Reportable Segments Information (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Jul. 31, 2011	Oct. 31, 2010	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Segment Reporting Information [Line Items]
Restructuring charges	$ 3,587	$ 3,562		$ 7,066	$ 690
Consulting fees			2,714
Depreciation and amortization			17,775	17,798	16,814
Share-based compensation expense			13,396	9,638	5,791
Gain on sale of other investments			2,500
Net interest income			532	711	633
Goodwill	1,849		1,849	1,849
Intangible assets, net	37,403		34,340	37,403
Corporate assets
Segment Reporting Information [Line Items]
Cash equivalents and marketable securities	135,069		153,122	135,069	134,219
Medical Imaging
Segment Reporting Information [Line Items]
Restructuring charges				2,829	527
Consulting fees			2,198
Depreciation and amortization			11,484	11,315	10,261
Share-based compensation expense			7,836	6,162	4,090
Goodwill	1,849		1,849	1,849
Intangible assets, net	35,503		32,447	35,503
Ultrasound
Segment Reporting Information [Line Items]
Restructuring charges				3,668
Depreciation and amortization			5,099	5,303	4,644
Share-based compensation expense			3,575	2,078	560
Security Technology
Segment Reporting Information [Line Items]
Restructuring charges				569	163
Consulting fees			516
Depreciation and amortization			1,192	1,180	1,909
Share-based compensation expense			$ 1,985	$ 1,398	$ 1,141