Share-based Compensation Expenses for Continuing Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 3,310	$ 3,150	$ 5,954	$ 5,401
Cost of Sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	242	187	406	319
Cost of Engineering Sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	295		695
Research and Development Expense
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	860	905	1,168	1,524
Selling and Marketing Expense
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	192	421	532	674
General and Administrative Expense
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 1,721	$ 1,637	$ 3,153	$ 2,884