Share-based Compensation Expenses (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 2.9	$ 2.0	$ 8.7	$ 8.0
Income tax effect	(0.9)	(0.5)	(2.7)	(2.5)
Share-based compensation expense included in net income	2.0	1.5	6.0	5.5
Cost of product sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	0.1	0.2	0.5	0.6
Cost of Engineering Sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	0.1	0.2	0.3	0.9
Research and Product Development
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	0.5	0.3	2.0	1.5
Selling and Marketing
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	0.3	0.2	0.9	0.7
General and Administrative
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based compensation expense before tax	$ 1.9	$ 1.1	$ 5.0	$ 4.3