v3.26.1
Shareholders' equity (Details)
 6 Months Ended
Mar. 07, 2025
shares
May 21, 2024
shares
Jun. 30, 2026
SFr / shares
shares
May 21, 2026
$ / shares
Dec. 31, 2025
SFr / shares
shares
May 15, 2025
$ / shares
May 16, 2024
$ / shares
Stockholders' Equity Note [Abstract]              
Common Shares, par value | SFr / shares     SFr 0.50   SFr 0.50    
Annual dividend per share approved by shareholders | $ / shares       $ 4.08   $ 3.88 $ 3.64
Common Stock, Dividend Rate Approved | $ / shares       1.02   0.97 0.91
Treasury Stock, Shares, Retired | shares 11,986,574 7,518,565 11,986,574        
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures | shares     1,040,203        
Equity, Class of Treasury Stock [Line Items]              
Common Stock, Dividend Rate Approved | $ / shares       1.02   0.97 0.91
Treasury Stock, Shares, Retired | shares 11,986,574 7,518,565 11,986,574        
Treasury Stock, Common, Shares | shares     14,486,798   21,006,194    
Common Shares, par value | SFr / shares     SFr 0.50   SFr 0.50    
Annual dividend per share approved by shareholders | $ / shares       $ 4.08   $ 3.88 $ 3.64