Changes in the Carrying of Goodwill by Reportable Segments (Detail) - USD ($)		3 Months Ended	9 Months Ended
	Dec. 31, 2016	Apr. 30, 2017	Apr. 30, 2017
Goodwill
Goodwill, beginning balance			$ 73,915,000
Impairment losses			(71,600,000)
Goodwill		$ 73,900,000	73,900,000
Accumulated impairment losses		(71,600,000)	(71,600,000)
Goodwill, Ending Balance		2,344,000	2,344,000
Medical Imaging
Goodwill
Goodwill, beginning balance			1,800,000
Impairment losses	$ 0
Goodwill		1,800,000	1,800,000
Goodwill, Ending Balance		1,800,000	1,800,000
Ultrasound
Goodwill
Goodwill, beginning balance			71,600,000
Impairment losses	0	(55,100,000)	(71,600,000)
Goodwill		71,600,000	71,600,000
Accumulated impairment losses		(71,600,000)	(71,600,000)
Goodwill, Ending Balance	55,100,000	0	0
Security and Detection
Goodwill
Goodwill, beginning balance			500,000
Impairment losses	$ 0
Goodwill		500,000	500,000
Goodwill, Ending Balance		$ 500,000	$ 500,000