Schedule of Stock Option Activity (Detail) - $ / shares	12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Stockholders' Equity
Outstanding at beginning of year, Shares	5,000	106,313	732,725
Exercised, Shares	(5,000)	(101,313)	(498,412)
Forfeited, Shares			(120,000)
Expired, Shares			(8,000)
Granted, Shares	0	0	0
Outstanding at end of year, Shares		5,000	106,313
Vested and expected to vest at end of year, Shares		5,000	106,313
Exercisable at year-end, Shares		5,000	106,313
Outstanding at beginning of year, Weighted-Average Exercise Price	$ 28.23	$ 31.48	$ 28.89
Exercised, Weighted-Average Exercise Price	28.23	31.64	28.62
Forfeited, Weighted-Average Exercise Price			27.84
Expired, Weighted-Average Exercise Price			26.91
Granted, Weighted-Average Exercise Price	$ 0	0	0
Outstanding at end of year, Weighted-Average Exercise Price		28.23	31.48
Vested and expected to vest at end of year, Weighted-Average Exercise Price		28.23	31.48
Exercisable at year-end, Weighted-Average Exercise Price		$ 28.23	$ 31.48