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, 2022	Jul. 31, 2021	Jul. 31, 2020
Earnings Per Share [Line Items]
Net income	$ 149,979	$ 129,659	$ 112,369
Denominator for basic earnings per share for both Class A and Class B	51,321	52,039	52,763
Plus: Effect of dilutive stock options	330	370	468
Denominator for diluted earnings per share for both Class A and Class B	51,651	52,409	53,231
Class A Nonvoting Common Stock
Earnings Per Share [Line Items]
Basic	$ 2.92	$ 2.49	$ 2.13
Diluted	$ 2.90	$ 2.47	$ 2.11
Class B Voting Common Stock
Earnings Per Share [Line Items]
Net Income (Loss) Available to Common Stockholders, Basic	$ 149,168	$ 128,847	$ 111,531
Basic	$ 2.91	$ 2.48	$ 2.11
Diluted	$ 2.89	$ 2.46	$ 2.10
Preferential Dividends on Class A Nonvoting Common Stock [Member]
Earnings Per Share [Line Items]
Cash dividends on Common Stock	$ 803	$ 807	$ 828
Preferential Dividends on Dilutive Shares [Member]
Earnings Per Share [Line Items]
Cash dividends on Common Stock	$ 8	$ 5	$ 10