Postemployment benefit plans - Schedule of benefit obligation in excess of plan assets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
U.S. Pension Benefits
Pension plans with projected benefit obligation in excess of plan assets:
Projected benefit obligation	$ 627	$ 10,557
Fair value of plan assets	0	9,805
Pension plans with accumulated benefit obligation in excess of plan assets:
Accumulated benefit obligation	627	10,557
Fair value of plan assets	0	9,805
Non-U.S.  Pension Benefits
Pension plans with projected benefit obligation in excess of plan assets:
Projected benefit obligation	370	623
Fair value of plan assets	43	262
Pension plans with accumulated benefit obligation in excess of plan assets:
Accumulated benefit obligation	279	534
Fair value of plan assets	$ 7	$ 224