Reportable Segment Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2014		Oct. 31, 2013	Jul. 31, 2014
Product Revenue:
Product Revenue	$ 116,935		$ 108,454
Engineering Revenue:
Engineering Revenue	1,381		1,628
Net Revenue:
Total net revenue	118,316		110,082
Income (loss) before income taxes:
Income (loss) from operations	4,957		(5,365)
Total other (expense) income, net	118		(421)
Income (loss) before income taxes	5,075		(5,786)
Identifiable assets by segment:
Assets	603,316			614,342
Goodwill by segment:
Goodwill	57,589			56,955
Reportable segments
Identifiable assets by segment:
Assets	481,900			489,000
Corporate
Identifiable assets by segment:
Assets	121,400	[1]		125,300	[1]
Medical Imaging
Product Revenue:
Product Revenue	66,300		59,200
Engineering Revenue:
Engineering Revenue	400		1,000
Net Revenue:
Total net revenue	66,700		60,200
Income (loss) before income taxes:
Income (loss) from operations	7,400		(500)
Medical Imaging | Reportable segments
Identifiable assets by segment:
Assets	207,200			218,500
Goodwill by segment:
Goodwill	1,900			1,900
Ultrasound
Product Revenue:
Product Revenue	37,300		34,700
Engineering Revenue:
Engineering Revenue	500
Net Revenue:
Total net revenue	37,800		34,700
Income (loss) before income taxes:
Income (loss) from operations	(3,000)		(4,000)
Ultrasound | Reportable segments
Identifiable assets by segment:
Assets	240,300			235,500
Goodwill by segment:
Goodwill	55,100			55,100
Security and Detection
Product Revenue:
Product Revenue	13,300		14,600
Engineering Revenue:
Engineering Revenue	500		600
Net Revenue:
Total net revenue	13,800		15,200
Income (loss) before income taxes:
Income (loss) from operations	600		(900)
Goodwill by segment:
Goodwill	600	[2]
Security and Detection | Reportable segments
Identifiable assets by segment:
Assets	$ 34,400			$ 35,000

[1] Includes cash and cash equivalents of $57.1 million and $60.9 million as of October 31, 2014 and July 31, 2014, respectively.

[2] Includes goodwill related to the acquisition of Pathfinder.