Customer and Geographic Information (Details) (USD $)	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
International sales including sales to domestic companies for inclusion in products sold to international customers	$ 184,848,000	$ 178,469,000	$ 188,145,000
Minimum percentage of consolidated net sales sold to one customer or individual country requiring additional and separate disclosure	10.00%	10.00%	10.00%
United States Sales [Member]
Percentage of revenue generated from external customer type	61.70%	71.10%	56.40%
International Sales [Member]
Percentage of revenue generated from external customer type	30.20%	22.90%	32.10%
Commercial [Member]
Percentage of revenue generated from external customer type	8.10%	6.00%	11.50%
Total United States [Member]
Percentage of revenue generated from external customer type	69.80%	77.10%	67.90%