Share-based Compensation Expense (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense before tax	$ 2.2	$ 2.9	$ 6.4	$ 7.1
Income tax effect	(0.7)	(1.0)	(2.0)	(2.2)
Share-based compensation expense included in net income	1.5	1.9	4.4	4.9
Cost of Product Sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense before tax	0.1	0.1	0.3	0.4
Cost of Engineering Sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense before tax			0.1
Research and Product Development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense before tax	0.4	0.6	1.2	1.8
Selling and Marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense before tax	0.2	0.4	1.1	1.1
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense before tax	$ 1.5	$ 1.8	$ 3.7	$ 3.8