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		6 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Earnings Per Share [Line Items]
Net income	$ 33,815	$ 30,860	$ 68,861	$ 64,341
Denominator for basic income per share for both Class A and Class B	51,800	52,018	51,887	52,020
Plus: Effect of dilutive equity awards	362	264	412	268
Denominator for diluted income per share for both Class A and Class B	52,162	52,282	52,299	52,288
Class A Nonvoting Common Stock [Member]
Earnings Per Share [Line Items]
Basic	$ 0.65	$ 0.59	$ 1.33	$ 1.24
Diluted	$ 0.65	$ 0.59	$ 1.32	$ 1.23
Class B Voting Common Stock [Member]
Earnings Per Share [Line Items]
Preferential dividends	$ 0	$ 0	$ 803	$ 808
Preferential dividends on dilutive stock options	0	0	8	(4)
Numerator for basic and diluted income per Class B Voting Common Share	$ 33,815	$ 30,860	$ 68,050	$ 63,529
Basic	$ 0.65	$ 0.59	$ 1.31	$ 1.22
Diluted	$ 0.65	$ 0.59	$ 1.30	$ 1.21