|**Identifiable Intangible Assets and Goodwill (Tables)**                                                                                                      | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
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|**Goodwill and Intangible Assets Disclosure [Abstract]**                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Schedule of Finite-Lived Intangible Assets                                                                                                                    | The following table provides the components ofIdentifiable intangible assets:March 31, 2019December 31, 2018(MILLIONS OF DOLLARS)GrossCarryingAmountAccumulatedAmortizationIdentifiableIntangibleAssets, lessAccumulatedAmortizationGrossCarryingAmountAccumulatedAmortizationIdentifiableIntangibleAssets, lessAccumulatedAmortizationFinite-lived intangible assetsDeveloped technology rights$89,379$(59,913)$29,465$89,430$(58,895)$30,535Brands923(717)206923(708)215Licensing agreements and other1,442(1,150)2921,436(1,140)29691,743(61,780)29,96391,788(60,743)31,045Indefinite-lived intangible assetsBrands and other1,9941,9941,9941,994IPR&D2,0822,0822,1712,1714,0764,0764,1654,165Identifiable intangible assets(a)$95,819$(61,780)$34,039$95,954$(60,743)$35,211(a)The decrease inIdentifiable intangible assets, less accumulated amortization,is primarily due to amortization and intangible asset impairment charges, partially offset by additions for the period. SeeNote 4for additional information on intangible asset impairments.
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|The following table provides the components ofIdentifiable intangible assets:                                                                                
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|(MILLIONS OF DOLLARS)                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Finite-lived intangible assets                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Developed technology rights                                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Brands                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Licensing agreements and other                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
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|Indefinite-lived intangible assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Brands and other                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|IPR&D                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
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|Identifiable intangible assets(a)                                                                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|(a)                                                                                                                                                           | The decrease inIdentifiable intangible assets, less accumulated amortization,is primarily due to amortization and intangible asset impairment charges, partially offset by additions for the period. SeeNote 4for additional information on intangible asset impairments.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Schedule of Indefinite Lived Intangible Assets                                                                                                                | The following table provides the components ofIdentifiable intangible assets:March 31, 2019December 31, 2018(MILLIONS OF DOLLARS)GrossCarryingAmountAccumulatedAmortizationIdentifiableIntangibleAssets, lessAccumulatedAmortizationGrossCarryingAmountAccumulatedAmortizationIdentifiableIntangibleAssets, lessAccumulatedAmortizationFinite-lived intangible assetsDeveloped technology rights$89,379$(59,913)$29,465$89,430$(58,895)$30,535Brands923(717)206923(708)215Licensing agreements and other1,442(1,150)2921,436(1,140)29691,743(61,780)29,96391,788(60,743)31,045Indefinite-lived intangible assetsBrands and other1,9941,9941,9941,994IPR&D2,0822,0822,1712,1714,0764,0764,1654,165Identifiable intangible assets(a)$95,819$(61,780)$34,039$95,954$(60,743)$35,211(a)The decrease inIdentifiable intangible assets, less accumulated amortization,is primarily due to amortization and intangible asset impairment charges, partially offset by additions for the period. SeeNote 4for additional information on intangible asset impairments.
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|                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|The following table provides the components ofIdentifiable intangible assets:                                                                                
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|(MILLIONS OF DOLLARS)                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Finite-lived intangible assets                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Developed technology rights                                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Brands                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Licensing agreements and other                                                                                                                                |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
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|Indefinite-lived intangible assets                                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Brands and other                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|IPR&D                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
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|Identifiable intangible assets(a)                                                                                                                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
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|(a)                                                                                                                                                           | The decrease inIdentifiable intangible assets, less accumulated amortization,is primarily due to amortization and intangible asset impairment charges, partially offset by additions for the period. SeeNote 4for additional information on intangible asset impairments.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   
|Identifiable Intangible Assets as a Percentage of Total Identifiable Intangible Assets Less Accumulated Amortization, By Segment                              | Our identifiable intangible assets are associated with the following, as a percentage of total identifiable intangible assets, less accumulated amortization:March 31, 2019BiopharmaUpjohnWRDMDeveloped technology rights99%1%—Brands, finite-lived100%——Brands, indefinite-lived42%58%—IPR&D87%—13%                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        
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|Our identifiable intangible assets are associated with the following, as a percentage of total identifiable intangible assets, less accumulated amortization:
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|Developed technology rights                                                                                                                                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Brands, finite-lived                                                                                                                                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Brands, indefinite-lived                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|IPR&D                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Schedule of Goodwill                                                                                                                                          | The following table provides the components of and changes in the carrying amount ofGoodwill:(MILLIONS OF DOLLARS)BiopharmaUpjohnTo be Allocated(a)TotalBalance, December 31, 2018$—$—$53,411$53,411Other(b)——7676Balance, March 31, 2019$—$—$53,487$53,487(a)The amount to be allocated includes the goodwill associated with our former operating segments (see above), for which the allocation to our new reporting units, and, as a result, to the new operating segments, is pending.(b)Primarily reflects the impact of foreign exchange.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
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|                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|The following table provides the components of and changes in the carrying amount ofGoodwill:                                                                
|(MILLIONS OF DOLLARS)                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Balance, December 31, 2018                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Other(b)                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|Balance, March 31, 2019                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|(a)                                                                                                                                                           | The amount to be allocated includes the goodwill associated with our former operating segments (see above), for which the allocation to our new reporting units, and, as a result, to the new operating segments, is pending.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|                                                                                                                                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
|(b)                                                                                                                                                           | Primarily reflects the impact of foreign exchange.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          

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