Certain Transactions - Other Transactions - Additional Information (Detail) $ in Millions				1 Months Ended		3 Months Ended				12 Months Ended
	Jan. 08, 2018 USD ($)	May 12, 2017 USD ($)	Mar. 03, 2016 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2016 USD ($) Lawsuit	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Noncash or Part Noncash Acquisitions [Line Items]
Other asset impairments, restructuring and other items										$ 479	$ 423	$ 987
Net (gain) loss from sale of long-lived assets and investments										(213)	$ (18)	(19)
PGT Healthcare Partnership [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Other asset impairments, restructuring and other items								$ 64
Write-down of investment								$ 94
Net (gain) loss from sale of long-lived assets and investments				$ 50
Rimsa [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Cash consideration			$ 2,300
Number of lawsuits filed \| Lawsuit					2
Alder [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Upfront payment	$ 25
Milestone payment							$ 25
Collaborative agreement milestone payments	$ 150
Otsuka [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Upfront payment		$ 50
Milestone payment						$ 15
Celltrion [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Refundable payment						60
Total associated cost						$ 160
Regeneron [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Upfront payment									$ 250
Collaborative agreement milestone payments					$ 2,230							$ 120	$ 120
Research and development costs					$ 1,000
Alvotech [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Collaborative agreement milestone payments										$ 450