v3.25.4
Common stock (Detail) - shares
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Class A [Member]      
Class of Stock [Line Items]      
Shares issued, beginning balance 623,902 639,328 651,450
Treasury shares, beginning balance (76,340) (71,553) (59,886)
Shares outstanding, beginning balance 547,562 567,775 591,564
Conversions of Class A to Class B common stock (31,727) (15,426) (12,122)
Conversions of Class A to Class B common stock, Outstanding (31,727) (15,426) (12,122)
Treasury stock acquired   (4,787) (11,667)
Shares issued, ending balance 592,175 623,902 639,328
Treasury shares, ending balance (76,340) (76,340) (71,553)
Shares outstanding, ending balance 515,835 547,562 567,775
Class B [Member]      
Class of Stock [Line Items]      
Shares issued, beginning balance 1,551,291,352 1,528,152,352 1,509,969,352
Treasury shares, beginning balance (215,299,213) (217,590,844) (207,715,276)
Shares outstanding, beginning balance 1,335,992,139 1,310,561,508 1,302,254,076
Conversions of Class A to Class B common stock 47,590,500 23,139,000 18,183,000
Conversions of Class A to Class B common stock, Outstanding 47,590,500 23,139,000 18,183,000
Treasury stock acquired     (9,875,568)
Treasury stock issued   2,291,631  
Shares issued, ending balance 1,598,881,852 1,551,291,352 1,528,152,352
Treasury shares, ending balance (215,299,213) (215,299,213) (217,590,844)
Shares outstanding, ending balance 1,383,582,639 1,335,992,139 1,310,561,508