Segment Reporting - Reconciliation of Segment Profits to Income Before Taxes (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Profits	$ 200	$ 2,887	$ 4,642	$ 6,015
Interest income	90	87	284	244
Interest expense	(189)	(170)	(564)	(513)
Equity income from affiliates	18	21	11	59
Depreciation and amortization			(3,509)	(4,286)
Research and development	(4,383)	(1,664)	(7,927)	(5,475)
Restructuring costs	(153)	(161)	(470)	(386)
Total segment profits
Segment Reporting Information [Line Items]
Profits	6,411	6,551	18,164	17,827
Total segment profits \| Pharmaceutical segment
Segment Reporting Information [Line Items]
Profits	5,929	6,162	16,722	16,698
Total segment profits \| Other segments
Segment Reporting Information [Line Items]
Profits	482	389	1,442	1,129
Other profits
Segment Reporting Information [Line Items]
Profits	(78)	21	107	341
Unallocated
Segment Reporting Information [Line Items]
Interest income	90	87	284	244
Interest expense	(189)	(170)	(564)	(513)
Equity income from affiliates	23	(27)	16	(13)
Depreciation and amortization	(334)	(365)	(1,036)	(1,228)
Research and development	(1,829)	(1,444)	(4,955)	(4,651)
Aggregate charge related to the formation of an oncology collaboration with AstraZeneca	(2,350)	0	(2,350)	0
Amortization of purchase accounting adjustments	(765)	(772)	(2,322)	(2,933)
Restructuring costs	(153)	(161)	(470)	(386)
Gain on sale of certain migraine clinical development programs	0	40	0	40
Other unallocated, net	$ (626)	$ (873)	$ (2,232)	$ (2,713)

Amortization of purchase accounting adjustments.

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Charge for upfront payment and future option payments related to the formation of a collaboration.

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Other net expenses not allocated to segments.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

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Amount of the cost of borrowed funds accounted for as interest expense.

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Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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