Quarterly Results of Operations - Additional information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended					12 Months Ended			3 Months Ended			12 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2012	Jul. 31, 2011	Oct. 31, 2010	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2013 Ultrasonix Acquisition	Apr. 30, 2013 Ultrasonix Acquisition	Jan. 31, 2013 Ultrasonix Acquisition	Jul. 31, 2013 Ultrasonix Acquisition	Jul. 25, 2011 China-based affiliate	Jan. 31, 2012 China-based affiliate	Jul. 31, 2012 China-based affiliate	Jul. 31, 2012 Income Tax Refund
Quarterly Financial Information [Line Items]
Income tax refund received			$ 12,007
Income tax expense benefit						12,976	1,128	4,312								(10,025)
Professional fees related to refund of Tax							2,714
Gain on sale of other investments							2,500							2,500	2,500
Percentage of interest in affiliate sold													25.00%	25.00%
Restructuring charge	3,023	496		3,587	3,562	3,519		7,066				3,519
Acquisition related cost									$ 3,057	$ 1,880	$ 663