Intangible assets and goodwill - Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Jan. 01, 2023
Goodwill [Roll Forward]
Goodwill beginning of period	$ 36,047	$ 25,436
Goodwill, related to acquisitions	0	11,056
Goodwill, related to divestitures	0	0
Currency translation/other	511	(445)
Goodwill end of period	36,558	36,047
Innovative Medicine
Goodwill [Roll Forward]
Goodwill beginning of period	10,184	10,580
Goodwill, related to acquisitions	0	0
Goodwill, related to divestitures	0	0
Currency translation/other	223	(396)
Goodwill end of period	10,407	10,184
MedTech
Goodwill [Roll Forward]
Goodwill beginning of period	25,863	14,856
Goodwill, related to acquisitions	0	11,056
Goodwill, related to divestitures	0	0
Currency translation/other	288	(49)
Goodwill end of period	$ 26,151	$ 25,863