Postemployment benefit plans - Company costs related to U.S. and non-U.S. defined contribution plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure
Costs related to defined contribution plans	$ 741	$ 681	$ 506
U.S. plans 1
Defined Benefit Plan Disclosure
Costs related to defined contribution plans	610	567	392
Non-U.S. plans
Defined Benefit Plan Disclosure
Costs related to defined contribution plans	$ 131	$ 114	$ 114