Share-Based Compensation - Share-Based Compensation Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Net compensation expense	$ 3,789	$ 2,751	$ 3,290
Cost Of Revenues Product [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Net compensation expense	164	185	237
Cost Of Services Revenue [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Net compensation expense	454	281	272
Research And Development Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Net compensation expense	1,519	848	1,092
Selling And Marketing Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Net compensation expense	749	719	924
General And Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Net compensation expense	$ 903	$ 718	$ 765