Net Income per Common Share - Reconciliation of Numerator and Denominator of Basic and Diluted Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013
Earnings Per Share [Line Items]
Business Acquisition, Pro Forma Net Income (Loss)	$ 10,517	$ (7,275)	$ 28,652	$ 19,920
Earnings (loss) from continuing operations	10,517	(10,671)	28,652	15,620
Denominator for basic earnings (loss) from continuing operations per share for both Class A and Class B	52,208	51,177	52,140	51,108
Plus: Effect of dilutive stock options	286	0	317	399
Denominator for diluted net income per share for both Class A and Class B	52,494	51,177	52,457	51,507
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ (0.14)		$ 0.39
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ (0.14)		$ 0.39
Class A nonvoting common stock [Member]
Earnings Per Share [Line Items]
Earnings (loss) from continuing operations	10,501	(10,731)	28,591	15,501
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 0.20		$ 0.55
Earnings (loss) from continuing operations per basic share	$ 0.20	$ (0.21)	$ 0.55	$ 0.30
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 0.20		$ 0.55
Earnings (loss) from continuing operations per diluted share	$ 0.20	$ (0.21)	$ 0.55	$ 0.30
Earnings from discontinued operations per basic share	$ 0.11	$ 0.04	$ 0.22	$ 0.06
Earnings from discontinued operations per diluted share	$ 0.11	$ 0.04	$ 0.22	$ 0.06
Net earnings (loss) per share, basic	$ 0.31	$ (0.17)	$ 0.77	$ 0.36
Net earnings (loss) per share, diluted	$ 0.31	$ (0.17)	$ 0.77	$ 0.36
Class B voting common stock [Member]
Earnings Per Share [Line Items]
Earnings (loss) from continuing operations	10,501	(10,731)	27,772	14,700
Earnings (loss) from continuing operations per basic share	$ 0.20	$ (0.21)	$ 0.53	$ 0.29
Earnings (loss) from continuing operations per diluted share	$ 0.20	$ (0.21)	$ 0.53	$ 0.29
Earnings from discontinued operations per basic share	$ 0.11	$ 0.04	$ 0.23	$ 0.05
Earnings from discontinued operations per diluted share	$ 0.11	$ 0.04	$ 0.22	$ 0.05
Net earnings (loss) per share, basic	$ 0.31	$ (0.17)	$ 0.76	$ 0.34
Net earnings (loss) per share, diluted	$ 0.31	$ (0.17)	$ 0.75	$ 0.34
Restricted Stock Dividends [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	(16)	(60)	(61)	(119)
Preferential Dividends on Class A Nonvoting Common Stock [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	0	0	(813)	(797)
Preferential Dividends on Dilutive Shares [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	$ 0	$ 0	$ (6)	$ (4)