Other (Income)/Deductions - Net - Footnotes (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Loss Contingencies [Line Items]
Unrealized gain (loss) on equity securities	[1]	$ (68)	$ 3	$ 391	$ 140
Intangible asset impairment charge				900
Other asset impairments					48
External incremental costs			121		146
Insurance recoveries					50
Subsidiaries [Member] | Upjohn Finance B.V. [Member]
Loss Contingencies [Line Items]
Charges related to remeasurement of Euro debt		144
Allogene [Member]
Loss Contingencies [Line Items]
Unrealized gain (loss) on equity securities		(131)		243
BioNTech [Member]
Loss Contingencies [Line Items]
Unrealized gain (loss) on equity securities				154
Cortexyme, Inc. and SpringWorks Therapeutics, Inc [Member]
Loss Contingencies [Line Items]
Unrealized gain (loss) on equity securities					115
ViiV [Member]
Loss Contingencies [Line Items]
Dividend income		44	$ 43	196	184
Puma Technologies [Member] | Collaborative Arrangement [Member]
Loss Contingencies [Line Items]
Milestone payment received				40
Eli Lilly & Company [Member] | Collaborative Arrangement [Member]
Loss Contingencies [Line Items]
Milestone payment received				30
Mylan [Member] | Collaborative Arrangement [Member]
Loss Contingencies [Line Items]
Milestone payment received					70
Disposed of by Sale [Member] | CK1 assets sold to Biogen, Inc [Member]
Loss Contingencies [Line Items]
Consideration transferred		75		75
IPR&D [Member]
Loss Contingencies [Line Items]
Intangible asset impairment charge	[2]			900
Upjohn [Member] | Operating Segments [Member] | Developed technology rights [Member] | King [Member]
Loss Contingencies [Line Items]
Intangible asset impairment charge					40
Biopharma [Member] | Operating Segments [Member] | Developed technology rights [Member] | Anacor [Member]
Loss Contingencies [Line Items]
Intangible asset impairment charge					10
Biopharma [Member] | Operating Segments [Member] | IPR&D [Member]
Loss Contingencies [Line Items]
Intangible asset impairment charge		$ 900		900
Gene Therapies [Member] | WRDM [Member] | IPR&D [Member]
Loss Contingencies [Line Items]
Intangible asset impairment charge					$ 90
ViiV [Member]
Loss Contingencies [Line Items]
Change in fair value of contingent consideration				$ 110

[1] Included in net unrealized gains are observable price changes on equity securities without readily determinable fair values. Since January 1, 2018, there were cumulative impairments and downward adjustments of $82 million and upward adjustments of $63 million. Impairments, downward and upward adjustments were not significant in the third quarters and the first nine months of 2020 and 2019.

[2] Reflects intangible assets written down to fair value in the first nine months of 2020. Fair value was determined using the income approach, specifically the multi-period excess earnings method, also known as the discounted cash flow method. We started with a forecast of all the expected net cash flows associated with the asset and then applied an asset-specific discount rate to arrive at a net present value amount. Some of the more significant estimates and assumptions inherent in this approach include: the amount and timing of the projected net cash flows, which includes the expected impact of competitive, legal and/or regulatory forces on the product; the discount rate, which seeks to reflect the various risks inherent in the projected cash flows; and the tax rate, which seeks to incorporate the geographic diversity of the projected cash flows.