Share-Based Compensation (Schedule Of Share-Based Compensation Expense Related To Stock Options And Restricted Stock Awards) (Details) (USD $)	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 1,077,000	$ 1,194,000
Employees And Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	1,082,000	1,159,000
Employees And Directors [Member] | Selling, General And Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	825,000	1,032,000
Employees And Directors [Member] | Research And Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	257,000	127,000
Consultants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	(5,000)	35,000
Consultants [Member] | Selling, General And Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	(5,000)	41,000
Consultants [Member] | Research And Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation expense	$ 0	$ (6,000)