Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2016	Apr. 30, 2015
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income		$ 4,970	$ 9,124	$ 3,361	$ 22,608
Weighted-average number of common shares outstanding-basic		12,392	12,419	12,412	12,401
Effect of dilutive securities:
Stock options and restricted stock units		161	184	211	200
Weighted-average number of common shares outstanding-diluted		12,553	12,603	12,623	12,601
Basic net income per share		$ 0.40	$ 0.73	$ 0.27	$ 1.82
Diluted net income per share		$ 0.40	$ 0.72	$ 0.27	$ 1.79
Anti-dilutive shares related to outstanding stock options and unvested restricted stock	[1]	87	16	5	179

[1] These shares related to outstanding stock options and unvested restricted stock. These shares were not included in our calculations of diluted earnings per share, as the effect of including them would be anti-dilutive.