Stock-based compensation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares issued from treasury stock for stock-based compensation (in shares)	1,972,037	2,497,799	2,340,887
Number of shares authorized under the plans (in shares)	42,500,000
Number of shares available for grant (in shares)	40,873,176
Required minimum age of a participant upon separation from service to meet the criteria for Long Service Separation (in years)	55 years
Minimum term of service to meet criteria for Long Service Separation (in years)	5 years
Requisite service period	6 months
Term life of SARs and option awards (in years)	10 years
Term life of vested options/SARs from separation date (in years)	5 years
Stock-based compensation expense, before tax (in dollars)	$ 223	$ 208	$ 193
Income tax benefit corresponding to stock-based compensation expense	30	33	32
Unrecognized compensation cost related to nonvested stock-based compensation awards (in dollars)	$ 148
Term of amortization of unrecognized compensation cost over weighted-average remaining requisite service periods (in years)	1 year 9 months 18 days
Cash tax benefits realized from stock awards exercised	$ 90	$ 89	$ 63
Percentage of award vested on first anniversary of grant date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Portion of the award vested on each anniversary of the grant date	33.33%
Percentage of award vested on second anniversary of grant date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Portion of the award vested on each anniversary of the grant date	33.33%
Percentage of award vested on third anniversary of grant date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Portion of the award vested on each anniversary of the grant date	33.33%
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Graded vesting period of awards granted	3 years
Outstanding (in shares)	776,637	829,386
Weighted average remaining contractual life (in years)	1 year 6 months
RSUs | Percentage of award vested on first anniversary of grant date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Portion of the award vested on each anniversary of the grant date	33.33%
RSUs | Percentage of award vested on second anniversary of grant date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Portion of the award vested on each anniversary of the grant date	33.33%
RSUs | Percentage of award vested on third anniversary of grant date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Portion of the award vested on each anniversary of the grant date	33.33%
PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cliff vested period of awards granted	3 years
Requisite service period	6 months
Outstanding (in shares)	390,013	480,759
Weighted average remaining contractual life (in years)	1 year 4 months 24 days