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, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Earnings Per Share [Line Items]
Net Income (Loss) Attributable to Parent	$ 25,297	$ 15,290	$ 47,850	$ 33,993
Denominator for basic earnings (loss) from continuing operations per share for both Class A and Class B	51,054	50,527	50,844	50,778
Plus: Effect of dilutive stock options	900	120	877	90
Denominator for diluted net income per share for both Class A and Class B	51,954	50,647	51,721	50,868
Class A nonvoting common stock
Earnings Per Share [Line Items]
Net earnings per share, basic	$ 0.50	$ 0.30	$ 0.94	$ 0.67
Net earnings per share, diluted	$ 0.49	$ 0.30	$ 0.93	$ 0.67
Class B voting common stock
Earnings Per Share [Line Items]
Earnings from continuing operations	$ 25,297	$ (15,290)	$ (47,048)	$ (33,209)
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	$ 0.50	$ 0.30	$ 0.93	$ 0.65
Net earnings per share, diluted	$ 0.49	$ 0.30	$ 0.91	$ 0.65