Share-based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 31, 2014	Oct. 31, 2013
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 2.6	$ 2.7
Income tax effect	(0.8)	(0.9)
Share-based compensation expense included in net income (loss)	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
Research and Product Development
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	0.7	0.6
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	$ 1.4	$ 1.5