Valuation and Qualifying Accounts and Reserves (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Inventory Reserves [Member]
Balance at Beginning of Period	$ 1,760	$ 1,864	$ 1,552
Charged to Costs and Expenses	2,279	2,203	1,914
Deductions	(1,903)	(2,307)	(1,602)
Balance at End of Period	2,136	1,760	1,864
Valuation Allowance On Income Taxes [Member]
Balance at Beginning of Period	3,062	1,588	1,588
Charged to Costs and Expenses	0	1,474	0
Deductions		0	0
Balance at End of Period	3,017	3,062	1,588
Trade Receivable Allowances [Member]
Balance at Beginning of Period	478	4,553	3,423
Charged to Costs and Expenses	914	773	2,456
Deductions	(711)	(4,848)	(1,326)
Balance at End of Period	$ 681	$ 478	$ 4,553