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
	Oct. 31, 2013	Oct. 31, 2012
Earnings Per Share [Line Items]
Business Acquisition, Pro Forma Net Income (Loss)	$ 17,423	$ 26,689
Income (Loss) from Continuing Operations Attributable to Parent	17,423	25,785
Denominator for basic net income per share for both Class A and Class B	52,071	51,039
Plus: Effect of dilutive stock options	348	273
Denominator for diluted net income per share for both Class A and Class B	52,419	51,312
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 0.33	$ 0.52
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 0.33	$ 0.52
Payments of Ordinary Dividends, Common Stock	10,149	9,705
Class A nonvoting common stock [Member]
Earnings Per Share [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent	17,378	25,726
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.33	$ 0.50
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.33	$ 0.50
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share	$ 0.13	$ 0.03
Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share	$ 0.13	$ 0.03
Earnings Per Share, Basic	$ 0.46	$ 0.53
Earnings Per Share, Diluted	$ 0.46	$ 0.53
Class B voting common stock [Member]
Earnings Per Share [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent	16,559	24,925
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.32	$ 0.49
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.32	$ 0.49
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share	$ 0.12	$ 0.03
Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share	$ 0.12	$ 0.02
Earnings Per Share, Basic	$ 0.44	$ 0.52
Earnings Per Share, Diluted	$ 0.44	$ 0.51
Restricted Stock [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	45	59
Preferential Dividends on Class A Nonvoting Common Stock [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	813	797
Preferential Dividends on Dilutive Shares [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	$ 6	$ 4