Stock-based compensation - Schedule of financial information related to stock-based compensation (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value per share of stock awards granted (in dollars per share)	$ 104.27	$ 75.79	$ 51.69
Intrinsic value of stock awards exercised	$ 354	$ 356	$ 217
Fair value of stock awards vested	56	53	56
Cash received from stock awards exercised	$ 113	$ 98	$ 123
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted to officers and key employees (in dollars per shares)	$ 338.65	$ 252.24	$ 196.06
Fair value of stock awards vested	$ 144	$ 126	$ 105
PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted to officers and key employees (in dollars per shares)	$ 408.64	$ 251.97	$ 195.17
Fair value of stock awards vested	$ 94	$ 80	$ 90

Amount of cash inflow from exercise of option under share-based payment arrangement.

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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