Restructuring and Related Charges by Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	$ 2.1	$ 1.8	$ 2.4	$ 8.3
Medical Imaging
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	0.2	1.1	0.4	5.1
Ultrasound
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	1.8	0.4	1.9	1.7
Security and Detection
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	$ 0.1	$ 0.3	$ 0.1	$ 1.5