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, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Earnings Per Share [Line Items]
Net Income (Loss) Attributable to Parent	$ 22,553	$ 20,981	$ 70,403	$ 54,974
Denominator for basic earnings (loss) from continuing operations per share for both Class A and Class B	51,227	50,251	50,972	50,602
Plus: Effect of dilutive stock options	974	254	910	145
Denominator for diluted net income per share for both Class A and Class B	52,201	50,505	51,882	50,747
Class A nonvoting common stock
Earnings Per Share [Line Items]
Net earnings per share, basic	$ 0.44	$ 0.42	$ 1.38	$ 1.09
Net earnings per share, diluted	$ 0.43	$ 0.42	$ 1.36	$ 1.08
Class B voting common stock
Earnings Per Share [Line Items]
Earnings from continuing operations	$ 22,553	$ (20,981)	$ (69,601)	$ (54,190)
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities	0	0	14	1
Payments of Ordinary Dividends	$ 0	$ 0	$ 788	$ 783
Net earnings per share, basic	$ 0.44	$ 0.42	$ 1.37	$ 1.07
Net earnings per share, diluted	$ 0.43	$ 0.42	$ 1.34	$ 1.07