Computation of Basic and Diluted net Income per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Oct. 31, 2012		Oct. 31, 2011
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income	$ 4,381		$ 4,026
Weighted average number of common shares outstanding-basic	12,323		12,437
Effect of dilutive securities:
Stock options and restricted stock awards	259		111
Weighted average number of common shares outstanding-diluted	12,582		12,548
Basic net income per share	$ 0.36		$ 0.32
Diluted net income per share	$ 0.35		$ 0.32
Anti-dilutive shares related to outstanding stock options and unvested restricted stock awards	29	[1]	274	[1]

[1] Certain outstanding stock options were not included in the computation of diluted income per share because the options' exercise prices were greater than the average market price of the Common Stock and, therefore, the effect would be anti-dilutive. Certain restricted stock units and awards were also excluded from the computation as their effect would be anti-dilutive.