Reportable Segment Information (Detail) (USD $)	3 Months Ended			9 Months Ended
	Apr. 30, 2014		Apr. 30, 2013	Apr. 30, 2014		Apr. 30, 2013	Jul. 31, 2013
Product revenue:
Product revenue	$ 122,067,000		$ 121,188,000	$ 369,992,000		$ 366,498,000
Engineering revenue:
Engineering revenue	1,965,000		4,577,000	5,559,000		17,688,000
Net revenue:
Total net revenue	124,032,000		125,765,000	375,551,000		384,186,000
Income from operations:
Income (loss) from continuing operations	9,417,000		6,712,000	17,136,000		27,950,000
Total other income (expenses), net	900,000		200,000	100,000		(1,100,000)
Income before income taxes	10,299,000		6,902,000	17,240,000		26,832,000
Identifiable assets
Assets	602,442,000			602,442,000			587,784,000
Goodwill by segment:
Goodwill	56,955,000			56,955,000			50,073,000
Reportable segment assets
Identifiable assets
Assets	470,400,000			470,400,000			488,900,000
Corporate assets
Identifiable assets
Assets	132,000,000	[1]		132,000,000	[1]		98,900,000	[1]
Goodwill by segment:
Goodwill	6,900,000	[2]		6,900,000	[2]
Medical Imaging
Product revenue:
Product revenue	70,700,000		68,800,000	208,300,000		218,500,000
Engineering revenue:
Engineering revenue	1,000,000		2,900,000	3,200,000		9,900,000
Net revenue:
Total net revenue	71,700,000		71,700,000	211,500,000		228,400,000
Income from operations:
Income (loss) from continuing operations	8,900,000		6,500,000	19,300,000		22,400,000
Medical Imaging | Reportable segment assets
Identifiable assets
Assets	215,800,000			215,800,000			217,100,000
Goodwill by segment:
Goodwill	1,900,000			1,900,000			1,900,000
Ultrasound
Product revenue:
Product revenue	37,300,000		33,900,000	112,100,000		106,000,000
Engineering revenue:
Engineering revenue			100,000			100,000
Net revenue:
Total net revenue	37,300,000		34,000,000	112,100,000		106,100,000
Income from operations:
Income (loss) from continuing operations	(1,300,000)		(4,400,000)	(6,100,000)		(1,700,000)
Ultrasound | Reportable segment assets
Identifiable assets
Assets	221,700,000			221,700,000			218,400,000
Goodwill by segment:
Goodwill	48,200,000			48,200,000			48,200,000
Security Technology
Product revenue:
Product revenue	14,100,000		18,500,000	49,600,000		42,000,000
Engineering revenue:
Engineering revenue	1,000,000		1,600,000	2,400,000		7,700,000
Net revenue:
Total net revenue	15,100,000		20,100,000	52,000,000		49,700,000
Income from operations:
Income (loss) from continuing operations	1,800,000		4,600,000	3,900,000		7,200,000
Security Technology | Reportable segment assets
Identifiable assets
Assets	$ 32,900,000			$ 32,900,000			$ 53,400,000

[1] Includes cash and cash equivalents of $73.5 million and $57.4 million as of April 30, 2014 and July 31, 2013, respectively.

[2] Includes goodwill related to the acquisition of PocketSonics. Please see Note 7. Goodwill and Other Intangible Assets for further discussion on PocketSonics.