Postemployment benefit plans (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure
Liability for postemployment benefits	$ 4,098	$ 4,203
ESOP, number of allocated shares	11.3	12.0
Insurance contracts | Level 3
Defined Benefit Plan Disclosure
Purchases	$ 633
Settlements	9
Unrealized gains	51
Other Postretirement  Benefits
Defined Benefit Plan Disclosure
Liability for postemployment benefits	$ 56	$ 58
Assumed increase in health care trend rate over the current period to calculate benefit expenses (as a percent)	6.50%
Assumed increase in health care trend rate for the next year to calculate benefit expenses (as a percent)	6.20%
Ultimate health care cost trend rate (as a percent)	4.70%
Year that heath care trend rate is assumed to reach ultimate trend rate (year)	2030
Other Postretirement  Benefits | Debt Security
Defined Benefit Plan Disclosure
Target allocation of plan assets (as a percent)	30.00%
Other Postretirement  Benefits | Equity Securities
Defined Benefit Plan Disclosure
Target allocation of plan assets (as a percent)	70.00%
Defined contribution
Defined Benefit Plan Disclosure
Liability for postemployment benefits	$ 565	$ 475
U.S. plans
Defined Benefit Plan Disclosure
Percentage that the employer generally matches of employee contributions to U.S. defined contribution plans	100.00%
Employee compensation percentage contributed to defined contribution plan eligible for employer matching contributions	6.00%
New annual employer contribution, percentage of compensation, low end of range	3.00%
New annual employer contribution, percentage of compensation, high end of range	5.00%
Pension Plan | Debt Security | U.S. Pension Benefits
Defined Benefit Plan Disclosure
Target allocation of plan assets (as a percent)	85.00%
Pension Plan | Debt Security | Non-U.S.  Pension Benefits
Defined Benefit Plan Disclosure
Target allocation of plan assets (as a percent)	59.00%
Pension Plan | Equity Securities | U.S. Pension Benefits
Defined Benefit Plan Disclosure
Target allocation of plan assets (as a percent)	15.00%
Pension Plan | Equity Securities | Non-U.S.  Pension Benefits
Defined Benefit Plan Disclosure
Target allocation of plan assets (as a percent)	12.00%
Pension Plan | Insurance contracts | Non-U.S.  Pension Benefits
Defined Benefit Plan Disclosure
Target allocation of plan assets (as a percent)	19.00%
Pension Plan | Real estate | Non-U.S.  Pension Benefits
Defined Benefit Plan Disclosure
Target allocation of plan assets (as a percent)	6.00%
Pension Plan | Other plan assets | Non-U.S.  Pension Benefits
Defined Benefit Plan Disclosure
Target allocation of plan assets (as a percent)	4.00%