Share-based Compensation Expenses (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 2.7	$ 2.6
Income tax effect	(0.9)	(0.8)
Share-based compensation expense included in net (loss) income	1.8	1.8
Cost of product sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	0.2	0.2
Cost of Engineering Sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	0.1	0.4
Research and Product Development
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	0.6	0.3
Selling and Marketing
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	0.3	0.3
General and Administrative
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 1.5	$ 1.4