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, 2016	Apr. 30, 2015	Apr. 30, 2016	Apr. 30, 2015
Earnings Per Share [Line Items]
Earnings from continuing operations	$ 20,981	$ 17,213	$ 54,974	$ 44,296
Denominator for basic earnings (loss) from continuing operations per share for both Class A and Class B	50,251	51,301	50,602	51,275
Plus: Effect of dilutive stock options	254	149	145	95
Denominator for diluted net income per share for both Class A and Class B	50,505	51,450	50,747	51,370
Class A nonvoting common stock
Earnings Per Share [Line Items]
Earnings from continuing operations per basic share	$ 0.42	$ 0.34	$ 1.09	$ 0.86
Earnings from continuing operations per diluted share	0.42	0.33	1.08	0.86
Earnings (loss) from discontinued operations per basic share	0.00	0.00	0.00	(0.03)
Earnings (loss) from discontinued operations per diluted share	0.00	0.00	0.00	(0.03)
Net earnings per share, basic	0.42	0.34	1.09	0.83
Net earnings per share, diluted	$ 0.42	$ 0.33	$ 1.08	$ 0.83
Class B voting common stock
Earnings Per Share [Line Items]
Earnings from continuing operations	$ 20,981	$ 17,213	$ 54,190	$ 43,501
Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities	0	0	1	1
Payments of Ordinary Dividends	$ 0	$ 0	$ 783	$ 794
Earnings from continuing operations per basic share	$ 0.42	$ 0.34	$ 1.07	$ 0.85
Earnings from continuing operations per diluted share	0.42	0.33	1.07	0.85
Earnings (loss) from discontinued operations per basic share	0.00	0.00	0.00	(0.04)
Earnings (loss) from discontinued operations per diluted share	0.00	0.00	0.00	(0.04)
Net earnings per share, basic	0.42	0.34	1.07	0.81
Net earnings per share, diluted	$ 0.42	$ 0.33	$ 1.07	$ 0.81