Reportable Segment Information (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016	Jul. 31, 2016	Jul. 31, 2015
Segment Reporting Information [Line Items]
Restructuring charge	$ 2,080	$ 1,839	$ 2,379	$ 8,269
Asset impairment charges	73,051		83,474
Cash and cash equivalents	158,633	128,124	158,633	128,124	$ 118,697	$ 123,800
Corporate
Segment Reporting Information [Line Items]
Cash and cash equivalents	144,900		144,900		$ 97,300
Pathfinder
Segment Reporting Information [Line Items]
Asset impairment charges	0		600
Medical Imaging
Segment Reporting Information [Line Items]
Restructuring charge	200	1,100	400	5,100
Ultrasound
Segment Reporting Information [Line Items]
Restructuring charge	1,800	400	1,900	1,700
Goodwill impairment charges	55,100		55,100
Oncura
Segment Reporting Information [Line Items]
Contingent consideration charges	(2,100)		(10,200)
Asset impairment charges	3,100		3,100
Goodwill impairment charges	6,700		16,500
PocketSonics
Segment Reporting Information [Line Items]
Asset impairment charges	8,100		8,100
BK Medical System
Segment Reporting Information [Line Items]
Impairment charges	0		10,100
Security and Detection
Segment Reporting Information [Line Items]
Restructuring charge	$ 100	$ 300	$ 100	$ 1,500