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, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013
Earnings Per Share [Line Items]
Earnings from continuing operations	$ 20,184	$ 21,680	$ 48,835	$ 37,300
Denominator for basic earnings (loss) from continuing operations per share for both Class A and Class B	51,933	51,415	52,071	51,210
Plus: Effect of dilutive stock options	67	626	233	475
Denominator for diluted net income per share for both Class A and Class B	52,000	52,041	52,304	51,685
Earnings from continuing operations per basic share	$ 0.39	$ 0.42	$ 0.94	$ 0.72
Earnings from continuing operations per diluted share	$ 0.39	$ 0.42	$ 0.93	$ 0.72
Class A nonvoting common stock
Earnings Per Share [Line Items]
Earnings from continuing operations	20,168	21,620	48,759	37,121
Earnings from continuing operations per basic share	$ 0.39	$ 0.42	$ 0.94	$ 0.72
Earnings from continuing operations per diluted share	$ 0.39	$ 0.42	$ 0.93	$ 0.72
Earnings (loss) from discontinued operations per basic share	$ 0.07	$ (0.34)	$ 0.30	$ (0.28)
Earnings (loss) from discontinued operations per diluted share	$ 0.07	$ (0.34)	$ 0.30	$ (0.28)
Net earnings per share, basic	$ 0.46	$ 0.08	$ 1.24	$ 0.44
Net earnings per share, diluted	$ 0.46	$ 0.08	$ 1.23	$ 0.44
Class B voting common stock
Earnings Per Share [Line Items]
Earnings from continuing operations	20,168	21,620	47,940	36,319
Earnings from continuing operations per basic share	$ 0.39	$ 0.42	$ 0.92	$ 0.71
Earnings from continuing operations per diluted share	$ 0.39	$ 0.42	$ 0.92	$ 0.70
Earnings (loss) from discontinued operations per basic share	$ 0.07	$ (0.34)	$ 0.30	$ (0.29)
Earnings (loss) from discontinued operations per diluted share	$ 0.07	$ (0.34)	$ 0.29	$ (0.28)
Net earnings per share, basic	$ 0.46	$ 0.08	$ 1.22	$ 0.42
Net earnings per share, diluted	$ 0.46	$ 0.08	$ 1.21	$ 0.42
Restricted Stock Dividends [Member]
Earnings Per Share [Line Items]
Payments of Ordinary Dividends, Common Stock	16	60	76	179
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	$ 5