Customer and Geographic Information (Details) (USD $)	3 Months Ended		9 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2015	Apr. 30, 2014
Major customer
Revenues from External Customers
Minimum percentage of consolidated net sales sold to one customer or individual country requiring additional and separate disclosure	10.00%	10.00%	10.00%	10.00%
U.S. government
Revenues from External Customers
Percentage of revenue generated from external customer type	37.50%	27.40%	29.70%	28.10%
Commercial (United States)
Revenues from External Customers
Percentage of revenue generated from external customer type	11.90%	10.30%	12.50%	12.90%
Total United States
Revenues from External Customers
Percentage of revenue generated from external customer type	49.40%	37.70%	42.20%	41.00%
North African country
Revenues from External Customers
Percentage of revenue generated from external customer type	17.30%	22.40%	15.60%	16.30%
Other international
Revenues from External Customers
Percentage of revenue generated from external customer type	33.30%	39.90%	42.20%	42.70%
Total International
Revenues from External Customers
Percentage of revenue generated from external customer type	50.60%	62.30%	57.80%	59.00%
Revenue generated from external customers	36,243,000	55,370,000	132,767,000	152,054,000
U.S. Prime Contractor | Major customer | Sales Revenue, Net
Revenues from External Customers
Percentage of revenue generated from external customer type	17.00%	22.50%	15.20%	16.30%