Accumulated Other Comprehensive Loss, Excluding Noncontrolling Interests (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		$ 63,447	$ 63,758	$ 71,656
Other comprehensive income/(loss)		14	(376)	(1,975)
Distribution of Upjohn Business	[1]	(2,018)
Ending balance		63,473	63,447	63,758
Accumulated Other Comprehensive Income/(Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(11,640)	(11,275)	(9,321)
Other comprehensive income/(loss)	[2]	23	(365)	(1,041)
Distribution of Upjohn Business	[1],[3]	(71)
Ending balance		(11,688)	(11,640)	(11,275)
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(5,952)	(6,075)	(5,180)
Other comprehensive income/(loss)	[2]	1,028	123	(893)
Distribution of Upjohn Business	[3]	(397)
Ending balance		(5,321)	(5,952)	(6,075)
Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		20	167	(30)
Other comprehensive income/(loss)	[2]	(448)	(146)	198
Distribution of Upjohn Business	[3]	0
Ending balance		(428)	20	167
Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(35)	(68)	401
Other comprehensive income/(loss)	[2]	151	33	(53)
Distribution of Upjohn Business	[3]	0
Ending balance		116	(35)	(68)
Actuarial Gains/(Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		(6,257)	(6,027)	(5,262)
Other comprehensive income/(loss)	[2]	(602)	(231)	(128)
Distribution of Upjohn Business	[3]	352
Ending balance		(6,507)	(6,257)	(6,027)
Prior Service (Costs)/Credits and Other [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance		584	728	750
Other comprehensive income/(loss)	[2]	(106)	(144)	(166)
Distribution of Upjohn Business	[3]	(26)
Ending balance		$ 452	$ 584	728
Cumulative Effect, Period of Adoption, Adjustment [Member] | Accumulated Other Comprehensive Income/(Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[4]			(913)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[4]			(2)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Derivative Financial Instruments [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[4]			(1)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[4]			(416)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Actuarial Gains/(Losses) [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[4]			(637)
Cumulative Effect, Period of Adoption, Adjustment [Member] | Prior Service (Costs)/Credits and Other [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[4]			$ 144

[1] See Note 2B.

[2] Amounts do not include foreign currency translation adjustments attributable to noncontrolling interests of $9 million loss in 2020, $11 million loss in 2019 and $20 million loss in 2018. Foreign currency translation adjustments in 2020 primarily include gains from the strengthening of the euro, Japanese yen, Australian dollar and U.K. pound against the U.S. dollar, and net gains related to foreign currency translation adjustments related to our equity method investment in the Consumer Healthcare JV (see Note 2C), partially offset by the impact of our net investment hedging program. Foreign currency translation adjustments in 2019 primarily include a gain of approximately $1.3 billion pre-tax ($978 million after-tax) related to foreign currency translation adjustments attributable to our equity method investment in the Consumer Healthcare JV (see Note 2C), partially offset by the strengthening of the U.S. dollar against the euro and the Australian dollar, and the results of our net investment hedging program. Amounts in 2018 primarily reflect the strengthening of the U.S. dollar against the euro, U.K. pound and Chinese renminbi.

[3] For more information, see Note 2B.

[4] Represent the cumulative effect adjustments as of January 1, 2018 from the adoption of accounting standards related to (i) financial assets and liabilities and (ii) the reclassification of certain tax effects from AOCI. See Note 1B in our 2018 Financial Report.