Computation of Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		12 Months Ended
		Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income		$ 33,481	$ 34,480	$ 31,121
Weighted-average number of common shares outstanding-basic		12,407	12,404	12,247
Effect of dilutive securities:
Stock options and restricted stock units		199	263	322
Weighted-average number of common shares outstanding-diluted		12,606	12,667	12,569
Basic net income per share		$ 2.70	$ 2.78	$ 2.54
Diluted net income per share		$ 2.66	$ 2.72	$ 2.48
Anti-dilutive shares related to outstanding stock options and unvested restricted stock	[1]	176	118	105

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