Reportable Segments Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended										12 Months Ended
	Jul. 31, 2012		Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011		Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2012		Jul. 31, 2011		Jul. 31, 2010
Net revenue:
Revenues	$ 151,011		$ 121,270	$ 126,433	$ 117,857	$ 135,349		$ 117,171	$ 117,253	$ 103,822	$ 516,571		$ 473,595		$ 414,813
Income (loss) from operations
Income (loss) from operations											39,963		20,736		21,320
Total other income, net											4,236	[1]	196	[1]	147	[1]
Income from continuing operations before income taxes											44,199		20,932		21,467
Identifiable assets:
Assets	557,996					521,552					557,996		521,552		485,776
Medical Imaging
Net revenue:
Revenues											301,766		293,032		251,498
Income (loss) from operations
Income (loss) from operations											18,854	[2]	12,680	[2]	9,234	[2]
Ultrasound
Net revenue:
Revenues											151,201		129,437		112,729
Income (loss) from operations
Income (loss) from operations											10,786	[3]	1,081	[3]	5,648	[3]
Security Technology
Net revenue:
Revenues											63,604		51,126		50,586
Income (loss) from operations
Income (loss) from operations											10,323	[4]	6,975	[4]	6,438	[4]
Reportable segment assets
Identifiable assets:
Assets	362,669					343,671					362,669		343,671		292,873
Reportable segment assets | Medical Imaging
Identifiable assets:
Assets	199,512	[5]				192,625	[5]				199,512	[5]	192,625	[5]	171,987	[5]
Reportable segment assets | Ultrasound
Identifiable assets:
Assets	136,388					127,402					136,388		127,402		103,380
Reportable segment assets | Security Technology
Identifiable assets:
Assets	26,769					23,644					26,769		23,644		17,506
Corporate assets
Identifiable assets:
Assets	$ 195,327	[6]				$ 177,881	[6]				$ 195,327	[6]	$ 177,881	[6]	$ 192,903	[6]

[1] Includes a gain of $2,500 from the sale of the Company's remaining interest in its China based affiliate received in fiscal year 2012. Includes net interest income of $532, $711, and $633 in fiscal years 2012, 2011, and 2010, respectively.

[2] Includes $2,198 of contingent consulting fees related to the tax refund and related interest received in fiscal year 2012. Includes restructuring charges of $2,829 for fiscal year 2011. Includes restructuring charges of $527 for fiscal year 2010. Includes depreciation and amortization of $11,484, $11,315, and $10,261 in fiscal years 2012, 2011, and 2010, respectively. Includes share-based compensation expense of $7,836, $6,162, and $4,090 in fiscal years 2012, 2011, and 2010, respectively.

[3] Includes restructuring charges of $3,668 for fiscal year 2011. Includes depreciation and amortization of $5,099, $5,303, and $4,644 in fiscal years 2012, 2011, and 2010, respectively. Includes share-based compensation expense of $3,575, $2,078, and $560 in fiscal years 2012, 2011, and 2010, respectively.

[4] Includes $516 of contingent consulting fees related to the tax refund and related interest received in fiscal year 2012. Includes restructuring of $569 for fiscal year 2011. Includes restructuring of $163 for fiscal year 2010. Includes depreciation and amortization of $1,192, $1,180, and $1,909 in fiscal years 2012, 2011, and 2010, respectively. Includes share-based compensation expense of $1,985, $1,398, and $1,141 in fiscal years 2012, 2011, and 2010, respectively.

[5] Includes goodwill and net intangible assets from acquisitions of $1,849 and $32,447, respectively, at July 31, 2012, and $1,849 and $35,503, respectively, at July 31, 2011.

[6] Includes cash equivalents and marketable securities of $153,122, $135,069, and $134,219, as of July 31, 2012, 2011, and 2010, respectively.