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, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Earnings Per Share [Line Items]
Earnings from continuing operations	$ 15,290	$ 11,584	$ 33,993	$ 27,083
Denominator for basic earnings (loss) from continuing operations per share for both Class A and Class B	50,527	51,272	50,778	51,262
Plus: Effect of dilutive stock options	120	76	90	68
Denominator for diluted net income per share for both Class A and Class B	50,647	51,348	50,868	51,330
Class A nonvoting common stock
Earnings Per Share [Line Items]
Earnings from continuing operations per basic share	$ 0.30	$ 0.23	$ 0.67	$ 0.53
Earnings from continuing operations per diluted share	0.30	0.23	0.67	0.53
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	0.30	0.23	0.67	0.49
Net earnings per share, diluted	$ 0.30	$ 0.23	$ 0.67	$ 0.49
Class B voting common stock
Earnings Per Share [Line Items]
Earnings from continuing operations	$ 15,290	$ 11,584	$ 33,209	$ 26,288
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	$ 0.30	$ 0.23	$ 0.65	$ 0.51
Earnings from continuing operations per diluted share	0.30	0.23	0.65	0.51
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	(0.04)
Net earnings per share, basic	0.30	0.23	0.65	0.48
Net earnings per share, diluted	$ 0.30	$ 0.23	$ 0.65	$ 0.47