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																12 Months Ended
	Jul. 31, 2016		Apr. 30, 2016		Jan. 31, 2016		Oct. 31, 2015		Jul. 31, 2015		Apr. 30, 2015		Jan. 31, 2015		Oct. 31, 2014		Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Earnings Per Share [Line Items]
Earnings (loss) from continuing operations	$ 25,136		$ 20,981		$ 15,290		$ 18,703		$ (39,394)		$ 17,213		$ 11,584		$ 15,499		$ 80,110	$ 4,902	$ (48,146)
Cash dividends on Common Stock																	$ 40,808	$ 40,976	$ 40,487
Denominator for basic earnings per share for both Class A and Class B																	50,541	51,285	51,866
Plus: Effect of dilutive stock options																	228	98	0
Denominator for diluted earnings per share for both Class A and Class B																	50,769	51,383	51,866
Class A Nonvoting Common Stock [Member]
Earnings Per Share [Line Items]
Earnings (loss) from continuing operations																	$ 80,110	$ 4,902	$ (48,238)
Earnings (loss) from continuing operations, per basic share	$ 0.50	[1]	$ 0.42	[1]	$ 0.30	[1]	$ 0.37	[1]	$ (0.77)	[1]	$ 0.34	[1]	$ 0.23	[1]	$ 0.30	[1]	$ 1.59	$ 0.10	$ (0.93)
Earnings (loss) from continuing operations, per diluted share	$ 0.49	[1]	$ 0.42	[1]	$ 0.30	[1]	$ 0.37	[1]	(0.77)	[1]	0.33	[1]	0.23	[1]	0.30	[1]	1.58	0.10	(0.93)
(Loss) earnings from discontinued operations, per basic share									0.00	[1]	0.00	[1]	0.00	[1]	(0.03)	[1]	0.00	(0.04)	0.04
(Loss) earnings from discontinued operations, per diluted share									$ 0.00	[1]	$ 0.00	[1]	$ 0.00	[1]	$ (0.04)	[1]	0.00	(0.04)	0.04
Net earnings (loss) per share, basic																	1.59	0.06	(0.89)
Net earnings (loss) per share, diluted																	$ 1.58	$ 0.06	$ (0.89)
Class B Voting Common Stock [Member]
Earnings Per Share [Line Items]
Earnings (loss) from continuing operations																	$ 79,326	$ 4,107	$ (49,057)
Earnings (loss) from continuing operations, per basic share																	$ 1.57	$ 0.08	$ (0.95)
Earnings (loss) from continuing operations, per diluted share																	1.56	0.08	(0.95)
(Loss) earnings from discontinued operations, per basic share																	0.00	(0.04)	0.05
(Loss) earnings from discontinued operations, per diluted share																	0.00	(0.04)	0.05
Net earnings (loss) per share, basic																	1.57	0.04	(0.90)
Net earnings (loss) per share, diluted																	$ 1.56	$ 0.04	$ (0.90)
Restricted Stock [Member]
Earnings Per Share [Line Items]
Cash dividends on Common Stock																	$ 0	$ 0	$ 92
Preferential Dividends on Class A Nonvoting Common Stock [Member]
Earnings Per Share [Line Items]
Cash dividends on Common Stock																	783	794	813
Preferential Dividends on Dilutive Shares [Member]
Earnings Per Share [Line Items]
Cash dividends on Common Stock																	$ 1	$ 1	$ 6

[1] *** The sum of the quarters does not equal the year-to-date total for fiscal 2015 due to the quarterly changes inweighted-average shares outstanding.