Reportable Segment Information (Detail) (USD $)	3 Months Ended			6 Months Ended
	Jan. 31, 2014		Jan. 31, 2013	Jan. 31, 2014		Jan. 31, 2013	Jul. 31, 2013
Product revenue:
Product revenue	$ 139,471,000		$ 132,763,000	$ 247,925,000		$ 245,310,000
Engineering revenue:
Engineering revenue	1,966,000		5,791,000	3,594,000		13,111,000
Net revenue:
Total net revenue	141,437,000		138,554,000	251,519,000		258,421,000
Income from operations:
Income (loss) from continuing operations	13,084,000		13,803,000	7,719,000		21,238,000
Total other expense, net	(400,000)		(400,000)	(800,000)		(1,300,000)
Income before income taxes	12,727,000		13,401,000	6,941,000		19,930,000
Identifiable assets
Assets	586,920,000			586,920,000			587,784,000
Goodwill by segment:
Goodwill	56,977,000			56,977,000			50,073,000
Reportable segment assets
Identifiable assets
Assets	450,600,000			450,600,000			488,900,000
Corporate assets
Identifiable assets
Assets	136,300,000	[1]		136,300,000	[1]		98,900,000	[1]
Goodwill by segment:
Goodwill	6,900,000	[2]		6,900,000	[2]
Medical Imaging
Product revenue:
Product revenue	78,400,000		77,500,000	137,600,000		149,700,000
Engineering revenue:
Engineering revenue	1,200,000		3,200,000	2,200,000		7,000,000
Net revenue:
Total net revenue	79,600,000		80,700,000	139,800,000		156,700,000
Income from operations:
Income (loss) from continuing operations	10,900,000		8,500,000	10,400,000		15,900,000
Medical Imaging | Reportable segment assets
Identifiable assets
Assets	199,900,000			199,900,000			217,100,000
Goodwill by segment:
Goodwill	1,900,000			1,900,000			1,900,000
Ultrasound
Product revenue:
Product revenue	40,100,000		40,500,000	74,800,000		72,100,000
Net revenue:
Total net revenue	40,100,000		40,500,000	74,800,000		72,100,000
Income from operations:
Income (loss) from continuing operations	(800,000)		3,500,000	(4,800,000)		2,700,000
Ultrasound | Reportable segment assets
Identifiable assets
Assets	209,600,000			209,600,000			218,400,000
Goodwill by segment:
Goodwill	48,200,000			48,200,000			48,200,000
Security Technology
Product revenue:
Product revenue	20,900,000		14,800,000	35,500,000		23,500,000
Engineering revenue:
Engineering revenue	800,000		2,600,000	1,400,000		6,100,000
Net revenue:
Total net revenue	21,700,000		17,400,000	36,900,000		29,600,000
Income from operations:
Income (loss) from continuing operations	3,000,000		1,800,000	2,100,000		2,600,000
Security Technology | Reportable segment assets
Identifiable assets
Assets	$ 41,100,000			$ 41,100,000			$ 53,400,000

[1] Includes cash and cash equivalents of $73.8 million and $57.4 million as of January 31, 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.