Share-based Compensation Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense before tax	$ 10.9	$ 11.5	$ 11.6
Income tax effect	(3.2)	(3.5)	(3.6)
Share-based compensation expense included in net income	7.7	8.0	8.0
Cost of product sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense before tax	0.7	0.7	0.8
Cost of Engineering Sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense before tax	0.2	0.4	1.2
Research and Product Development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense before tax	2.7	2.8	2.4
Selling and Marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense before tax	1.4	1.2	1.1
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense before tax	$ 5.9	$ 6.4	$ 6.1