Legal Settlements and Loss Contingencies - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Loss Contingencies [Line Items]
Legal settlements and loss contingencies, expense	$ 104
Legal settlements, income		$ 25
Accrued amount for legal settlements and loss contingencies	$ 1,730		$ 1,625
Restructuring expense and income	The expense in the first quarter of 2021 was mainly due to the provision for the carvedilol patent litigation (see note 10). The income in the first quarter of 2020 was mainly due to proceeds received following a settlement of an action brought against the sellers of Auden McKenzie (an acquisition made by Actavis Generics).