Certain Transactions - Other Transactions - Additional Information (Detail) $ in Millions			1 Months Ended			3 Months Ended						9 Months Ended
	Jan. 08, 2018 USD ($)	May 12, 2017 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($) Lawsuit	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Oct. 31, 2016 USD ($)
Noncash or Part Noncash Acquisitions [Line Items]
Other asset impairments, restructuring and other items						$ 160		$ 139				$ 263	$ 834
Net (gain) loss from sale of long-lived assets and investments												$ 10	$ (53)
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]
Number of lawsuits filed \| Lawsuit					2
Alder [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Upfront payment	$ 25
Collaborative agreement milestone payments	$ 175
Otsuka [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Upfront payment		$ 50
Attenukine [Member]
Noncash or Part Noncash Acquisitions [Line Items]
Upfront payment				$ 30
Additional considerations				$ 280
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							$ 60		$ 35	$ 25
Research and development costs					$ 1,000