Accumulated Other Comprehensive Loss, Excluding Noncontrolling Interests (Detail) $ in Millions	3 Months Ended
	Mar. 29, 2020 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2019	$ 63,143	[1]
Balance, March 29, 2020	65,026	[1]
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2019	(11,640)
Other comprehensive income/(loss)	(1,490)	[2]
Balance, March 29, 2020	(13,131)
Foreign Currency Translation Adjustment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2019	(5,952)
Other comprehensive income/(loss)	(1,020)	[2]
Balance, March 29, 2020	(6,973)
Derivative Financial Instruments [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2019	20
Other comprehensive income/(loss)	(364)	[2]
Balance, March 29, 2020	(344)
Cash flow hedge gain to be reclassified within twelve months	294
Available-For-Sale Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2019	(35)
Other comprehensive income/(loss)	(32)	[2]
Balance, March 29, 2020	(67)
Actuarial Gains/(Losses) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2019	(6,257)
Other comprehensive income/(loss)	(39)	[2]
Balance, March 29, 2020	(6,296)
Prior Service (Costs)/Credits and Other [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, December 31, 2019	584
Other comprehensive income/(loss)	(35)	[2]
Balance, March 29, 2020	549
GSK Consumer Healthcare [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), foreign currency transaction and translation adjustment, net of tax	$ 1,200

[1] Amounts may not add due to rounding.

[2] Includes after-tax losses of approximately $1.2 billion related to foreign currency translation adjustments attributable to our equity method investment in GSK Consumer Healthcare (see Note 2B), partially offset by the results of our net investment hedging program.