Restructuring and Related Charges by Segment (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2016	Apr. 30, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	$ 1.8	$ (0.1)	$ 8.3	$ (0.3)
Medical Imaging
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	1.1	$ (0.1)	5.1	(0.2)
Ultrasound
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	0.4		1.7	$ (0.1)
Security and Detection
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	$ 0.3		$ 1.5