Stock Option Transactions (Detail)	3 Months Ended
	Apr. 30, 2022 $ / shares shares
Number of Shares
Options Outstanding at Beginning of Period | shares	1,097,558
Options Granted | shares	6,993
Options Exercised | shares	(41,673)	[1]
Options Forfeited | shares	(3,414)
Options Outstanding at End of Period | shares	1,059,464
Weighted Average Exercise Price Per Share
Options Outstanding at Beginning of Period | $ / shares	$ 181.17
Options Granted | $ / shares	214.03
Options Exercised | $ / shares	113.29	[1]
Options Forfeited | $ / shares	213.94
Options Outstanding at End of Period | $ / shares	$ 183.95

[1] Options exercised during the three month period ended April 30, 2022 had a total intrinsic value of $3.8 million.