Restructuring and Related Charges by Segment (Detail) - USD ($) $ in Millions	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	$ 9.6	$ (0.4)	$ 3.5
Medical Imaging
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	6.0	(0.2)	1.7
Ultrasound
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	1.9	(0.1)	1.4
Security and Detection
Restructuring Cost and Reserve [Line Items]
Restructuring and related charges	$ 1.7	$ (0.1)	$ 0.4