535 ) (196 ) (245 ) (99 ) (110 ) Effects of exchange rate changes — — (647 ) (864 ) (11 ) (6 ) Plan amendments — — (1 ) (4 ) (531 ) — Curtailments (14 ) (70 ) (15 ) (76 ) (3 ) 3 Termination benefits 22 53 1 11 7 22 Settlements (35 ) (64 ) (66 ) (31 ) — — Other 2 — (4 ) 11 3 (5 ) Benefit obligation December 31 $ 9,723 $ 10,632 $ 7,733 $ 8,331 $ 1,810 $ 2,638 Funded status December 31 $ (457 ) $ (648 ) $ (529 ) $ (607 ) $ 103 $ (654 ) Recognized as: Other assets $ 179 $ 68 $ 567 $ 565 $ 359 $ 1 Accrued and other current liabilities (48 ) (41 ) (7 ) (11 ) (10 ) (11 ) Other noncurrent liabilities (588 ) (675 ) (1,089 ) (1,161 ) (246 ) (644 )
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 2015 2014 2015 2014 Pension plans with a projected benefit obligation in excess of plan assets Projected benefit obligation $ 1,310 $ 3,963 $ 5,093 $ 5,513 Fair value of plan assets 674 3,247 3,996 4,341 Pension plans with an accumulated benefit obligation in excess of plan assets Accumulated benefit obligation $ 611 $ 810 $ 4,812 $ 2,749 Fair value of plan assets — 138 3,964 1,870
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: 2015 2014 Insurance Contracts Real Estate Other Total Insurance Contracts Real Estate Other Total U.S. Pension Plans Balance January 1 $ — $ — $ 28 $ 28 $ — $ — $ 31 $ 31 Actual return on plan assets: Relating to assets still held at December 31 — — (3 ) (3 ) — — 1 1 Relating to assets sold during the year — — 5 5 — — 4 4 Purchases — — 1 1 — — 1 1 Sales — — (8 ) (8 ) — — (9 ) (9 ) Balance December 31 $ — $ — $ 23 $ 23 $ — $ — $ 28 $ 28 International Pension Plans Balance January 1 $ 521 $ 29 $ 2 $ 552 $ 540 $ 49 $ 2 $ 591 Actual return on plan assets: Relating to assets still held at December 31 (23 ) (3 ) — (26 ) (35 ) (4 ) — (39 ) Relating to assets sold during the year — — — — — — — — Purchases 20 — — 20 22 — — 22 Sales (31 ) (16 ) — (47 ) (3 ) (10 ) — (13 ) Transfers out of Level 3 (6 ) — — (6 ) (3 ) (6 ) — (9 ) Balance December 31 $ 481 $ 10 $ 2 $ 493 $ 521 $ 29 $ 2 $ 552
Summary of Expected Benefit Payments	Expected benefit payments are as follows: U.S. Pension Benefits International Pension Benefits Other Postretirement Benefits 2016 $ 528 $ 206 $ 101 2017 532 188 100 2018 555 198 104 2019 596 201 108 2020 610 211 111 2021 — 2025 3,414 1,179 624
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 2015 2014 2013 2015 2014 2013 2015 2014 2013 Net gain (loss) arising during the period $ 73 $ (2,085 ) $ 2,676 $ (66 ) $ (779 ) $ 513 $ 209 $ (223 ) $ 499 Prior service (cost) credit arising during the period (13 ) (59 ) (23 ) (4 ) (8 ) 226 511 (42 ) 26 $ 60 $ (2,144 ) $ 2,653 $ (70 ) $ (787 ) $ 739 $ 720 $ (265 ) $ 525 Net loss amortization included in benefit cost $ 214 $ 135 $ 318 $ 118 $ 74 $ 89 $ 5 $ 1 $ 23 Prior service (credit) cost amortization included in benefit cost (56 ) (61 ) (67 ) (14 ) (15 ) (4 ) (64 ) (72 ) (73 ) $ 158 $ 74 $ 251 $ 104 $ 59 $ 85 $ (59 ) $ (71 ) $ (50 )
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 2015 2014 2013 2015 2014 2013 Net periodic benefit cost Discount rate 4.20 % 4.90 % 4.10 % 2.70 % 3.80 % 3.60 % Expected rate of return on plan assets 8.50 % 8.50 % 8.50 % 5.70 % 6.00 % 5.80 % Salary growth rate 4.40 % 4.50 % 4.50 % 2.90 % 3.10 % 3.30 % Benefit obligation Discount rate 4.80 % 4.20 % 5.10 % 2.80 % 2.70 % 3.80 % Salary growth rate 4.30 % 4.40 % 4.50 % 2.90 % 2.90 % 3.10 %
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 2015 2014 Health care cost trend rate assumed for next year 6.8 % 6.9 % Rate to which the cost trend rate is assumed to decline 4.5 % 4.6 % Year that the trend rate reaches the ultimate trend rate 2027 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 $ 34 $ (27 ) Effect on benefit obligation 75 (64 )
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 2015 2014 U.S. Pension Plans Assets Cash and cash equivalents $ — $ 189 $ — $ 189 $ 2 $ 234 $ — $ 236 Investment funds Developed markets equities 566 3,704 — 4,270 540 4,518 — 5,058 Emerging markets equities 87 632 — 719 107 718 — 825 Government and agency obligations — 181 — 181 — 31 — 31 Fixed income obligations — 134 — 134 — 132 — 132 Equity securities Developed markets 2,444 — — 2,444 2,169 — — 2,169 Fixed income securities Government and agency obligations — 391 — 391 — 516 — 516 Corporate obligations — 679 — 679 — 722 — 722 Mortgage and asset-backed securities — 236 — 236 — 245 — 245 Other investments Derivatives — — — — 1 31 — 32 Other — — 23 23 — — 28 28 Liabilities Derivatives — — — — — 10 — 10 $ 3,097 $ 6,146 $ 23 $ 9,266 $ 2,819 $ 7,137 $ 28 $ 9,984 International Pension Plans Assets Cash and cash equivalents $ 63 $ 9 $ — $ 72 $ 208 $ 13 $ — $ 221 Investment funds Developed markets equities 184 3,024 — 3,208 217 2,991 — 3,208 Emerging markets equities 21 228 — 249 31 256 — 287 Government and agency obligations 305 1,269 — 1,574 317 1,410 — 1,727 Corporate obligations 173 159 — 332 183 170 — 353 Fixed income obligations 8 10 — 18 9 16 — 25 Real estate (1) — 3 10 13 — 8 29 37 Equity securities Developed markets 496 — — 496 509 — — 509 Fixed income securities Government and agency obligations 2 465 — 467 28 448 — 476 Corporate obligations — 161 — 161 2 190 1 193 Mortgage and asset-backed securities — 68 — 68 — 90 — 90 Other investments Insurance contracts (2) — 60 481 541 — 69 521 590 Other — 3 2 5 3 4 1 8 $ 1,252 $ 5,459 $ 493 $ 7,204 $ 1,507 $ 5,665 $ 552 $ 7,724 (1) The plans’ Level 3 investments in real estate funds are generally valued by market appraisals of the underlying investments in the funds. (2) The plans’ Level 3 investments in insurance contracts are generally valued using a crediting rate that approximates market returns and invest in underlying securities whose market values are unobservable and determined using pricing models, discounted cash flow methodologies, or similar techniques.
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 2015 2014 Assets Cash and cash equivalents $ 65 $ 17 $ — $ 82 $ 60 $ 20 $ — $ 80 Investment funds Developed markets equities 53 540 — 593 51 613 — 664 Emerging markets equities 29 82 — 111 36 93 — 129 Government and agency obligations 2 16 — 18 3 2 — 5 Fixed income obligations — 12 — 12 — 12 — 12 Equity securities Developed markets 229 — — 229 204 — — 204 Fixed income securities Government and agency obligations — 339 — 339 — 333 — 333 Corporate obligations — 311 — 311 — 336 — 336 Mortgage and asset-backed securities — 218 — 218 — 219 — 219 Other investments Derivatives — — — — — 2 — 2 $ 378 $ 1,535 $ — $ 1,913 $ 354 $ 1,630 $ — $ 1,984

Other (Income) Expense, Net (Ta

Other (Income) Expense, Net (Tables)	12 Months Ended
	Dec. 31, 2015
Other Income and Expenses [Abstract]
Other (Income) Expense, Net	Other (income) expense, net, consisted of: Years Ended December 31 2015 2014 2013 Interest income $ (289 ) $ (266 ) $ (264 ) Interest expense 672 732 801 Exchange losses 1,277 180 290 Equity income from affiliates (205 ) (257 ) (404 ) Other, net 72 (12,002 ) (12 ) $ 1,527 $ (11,613 ) $ 411

Taxes on Income (Tables)

Taxes on Income (Tables)	12 Months Ended
	Dec. 31, 2015
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: 2015 2014 2013 Amount Tax Rate Amount Tax Rate Amount Tax Rate U.S. statutory rate applied to income before taxes $ 1,890 35.0 % $ 6,049 35.0 % $ 1,941 35.0 % Differential arising from: Foreign earnings (2,105 ) (39.0 ) (1,367 ) (7.9 ) (1,296 ) (23.4 ) Tax settlements (417 ) (7.7 ) (89 ) (0.5 ) (497 ) (9.0 ) AstraZeneca option exercise — — (774 ) (4.5 ) — — Sale of Sirna Therapeutics, Inc. — — (357 ) (2.1 ) — — The American Taxpayer Relief Act of 2012 — — — — (269 ) (4.8 ) Impact of purchase accounting adjustments, including amortization 797 14.8 1,013 5.9 990 17.8 Foreign currency devaluation related to Venezuela 321 5.9 — — 27 0.5 Unremitted foreign earnings 260 4.8 (209 ) (1.2 ) (81 ) (1.5 ) Restructuring 167 3.1 289 1.7 224 4.0 State taxes 159 2.9 7 — 44 0.8 U.S. health care reform legislation 66 1.2 134 0.8 65 1.2 Divestiture of Merck Consumer Care — — 440 2.5 — — Other (1) (196 ) (3.6 ) 213 1.2 (120 ) (2.1 ) $ 942 17.4 % $ 5,349 30.9 % $ 1,028 18.5 % (1) Other includes the tax effect of contingency reserves, research credits, tax rate changes and miscellaneous items.
Income Before Taxes	Income before taxes consisted of: Years Ended December 31 2015 2014 2013 Domestic $ 2,247 $ 15,730 $ 3,513 Foreign 3,154 1,553 2,032 $ 5,401 $ 17,283 $ 5,545
Taxes on Income	Taxes on income consisted of: Years Ended December 31 2015 2014 2013 Current provision Federal $ 732 $ 7,136 $ 568 Foreign 844 438 923 State 130 375 (133 ) 1,706 7,949 1,358 Deferred provision Federal (552 ) (2,162 ) 30 Foreign (163 ) (201 ) (398 ) State (49 ) (237 ) 38 (764 ) (2,600 ) (330 ) $ 942 $ 5,349 $ 1,028
Deferred Income Taxes	Deferred income taxes at December 31 consisted of: 2015 2014 Assets Liabilities Assets Liabilities Intangibles $ — $ 4,962 $ — $ 3,358 Inventory related 49 752 56 699 Accelerated depreciation 43 910 58 892 Unremitted foreign earnings — 2,124 — 2,016 Pensions and other postretirement benefits 435 131 778 156 Compensation related 535 — 578 — Unrecognized tax benefits 412 — 401 — Net operating losses and other tax credit carryforwards 565 — 379 — Other 1,217 — 1,535 65 Subtotal 3,256 8,879 3,785 7,186 Valuation allowance (304 ) (265 ) Total deferred taxes $ 2,952 $ 8,879 $ 3,520 $ 7,186 Net deferred income taxes $ 5,927 $ 3,666 Recognized as: Other assets $ 608 $ 801 Deferred income taxes $ 6,535 $ 4,467
Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: 2015 2014 2013 Balance January 1 $ 3,534 $ 3,503 $ 4,425 Additions related to current year positions 198 389 320 Additions related to prior year positions 53 23 177 Reductions for tax positions of prior years (1) (59 ) (156 ) (747 ) Settlements (1) (184 ) (161 ) (603 ) Lapse of statute of limitations (94 ) (64 ) (69 ) Balance December 31 $ 3,448 $ 3,534 $ 3,503 (1) Amounts reflect the settlements with the IRS as discussed below.

Earnings per Share (Tables)

Earnings per Share (Tables)	12 Months Ended
	Dec. 31, 2015
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 2015 2014 2013 Net income attributable to Merck & Co., Inc. $ 4,442 $ 11,920 $ 4,404 Average common shares outstanding 2,816 2,894 2,963 Common shares issuable (1) 25 34 33 Average common shares outstanding assuming dilution 2,841 2,928 2,996 Basic earnings per common share attributable to Merck & Co., Inc. common shareholders $ 1.58 $ 4.12 $ 1.49 Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders $ 1.56 $ 4.07 $ 1.47 (1) Issuable primarily under share-based compensation plans.

Other Comprehensive Income (L41

Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2015
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Components of Accumulated 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, 2013, net of taxes $ (97 ) $ 73 $ (3,667 ) $ (991 ) $ (4,682 ) Other comprehensive income (loss) before reclassification adjustments, pretax 335 33 3,917 (383 ) 3,902 Tax (132 ) (23 ) (1,365 ) (100 ) (1,620 ) Other comprehensive income (loss) before reclassification adjustments, net of taxes 203 10 2,552 (483 ) 2,282 Reclassification adjustments, pretax 42 (1) (39 ) (2) 286 (3) — 289 Tax (16 ) 10 (80 ) — (86 ) Reclassification adjustments, net of taxes 26 (29 ) 206 — 203 Other comprehensive income (loss), net of taxes 229 (19 ) 2,758 (483 ) 2,485 Balance December 31, 2013, 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 ) (4) (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 ) (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 $ 3.3 billion and $3.5 billion at December 31, 2015 and 2014 , respectively, and other postretirement benefit plan net loss of $86 million and $228 million at December 31, 2015 and in 2014 , respectively, as well as pension plan prior service credit of $414 million and $473 million at December 31, 2015 and 2014 , respectively, and other postretirement benefit plan prior service credit of $547 million and $257 million at December 31, 2015 and 2014 .

Segment Reporting (Tables)

Segment Reporting (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Sales of Company's Products	Sales of the Company’s products were as follows: Years Ended December 31 2015 2014 2013 Primary Care and Women’s Health Cardiovascular Zetia $ 2,526 $ 2,650 $ 2,658 Vytorin 1,251 1,516 1,643 Diabetes Januvia 3,863 3,931 4,004 Janumet 2,151 2,071 1,829 General Medicine and Women’s Health NuvaRing 732 723 686 Implanon/Nexplanon 588 502 403 Dulera 536 460 324 Follistim AQ 383 412 481 Hospital and Specialty Hepatitis PegIntron 182 381 496 HIV Isentress 1,511 1,673 1,643 Hospital Acute Care Cubicin (1) 1,127 25 24 Cancidas 573 681 660 Invanz 569 529 488 Noxafil 487 402 309 Bridion 353 340 288 Primaxin 313 329 335 Immunology Remicade 1,794 2,372 2,271 Simponi 690 689 500 Oncology Keytruda 566 55 — Emend 535 553 507 Temodar 312 350 708 Diversified Brands Respiratory Singulair 931 1,092 1,196 Nasonex 858 1,099 1,335 Clarinex 187 232 235 Other Cozaar/Hyzaar 667 806 1,006 Arcoxia 471 519 484 Fosamax 359 470 560 Zocor 217 258 301 Propecia 183 264 283 Vaccines (2) Gardasil/Gardasil 9 1,908 1,738 1,831 ProQuad/M-M-R II/Varivax 1,505 1,394 1,306 Zostavax 749 765 758 RotaTeq 610 659 636 Pneumovax 23 542 746 653 Other pharmaceutical (3) 4,553 5,356 6,596 Total Pharmaceutical segment sales 34,782 36,042 37,437 Other segment sales (4) 3,659 5,758 6,397 Total segment sales 38,441 41,800 43,834 Other (5) 1,057 437 199 $ 39,498 $ 42,237 $ 44,033 (1) Sales of Cubicin in 2015 represent sales subsequent to the Cubist acquisition date. Sales of Cubicin in 2014 and 2013 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, Sanofi Pasteur MSD, 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 Sanofi Pasteur MSD. (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, Alliances and Healthcare Services, as well as Consumer Care until its divestiture on October 1, 2014 (see Note 4). The Alliances segment includes revenue from the Company’s relationship with AZLP until termination on June 30, 2014 (see Note 8). (5) Other revenues are primarily comprised of miscellaneous corporate revenues, including revenue hedging activities, as well as third-party manufacturing sales. Other revenues in 2014 also include $232 million received by Merck in connection with the sale of the U.S. marketing rights to Saphris (see Note 4). Other revenues in 2013 reflect $50 million of revenue for the out-license of a pipeline compound.
Consolidated Revenues by Geographic Area	Consolidated revenues by geographic area where derived are as follows: Years Ended December 31 2015 2014 2013 United States $ 17,519 $ 17,071 $ 18,246 Europe, Middle East and Africa 10,677 13,174 13,140 Asia Pacific 3,820 3,951 3,845 Japan 2,673 3,471 4,044 Latin America 2,823 3,151 3,203 Other 1,986 1,419 1,555 $ 39,498 $ 42,237 $ 44,033
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 2015 2014 2013 Segment profits: Pharmaceutical segment $ 21,658 $ 22,164 $ 22,983 Other segments 1,659 2,458 3,049 Total segment profits 23,317 24,622 26,032 Other profits 810 627 63 Unallocated: Interest income 289 266 264 Interest expense (672 ) (732 ) (801 ) Equity income from affiliates 135 59 (159 ) Depreciation and amortization (1,573 ) (2,452 ) (2,250 ) Research and development (5,871 ) (5,823 ) (6,381 ) Amortization of purchase accounting adjustments (4,856 ) (4,182 ) (4,690 ) Restructuring costs (619 ) (1,013 ) (1,709 ) Gain on sale of certain migraine clinical development programs 250 — — Gain on the divestiture of certain ophthalmic products 147 480 — Foreign currency devaluation related to Venezuela (876 ) — (140 ) 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 (4,400 ) (5,891 ) (4,684 ) $ 5,401 $ 17,283 $ 5,545
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, 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 ) Year Ended December 31, 2013 Included in segment profits: Equity income from affiliates $ 88 $ 475 $ 563 Depreciation and amortization (27 ) (22 ) (49 )
Property, Plant and Equipment, Net by Geographic Area	Property, plant and equipment, net by geographic area where located is as follows: December 31 2015 2014 2013 United States $ 8,467 $ 8,727 $ 10,076 Europe, Middle East and Africa 2,844 3,120 3,346 Asia Pacific 842 897 1,001 Latin America 182 207 242 Japan 164 172 211 Other 8 13 97 $ 12,507 $ 13,136 $ 14,973

Nature of Operations (Details)

Nature of Operations (Details)	12 Months Ended
	Dec. 31, 2015segment
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, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]
Accrual for chargebacks reflected as direct reduction to Accounts receivable	$ 145	$ 112
Accrual for rebates included in Accrued and other current liabilities	2,700	2,000
Depreciation expense	1,600	2,500	$ 2,200
Advertising expenses	2,100	2,300	$ 2,500
Unamortized Debt Issuance Expense	100
Enterprise wide resource planning system
Summary Of Significant Accounting Policies [Line Items]
Unamortized capitalized software costs	$ 421	$ 505
Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of intangible assets	1 year
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

Restructuring - Narrative (Deta

Restructuring - Narrative (Details) $ in Millions	Oct. 01, 2013USD ($)	Jan. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)position	Dec. 31, 2014USD ($)position	Dec. 31, 2013USD ($)position
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost				$ 1,110	$ 1,978	$ 2,401
Expected cumulative restructuring costs, pretax				$ 1,500
Percentage estimate of cumulative pretax costs that will result in cash outlays (primarily from employee separation expense)				66.67%
Percentage estimate of cumulative pretax costs that will be non-cash (primarily from accelerated depreciation of facilities)				33.33%
2013 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost				$ 527	$ 1,248	$ 1,241
Cumulative restructuring costs incurred to date since program inception				$ 3,000
Positions eliminated since inception of program | position				8,630
Number of positions eliminated | position				2,535	4,555	1,540
Merger Restructuring Program
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost				$ 583	$ 730	$ 1,106
Cumulative restructuring costs incurred to date since program inception				$ 8,500
Positions eliminated since inception of program | position				29,645
Number of positions eliminated | position				1,235	1,530	4,475
Merger Restructuring Program | API Manufacturing Business
Restructuring Cost and Reserve [Line Items]
Proceeds from divestiture of business	$ 705	$ 533	$ 172
Noncash consideration received	$ 198
2008 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost						$ 54
Asset abandonment, shut-down and other related costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost				$ 550	$ 240	259
Facility Closing
Restructuring Cost and Reserve [Line Items]
Pretax losses resulting from sales of facilities				$ 117	$ 133	$ 64

Restructuring - Charges Related

Restructuring - Charges Related to Restructuring Program Activities by Type of Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Expenses	$ 1,110	$ 1,978	$ 2,401
Separation Costs
Restructuring Cost and Reserve [Line Items]
Expenses	208	674	1,381
Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Expenses	174	900	577
Other
Restructuring Cost and Reserve [Line Items]
Expenses	728	404	443
2013 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Expenses	527	1,248	1,241
2013 Restructuring Program | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses	43	227	193
2013 Restructuring Program | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses	70	145	75
2013 Restructuring Program | Research and development
Restructuring Cost and Reserve [Line Items]
Expenses	51	282	75
2013 Restructuring Program | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses	363	594	898
2013 Restructuring Program | Separation Costs
Restructuring Cost and Reserve [Line Items]
Expenses	199	566	866
2013 Restructuring Program | Separation Costs | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses	0	0	0
2013 Restructuring Program | Separation Costs | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses	0	0	0
2013 Restructuring Program | Separation Costs | Research and development
Restructuring Cost and Reserve [Line Items]
Expenses	0	0	0
2013 Restructuring Program | Separation Costs | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses	199	566	866
2013 Restructuring Program | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Expenses	129	619	334
2013 Restructuring Program | Accelerated Depreciation | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses	41	204	186
2013 Restructuring Program | Accelerated Depreciation | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses	52	142	72
2013 Restructuring Program | Accelerated Depreciation | Research and development
Restructuring Cost and Reserve [Line Items]
Expenses	36	273	76
2013 Restructuring Program | Accelerated Depreciation | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses	0	0	0
2013 Restructuring Program | Other
Restructuring Cost and Reserve [Line Items]
Expenses	199	63	41
2013 Restructuring Program | Other | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses	2	23	7
2013 Restructuring Program | Other | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses	18	3	3
2013 Restructuring Program | Other | Research and development
Restructuring Cost and Reserve [Line Items]
Expenses	15	9	(1)
2013 Restructuring Program | Other | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses	164	28	32
Merger Restructuring Program
Restructuring Cost and Reserve [Line Items]
Expenses	583	730	1,106
Merger Restructuring Program | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses	318	255	249
Merger Restructuring Program | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses	8	55	66
Merger Restructuring Program | Research and development
Restructuring Cost and Reserve [Line Items]
Expenses	1	1	26
Merger Restructuring Program | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses	256	419	765
Merger Restructuring Program | Separation Costs
Restructuring Cost and Reserve [Line Items]
Expenses	9	108	481
Merger Restructuring Program | Separation Costs | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses	0	0	0
Merger Restructuring Program | Separation Costs | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses	0	0	0
Merger Restructuring Program | Separation Costs | Research and development
Restructuring Cost and Reserve [Line Items]
Expenses	0	0	0
Merger Restructuring Program | Separation Costs | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses	9	108	481
Merger Restructuring Program | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Expenses	45	281	241
Merger Restructuring Program | Accelerated Depreciation | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses	37	225	151
Merger Restructuring Program | Accelerated Depreciation | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses	7	56	63
Merger Restructuring Program | Accelerated Depreciation | Research and development
Restructuring Cost and Reserve [Line Items]
Expenses	1	0	27
Merger Restructuring Program | Accelerated Depreciation | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses	0	0	0
Merger Restructuring Program | Other
Restructuring Cost and Reserve [Line Items]
Expenses	529	341	384
Merger Restructuring Program | Other | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses	281	30	98
Merger Restructuring Program | Other | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses	1	(1)	3
Merger Restructuring Program | Other | Research and development
Restructuring Cost and Reserve [Line Items]
Expenses	0	1	(1)
Merger Restructuring Program | Other | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses	$ 247	$ 311	284
2008 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Expenses			54
2008 Restructuring Program | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses			4
2008 Restructuring Program | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses			4
2008 Restructuring Program | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses			46
2008 Restructuring Program | Separation Costs
Restructuring Cost and Reserve [Line Items]
Expenses			34
2008 Restructuring Program | Separation Costs | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses			0
2008 Restructuring Program | Separation Costs | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses			0
2008 Restructuring Program | Separation Costs | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses			34
2008 Restructuring Program | Accelerated Depreciation
Restructuring Cost and Reserve [Line Items]
Expenses			2
2008 Restructuring Program | Accelerated Depreciation | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses			(2)
2008 Restructuring Program | Accelerated Depreciation | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses			4
2008 Restructuring Program | Accelerated Depreciation | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses			0
2008 Restructuring Program | Other
Restructuring Cost and Reserve [Line Items]
Expenses			18
2008 Restructuring Program | Other | Materials and production
Restructuring Cost and Reserve [Line Items]
Expenses			6
2008 Restructuring Program | Other | Marketing and administrative
Restructuring Cost and Reserve [Line Items]
Expenses			0
2008 Restructuring Program | Other | Restructuring costs
Restructuring Cost and Reserve [Line Items]
Expenses			$ 12

Restructuring - Charges and Spe

Restructuring - Charges and Spending Relating to Restructuring Activities by Program (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring Reserve [Roll Forward]
Expenses	$ 1,110	$ 1,978	$ 2,401
2013 Restructuring Program
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	509	768
Expenses	527	1,248	1,241
(Payments) receipts, net	(637)	(940)
Non-cash activity	(128)	(567)
Restructuring reserve, ending balance	271	509	768
Merger Restructuring Program
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	542	737
Expenses	583	730	1,106
(Payments) receipts, net	(445)	(529)
Non-cash activity	(306)	(396)
Restructuring reserve, ending balance	374	542	737
Separation Costs
Restructuring Reserve [Roll Forward]
Expenses	208	674	1,381
Separation Costs | 2013 Restructuring Program
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	495	745
Expenses	199	566	866
(Payments) receipts, net	(425)	(816)
Non-cash activity	0	0
Restructuring reserve, ending balance	269	495	745
Separation Costs | Merger Restructuring Program
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	536	725
Expenses	9	108	481
(Payments) receipts, net	(222)	(297)
Non-cash activity	0	0
Restructuring reserve, ending balance	323	536	725
Accelerated Depreciation
Restructuring Reserve [Roll Forward]
Expenses	174	900	577
Accelerated Depreciation | 2013 Restructuring Program
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	0	0
Expenses	129	619	334
(Payments) receipts, net	0	0
Non-cash activity	(129)	(619)
Restructuring reserve, ending balance	0	0	0
Accelerated Depreciation | Merger Restructuring Program
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	0	0
Expenses	45	281	241
(Payments) receipts, net	0	0
Non-cash activity	(45)	(281)
Restructuring reserve, ending balance	0	0	0
Other
Restructuring Reserve [Roll Forward]
Expenses	728	404	443
Other | 2013 Restructuring Program
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	14	23
Expenses	199	63	41
(Payments) receipts, net	(212)	(124)
Non-cash activity	1	52
Restructuring reserve, ending balance	2	14	23
Other | Merger Restructuring Program
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance	6	12
Expenses	529	341	384
(Payments) receipts, net	(223)	(232)
Non-cash activity	(261)	(115)
Restructuring reserve, ending balance	$ 51	$ 6	$ 12

Acquisitions, Divestitures, R48

Acquisitions, Divestitures, Research Collaborations and License Agreements - Narrative (Detail)	Jul. 31, 2015USD ($)	Jan. 21, 2015USD ($)	Dec. 18, 2014USD ($)	Oct. 01, 2014USD ($)	Aug. 05, 2014USD ($)	Oct. 06, 2009	Feb. 28, 2015USD ($)renewal	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Feb. 01, 2013USD ($)
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Contingent consideration								$ 590,000,000	$ 428,000,000	$ 69,000,000
Goodwill								17,723,000,000	12,992,000,000	12,301,000,000
Agreement Term							2 years
Payment to Bayer AG for collaboration rights								0	1,000,000,000	0
Payments to acquire business, net of cash acquired								146,000,000	$ 181,000,000	$ 246,000,000
Extended period of marketing rights						15 years
Cubist Pharmaceuticals Inc
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Business Combination, Consideration Transferred		$ 8,300,000,000
Cash paid for acquisition for business		7,800,000,000
Fair value of debt assumed in business combination		$ 1,900,000,000
Fair Value Inputs, Discount Rate		8.00%
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual								1,300,000,000
Business Combination, Transaction Costs								324,000,000
Contingent consideration								$ 123,000,000
IPR&D		$ 50,000,000
Other net noncurrent assets		184,000,000
Goodwill		4,670,000,000
Business combination, fair value of marketed products		6,923,000,000
Deferred income tax liabilities		2,519,000,000
Other net liabilities		$ 122,000,000
Cubist Pharmaceuticals Inc | surotomycin
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Fair Value Inputs, Discount Rate		9.00%
cCAM Biotherapeutics
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Business Combination, Consideration Transferred	$ 201,000,000
Cash paid for acquisition for business	$ 96,000,000
Fair Value Inputs, Discount Rate	10.50%
Potential future milestone payments, maximum (up to)	$ 510,000,000
Contingent consideration	105,000,000
IPR&D	180,000,000
Other net noncurrent assets	7,000,000
Goodwill	$ 14,000,000
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
Long-term Purchase Commitment, Maximum Amount (up to)							$ 250,000,000
Agreement Term							5 years
Revenue and cost allocation percentage (up to)							50.00%
Times of Agreement Extension | renewal							2
OncoEthix
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Business Combination, Consideration Transferred			$ 153,000,000
Cash paid for acquisition for business			$ 110,000,000
Fair Value Inputs, Discount Rate			11.50%
Potential future milestone payments, maximum (up to)			$ 265,000,000
Contingent consideration			43,000,000
IPR&D			143,000,000
Other net noncurrent assets			$ 10,000,000
Bayer AG
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Payment to Bayer AG for collaboration rights				$ 1,000,000,000
Potential future milestone payments				1,100,000,000
Business combination, fair value of marketed products				915,000,000
Fair value of IPR&D that was expensed				$ 85,000,000
Bayer AG | Adempas
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Fair Value Inputs, Discount Rate				10.00%
Estimated useful life of intangible assets				12 years
Bayer AG | vericiguat
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Fair Value Inputs, Discount Rate				10.50%
Idenix Pharmaceuticals, Inc.
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Business Combination, Consideration Transferred					$ 3,900,000,000
Fair Value Inputs, Discount Rate					11.50%
IPR&D					$ 3,200,000,000
Goodwill					1,500,000,000
Payments to acquire business, net of cash acquired					3,700,000,000
Deferred income tax liabilities					951,000,000
Other net liabilities					$ 12,000,000
Supera
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
IPR&D											$ 100,000,000
Goodwill											103,000,000
Business combination, fair value of marketed products											89,000,000
Deferred income tax liabilities											$ 64,000,000
Controlling interest ownership of the joint venture, percentage											51.00%
Noncontrolling interest ownership of the joint venture, percentage											49.00%
Increase in noncontrolling interests											$ 112,000,000
Increase in other paid-in-capital											$ 116,000,000

Acquisitions, Divestitures, R49

Acquisitions, Divestitures, Research Collaborations and License Agreements - Divestitures Narrative (Detail) - USD ($) $ in Millions	Jul. 31, 2015	Oct. 01, 2014	Dec. 31, 2015	Aug. 31, 2015	Feb. 28, 2015	Sep. 30, 2014	May. 31, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Divestiture of Merck Consumer Care business, net of cash divested									$ 0	$ 13,951	$ 0
Gain on divestiture of Merck Consumer Care									0	11,209	0
Agreement Term					2 years
Income tax expense (benefit)									942	5,349	$ 1,028
CGRP receptor antagonists
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Total consideration received for sale of asset	$ 250
Proceeds from collaborators				$ 125
Noncash consideration received	$ 125
Gain (loss) on sale of clinical development program									250
Consumer Care
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Proceeds from divestiture of business		$ 14,200
Divestiture of Merck Consumer Care business, net of cash divested		$ 14,000
Gain on divestiture of Merck Consumer Care										11,200
tildrakizumab
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Proceeds from collaborators						$ 80
Gain (loss) on sale of clinical development program										(47)
ophthalmic products
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Proceeds from divestiture of business			$ 170							565
Gain (Loss) on Disposition of Business									$ 147	480
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
Shares received in consideration for sale of asset								2,520,044
Gain on disposition of subsidiary										204
Income tax expense (benefit)										(300)
Saphris/Sycrest
Acquisitions Divestitures Research Collaborations and License Agreements Transactions [Line Items]
Proceeds from sale of intangible assets										$ 232

Acquisitions, Divestitures, R50

Acquisitions, Divestitures, Research Collaborations and License Agreements - Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Jan. 21, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items]
Goodwill		$ 17,723	$ 12,992	$ 12,301
Contingent consideration		590	$ 428	$ 69
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
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	11 years
Contingent consideration		$ 123
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, R51

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) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)interest_rate_swap	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Jul. 31, 2015USD ($)	Dec. 18, 2014USD ($)	Dec. 31, 2012USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Maximum planning cycle of third-party sales hedges (no more than)	3 years
Pretax gains (losses) from euro-denominated notes included in cumulative translation adjustments	$ 304	$ 294	$ (84)
Number of Interest Rate Swaps Held | interest_rate_swap	30
Pre tax net unrealized gain (loss) on derivatives maturing within next 12 months estimated to be reclassified from AOCI to sales	$ 429
Available-for-sale debt securities included in Short-term investments	4,800
Available-for-sale debt securities maturing after one year through five years	11,800
Derivative [Line Items]
Cash and cash equivalents	8,524	7,441	15,621			$ 13,451
Contingent consideration	590	428	$ 69
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	50	0
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	(16)	316
Fair value of loans payable and long-term debt, including current portion	27,000	22,500
Carrying value of Loans payable and long-term debt, including current portion	26,500	21,400
Noncurrent accounts receivable	10	80
Total accounts receivable outstanding in excess of one year	$ 125
Percentage of accounts receivable represented by customers with largest balances	33.33%
Cash collateral received from counterparties	$ 862	$ 1,410
Cubist Pharmaceuticals Inc
Derivative [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	50
Cubist Pharmaceuticals Inc
Derivative [Line Items]
Contingent consideration	123
cCAM Biotherapeutics
Derivative [Line Items]
Contingent consideration				$ 105
OncoEthix
Derivative [Line Items]
Contingent consideration					$ 43
Significant Other Observable Inputs (Level 2)
Derivative [Line Items]
Cash and cash equivalents	8,500
Cash equivalents	$ 7,700

Financial Instruments - Informa

Financial Instruments - Information About Interest Rate Swaps (Details)	Dec. 31, 2015USD ($)interest_rate_swap	Feb. 28, 2015USD ($)	Dec. 31, 2014USD ($)	Oct. 31, 2014EUR (€)
Derivative [Line Items]
Par Value of Debt		$ 8,000,000,000		€ 2,500,000,000
Number of Interest Rate Swaps Held | interest_rate_swap	30
Total Swap Notional Amount	$ 27,060,000,000		$ 26,068,000,000
0.70% notes due 2016
Derivative [Line Items]
Fixed-rate notes, stated interest rate	0.70%
0.70% notes due 2016 | Interest Rate Swap
Derivative [Line Items]
Par Value of Debt	$ 1,000,000,000
Number of Interest Rate Swaps Held | interest_rate_swap	4
Total Swap Notional Amount	$ 1,000,000,000
Fixed-rate notes, stated interest rate	0.70%
1.30% notes due 2018
Derivative [Line Items]
Fixed-rate notes, stated interest rate	1.30%
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
Total Swap Notional Amount	$ 1,000,000,000
Fixed-rate notes, stated interest rate	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
Total Swap Notional Amount	$ 550,000,000
Fixed-rate notes, stated interest rate	5.00%
1.85% notes due 2020
Derivative [Line Items]
Par Value of Debt		$ 1,250,000,000
Fixed-rate notes, stated interest rate	1.85%	1.85%
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
Total Swap Notional Amount	$ 1,250,000,000
Fixed-rate notes, stated interest rate	1.85%
3.875% notes due 2021
Derivative [Line Items]
Fixed-rate notes, stated interest rate	3.875%
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
Total Swap Notional Amount	$ 1,150,000,000
Fixed-rate notes, stated interest rate	3.875%
2.40% notes due 2022
Derivative [Line Items]
Fixed-rate notes, stated interest rate	2.40%
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
Total Swap Notional Amount	$ 1,000,000,000
Fixed-rate notes, stated interest rate	2.40%
2.35% notes due 2022
Derivative [Line Items]
Par Value of Debt		$ 1,250,000,000
Fixed-rate notes, stated interest rate	2.35%	2.35%
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
Total Swap Notional Amount	$ 1,250,000,000
Fixed-rate notes, stated interest rate	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, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	$ 1,237	$ 1,847
Fair Value of Derivative, Liability	63	103
U.S. Dollar Notional	27,060	26,068
Derivatives Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	1,007	1,482
Fair Value of Derivative, Liability	25	15
U.S. Dollar Notional	15,584	15,716
Derivatives Not Designated as Hedging Instruments
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	230	365
Fair Value of Derivative, Liability	38	88
U.S. Dollar Notional	11,476	10,352
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	42	19
U.S. Dollar Notional	2,700	1,950
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1
U.S. Dollar Notional	1,000
Interest rate swap contracts | Derivatives Designated as Hedging Instruments | Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	23	15
U.S. Dollar Notional	3,500	2,000
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	$ 386	$ 691
Fair Value of Derivative, Liability
U.S. Dollar Notional	$ 4,136	$ 6,253
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Accrued and other current liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1
U.S. Dollar Notional	77
Foreign exchange contracts | Derivatives Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	579	772
U.S. Dollar Notional	4,171	5,513
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	18
U.S. Dollar Notional	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	37	88
U.S. Dollar Notional	2,508	3,386
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Liability	1
U.S. Dollar Notional	6
Foreign exchange contracts | Derivatives Not Designated as Hedging Instruments | Other current assets
Derivatives, Fair Value [Line Items]
Fair Value of Derivative, Asset	212	365
U.S. Dollar Notional	$ 8,783	$ 6,966

Financial Instruments - Infor55

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, 2015	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross amounts recognized in the consolidated balance sheet, Asset	$ 1,237	$ 1,847
Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet, Asset	(59)	(97)
Cash collateral (received) posted, Asset	(862)	(1,410)
Net amounts, Asset	316	340
Gross amounts recognized in the consolidated balance sheet, Liability	63	103
Gross amount subject to offset in master netting arrangements not offset in the consolidated balance sheet, Liability	(59)	(97)
Cash collateral (received) posted, Liability	0	0
Net amounts, Liability	$ 4	$ 6

Financial Instruments - Locatio

Financial Instruments - Location and Pretax Gain or Loss Amounts for Derivatives (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Ineffectiveness on the hedged item	$ 7	$ 3	$ 2
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	(461)	(516)	183
Amount of (gain) loss recognized in Sales	(1)	15	8
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	(14)	(17)	12
Amount of loss (gain) recognized in Other (income) expense, net on hedged item	7	14	(14)
Derivatives designated in foreign currency cash flow hedging relationships | Foreign exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Amount of (gain) loss reclassified from AOCI to Sales	(724)	(143)	45
Amount of gain recognized in OCI on derivatives	(526)	(775)	(306)
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	(4)	(6)	(10)
Amount of gain recognized in OCI on derivatives	$ (10)	$ (192)	$ (363)

Financial Instruments - Infor57

Financial Instruments - Information on Available-for-sale Investments (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Fair Value	$ 18,116	$ 22,028
Amortized Cost	18,025	21,855
Gross Unrealized Gains	155	199
Gross Unrealized Losses	(64)	(26)
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Fair Value	2,977	6,970
Amortized Cost	2,977	6,970
Corporate notes and bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value	10,259	10,107
Amortized Cost	10,299	10,102
Gross Unrealized Gains	7	22
Gross Unrealized Losses	(47)	(17)
U.S. government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	1,761	1,774
Amortized Cost	1,767	1,775
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(6)	(2)
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	1,284	1,460
Amortized Cost	1,290	1,462
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(6)	(3)
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	694	602
Amortized Cost	697	604
Gross Unrealized Gains	1	2
Gross Unrealized Losses	(4)	(4)
Foreign government bonds
Schedule of Available-for-sale Securities [Line Items]
Fair Value	607	385
Amortized Cost	586	385
Gross Unrealized Gains	22	0
Gross Unrealized Losses	(1)
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value	534	730
Amortized Cost	409	557
Gross Unrealized Gains	$ 125	$ 173

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, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets
Fair Value	$ 18,116	$ 22,028
Derivative assets	1,237	1,847
Liabilities
Contingent consideration	590	428	$ 69
Derivative liabilities	63	103
Commercial paper
Assets
Fair Value	2,977	6,970
Corporate notes and bonds
Assets
Fair Value	10,259	10,107
U.S. government and agency securities
Assets
Fair Value	1,761	1,774
Asset-backed securities
Assets
Fair Value	$ 1,284	1,460
Liabilities
Primary weighted-average lives of investment collateral (or less)	5 years
Mortgage-backed securities
Assets
Fair Value	$ 694	602
Foreign government bonds
Assets
Fair Value	607	385
Equity securities
Assets
Fair Value	534	730
Fair Value, Measurements, Recurring
Assets
Investments	17,942	21,793
Securities held for employee compensation	174	235
Derivative assets	1,237	1,847
Total assets	19,353	23,875
Liabilities
Contingent consideration	590	428
Derivative liabilities	63	103
Total liabilities	653	531
Fair Value, Measurements, Recurring | Purchased currency options
Assets
Derivative assets	1,041	1,252
Liabilities
Derivative liabilities	1	42
Fair Value, Measurements, Recurring | Foreign exchange contracts
Assets
Derivative assets	154	576
Liabilities
Derivative liabilities	38	46
Fair Value, Measurements, Recurring | Interest rate swap contracts
Assets
Derivative assets	42	19
Liabilities
Derivative liabilities	24	15
Fair Value, Measurements, Recurring | Commercial paper
Assets
Fair Value	2,977	6,970
Fair Value, Measurements, Recurring | Corporate notes and bonds
Assets
Fair Value	10,259	10,107
Fair Value, Measurements, Recurring | U.S. government and agency securities
Assets
Fair Value	1,761	1,774
Fair Value, Measurements, Recurring | Asset-backed securities
Assets
Fair Value	1,284	1,460
Fair Value, Measurements, Recurring | Mortgage-backed securities
Assets
Fair Value	694	602
Fair Value, Measurements, Recurring | Foreign government bonds
Assets
Fair Value	607	385
Fair Value, Measurements, Recurring | Equity securities
Assets
Fair Value	360	495
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1)
Assets
Investments	360	495
Securities held for employee compensation	155	181
Derivative assets	0	0
Total assets	515	676
Fair Value, Measurements, Recurring | Quoted Prices In Active Markets for Identical Assets (Level 1) | Equity securities
Assets
Fair Value	360	495
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Assets
Investments	17,582	21,298
Securities held for employee compensation	19	54
Derivative assets	1,237	1,847
Total assets	18,838	23,199
Liabilities
Derivative liabilities	63	103
Total liabilities	63	103
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Purchased currency options
Assets
Derivative assets	1,041	1,252
Liabilities
Derivative liabilities	1	42
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign exchange contracts
Assets
Derivative assets	154	576
Liabilities
Derivative liabilities	38	46
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swap contracts
Assets
Derivative assets	42	19
Liabilities
Derivative liabilities	24	15
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets
Fair Value	2,977	6,970
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate notes and bonds
Assets
Fair Value	10,259	10,107
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | U.S. government and agency securities
Assets
Fair Value	1,761	1,774
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed securities
Assets
Fair Value	1,284	1,460
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-backed securities
Assets
Fair Value	694	602
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign government bonds
Assets
Fair Value	607	385
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Assets
Derivative assets	0	0
Liabilities
Contingent consideration	590	428
Total liabilities	$ 590	$ 428

Financial Instruments - Summari

Financial Instruments - Summarized Information About Changes in Liabilities for Contingent Consideration (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Contingent consideration	$ 428	$ 69
Changes in fair value	(16)	316
Additions	228	43
Payments	(50)	0
Contingent consideration	$ 590	$ 428

Inventories - Narrative (Detail

Inventories - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
LIFO Inventory Amount	$ 2,400	$ 2,600
Inventories not expected to be sold within one year included in Other assets	1,500	1,600
Inventories produced in preparation for product launches included in Other Assets	$ 63	$ 74

Inventories - Inventories (Deta

Inventories - Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Finished goods	$ 1,343	$ 1,588
Raw materials and work in process	4,374	5,141
Supplies	168	197
Total (approximates current cost)	5,885	6,926
Increase to LIFO costs	384	309
Total current and noncurrent inventories	6,269	7,235
Recognized as:
Inventories	4,700	5,571
Other assets	$ 1,569	$ 1,664

Goodwill and Other Intangible62

Goodwill and Other Intangibles - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	$ 22,602	$ 20,386
Intangible asset impairment charge related to marketed product	45	1,100	$ 486
IPR&D reclassified to products and product rights upon receipt of marketing approval	280	654	346
In-process research and development impairment charges	63	49	279
Amortization expense for intangible assets	4,800	4,200	4,800
Estimated Future Amortization Expense, 2016	4,000
Estimated Future Amortization Expense, 2017	3,500
Estimated Future Amortization Expense, 2018	2,000
Estimated Future Amortization Expense, 2019	1,200
Estimated Future Amortization Expense, 2020	1,000
Zerbaxa
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	3,500
Zetia
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	2,400
Vytorin
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	1,500
Sivextro
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	1,000
Implanon/Nexplanon
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	645
Dificid
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	644
NuvaRing
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	502
Nasonex
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	431
Cubicin
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	418
Adempas
Intangible Assets Excluding Goodwill [Line Items]
Other Intangibles, Net	706
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	156
Saphris/Sycrest
Intangible Assets Excluding Goodwill [Line Items]
Intangible asset impairment charge related to marketed product			330
surotomycin
Intangible Assets Excluding Goodwill [Line Items]
In-process research and development impairment charges	$ 50
preladenant
Intangible Assets Excluding Goodwill [Line Items]
In-process research and development impairment charges			$ 181

Goodwill and Other Intangible63

Goodwill and Other Intangibles - Goodwill Activity by Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 12,992	$ 12,301
Acquisitions	4,713	1,407
Divestitures	(18)	(562)
Impairments	(47)	(93)
Other	83	(61)
Goodwill, Ending Balance	17,723	12,992
Goodwill, Impaired, Accumulated Impairment Loss	140	93
Pharmaceutical
Goodwill [Roll Forward]
Goodwill, Beginning Balance	11,108	10,065
Acquisitions	4,684	1,369
Divestitures	(18)	(200)
Impairments	0	(93)
Other	88	(33)
Goodwill, Ending Balance	15,862	11,108
All Other
Goodwill [Roll Forward]
Goodwill, Beginning Balance	1,884	2,236
Acquisitions	29	38
Divestitures	0	(362)
Impairments	(47)	0
Other	(5)	(28)
Goodwill, Ending Balance	$ 1,861	$ 1,884

Goodwill and Other Intangible64

Goodwill and Other Intangibles - Other Intangibles (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	$ 51,791	$ 44,784
Accumulated Amortization	29,189	24,398
Net	22,602	20,386
Products and product rights
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	45,949	38,714
Accumulated Amortization	28,514	23,830
Net	17,435	14,884
In-process research and development
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	4,226	4,345
Net	4,226	4,345
Tradenames
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	198	198
Accumulated Amortization	79	71
Net	119	127
Other
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	1,418	1,527
Accumulated Amortization	596	497
Net	$ 822	$ 1,030

Joint Ventures and Other Equi65

Joint Ventures and Other Equity Method Affiliates - Narrative (Details) $ in Millions	Jun. 30, 2014USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 1998	Dec. 31, 2015USD ($)	Dec. 31, 1993
Equity Income from Affiliates [Line Items]
Equity income from affiliates		$ 205	$ 257	$ 404
Investments in affiliates accounted for using the equity method		702	337			$ 702
Amounts due from equity method affiliates		34	45			34
Proceeds from AstraZeneca option exercise		0	419	0
Recognition of Deferred Income		182	140			$ 322
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests			2,400
Goodwill, Written off Related to Sale of Business Unit		18	562
Deferred income taxes		764	2,600	330
AMI
Equity Income from Affiliates [Line Items]
Percentage of ownership in joint venture							50.00%
AstraZeneca LP
Equity Income from Affiliates [Line Items]
Equity income from affiliates			192	352
Limited partner interest in AZLP					1.00%
General partner interest in AZLP					99.00%
Revenue from AZLP			463	920
Proceeds from AstraZeneca option exercise	$ 419
Agreed-upon payment to be made by AstraZeneca at closing for exercise of option	$ 327
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
Other Noncash Income			$ 650
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests			2,400
Equity Method Investment, Amount Sold			1,400
Goodwill, Written off Related to Sale of Business Unit			340
Deferred income taxes			517
Sales of products marketed by the joint venture			2,205	4,611
Sanofi Pasteur MSD
Equity Income from Affiliates [Line Items]
Sales of products marketed by the joint venture		$ 923	$ 1,100	$ 1,200

Joint Ventures and Other Equi66

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, 2013	Dec. 31, 1998
Equity Income from Affiliates [Line Items]
Sales	$ 2,205	$ 4,611
Materials and production costs	1,044	2,222
Other expense, net	604	1,175
Income before taxes	$ 557	$ 1,214
Limited partner interest in AZLP			1.00%

Loans Payable, Long-Term Debt67

Loans Payable, Long-Term Debt and Other Commitments - Narrative (Details)	1 Months Ended			12 Months Ended
	Feb. 28, 2015USD ($)	Oct. 31, 2014USD ($)	Aug. 31, 2014USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Nov. 30, 2014USD ($)	Oct. 31, 2014EUR (€)
Debt Instrument [Line Items]
Long-term debt, current maturities				$ 2,300,000,000	$ 1,000,000,000
Loans payable and current portion of long-term debt				2,585,000,000	2,704,000,000
Long-Term Debt				23,929,000,000	18,699,000,000
Par Value of Debt	$ 8,000,000,000							€ 2,500,000,000
Proceeds from Debt, Net of Issuance Costs	7,900,000,000
Repayments of Long-term Debt				2,906,000,000	6,617,000,000	$ 1,775,000,000
Proceeds from Issuance of Debt		$ 3,100,000,000
Repayments of Debt		2,500,000,000
Extinguishment of Debt, Amount		$ 1,800,000,000
Debt Instrument, Repurchased Face Amount							$ 2,000,000,000
Loss on extinguishment of debt				$ 0	628,000,000	0
Maximum total debt to capitalization ratio allowable by financial covenants under certain borrowings (not to exceed)				60.00%
Long-term debt, maturities, repayments of principal in 2016				$ 2,400,000,000
Long-term debt, maturities, repayments of principal in 2017				317,000,000
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				2,000,000,000
Available borrowing capacity under credit facility			$ 6,000,000,000
Line of Credit Facility, Term			5 years
Rental expense under operating leases net of sublease income				303,000,000	350,000,000	$ 367,000,000
Minimum aggregate rental commitments under noncancellable leases in 2016				213,000,000
Minimum aggregate rental commitments under noncancellable leases in 2017				136,000,000
Minimum aggregate rental commitments under noncancellable leases in 2018				114,000,000
Minimum aggregate rental commitments under noncancellable leases in 2019				97,000,000
Minimum aggregate rental commitments under noncancellable leases in 2020				69,000,000
Minimum aggregate rental commitments under noncancellable leases thereafter				160,000,000
Cubist Pharmaceuticals Inc
Debt Instrument [Line Items]
Repayments of Long-term Debt	1,900,000,000
Other Variable Rate Debt
Debt Instrument [Line Items]
Long-Term Debt				$ 225,000,000	$ 309,000,000
Average variable rate of other long term debt borrowings				0.00%	0.00%
Other Foreign Debt
Debt Instrument [Line Items]
Long-Term Debt				$ 43,000,000	$ 53,000,000
Maximum rate of foreign borrowings (up to)				4.75%	6.25%
6.30% debentures due 2026
Debt Instrument [Line Items]
Long-Term Debt				$ 152,000,000	$ 152,000,000
Stated interest rate of senior unsecured notes				6.30%
Floating-rate notes due 2017
Debt Instrument [Line Items]
Long-Term Debt				$ 300,000,000	0
Par Value of Debt	300,000,000
Floating-rate notes due 2020
Debt Instrument [Line Items]
Long-Term Debt				700,000,000	0
Par Value of Debt	$ 700,000,000
1.85% notes due 2020
Debt Instrument [Line Items]
Long-Term Debt				$ 1,243,000,000	0
Stated interest rate of senior unsecured notes	1.85%			1.85%
Par Value of Debt	$ 1,250,000,000
2.35% notes due 2022
Debt Instrument [Line Items]
Long-Term Debt				$ 1,237,000,000	0
Stated interest rate of senior unsecured notes	2.35%			2.35%
Par Value of Debt	$ 1,250,000,000
2.75% notes due 2025
Debt Instrument [Line Items]
Long-Term Debt				$ 2,496,000,000	0
Stated interest rate of senior unsecured notes	2.75%			2.75%
Par Value of Debt	$ 2,500,000,000
3.70% notes due 2045
Debt Instrument [Line Items]
Long-Term Debt				$ 1,989,000,000	0
Stated interest rate of senior unsecured notes	3.70%			3.70%
Par Value of Debt	$ 2,000,000,000
Commercial paper
Debt Instrument [Line Items]
Loans payable and current portion of long-term debt					$ 1,500,000,000
Weighted-average interest rate of commercial paper				0.07%	0.15%
Short Term Foreign Borrowings
Debt Instrument [Line Items]
Loans payable and current portion of long-term debt				$ 10,000,000	$ 55,000,000
Notes Subject To Repayment At Option Of Holder
Debt Instrument [Line Items]
Loans payable and current portion of long-term debt				$ 226,000,000	$ 143,000,000

Loans Payable, Long-Term Debt68

Loans Payable, Long-Term Debt and Other Commitments - Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2015	Feb. 28, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-Term Debt	$ 23,929		$ 18,699
2.75% notes due 2025
Debt Instrument [Line Items]
Long-Term Debt	$ 2,496		0
Stated interest rate of senior unsecured notes	2.75%	2.75%
3.70% notes due 2045
Debt Instrument [Line Items]
Long-Term Debt	$ 1,989		0
Stated interest rate of senior unsecured notes	3.70%	3.70%
2.80% notes due 2023
Debt Instrument [Line Items]
Long-Term Debt	$ 1,749		1,749
Stated interest rate of senior unsecured notes	2.80%
5.00% notes due 2019
Debt Instrument [Line Items]
Long-Term Debt	$ 1,285		1,291
Stated interest rate of senior unsecured notes	5.00%
4.15% notes due 2043
Debt Instrument [Line Items]
Long-Term Debt	$ 1,247		1,246
Stated interest rate of senior unsecured notes	4.15%
1.85% notes due 2020
Debt Instrument [Line Items]
Long-Term Debt	$ 1,243		0
Stated interest rate of senior unsecured notes	1.85%	1.85%
2.35% notes due 2022
Debt Instrument [Line Items]
Long-Term Debt	$ 1,237		0
Stated interest rate of senior unsecured notes	2.35%	2.35%
3.875% notes due 2021
Debt Instrument [Line Items]
Long-Term Debt	$ 1,161		1,150
Stated interest rate of senior unsecured notes	3.875%
1.125% euro-denominated notes due 2021
Debt Instrument [Line Items]
Long-Term Debt	$ 1,096		1,218
Stated interest rate of senior unsecured notes	1.125%
1.875% euro-denominated notes due 2026
Debt Instrument [Line Items]
Long-Term Debt	$ 1,090		1,210
Stated interest rate of senior unsecured notes	1.875%
2.40% notes due 2022
Debt Instrument [Line Items]
Long-Term Debt	$ 1,014		1,000
Stated interest rate of senior unsecured notes	2.40%
Floating-rate borrowing due 2018
Debt Instrument [Line Items]
Long-Term Debt	$ 1,000		1,000
1.10% notes due 2018
Debt Instrument [Line Items]
Long-Term Debt	$ 999		999
Stated interest rate of senior unsecured notes	1.10%
1.30% notes due 2018
Debt Instrument [Line Items]
Long-Term Debt	$ 987		984
Stated interest rate of senior unsecured notes	1.30%
6.50% notes due 2033
Debt Instrument [Line Items]
Long-Term Debt	$ 809		812
Stated interest rate of senior unsecured notes	6.50%
Floating-rate notes due 2020
Debt Instrument [Line Items]
Long-Term Debt	$ 700		0
6.55% notes due 2037
Debt Instrument [Line Items]
Long-Term Debt	$ 596		597
Stated interest rate of senior unsecured notes	6.55%
2.50% euro-denominated notes due 2034
Debt Instrument [Line Items]
Long-Term Debt	$ 543		603
Stated interest rate of senior unsecured notes	2.50%
3.60% notes due 2042
Debt Instrument [Line Items]
Long-Term Debt	$ 493		493
Stated interest rate of senior unsecured notes	3.60%
5.85% notes due 2039
Debt Instrument [Line Items]
Long-Term Debt	$ 418		418
Stated interest rate of senior unsecured notes	5.85%
5.75% notes due 2036
Debt Instrument [Line Items]
Long-Term Debt	$ 371		371
Stated interest rate of senior unsecured notes	5.75%
5.95% debentures due 2028
Debt Instrument [Line Items]
Long-Term Debt	$ 356		356
Stated interest rate of senior unsecured notes	5.95%
6.40% debentures due 2028
Debt Instrument [Line Items]
Long-Term Debt	$ 326		326
Stated interest rate of senior unsecured notes	6.40%
Floating-rate notes due 2017
Debt Instrument [Line Items]
Long-Term Debt	$ 300		0
6.30% debentures due 2026
Debt Instrument [Line Items]
Long-Term Debt	$ 152		152
Stated interest rate of senior unsecured notes	6.30%
0.70% notes due 2016
Debt Instrument [Line Items]
Long-Term Debt	$ 0		998
Stated interest rate of senior unsecured notes	0.70%
2.25% notes due 2016
Debt Instrument [Line Items]
Long-Term Debt	$ 0		858
Stated interest rate of senior unsecured notes	2.25%
Floating-rate borrowing due 2016
Debt Instrument [Line Items]
Long-Term Debt	$ 0		500
Other
Debt Instrument [Line Items]
Long-Term Debt	$ 272		$ 368

Contingencies and Environment69

Contingencies and Environmental Liabilities - Vioxx Litigation - Narrative (Details)	Jan. 15, 2016USD ($)	Dec. 31, 2015USD ($)legalmatter	Apr. 30, 2013USD ($)	Dec. 31, 2015USD ($)legalmatter	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Feb. 28, 2015legalmatter
Loss Contingencies [Line Items]
Net charge related to the settlement of Vioxx shareholder class action litigation				$ 680,000,000	$ 0	$ 0
Canadian Litigation
Loss Contingencies [Line Items]
Payments for Legal Settlements		$ 5,000,000	$ 21,000,000
Vioxx Cases Brought by State Attorneys General
Loss Contingencies [Line Items]
Loss contingency, pending claims number | legalmatter		3		3
Vioxx Securities Lawsuits
Loss Contingencies [Line Items]
Loss contingency, pending claims number | legalmatter							13
Loss contingency, receivable		$ 380,000,000		$ 380,000,000
Vioxx Securities Lawsuits | Maximum
Loss Contingencies [Line Items]
Upper limit of Directors and Officers insurance coverage		$ 145,000,000		$ 145,000,000
Vioxx | Vioxx MDL Litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims number | legalmatter		10		10
Vioxx | Cases alleging economic loss
Loss Contingencies [Line Items]
Loss contingency, pending claims number | legalmatter		30		30
Litigation settlement agreement amount				$ 23,000,000
Vioxx | Vioxx Securities Lawsuits
Loss Contingencies [Line Items]
Net charge related to the settlement of Vioxx shareholder class action litigation				$ 680,000,000
Vioxx | Vioxx Securities Lawsuits | Subsequent Event
Loss Contingencies [Line Items]
Litigation settlement agreement amount	$ 830,000,000

Contingencies and Environment70

Contingencies and Environmental Liabilities - Fosamax Product Liability Litigation - Narrative (Details) - Fosamax $ in Millions	Mar. 26, 2014legalmatter	Jun. 30, 2015legalmatter	Dec. 31, 2013USD ($)	Dec. 31, 2015legalmatter	Jul. 31, 2015legalmatter	Jul. 14, 2014	Mar. 31, 2014legalmatter	Nov. 30, 2013legalmatter
Loss Contingencies [Line Items]
Loss contingency, pending claims number				4,675
ONJ Litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims number				210
Litigation settlement agreement amount | $			$ 27.7
Percentage of participation in litigation settlement condition			100.00%
Percentage of Participation in Litigation Settlement						95.00%
Femur Fracture Litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims number				4,460
ONJ MDL
Loss Contingencies [Line Items]
Loss contingency, pending claims number				40
Federal
Loss Contingencies [Line Items]
Loss contingency, pending claims number				30
Loss contingency, claims dismissed number	650	520
Loss Contingency, Claims on Appeal, Number				500
New Jersey
Loss Contingencies [Line Items]
Loss contingency, pending claims number				3,100
Initial number of cases selected for review				30
Subsequent number of cases selected for review					25		50	50
California State Court
Loss Contingencies [Line Items]
Loss contingency, pending claims number				305
Initial number of cases selected for review							10
Other State Court | Femur Fracture Litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims number				6

Contingencies and Environment71

Contingencies and Environmental Liabilities - Januvia/Janumet Litigation - Narrative (Details) - Januvia - legalmatter	Nov. 30, 2015	Nov. 16, 2015	Dec. 31, 2015
Loss Contingencies [Line Items]
Loss contingency, pending claims number			785
Loss contingency, claims dismissed number	665	350
Other State Court
Loss Contingencies [Line Items]
Loss contingency, pending claims number			13
Cases Company Agreed ToToll Statute Of Limitations
Loss Contingencies [Line Items]
Loss contingency, pending claims number			20

Contingencies and Environment72

Contingencies and Environmental Liabilities - NuvaRing Litigation - Narrative (Details) - NuvaRing	Jun. 04, 2014USD ($)legalmatter	Dec. 31, 2015legalmatter
Loss Contingencies [Line Items]
Litigation settlement agreement amount | $	$ 100,000,000
Percentage of Participation in Litigation Settlement (more than)	95.00%
Loss Contingency, Claims Settled, Number	3,700
Loss contingency, pending claims number		16
NuvaRingMDL
Loss Contingencies [Line Items]
Loss contingency, pending claims number		15

Contingencies and Environment73

Contingencies and Environmental Liabilities - Propecia/Proscar Litigation - Narrative (Details)	12 Months Ended
	Dec. 31, 2015Plaintifflegalmatter
Propecia
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1,400
Propecia | Cases alleging cancer
Loss Contingencies [Line Items]
Number of plaintiff groups | Plaintiff	60
Propecia/Proscar | Other State Court | New York
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1
Other State Court | Propecia/Proscar | Massachusetts
Loss Contingencies [Line Items]
Loss contingency, pending claims number	1

Contingencies and Environment74

Contingencies and Environmental Liabilities - Commercial and Other Litigation- Narrative (Details)	Dec. 31, 2015legalmatter
Commercial Litigation
Loss Contingencies [Line Items]
Loss contingency, pending claims number	2

Contingencies and Environment75

Contingencies and Environmental Liabilities - Legal Defense Reserves - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Legal Defense Costs
Loss Contingencies [Line Items]
Legal defense costs reserve	$ 245	$ 215

Contingencies and Environment76

Contingencies and Environmental Liabilities - Environmental Litigation and Matters - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Site Contingency [Line Items]
Accrued liabilities for environmental matters	$ 109,000	$ 125,000
Term for paying off environmental liabilities	15 years
Aggregate possible expenditure on environmental matters in excess of amounts accrued	$ 57,000
Oss Netherlands
Site Contingency [Line Items]
Environmental remediation expense	$ 235

Equity - Narrative (Details)

Equity - Narrative (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 1998	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Common stock, shares authorized		6,500,000,000	6,500,000,000
Preferred stock, shares authorized		20,000,000
Preferred stock dividend rate	5.00%
AstraZeneca LP
Class of Stock [Line Items]
Par value preferred stock obligation assumed in connection with 1998 restructuring of AMI	$ 2.4

Equity - Shareholders' Equity (

Equity - Shareholders' Equity (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	739,000,000	650,000,000	550,000,000
Purchases of treasury stock	75,000,000	134,000,000	139,000,000
Issuances	(18,000,000)	(45,000,000)	(39,000,000)
Balance December 31	796,000,000	739,000,000	650,000,000

Share-Based Compensation Plan79

Share-Based Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares collectively authorized for future grants under share-based compensation plans	134
Quantity of stock options that vest per year	33.33%
Period for 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	$ 299	$ 278	$ 276
Income tax benefits related to share-based compensation	$ 93	$ 86	$ 84
Weighted average exercise price of options granted (in dollars per share)	$ 59.73	$ 58.14	$ 45.01
Weighted average fair value of options granted (in dollars per share)	$ 6.46	$ 6.79	$ 6.21
Total pre tax unrecognized compensation expense related to nonvested stock options, RSU and PSU awards	$ 407
Weighted average period in years of recognition for nonvested stock options, RSU and PSU awards	1 year 10 months 24 days
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term of options	7 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual term of options	10 years

Share-Based Compensation Plan80

Share-Based Compensation Plans - Assumptions Used to Determine Weighted-Average Fair Value of Options Granted (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected dividend yield	4.10%	4.30%	4.20%
Risk-free interest rate	1.70%	2.00%	1.20%
Expected volatility	19.90%	22.00%	25.00%
Expected life (years)	6 years 2 months 12 days	6 years 4 months 24 days	7 years

Share-Based Compensation Plan81

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, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of Options, Outstanding, January 1 (in shares)	76,135
Number of Options, Granted (in shares)	5,565
Number of Options, Exercised (in shares)	(13,779)
Number of Options, Forfeited (in shares)	(3,253)
Number of Options, Outstanding, December 31 (in shares)	64,668	76,135
Number of Options, Exercisable (in shares)	54,990
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)	$ 39.05
Weighted Average Exercise Price, Granted (in dollars per share)	59.73	$ 58.14	$ 45.01
Weighted Average Exercise Price, Exercised (in dollars per share)	35.23
Weighted Average Exercise Price, Forfeited (in dollars per share)	39.10
Weighted Average Exercise Price, Options Outstanding, December 31 (in dollars per share)	41.64	$ 39.05
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 39.12
Weighted Average Remaining Contractual Term, Outstanding	3 years 8 months 15 days
Weighted Average Remaining Contractual Term, Exercisable	2 years 10 months 15 days
Aggregate Intrinsic Value, Outstanding	$ 785
Aggregate Intrinsic Value, Exercisable	$ 765

Share-Based Compensation Plan82

Share-Based Compensation Plans - Additional Information Pertaining to Stock Option Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Total intrinsic value of stock options exercised	$ 332	$ 626	$ 374
Fair value of stock options vested	30	35	42
Cash received from the exercise of stock options	$ 485	$ 1,560	$ 1,210

Share-Based Compensation Plan83

Share-Based Compensation Plans - Summary of Nonvested RSU and PSU Activity (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2015$ / 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	15,634
Number of Shares, Granted | shares	4,562
Number of Shares, Vested | shares	(5,774)
Number of Shares, Forfeited | shares	(1,022)
Number of Shares, Nonvested December 31 | shares	13,400
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	$ 46.66
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	59.66
Weighted Average Grant Date Fair Value, Vested (in dollars per share) | $ / shares	39.45
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	52.64
Weighted Average Grant Date Fair Value, Nonvested December 31 (in dollars per share) | $ / shares	$ 53.73
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	1,882
Number of Shares, Granted | shares	909
Number of Shares, Vested | shares	(743)
Number of Shares, Forfeited | shares	(164)
Number of Shares, Nonvested December 31 | shares	1,884
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	$ 52.81
Weighted Average Grant Date Fair Value, Granted (in dollars per share) | $ / shares	51.84
Weighted Average Grant Date Fair Value, Vested (in dollars per share) | $ / shares	44.58
Weighted Average Grant Date Fair Value, Forfeited (in dollars per share) | $ / shares	55.66
Weighted Average Grant Date Fair Value, Nonvested December 31 (in dollars per share) | $ / shares	$ 55.33

Pension and Other Postretirem84

Pension and Other Postretirement Benefit Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation		$ 16,700	$ 17,900
Percentage of Company's pension investments categorized as Level 3 assets		3.00%	3.00%
Employer contributions to defined contribution savings plans		$ 125	$ 124	$ 138
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		13.00%
Expected rate of return on plan assets		8.50%	8.50%	8.50%
Scenario, Forecast | United States | Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets	7.30%
Scenario, Forecast | United States | Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected rate of return on plan assets	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		40.00%
Maximum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans		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		20.00%
Maximum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans		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		15.00%
Maximum percentage allocation of target investment portfolio of the Company's U.S. pension and other postretirement benefit plans		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		5.00%
Pension Benefits, U.S.
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation		$ 9,400	$ 10,100
Fair Value of Plan Assets		9,266	9,984	$ 10,007
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		115
Estimated prior service cost (credit) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during next fiscal year		(55)
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		23	28	31
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		202
Estimated prior service cost (credit) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during next fiscal year		(67)
Pension Plan | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		516	580
Pension Benefits, International
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		7,204	$ 7,724	$ 7,428
Expected contributions to the pension plans and other postretirement benefit plans during next fiscal year		$ 150
Expected rate of return on plan assets		5.70%	6.00%	5.80%
Pension Benefits, International | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 493	$ 552	$ 591
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		1,913	1,984	$ 1,913
Expected contributions to the pension plans and other postretirement benefit plans during next fiscal year		60
Estimated prior service cost (credit) amounts that will be amortized from AOCI into net pension and postretirement benefit cost during next fiscal year		(106)
Other Postretirement Benefits | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 0	$ 0

Pension and Other Postretirem85

Pension and Other Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits, U.S.
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 307	$ 300	$ 386
Interest cost	434	425	402
Expected return on plan assets	(819)	(782)	(721)
Net amortization	158	74	251
Termination benefits	22	53	51
Curtailments	(12)	(69)	(22)
Settlements	1	11	1
Net periodic benefit cost (credit)	91	12	348
Pension Benefits, International
Defined Benefit Plan Disclosure [Line Items]
Service cost	251	266	296
Interest cost	206	269	263
Expected return on plan assets	(379)	(416)	(376)
Net amortization	104	59	85
Termination benefits	1	11	7
Curtailments	(9)	(4)	(1)
Settlements	12	6	22
Net periodic benefit cost (credit)	186	191	296
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	80	78	102
Interest cost	110	115	107
Expected return on plan assets	(143)	(139)	(126)
Net amortization	(59)	(71)	(50)
Termination benefits	7	22	50
Curtailments	(19)	(39)	(11)
Settlements	0	0	0
Net periodic benefit cost (credit)	$ (24)	$ (34)	$ 72

Pension and Other Postretirem86

Pension and Other Postretirement Benefit Plans - Obligation and Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits, U.S.
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	$ 9,984	$ 10,007
Actual return on plan assets	(226)	484
Company contributions	66	92
Effects of exchange rate changes	0	0
Benefits paid	(523)	(535)
Settlements	(35)	(64)
Other	0	0
Fair value of plan assets December 31	9,266	9,984	$ 10,007
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation January 1	10,632	8,666
Service cost	307	300	386
Interest cost	434	425	402
Actuarial (gains) losses	(1,102)	1,857
Benefits paid	(523)	(535)
Effects of exchange rate changes	0	0
Plan amendments	0	0
Curtailments	(14)	(70)
Termination benefits	22	53	51
Settlements	(35)	(64)
Other	2	0
Benefit obligation December 31	9,723	10,632	8,666
Funded status December 31	(457)	(648)
Recognized as:
Other assets	179	68
Accrued and other current liabilities	(48)	(41)
Other noncurrent liabilities	(588)	(675)
Pension Benefits, International
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	7,724	7,428
Actual return on plan assets	138	1,099
Company contributions	163	276
Effects of exchange rate changes	(568)	(816)
Benefits paid	(196)	(245)
Settlements	(66)	(31)
Other	9	13
Fair value of plan assets December 31	7,204	7,724	7,428
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation January 1	8,331	7,389
Service cost	251	266	296
Interest cost	206	269	263
Actuarial (gains) losses	(127)	1,605
Benefits paid	(196)	(245)
Effects of exchange rate changes	(647)	(864)
Plan amendments	(1)	(4)
Curtailments	(15)	(76)
Termination benefits	1	11	7
Settlements	(66)	(31)
Other	(4)	11
Benefit obligation December 31	7,733	8,331	7,389
Funded status December 31	(529)	(607)
Recognized as:
Other assets	567	565
Accrued and other current liabilities	(7)	(11)
Other noncurrent liabilities	(1,089)	(1,161)
Other Postretirement Benefits
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	1,984	1,913
Actual return on plan assets	(34)	114
Company contributions	63	67
Effects of exchange rate changes	(1)	0
Benefits paid	(99)	(110)
Settlements	0	0
Other	0	0
Fair value of plan assets December 31	1,913	1,984	1,913
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation January 1	2,638	2,329
Service cost	80	78	102
Interest cost	110	115	107
Actuarial (gains) losses	(384)	212
Benefits paid	(99)	(110)
Effects of exchange rate changes	(11)	(6)
Plan amendments	(531)	0
Curtailments	(3)	3
Termination benefits	7	22	50
Settlements	0	0
Other	3	(5)
Benefit obligation December 31	1,810	2,638	$ 2,329
Funded status December 31	103	(654)
Recognized as:
Other assets	359	1
Accrued and other current liabilities	(10)	(11)
Other noncurrent liabilities	$ (246)	$ (644)

Pension and Other Postretirem87

Pension and Other Postretirement Benefit Plans - Accumulated and Projected Benefit Obligation in Excess of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits, U.S.
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Projected benefit obligation	$ 1,310	$ 3,963
Fair value of plan assets	674	3,247
Accumulated benefit obligation	611	810
Fair value of plan assets	0	138
Pension Benefits, International
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Projected benefit obligation	5,093	5,513
Fair value of plan assets	3,996	4,341
Accumulated benefit obligation	4,812	2,749
Fair value of plan assets	$ 3,964	$ 1,870

Pension and Other Postretirem88

Pension and Other Postretirement Benefit Plans - Fair Values of Pension Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits, U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 9,266	$ 9,984	$ 10,007
Pension Benefits, U.S. | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	189	236
Pension Benefits, U.S. | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	4,270	5,058
Pension Benefits, U.S. | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	719	825
Pension Benefits, U.S. | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	181	31
Pension Benefits, U.S. | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	134	132
Pension Benefits, U.S. | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	2,444	2,169
Pension Benefits, U.S. | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	391	516
Pension Benefits, U.S. | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	679	722
Pension Benefits, U.S. | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	236	245
Pension Benefits, U.S. | Derivatives, Other investments | Liabilities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	10
Pension Benefits, U.S. | Derivatives, Other investments | Assets
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	32
Pension Benefits, U.S. | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	23	28
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	3,097	2,819
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	0	2
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	566	540
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	87	107
Pension Benefits, U.S. | 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	0	0
Pension Benefits, U.S. | 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	0	0
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	2,444	2,169
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) | Derivatives, Other investments | Liabilities
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) | Derivatives, Other investments | Assets
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	1
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	6,146	7,137
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	189	234
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	3,704	4,518
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	632	718
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	181	31
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	134	132
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	391	516
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	679	722
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	236	245
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Derivatives, Other investments | Liabilities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	10
Pension Benefits, U.S. | Significant Other Observable Inputs (Level 2) | Derivatives, Other investments | Assets
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	31
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	23	28	31
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) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pension Benefits, U.S. | 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, 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) | Derivatives, Other investments | Liabilities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Pension Benefits, U.S. | Significant Unobservable Inputs (Level 3) | Derivatives, Other investments | Assets
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	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	23	28
Pension Benefits, International
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	7,204	7,724	7,428
Pension Benefits, International | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	72	221
Pension Benefits, International | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3,208	3,208
Pension Benefits, International | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	249	287
Pension Benefits, International | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,574	1,727
Pension Benefits, International | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	332	353
Pension Benefits, International | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	18	25
Pension Benefits, International | Real estate, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	13	37
Pension Benefits, International | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	496	509
Pension Benefits, International | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	467	476
Pension Benefits, International | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	161	193
Pension Benefits, International | Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	68	90
Pension Benefits, International | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	541	590
Pension Benefits, International | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5	8
Pension Benefits, International | Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,252	1,507
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	63	208
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	184	217
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	21	31
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	305	317
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	173	183
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	8	9
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	496	509
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	28
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	2
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	0	3
Pension Benefits, International | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	5,459	5,665
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	9	13
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	3,024	2,991
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	228	256
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	1,269	1,410
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Corporate obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	159	170
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	10	16
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	8
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	465	448
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	161	190
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	68	90
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Insurance contracts, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	60	69
Pension Benefits, International | Significant Other Observable Inputs (Level 2) | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	3	4
Pension Benefits, International | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	493	552	591
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	10	29
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	1
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	481	521	$ 540
Pension Benefits, International | Significant Unobservable Inputs (Level 3) | Other, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 2	$ 1

Pension and Other Postretirem89

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, 2015	Dec. 31, 2014
U.S. Pension Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	$ 9,984	$ 10,007
Actual return on plan assets:
Fair value of plan assets December 31	9,266	9,984
U.S. Pension Plans | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	28	31
Actual return on plan assets:
Relating to assets still held at December 31	(3)	1
Relating to assets sold during the year	5	4
Purchases	1	1
Sales	(8)	(9)
Fair value of plan assets December 31	23	28
U.S. Pension Plans | Significant Unobservable Inputs (Level 3) | Insurance Contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	0	0
Actual return on plan assets:
Relating to assets still held at December 31	0	0
Relating to assets sold during the year	0	0
Purchases	0	0
Sales	0	0
Fair value of plan assets 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]
Fair value of plan assets January 1	0	0
Actual return on plan assets:
Relating to assets still held at December 31	0	0
Relating to assets sold during the year	0	0
Purchases	0	0
Sales	0	0
Fair value of plan assets 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]
Fair value of plan assets January 1	28	31
Actual return on plan assets:
Relating to assets still held at December 31	(3)	1
Relating to assets sold during the year	5	4
Purchases	1	1
Sales	(8)	(9)
Fair value of plan assets December 31	23	28
International Pension Plans
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	7,724	7,428
Actual return on plan assets:
Fair value of plan assets December 31	7,204	7,724
International Pension Plans | Insurance Contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	590
Actual return on plan assets:
Fair value of plan assets December 31	541	590
International Pension Plans | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	552	591
Actual return on plan assets:
Relating to assets still held at December 31	(26)	(39)
Relating to assets sold during the year	0	0
Purchases	20	22
Sales	(47)	(13)
Transfers out of Level 3	(6)	(9)
Fair value of plan assets December 31	493	552
International Pension Plans | Significant Unobservable Inputs (Level 3) | Insurance Contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	521	540
Actual return on plan assets:
Relating to assets still held at December 31	(23)	(35)
Relating to assets sold during the year	0	0
Purchases	20	22
Sales	(31)	(3)
Transfers out of Level 3	(6)	(3)
Fair value of plan assets December 31	481	521
International Pension Plans | Significant Unobservable Inputs (Level 3) | Real Estate
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	29	49
Actual return on plan assets:
Relating to assets still held at December 31	(3)	(4)
Relating to assets sold during the year	0	0
Purchases	0	0
Sales	(16)	(10)
Transfers out of Level 3	0	(6)
Fair value of plan assets December 31	10	29
International Pension Plans | Significant Unobservable Inputs (Level 3) | Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets January 1	2	2
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	0	0
Sales	0	0
Transfers out of Level 3	0	0
Fair value of plan assets December 31	$ 2	$ 2

Pension and Other Postretirem90

Pension and Other Postretirement Benefit Plans - Fair Values of Other Postretirement Benefit Plan Assets (Details) - Other Postretirement Benefits - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 1,913	$ 1,984	$ 1,913
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	82	80
Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	593	664
Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	111	129
Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	18	5
Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	12	12
Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	229	204
Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	339	333
Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	311	336
Mortgage and asset backed-securities, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	218	219
Derivatives, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	2
Quoted Prices In Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	378	354
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	65	60
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	53	51
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	29	36
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	2	3
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	0	0
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	229	204
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
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
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
Quoted Prices In Active Markets for Identical Assets (Level 1) | Derivatives, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	1,535	1,630
Significant Other Observable Inputs (Level 2) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	17	20
Significant Other Observable Inputs (Level 2) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	540	613
Significant Other Observable Inputs (Level 2) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	82	93
Significant Other Observable Inputs (Level 2) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	16	2
Significant Other Observable Inputs (Level 2) | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	12	12
Significant Other Observable Inputs (Level 2) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Significant Other Observable Inputs (Level 2) | Government and agency obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	339	333
Significant Other Observable Inputs (Level 2) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	311	336
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	218	219
Significant Other Observable Inputs (Level 2) | Derivatives, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	2
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | Developed markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | Emerging markets equities, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | Government and agency obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | Fixed income obligations, Investment funds
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
Significant Unobservable Inputs (Level 3) | Developed markets, Equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
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
Significant Unobservable Inputs (Level 3) | Corporate obligations, Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	0	0
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
Significant Unobservable Inputs (Level 3) | Derivatives, Other investments
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	$ 0	$ 0

Pension and Other Postretirem91

Pension and Other Postretirement Benefit Plans - Summary of Expected Benefit Payments (Details) $ in Millions	Dec. 31, 2015USD ($)
U.S. Pension Plans
Defined Benefit Plan Disclosure [Line Items]
2,016	$ 528
2,017	532
2,018	555
2,019	596
2,020	610
2021 — 2025	3,414
International Pension Plans
Defined Benefit Plan Disclosure [Line Items]
2,016	206
2,017	188
2,018	198
2,019	201
2,020	211
2021 — 2025	1,179
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
2,016	101
2,017	100
2,018	104
2,019	108
2,020	111
2021 — 2025	$ 624

Pension and Other Postretirem92

Pension and Other Postretirement Benefit Plans - Components of Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits, U.S.
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss) arising during the period	$ 73	$ (2,085)	$ 2,676
Prior service (cost) credit arising during the period	(13)	(59)	(23)
Total	60	(2,144)	2,653
Net loss amortization included in benefit cost	214	135	318
Prior service (credit) cost amortization included in benefit cost	(56)	(61)	(67)
Total	158	74	251
Pension Benefits, International
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss) arising during the period	(66)	(779)	513
Prior service (cost) credit arising during the period	(4)	(8)	226
Total	(70)	(787)	739
Net loss amortization included in benefit cost	118	74	89
Prior service (credit) cost amortization included in benefit cost	(14)	(15)	(4)
Total	104	59	85
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net gain (loss) arising during the period	209	(223)	499
Prior service (cost) credit arising during the period	511	(42)	26
Total	720	(265)	525
Net loss amortization included in benefit cost	5	1	23
Prior service (credit) cost amortization included in benefit cost	(64)	(72)	(73)
Total	$ (59)	$ (71)	$ (50)

Pension and Other Postretirem93

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, 2015	Dec. 31, 2014	Dec. 31, 2013
United States
Net periodic benefit cost
Discount rate	4.20%	4.90%	4.10%
Expected rate of return on plan assets	8.50%	8.50%	8.50%
Salary growth rate	4.40%	4.50%	4.50%
Benefit obligation
Discount rate	4.80%	4.20%	5.10%
Salary growth rate	4.30%	4.40%	4.50%
International Pension Plans
Net periodic benefit cost
Discount rate	2.70%	3.80%	3.60%
Expected rate of return on plan assets	5.70%	6.00%	5.80%
Salary growth rate	2.90%	3.10%	3.30%
Benefit obligation
Discount rate	2.80%	2.70%	3.80%
Salary growth rate	2.90%	2.90%	3.10%

Pension and Other Postretirem94

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, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	6.80%	6.90%
Rate to which the cost trend rate is assumed to decline	4.50%	4.60%

Pension and Other Postretirem95

Pension and Other Postretirement Benefit Plans - One Percentage Point Change in Health Care Cost Trend Rate (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Compensation and Retirement Disclosure [Abstract]
Effect on total service and interest cost components, Increase	$ 34
Effect on benefit obligation, Increase	75
Effect on total service and interest cost components, Decrease	(27)
Effect on benefit obligation, Decrease	$ (64)

Other (Income) Expense, Net - N

Other (Income) Expense, Net - Narrative (Details) $ in Millions	3 Months Ended			12 Months Ended			18 Months Ended
	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)VEF / $	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)	Feb. 28, 2013VEF / $	Jan. 31, 2013VEF / $
Component of Other Income / Expense of Nonoperating [Line Items]
Foreign currency devaluation related to Venezuela				$ 876	$ 0	$ 140
Net charge related to the settlement of Vioxx shareholder class action litigation				680	0	0
Noncash Contribution Expense				78
Recognition of Deferred Income				182	140		$ 322
Gain on divestiture of Merck Consumer Care				0	11,209	0
Gain on disposition of interest in equity method investment				0	741	0
Loss on extinguishment of debt				0	628	0
Goodwill, Impairment Loss				47	93
Interest paid				653	852	922
Supera
Component of Other Income / Expense of Nonoperating [Line Items]
Goodwill, Impairment Loss					93
CGRP receptor antagonists
Component of Other Income / Expense of Nonoperating [Line Items]
Gain (loss) on sale of clinical development program				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 (Loss) on Disposition of Business				$ 147	480
Sirna Therapeutics Inc.
Component of Other Income / Expense of Nonoperating [Line Items]
Gain on disposition of subsidiary					$ 204
Venezuela
Component of Other Income / Expense of Nonoperating [Line Items]
Foreign Currency Exchange Rate, Translation | VEF / $			6.30					6.30	4.30
Foreign currency devaluation related to Venezuela	$ 161	$ 138	$ 715			$ 140

Other (Income) Expense, Net (De

Other (Income) Expense, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Income and Expenses [Abstract]
Interest income	$ (289)	$ (266)	$ (264)
Interest expense	672	732	801
Exchange losses	1,277	180	290
Equity income from affiliates	(205)	(257)	(404)
Other, net	72	(12,002)	(12)
Other (income) expense, net	$ 1,527	$ (11,613)	$ 411

Taxes on Income - Narrative (De

Taxes on Income - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
U.S. statutory rate applied to income before taxes		35.00%	35.00%	35.00%
The American Taxpayer Relief Act of 2012		$ 0	$ 0	$ 269
Income Tax [Line Items]
Deferred tax assets on NOL carryforwards relating to foreign jurisdictions		257
Deferred tax assets relating to various U.S. tax credit carryforwards and NOL carryforwards		308
Income taxes paid		1,800	7,900	2,300
Tax Benefit Realized from Exercise of Stock Options		109	202	70
Unrecognized tax benefits	$ 3,534	3,448	3,534	3,503	$ 4,425
Favorable net impact to income tax provision if unrecognized tax benefits were recognized		3,200
Reasonably possible amount that liability for unrecognized tax benefits could decline up to in next 12 months (up to)		1,200
Interest and penalties associated with uncertain tax positions, expense (benefit)		102	9	(319)
Liabilities for accrued interest and penalties	659	766	659
Proceeds from refunds		715
Income tax expense (benefit)		942	5,349	1,028
Decrease in unrecognized tax benefits resulting from prior period tax positions		59	156	747
Foreign earnings retained indefinitely by subsidiary companies for reinvestments		59,200
Consumer Care
Income Tax [Line Items]
Income taxes paid			$ 5,000
Foreign Jurisdiction
Income Tax [Line Items]
Valuation allowance on foreign NOL carryforwards		304
IRS
Income Tax [Line Items]
Income tax expense (benefit)		$ (410)
Decrease in unrecognized tax benefits resulting from prior period tax positions				165
IRS | Intercompany pricing matters
Income Tax [Line Items]
Decrease in unrecognized tax benefits resulting from prior period tax positions				$ 160
Other current assets
Income Tax [Line Items]
Effect of New Accounting Pronouncement, Increase (Decrease)	(568)
Other assets
Income Tax [Line Items]
Effect of New Accounting Pronouncement, Increase (Decrease)	400
Accrued and other current liabilities
Income Tax [Line Items]
Effect of New Accounting Pronouncement, Increase (Decrease)	(369)
Deferred income taxes
Income Tax [Line Items]
Effect of New Accounting Pronouncement, Increase (Decrease)	201
Assets
Income Tax [Line Items]
Effect of New Accounting Pronouncement, Increase (Decrease)	(168)
Liabilities
Income Tax [Line Items]
Effect of New Accounting Pronouncement, Increase (Decrease)	$ (168)

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, 2015	Dec. 31, 2014	Dec. 31, 2013
Amount
U.S. statutory rate applied to income before taxes	$ 1,890	$ 6,049	$ 1,941
Differential arising from:
Foreign earnings	(2,105)	(1,367)	(1,296)
Tax settlements	(417)	(89)	(497)
AstraZeneca option exercise	0	(774)	0
Sale of Sirna Therapeutics, Inc.	0	(357)	0
The American Taxpayer Relief Act of 2012	0	0	(269)
Impact of purchase accounting adjustments, including amortization	797	1,013	990
Foreign currency devaluation related to Venezuela	321	0	27
Unremitted foreign earnings	260	(209)	(81)
Restructuring	167	289	224
State taxes	159	7	44
U.S. health care reform legislation	66	134	65
Divestiture of Merck Consumer Care	0	440	0
Other	(196)	213	(120)
Taxes on income	$ 942	$ 5,349	$ 1,028
Tax Rate
U.S. statutory rate applied to income before taxes	35.00%	35.00%	35.00%
Differential arising from:
Foreign earnings	(39.00%)	(7.90%)	(23.40%)
Tax settlements	(7.70%)	(0.50%)	(9.00%)
AstraZeneca option exercise	0.00%	(4.50%)	0.00%
Sale of Sirna Therapeutics, Inc.	0.00%	(2.10%)	0.00%
The American Taxpayer Relief Act of 2012	0.00%	0.00%	(4.80%)
Impact of purchase accounting adjustments, including amortization	14.80%	5.90%	17.80%
Foreign currency devaluation related to Venezuela	5.90%	0.00%	0.50%
Unremitted foreign earnings	4.80%	(1.20%)	(1.50%)
Restructuring	3.10%	1.70%	4.00%
State taxes	2.90%	0.00%	0.80%
U.S. health care reform legislation	1.20%	0.80%	1.20%
Divestiture of Merck Consumer Care	0.00%	2.50%	0.00%
Other	(3.60%)	1.20%	(2.10%)
Total, Tax Rate	17.40%	30.90%	18.50%

Taxes on Income - Income Before

Taxes on Income - Income Before Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Domestic	$ 2,247	$ 15,730	$ 3,513
Foreign	3,154	1,553	2,032
Income Before Taxes	$ 5,401	$ 17,283	$ 5,545

Taxes on Income - Taxes on Inco

Taxes on Income - Taxes on Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current provision
Federal	$ 732	$ 7,136	$ 568
Foreign	844	438	923
State	130	375	(133)
Total current provision	1,706	7,949	1,358
Deferred provision
Federal	(552)	(2,162)	30
Foreign	(163)	(201)	(398)
State	(49)	(237)	38
Total deferred provision	(764)	(2,600)	(330)
Taxes on income	$ 942	$ 5,349	$ 1,028

Taxes on Income - Deferred Inco

Taxes on Income - Deferred Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Income Tax [Line Items]
Inventory related, Assets	$ 49	$ 56
Accelerated depreciation, Assets	43	58
Pensions and other postretirement benefits, Assets	435	778
Compensation related, Assets	535	578
Unrecognized tax benefits, Assets	412	401
Net operating losses and other tax credit carryforwards, Assets	565	379
Other, Assets	1,217	1,535
Subtotal, Assets	3,256	3,785
Valuation allowance, Assets	(304)	(265)
Deferred Tax Assets	2,952	3,520
Intangibles, Liabilities	4,962	3,358
Inventory related, Liabilities	752	699
Accelerated depreciation, Liabilities	910	892
Unremitted foreign earnings, Liabilities	2,124	2,016
Pensions and other postretirement benefits, Liabilities	131	156
Other, Liabilities	0	65
Subtotal, Liabilities	8,879	7,186
Deferred income taxes, Liabilities	5,927	3,666
Deferred income taxes, Liabilities	6,535	4,467
Other assets
Income Tax [Line Items]
Deferred Tax Assets	$ 608	$ 801

Taxes on Income - Unrecognized

Taxes on Income - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance January 1	$ 3,534	$ 3,503	$ 4,425
Additions related to current year positions	198	389	320
Additions related to prior year positions	53	23	177
Reductions for tax positions of prior years	(59)	(156)	(747)
Settlements	(184)	(161)	(603)
Lapse of statute of limitations	(94)	(64)	(69)
Balance December 31	$ 3,448	$ 3,534	$ 3,503

Earnings Per Share - Narrative

Earnings Per Share - Narrative (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	9	4	25

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, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net Income Attributable to Merck & Co., Inc.	$ 4,442	$ 11,920	$ 4,404
Average common shares outstanding, in shares	2,816	2,894	2,963
Common shares issuable, in shares	25	34	33
Average common shares outstanding assuming dilution, in shares	2,841	2,928	2,996
Basic earnings per common share attributable to Merck & Co., Inc. common shareholders, in dollars per share	$ 1.58	$ 4.12	$ 1.49
Earnings per common share assuming dilution attributable to Merck & Co., Inc. common shareholders, in dollars per share	$ 1.56	$ 4.07	$ 1.47

Other Comprehensive Income (106

Other Comprehensive Income (Loss) - Changes in AOCI by Component (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), beginning balance	$ (4,323)	$ (2,197)	$ (4,682)
Other comprehensive income (loss) before reclassification adjustments, pretax	1,069	(2,782)	3,902
Tax	(490)	673	(1,620)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	579	(2,109)	2,282
Reclassification adjustments, pretax	(623)	(41)	289
Tax	219	24	(86)
Reclassification adjustments, net of taxes	(404)	(17)	203
Other comprehensive income (loss), net of taxes	175	(2,126)	2,485
Accumulated Other Comprehensive Income (Loss), ending balance	(4,148)	(4,323)	(2,197)
Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), beginning balance	530	132	(97)
Other comprehensive income (loss) before reclassification adjustments, pretax	526	778	335
Tax	(177)	(285)	(132)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	349	493	203
Reclassification adjustments, pretax	(731)	(146)	42
Tax	256	51	(16)
Reclassification adjustments, net of taxes	(475)	(95)	26
Other comprehensive income (loss), net of taxes	(126)	398	229
Accumulated Other Comprehensive Income (Loss), ending balance	404	530	132
Investments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), beginning balance	111	54	73
Other comprehensive income (loss) before reclassification adjustments, pretax	(9)	48	33
Tax	(13)	(17)	(23)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(22)	31	10
Reclassification adjustments, pretax	(73)	43	(39)
Tax	25	(17)	10
Reclassification adjustments, net of taxes	(48)	26	(29)
Other comprehensive income (loss), net of taxes	(70)	57	(19)
Accumulated Other Comprehensive Income (Loss), ending balance	41	111	54
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), beginning balance	(2,986)	(909)	(3,667)
Other comprehensive income (loss) before reclassification adjustments, pretax	710	(3,196)	3,917
Tax	(272)	1,067	(1,365)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	438	(2,129)	2,552
Reclassification adjustments, pretax	203	62	286
Tax	(62)	(10)	(80)
Reclassification adjustments, net of taxes	141	52	206
Other comprehensive income (loss), net of taxes	579	(2,077)	2,758
Accumulated Other Comprehensive Income (Loss), ending balance	(2,407)	(2,986)	(909)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated Other Comprehensive Income (Loss), beginning balance	(1,978)	(1,474)	(991)
Other comprehensive income (loss) before reclassification adjustments, pretax	(158)	(412)	(383)
Tax	(28)	(92)	(100)
Other comprehensive income (loss) before reclassification adjustments, net of taxes	(186)	(504)	(483)
Reclassification adjustments, pretax	(22)	0	0
Tax	0	0	0
Reclassification adjustments, net of taxes	(22)	0	0
Other comprehensive income (loss), net of taxes	(208)	(504)	(483)
Accumulated Other Comprehensive Income (Loss), ending balance	(2,186)	(1,978)	$ (1,474)
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	3,300	3,500
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	86	228
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	414	473
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	$ 547	$ 257

Segment Reporting - Narrative (

Segment Reporting - Narrative (Details)	12 Months Ended
	Dec. 31, 2015segment
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, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Sales	$ 39,498	$ 42,237	$ 44,033
Revenue for the out-license of a pipeline compound			50
Operating Segments
Segment Reporting Information [Line Items]
Sales	38,441	41,800	43,834
Operating Segments | Pharmaceutical segment
Segment Reporting Information [Line Items]
Sales	34,782	36,042	37,437
Operating Segments | Pharmaceutical segment | Zetia
Segment Reporting Information [Line Items]
Sales	2,526	2,650	2,658
Operating Segments | Pharmaceutical segment | Vytorin
Segment Reporting Information [Line Items]
Sales	1,251	1,516	1,643
Operating Segments | Pharmaceutical segment | Januvia
Segment Reporting Information [Line Items]
Sales	3,863	3,931	4,004
Operating Segments | Pharmaceutical segment | Janumet
Segment Reporting Information [Line Items]
Sales	2,151	2,071	1,829
Operating Segments | Pharmaceutical segment | NuvaRing
Segment Reporting Information [Line Items]
Sales	732	723	686
Operating Segments | Pharmaceutical segment | Implanon/Nexplanon
Segment Reporting Information [Line Items]
Sales	588	502	403
Operating Segments | Pharmaceutical segment | Dulera
Segment Reporting Information [Line Items]
Sales	536	460	324
Operating Segments | Pharmaceutical segment | Follistim AQ
Segment Reporting Information [Line Items]
Sales	383	412	481
Operating Segments | Pharmaceutical segment | PegIntron
Segment Reporting Information [Line Items]
Sales	182	381	496
Operating Segments | Pharmaceutical segment | Isentress
Segment Reporting Information [Line Items]
Sales	1,511	1,673	1,643
Operating Segments | Pharmaceutical segment | Cubicin
Segment Reporting Information [Line Items]
Sales	1,127	25	24
Operating Segments | Pharmaceutical segment | Cancidas
Segment Reporting Information [Line Items]
Sales	573	681	660
Operating Segments | Pharmaceutical segment | Invanz
Segment Reporting Information [Line Items]
Sales	569	529	488
Operating Segments | Pharmaceutical segment | Noxafil
Segment Reporting Information [Line Items]
Sales	487	402	309
Operating Segments | Pharmaceutical segment | Bridion
Segment Reporting Information [Line Items]
Sales	353	340	288
Operating Segments | Pharmaceutical segment | Primaxin
Segment Reporting Information [Line Items]
Sales	313	329	335
Operating Segments | Pharmaceutical segment | Remicade
Segment Reporting Information [Line Items]
Sales	1,794	2,372	2,271
Operating Segments | Pharmaceutical segment | Simponi
Segment Reporting Information [Line Items]
Sales	690	689	500
Operating Segments | Pharmaceutical segment | Keytruda
Segment Reporting Information [Line Items]
Sales	566	55	0
Operating Segments | Pharmaceutical segment | Emend
Segment Reporting Information [Line Items]
Sales	535	553	507
Operating Segments | Pharmaceutical segment | Temodar
Segment Reporting Information [Line Items]
Sales	312	350	708
Operating Segments | Pharmaceutical segment | Singulair
Segment Reporting Information [Line Items]
Sales	931	1,092	1,196
Operating Segments | Pharmaceutical segment | Nasonex
Segment Reporting Information [Line Items]
Sales	858	1,099	1,335
Operating Segments | Pharmaceutical segment | Clarinex
Segment Reporting Information [Line Items]
Sales	187	232	235
Operating Segments | Pharmaceutical segment | Cozaar/Hyzaar
Segment Reporting Information [Line Items]
Sales	667	806	1,006
Operating Segments | Pharmaceutical segment | Arcoxia
Segment Reporting Information [Line Items]
Sales	471	519	484
Operating Segments | Pharmaceutical segment | Fosamax
Segment Reporting Information [Line Items]
Sales	359	470	560
Operating Segments | Pharmaceutical segment | Zocor
Segment Reporting Information [Line Items]
Sales	217	258	301
Operating Segments | Pharmaceutical segment | Propecia
Segment Reporting Information [Line Items]
Sales	183	264	283
Operating Segments | Pharmaceutical segment | Gardasil/Gardasil 9
Segment Reporting Information [Line Items]
Sales	1,908	1,738	1,831
Operating Segments | Pharmaceutical segment | ProQuad/M-M-R II/Varivax
Segment Reporting Information [Line Items]
Sales	1,505	1,394	1,306
Operating Segments | Pharmaceutical segment | Zostavax
Segment Reporting Information [Line Items]
Sales	749	765	758
Operating Segments | Pharmaceutical segment | RotaTeq
Segment Reporting Information [Line Items]
Sales	610	659	636
Operating Segments | Pharmaceutical segment | Pneumovax 23
Segment Reporting Information [Line Items]
Sales	542	746	653
Operating Segments | Pharmaceutical segment | Other pharmaceutical
Segment Reporting Information [Line Items]
Sales	4,553	5,356	6,596
Operating Segments | Other segments
Segment Reporting Information [Line Items]
Sales	3,659	5,758	6,397
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Sales	$ 1,057	437	$ 199
Saphris
Segment Reporting Information [Line Items]
Proceeds from sale of intangible assets		$ 232

Segment Reporting - Consolidate

Segment Reporting - Consolidated Revenues by Geographic Area (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 39,498	$ 42,237	$ 44,033
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	17,519	17,071	18,246
Europe, Middle East, and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	10,677	13,174	13,140
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	3,820	3,951	3,845
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	2,673	3,471	4,044
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	2,823	3,151	3,203
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales	$ 1,986	$ 1,419	$ 1,555

Segment Reporting - Reconciliat

Segment Reporting - Reconciliation of Segment Profits to Income Before Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Income Before Taxes	$ 5,401	$ 17,283	$ 5,545
Interest income	289	266	264
Interest expense	(672)	(732)	(801)
Equity income from affiliates	205	257	404
Depreciation and amortization	(6,375)	(6,691)	(6,988)
Research and development	(6,704)	(7,180)	(7,503)
Restructuring costs	(619)	(1,013)	(1,709)
Foreign currency devaluation related to Venezuela	(876)	0	(140)
Net charge related to the settlement of Vioxx shareholder class action litigation	(680)	0	0
Gain on divestiture of Merck Consumer Care	0	11,209	0
Gain on AstraZeneca option exercise	0	741	0
Loss on extinguishment of debt	0	(628)	0
Segment profits:
Segment Reporting Information [Line Items]
Income Before Taxes	23,317	24,622	26,032
Segment profits: | Pharmaceutical segment
Segment Reporting Information [Line Items]
Income Before Taxes	21,658	22,164	22,983
Equity income from affiliates	70	90	88
Depreciation and amortization	(82)	(39)	(27)
Segment profits: | Other segments
Segment Reporting Information [Line Items]
Income Before Taxes	1,659	2,458	3,049
Equity income from affiliates	0	108	475
Depreciation and amortization	(18)	(18)	(22)
Other profits
Segment Reporting Information [Line Items]
Income Before Taxes	810	627	63
Unallocated:
Segment Reporting Information [Line Items]
Interest income	289	266	264
Interest expense	(672)	(732)	(801)
Equity income from affiliates	135	59	(159)
Depreciation and amortization	(1,573)	(2,452)	(2,250)
Research and development	(5,871)	(5,823)	(6,381)
Amortization of purchase accounting adjustments	(4,856)	(4,182)	(4,690)
Restructuring costs	(619)	(1,013)	(1,709)
Gain on sale of certain migraine clinical development programs	250	0	0
Gain on the divestiture of certain ophthalmic products	147	480	0
Foreign currency devaluation related to Venezuela	(876)	0	(140)
Net charge related to the settlement of Vioxx shareholder class action litigation	(680)	0	0
Gain on divestiture of Merck Consumer Care	0	11,209	0
Gain on AstraZeneca option exercise	0	741	0
Loss on extinguishment of debt	0	(628)	0
Other unallocated, net	$ (4,400)	$ (5,891)	$ (4,684)

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, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Equity income from affiliates	$ 205	$ 257	$ 404
Depreciation and amortization	(6,375)	(6,691)	(6,988)
Segment profits: | Pharmaceutical
Segment Reporting Information [Line Items]
Equity income from affiliates	70	90	88
Depreciation and amortization	(82)	(39)	(27)
Segment profits: | All Other
Segment Reporting Information [Line Items]
Equity income from affiliates	0	108	475
Depreciation and amortization	(18)	(18)	(22)
Segment profits: | Segment profits:
Segment Reporting Information [Line Items]
Equity income from affiliates	70	198	563
Depreciation and amortization	$ (100)	$ (57)	$ (49)

Segment Reporting - Property, P

Segment Reporting - Property, Plant and Equipment, Net by Geographic Area (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	$ 12,507	$ 13,136	$ 14,973
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	8,467	8,727	10,076
Europe, Middle East, and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	2,844	3,120	3,346
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	842	897	1,001
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	182	207	242
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	164	172	211
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, Plant and Equipment, Net	$ 8	$ 13	$ 97