Share-based Compensation Expenses (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 2,004	$ 2,315	$ 7,957	$ 7,716
Cost of Sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	127	142	533	461
Cost of Engineering Sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	223		918
Research and Development Expense
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	340	633	1,508	2,157
Selling and Marketing Expense
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	181	238	713	912
General and Administrative Expense
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 1,133	$ 1,302	$ 4,285	$ 4,186