Share-based Compensation Expenses for Continuing Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2012	Oct. 31, 2011
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 2,644	$ 2,251
Cost of Sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	164	132
Cost of Engineering Sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	400
Research and Development Expense
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	308	619
Selling and Marketing Expense
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	340	253
General and Administrative Expense
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 1,432	$ 1,247