Common stock (Detail)	3 Months Ended
	Mar. 31, 2025 shares
Class A [Member]
Class of Stock [Line Items]
Shares issued, beginning balance	623,902
Treasury shares, beginning balance	(76,340)
Shares outstanding, beginning balance	547,562
Conversions of Class A to Class B common stock	(3,717)
Conversions of Class A to Class B common stock, Outstanding	(3,717)
Shares issued, ending balance	620,185
Treasury shares, ending balance	(76,340)
Shares outstanding, ending balance	543,845
Class B [Member]
Class of Stock [Line Items]
Shares issued, beginning balance	1,551,291,352
Treasury shares, beginning balance	(215,299,213)
Shares outstanding, beginning balance	1,335,992,139
Conversions of Class A to Class B common stock	5,575,500
Conversions of Class A to Class B common stock, Outstanding	5,575,500
Shares issued, ending balance	1,556,866,852
Treasury shares, ending balance	(215,299,213)
Shares outstanding, ending balance	1,341,567,639