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		9 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2021	Apr. 30, 2020
Earnings Per Share [Line Items]
Net Income	$ 37,291	$ 13,633	$ 101,632	$ 84,684
Denominator for basic earnings per share for both Class A and Class B	52,050	52,607	52,030	53,023
Plus: Effect of dilutive stock options	399	365	311	489
Denominator for diluted income per share for both Class A and Class B	52,449	52,972	52,341	53,512
Class A nonvoting common stock
Earnings Per Share [Line Items]
Basic	$ 0.72	$ 0.26	$ 1.95	$ 1.60
Diluted	$ 0.71	$ 0.26	$ 1.94	$ 1.58
Common Class B
Earnings Per Share [Line Items]
Preferential dividends	$ 0	$ 0	$ 808	$ 828
Preferential dividends on dilutive stock options	0	0	4	(10)
Numerator for basic and diluted earnings per Class B Voting Common Share	$ 37,291	$ 13,633	$ 100,820	$ 83,846
Basic	$ 0.72	$ 0.26	$ 1.94	$ 1.58
Diluted	$ 0.71	$ 0.26	$ 1.93	$ 1.57