v3.25.4
Stock-based compensation - Schedule of stock-based compensation activity (Details) - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Shares      
Outstanding (in shares) 3,732,862    
Granted to officers and key employees (in shares) 299,523    
Exercised (in shares) (997,947)    
Forfeited/expired (in shares) (17,385)    
Outstanding (in shares) 3,017,053 3,732,862  
Exercisable (in shares) 2,279,192    
Weighted- Average Exercise Price      
Outstanding (in dollars per shares) $ 195.28    
Granted to officers and key employees (in dollars per shares) 331.62    
Exercised (in dollars per shares) 159.25    
Forfeited / expired (in dollars per shares) 232.23    
Outstanding (in dollars per shares) 220.52 $ 195.28  
Exercisable at year-end (in dollars per share) $ 192.44    
Weighted-Average Remaining Contractual Life (Years), Outstanding 5 years 9 months 21 days    
Weighted-Average Remaining Contractual Life (Years), Exercisable 5 years 7 days    
Aggregate Intrinsic Value, Outstanding $ 1,063    
Aggregate Intrinsic Value, Exercisable $ 867    
RSUs      
Shares      
Beginning of year, outstanding (in shares) 776,637    
Granted to officers and key employees (in shares) 530,834    
Vested (in shares) (403,533)    
Forfeited/expired (in shares) (25,108)    
End of year, outstanding (in shares) 878,830 776,637  
Weighted- Average Grant Date Fair Value      
Outstanding (in dollars per shares) $ 284.36    
Granted to officers and key employees (in dollars per shares) 357.02 $ 338.65 $ 252.24
Vested (in dollars per shares) 259.27    
Forfeited (in dollars per shares) 316.72    
Outstanding (in dollars per shares) $ 338.27 $ 284.36  
PRSUs      
Shares      
Beginning of year, outstanding (in shares) 390,013    
Granted to officers and key employees (in shares) 203,491    
Vested (in shares) (220,897)    
Forfeited/expired (in shares) (8,323)    
End of year, outstanding (in shares) 364,284 390,013  
Weighted- Average Grant Date Fair Value      
Outstanding (in dollars per shares) $ 321.58    
Granted to officers and key employees (in dollars per shares) 345.60 $ 408.64 $ 251.97
Vested (in dollars per shares) 253.98    
Forfeited (in dollars per shares) 326.09    
Outstanding (in dollars per shares) $ 374.52 $ 321.58