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	12 Months Ended
	Jul. 31, 2023	Jul. 31, 2022	Jul. 31, 2021
Earnings Per Share [Line Items]
Net income	$ 174,857	$ 149,979	$ 129,659
Denominator for basic earnings per share for both Class A and Class B	49,591	51,321	52,039
Plus: Effect of dilutive stock options	278	330	370
Denominator for diluted earnings per share for both Class A and Class B	49,869	51,651	52,409
Class A Nonvoting Common Stock
Earnings Per Share [Line Items]
Basic	$ 3.53	$ 2.92	$ 2.49
Diluted	$ 3.51	$ 2.90	$ 2.47
Class B Voting Common Stock
Earnings Per Share [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic	$ 174,085	$ 149,168	$ 128,847
Cash dividends on Common Stock	769	803	807
Preferential dividends on dilutive stock options	$ 3	$ 8	$ 5
Basic	$ 3.51	$ 2.91	$ 2.48
Diluted	$ 3.49	$ 2.89	$ 2.46