Common stock (Detail)	6 Months Ended
	Jun. 30, 2023 shares
Class A [Member]
Class of Stock [Line Items]
Shares issued, beginning balance	651,450
Treasury shares, beginning balance	(59,886)
Shares outstanding, beginning balance	591,564
Conversions of Class A to Class B common stock	(9,871)
Conversions of Class A to Class B common stock, Outstanding	(9,871)
Treasury stock acquired	(6,145)
Shares issued, ending balance	641,579
Treasury shares, ending balance	(66,031)
Shares outstanding, ending balance	575,548
Class B [Member]
Class of Stock [Line Items]
Shares issued, beginning balance	1,509,969,352
Treasury shares, beginning balance	(207,715,276)
Shares outstanding, beginning balance	1,302,254,076
Conversions of Class A to Class B common stock	14,806,500
Conversions of Class A to Class B common stock, Outstanding	14,806,500
Treasury stock acquired	(9,071,308)
Shares issued, ending balance	1,524,775,852
Treasury shares, ending balance	(216,786,584)
Shares outstanding, ending balance	1,307,989,268