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Acquisitions, Divestitures, Research Collaborations and License Agreements - Acqusitions Narrative (Detail) AUD / shares in Units, € in Millions, AUD in Millions |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended |
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Dec. 31, 2016 USD ($) | Jan. 21, 2015 USD ($) | Oct. 31, 2017 USD ($) | Oct. 31, 2017 EUR (€) | Jul. 31, 2017 USD ($) | Mar. 31, 2017 USD ($) | Jul. 31, 2016 USD ($) | Jun. 30, 2016 USD ($) | Jan. 31, 2016 USD ($) | Jul. 31, 2015 USD ($) | Feb. 28, 2015 USD ($) renewal | Dec. 31, 2017 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Feb. 28, 2018 AUD AUD / shares | Feb. 28, 2018 USD ($)
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration | $ 891,000,000 |  |  |  |  |  |  |  |  |  |  | $ 935,000,000 | $ 935,000,000 | $ 891,000,000 | $ 590,000,000 |  |
Goodwill | $ 18,162,000,000 |  |  |  |  |  |  |  |  |  |  | 18,284,000,000 | 18,284,000,000 | 18,162,000,000 | 17,723,000,000 |  |
Discount rate (as percent) | 11.50% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
In-process research and development impairment charges |  |  |  |  |  |  |  |  |  |  |  |  | 483,000,000 | 3,600,000,000 | 63,000,000 |  |
Changes in fair value |  |  |  |  |  |  |  |  |  |  |  |  | (141,000,000) | 407,000,000 |  |  |
Agreement term |  |  |  |  |  |  |  |  |  |  | 2 years |  |  |  |  |  |
Payments to acquire business, net of cash acquired |  |  |  |  |  |  |  |  |  |  |  |  | 396,000,000 | 780,000,000 | 146,000,000 |  |
Liability | $ 8,514,000,000 |  |  |  |  |  |  |  |  |  |  | $ 11,117,000,000 | 11,117,000,000 | 8,514,000,000 |  |  |
Amortization expense for intangible assets |  |  |  |  |  |  |  |  |  |  |  |  | 3,200,000,000 | 3,800,000,000 | 4,800,000,000 |  |
Payments of contingent consideration |  |  |  |  |  |  |  |  |  |  |  |  | 100,000,000 | 25,000,000 |  |  |
monoclonal antibody (cCAM) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
In-process research and development impairment charges |  |  |  |  |  |  |  |  |  |  |  |  |  | 180,000,000 |  |  |
Changes in fair value |  |  |  |  |  |  |  |  |  |  |  |  |  | 116,000,000 |  |  |
uprifosbuvir |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
In-process research and development impairment charges |  |  |  |  |  |  |  |  |  |  |  |  | $ 240,000,000 | $ 2,900,000,000 |  |  |
Rigontec |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid for acquisition of business |  |  | $ 140,000,000 | € 119 |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future milestone payments, maximum | € |  |  |  | 349 |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future milestone payment, research milestones and regulatory approvals | € |  |  |  | 184 |  |  |  |  |  |  |  |  |  |  |  |  |
Potential future milestone payment, commercial targets | € |  |  |  | € 165 |  |  |  |  |  |  |  |  |  |  |  |  |
Afferent Pharmaceuticals |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred in business combination |  |  |  |  |  |  | $ 510,000,000 |  |  |  |  |  |  |  |  |  |
Cash paid for acquisition of business |  |  |  |  |  |  | 487,000,000 |  |  |  |  |  |  |  |  |  |
Potential future milestone payments, maximum |  |  |  |  |  |  | 750,000,000 |  |  |  |  |  |  |  |  |  |
Contingent consideration |  |  |  |  |  |  | 223,000,000 |  |  |  |  |  |  |  |  |  |
In-process research and development (IPR&D) |  |  |  |  |  |  | 832,000,000 |  |  |  |  |  |  |  |  |  |
Other net assets |  |  |  |  |  |  | 29,000,000 |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  | $ 130,000,000 |  |  |  |  |  |  |  |  |  |
Discount rate (as percent) |  |  |  |  |  |  | 11.50% |  |  |  |  |  |  |  |  |  |
Deferred tax liabilities |  |  |  |  |  |  | $ 258,000,000 |  |  |  |  |  |  |  |  |  |
StayWell Company |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid for acquisition of business |  |  |  |  |  |  | 150,000,000 |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  | 275,000,000 |  |  |  |  |  |  |  |  |  |
Fair value of debt assumed in business combination |  |  |  |  |  |  | $ 150,000,000 |  |  |  |  |  |  |  |  |  |
Period before option becomes exercisable |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |  |  |  |
Identifiable intangible assets |  |  |  |  |  |  | $ 238,000,000 |  |  |  |  |  |  |  |  |  |
Deferred tax liabilities |  |  |  |  |  |  | 84,000,000 |  |  |  |  |  |  |  |  |  |
Other net liabilities |  |  |  |  |  |  | 5,000,000 |  |  |  |  |  |  |  |  |  |
Noncontrolling interest |  |  |  |  |  |  | $ 124,000,000 |  |  |  |  |  |  |  |  |  |
Estimated useful life of intangible assets, acquired |  |  |  |  |  |  | 10 years |  |  |  |  |  |  |  |  |  |
Estimated useful life of intangible assets |  |  |  |  |  |  | 5 years |  |  |  |  |  |  |  |  |  |
Vallee SA |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired |  |  |  |  |  | 93.50% |  |  |  |  |  | 4.50% | 4.50% |  |  |  |
Cash paid for acquisition of business |  |  |  |  |  | $ 358,000,000 |  |  |  |  |  |  |  |  |  |  |
Escrow Deposit |  |  |  |  |  | 176,000,000 |  |  |  |  |  |  |  |  |  |  |
Other net assets |  |  |  |  |  | 14,000,000 |  |  |  |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  | $ 171,000,000 |  |  |  |  |  |  |  |  |  |  |
Discount rate (as percent) |  |  |  |  |  | 15.50% |  |  |  |  |  |  |  |  |  |  |
Identifiable intangible assets |  |  |  |  |  | $ 291,000,000 |  |  |  |  |  |  |  |  |  |  |
Deferred tax liabilities |  |  |  |  |  | 93,000,000 |  |  |  |  |  |  |  |  |  |  |
Noncontrolling interest |  |  |  |  |  | $ 25,000,000 |  |  |  |  |  |  |  |  |  |  |
Estimated useful life of intangible assets, acquired |  |  |  |  |  | 15 years |  |  |  |  |  |  |  |  |  |  |
Payments to Acquire Additional Interest in Subsidiaries |  |  |  |  |  |  |  |  |  |  |  | $ 18,000,000 |  |  |  |  |
Contingent liabilities |  |  |  |  |  | $ 37,000,000 |  |  |  |  |  |  |  |  |  |  |
Indemnification assets |  |  |  |  |  | $ 37,000,000 |  |  |  |  |  |  |  |  |  |  |
Moderna Therapeutics |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Upfront and milestone payments |  |  |  |  |  |  |  | $ 200,000,000 |  |  |  |  |  |  |  |  |
IOmet Pharma Ltd |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid for acquisition of business |  |  |  |  |  |  |  |  | $ 150,000,000 |  |  |  |  |  |  |  |
Potential future milestone payments, maximum |  |  |  |  |  |  |  |  | 250,000,000 |  |  |  |  |  |  |  |
Contingent consideration |  |  |  |  |  |  |  |  | 94,000,000 |  |  |  |  |  |  |  |
In-process research and development (IPR&D) |  |  |  |  |  |  |  |  | 155,000,000 |  |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  |  |  | $ 57,000,000 |  |  |  |  |  |  |  |
Discount rate (as percent) |  |  |  |  |  |  |  |  | 10.50% |  |  |  |  |  |  |  |
Deferred tax assets |  |  |  |  |  |  |  |  | $ 32,000,000 |  |  |  |  |  |  |  |
Payments of contingent consideration |  |  |  |  | $ 100,000,000 |  |  |  |  |  |  |  |  |  |  |  |
cCAM Biotherapeutics |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid for acquisition of business |  |  |  |  |  |  |  |  |  | $ 96,000,000 |  |  |  |  |  |  |
Contingent consideration |  |  |  |  |  |  |  |  |  | 105,000,000 |  |  |  |  |  |  |
In-process research and development (IPR&D) |  |  |  |  |  |  |  |  |  | 180,000,000 |  |  |  |  |  |  |
Goodwill |  |  |  |  |  |  |  |  |  | 14,000,000 |  |  |  |  |  |  |
Other net noncurrent assets |  |  |  |  |  |  |  |  |  | $ 7,000,000 |  |  |  |  |  |  |
NGM Biopharmaceuticals |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Upfront and milestone payments |  |  |  |  |  |  |  |  |  |  | $ 94,000,000 |  |  |  |  |  |
Cost Method Investment, ownership percentage |  |  |  |  |  |  |  |  |  |  | 15.00% |  |  |  |  |  |
Payments to acquire cost method investment |  |  |  |  |  |  |  |  |  |  | $ 106,000,000 |  |  |  |  |  |
Purchase commitment, maximum amount (up to) |  |  |  |  |  |  |  |  |  |  | $ 250,000,000 |  |  |  |  |  |
Agreement term |  |  |  |  |  |  |  |  |  |  | 5 years |  |  |  |  |  |
Revenue and cost allocation percentage (as percent) (up to) |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |  |  |  |
Number of extensions for research agreement | renewal |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |
Cubist Pharmaceuticals Inc |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consideration transferred in business combination |  | $ 8,300,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash paid for acquisition of business |  | 7,800,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
In-process research and development (IPR&D) |  | 50,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other net assets |  | 55,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill |  | $ 4,670,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discount rate (as percent) |  | 8.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of debt assumed in business combination |  | $ 1,900,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Identifiable intangible assets |  | 6,923,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Deferred tax liabilities |  | 2,519,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other net liabilities |  | $ 122,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Estimated useful life of intangible assets, acquired |  | 11 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Transaction costs |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 324,000,000 |  |
Other net noncurrent assets |  | $ 184,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cubist Pharmaceuticals Inc | Other noncurrent liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Contingent consideration |  | $ 50,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event | Viralytics Limited [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Acquisitions Divestitures Research Collaborations And License Agreements Transactions [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Business acquisition, share price (in dollars per share) | AUD / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | AUD 1.75 |
Future Payment That Will Be Made To Acquire Business |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | AUD 502 | $ 394,000,000

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- Definition For contingent consideration arrangements recognized in connection with a business combination, this element represents an estimate of the high-end of the potential range (undiscounted) of the consideration which may be paid. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
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- Definition Amount of liability recognized arising from contingent consideration in a business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 35 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 25 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476 + Details
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- Definition The amount of indemnification assets (amounts to be reimbursed if and when certain assumed liabilities are paid) recognized at the acquisition date of a business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
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- Definition The amount of liability arising from an inherited contingency (as defined) which has been recognized as of the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=84160947&loc=d3e2207-128464 + Details
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- Definition Amount of other assets expected to be realized or consumed before one year or the normal operating cycle, if longer, acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
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- Definition Amount of deferred tax asset attributable to deductible temporary differences and carryforwards acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e31917-109318 + Details
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- Definition Amount of assets, excluding financial assets and goodwill, that lack physical substance, having a projected indefinite period of benefit, acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
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- Definition The amount of identifiable intangible assets recognized as of the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=84160947&loc=d3e2207-128464 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
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- Definition Amount of long-term debt due after one year or the normal operating cycle, if longer, assumed at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
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- Definition Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
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- Definition Amount of other assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
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- Definition For transactions that are recognized separately from the acquisition of assets and assumptions of liabilities in the business combination, such as related to pre-existing relationships with the acquiree, this element represents the disclosure of the amount of acquisition related costs which have been expensed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463 + Details
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