Marketing Partner Agreements (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				12 Months Ended
	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2012 Codman collaborative arrangement [Member]	Jul. 31, 2011 Codman collaborative arrangement [Member]	Jul. 31, 2010 Codman collaborative arrangement [Member]	Jul. 31, 2011 Codman collaborative arrangement [Member] Bipolar generators and related disposables and accessories [Member]	Jul. 31, 2009 Codman collaborative arrangement [Member] Bipolar generators and related disposables and accessories [Member]	Jul. 31, 2009 Codman collaborative arrangement [Member] Malis Trademark [Member]	Jul. 31, 2012 Stryker collaborative arrangement [Member]	Jul. 31, 2011 Stryker collaborative arrangement [Member]	Jul. 31, 2010 Stryker collaborative arrangement [Member]	Jul. 31, 2009 Stryker collaborative arrangement [Member]	Jul. 31, 2010 Stryker collaborative arrangement [Member] Lesion Generator [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of U.S.-based national and international marketing partners						2
Numbers of years a product was sold						25 years
Collaborative arrangement time frame											3 years	3 years						3 years
Collaborative arrangements extension													3 years			1 year	5 years
Net Sales					$ 60,014	$ 55,657	$ 52,010	$ 11,150	$ 10,507	$ 6,823				$ 10,398	$ 7,710	$ 4,811
Percent of net sales (in hundredths)								18.60%	18.90%	13.10%				17.30%	13.90%	9.30%
Collaborative arrangement purchase obligation (in units)							300
Gain (loss) on sale of product line	$ 0	$ 0	$ (99)	$ 0	$ 0	$ (99)	$ 817								$ 99,000