Customer and Geographic Information (Details) (USD $)	3 Months Ended		6 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 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	27.50%	31.20%	26.20%	28.40%
Commercial (United States)
Revenues from External Customers
Percentage of revenue generated from external customer type	11.70%	11.30%	12.80%	14.30%
Total United States
Revenues from External Customers
Percentage of revenue generated from external customer type	39.20%	42.50%	39.00%	42.70%
North African country
Revenues from External Customers
Percentage of revenue generated from external customer type	15.00%	13.70%	14.80%	13.10%
Other international
Revenues from External Customers
Percentage of revenue generated from external customer type	45.80%	43.80%	46.20%	44.20%
Total International
Revenues from External Customers
Percentage of revenue generated from external customer type	60.80%	57.50%	61.00%	57.30%
Revenue generated from external customers	49,768,000	49,144,000	96,524,000	96,684,000
U.S. Prime Contractor | Major customer | Sales Revenue, Net [Member]
Revenues from External Customers
Percentage of revenue generated from external customer type	14.40%	13.50%	14.40%	13.00%