Net Income per Common Share - Reconciliation of Numerator and Denominator of Basic and Diluted Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Oct. 31, 2021	Oct. 31, 2020
Earnings Per Share [Line Items]
Net income	$ 35,046	$ 33,481
Denominator for basic income per share for both Class A and Class B	51,973	52,021
Plus: Effect of dilutive equity awards	463	271
Denominator for diluted income per share for both Class A and Class B	52,436	52,292
Class A Nonvoting Common Stock
Earnings Per Share [Line Items]
Net income per share, basic	$ 0.67	$ 0.64
Net income per share, diluted	$ 0.67	$ 0.64
Class B Voting Common Stock
Earnings Per Share [Line Items]
Preferential dividends	$ (803)	$ (808)
Preferential dividends on dilutive stock options	(8)	(4)
Net income	$ 34,235	$ 32,669
Net income per share, basic	$ 0.66	$ 0.63
Net income per share, diluted	$ 0.65	$ 0.62