Schedule of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Stockholders' Equity
Outstanding at beginning of year, Shares	106,313	732,725	1,433,225
Exercised, Shares	(101,313)	(498,412)	(80,500)
Forfeited, Shares		(120,000)	(600,000)
Expired, Shares		(8,000)	(20,000)
Granted, Shares	0	0	0
Outstanding at end of year, Shares	5,000	106,313	732,725
Vested and expected to vest at end of year, Shares	5,000	106,313	712,725
Exercisable at year-end, Shares	5,000	106,313	566,059
Outstanding at beginning of year, Weighted-Average Exercise Price	$ 31.48	$ 28.89	$ 30.90
Exercised, Weighted-Average Exercise Price	$ 31.64	$ 28.62	$ 17.74
Forfeited, Weighted-Average Exercise Price		$ 27.84	$ 35.18
Expired, Weighted-Average Exercise Price		$ 26.91	$ 29.25
Granted, Weighted-Average Exercise Price	$ 0	$ 0	$ 0
Outstanding at end of year, Weighted-Average Exercise Price	$ 28.23	$ 31.48	$ 28.89
Vested and expected to vest at end of year, Weighted-Average Exercise Price	$ 28.23	$ 31.48	$ 28.82
Exercisable at year-end, Weighted-Average Exercise Price	$ 28.23	$ 31.48	$ 29.24