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		9 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012
Earnings Per Share [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent	$ 21,838	$ 28,039	$ 37,669	$ 84,328
Denominator for basic net income per share for both Class A and Class B	51,415	52,513	51,210	52,539
Plus: Effect of dilutive stock options	626	490	475	407
Denominator for diluted net income per share for both Class A and Class B	52,041	53,003	51,685	52,946
Payments of Ordinary Dividends, Common Stock			29,344	29,235
Class A nonvoting common stock [Member]
Earnings Per Share [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent	21,778	27,982	37,490	84,156
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.42	$ 0.53	$ 0.73	$ 1.60
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.42	$ 0.53	$ 0.73	$ 1.59
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share	$ (0.34)	$ 0.00	$ (0.29)	$ (2.17)
Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share	$ (0.34)	$ (0.01)	$ (0.29)	$ (2.16)
Earnings Per Share, Basic	$ 0.08	$ 0.53	$ 0.44	$ (0.57)
Earnings Per Share, Diluted	$ 0.08	$ 0.52	$ 0.44	$ (0.57)
Class B voting common stock [Member]
Earnings Per Share [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent	21,778	27,982	36,688	83,333
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.42	$ 0.53	$ 0.72	$ 1.59
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.42	$ 0.53	$ 0.71	$ 1.57
Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share	$ (0.34)	$ 0.00	$ (0.30)	$ (2.17)
Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share	$ (0.34)	$ (0.01)	$ (0.29)	$ (2.15)
Earnings Per Share, Basic	$ 0.08	$ 0.53	$ 0.42	$ (0.58)
Earnings Per Share, Diluted	$ 0.08	$ 0.52	$ 0.42	$ (0.58)
Restricted Stock [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	60	57	179	172
Preferential Dividends on Class A Nonvoting Common Stock [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	0	0	797	818
Preferential Dividends on Dilutive Shares [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	$ 0	$ 0	$ 5	$ 5