Goodwill and other intangible assets - Goodwill (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Balance at the beginning of the year	[1]	$ 84,626	$ 78,119
Business acquisitions		87	7,347
Other, including acquisition period remeasurements and foreign currency translation		(833)	(840)
Balance at the end of the year	[1]	$ 83,880	$ 84,626

[1] Net of accumulated goodwill impairments of $11.5 billion as of December 31, 2024, $11.1 billion as of December 31, 2023 and $11.0 billion as of December 31, 2022.