Goodwill and other intangible assets - Goodwill (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023		Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Balance at the beginning of the year		$ 78,119	[1]	$ 73,875
Business acquisitions		7,347		4,657
Other, including acquisition period remeasurements and foreign currency translation		(840)		(413)
Balance at the end of the year	[1]	$ 84,626		$ 78,119

[1] Net of accumulated goodwill impairments of $11.1 billion as of December 31, 2023 and $11.0 billion as of December 31, 2022.