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, 2015	Oct. 31, 2014
Earnings Per Share [Line Items]
Earnings from continuing operations	$ 18,703	$ 15,499
Denominator for basic earnings from continuing operations per share for both Class A and Class B	51,029	51,251
Plus: Effect of dilutive stock options	60	62
Denominator for diluted earnings from continuing operations per share for both Class A and Class B	51,089	51,313
Class A Nonvoting Common Stock
Earnings Per Share [Line Items]
Earnings from continuing operations per basic share	$ 0.37	$ 0.30
Earnings from continuing operations per diluted share	0.37	0.30
Loss from discontinued operations per basic share	0.00	(0.03)
Loss from discontinued operations per diluted share	0.00	(0.04)
Net earnings per share, basic	0.37	0.27
Net earnings per share, diluted	$ 0.37	$ 0.26
Class B Voting Common Stock
Earnings Per Share [Line Items]
Preferential dividends	$ (783)	$ (794)
Preferential dividends on dilutive stock options	(1)	(1)
Earnings from continuing operations	$ 17,919	$ 14,704
Earnings from continuing operations per basic share	$ 0.35	$ 0.29
Earnings from continuing operations per diluted share	0.35	0.29
Loss from discontinued operations per basic share	0.00	(0.04)
Loss from discontinued operations per diluted share	0.00	(0.04)
Net earnings per share, basic	0.35	0.25
Net earnings per share, diluted	$ 0.35	$ 0.25