Share-based Compensation Expenses for Continuing Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 11,601	$ 13,396	$ 9,638
Income tax effect	(3,586)	(4,217)	(3,055)
Share-based compensation expense included in net income	8,015	9,179	6,583
Cost of product sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	783	802	570
Cost of Engineering Sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	1,156	1,134
Research and Product Development
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	2,424	2,680	3,181
Selling and Marketing
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	1,096	1,686	1,110
General and Administrative
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 6,142	$ 7,094	$ 4,777