Reportable Segment Information (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Jul. 31, 2016	Jul. 31, 2015
Segment Reporting Information [Line Items]
Restructuring Charge	$ 32	$ 3,283
Cash and cash equivalents	141,952	130,506	$ 118,697	$ 123,800
Medical Imaging
Segment Reporting Information [Line Items]
Restructuring Charge	20	2,000
Ultrasound
Segment Reporting Information [Line Items]
Restructuring Charge	10	700
Security and Detection
Segment Reporting Information [Line Items]
Restructuring Charge	0	$ 600
Corporate
Segment Reporting Information [Line Items]
Cash and cash equivalents	$ 121,200		$ 97,300