Customer and Geographic Information (Details) (USD $)	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Customer Concentration Risk [Member]
Revenue from External Customers [Line Items]
Minimum percentage of consolidated net sales sold to one customer or individual country requiring additional and separate disclosure	10.00%	10.00%	10.00%
U.S. government
Revenue from External Customers [Line Items]
Percentage of revenue generated from external customer type	28.00%	34.70%	48.90%
U.S. government | Excluding Mobile Data Communications Segment
Revenue from External Customers [Line Items]
Percentage of revenue generated from external customer type	23.00%	28.20%	32.40%
Commercial (United States)
Revenue from External Customers [Line Items]
Percentage of revenue generated from external customer type	12.60%	15.20%	12.40%
Total United States
Revenue from External Customers [Line Items]
Percentage of revenue generated from external customer type	40.60%	49.90%	61.30%
North African country
Revenue from External Customers [Line Items]
Percentage of revenue generated from external customer type	15.40%	5.70%	2.60%
Other international
Revenue from External Customers [Line Items]
Percentage of revenue generated from external customer type	44.00%	44.40%	36.10%
Total International
Revenue from External Customers [Line Items]
Percentage of revenue generated from external customer type	59.40%	50.10%	38.70%
Sales	$ 205,993,000	$ 160,217,000	$ 164,503,000
U.S. Prime Contractor [Member] | Customer Concentration Risk [Member] | Sales Revenue, Net [Member]
Revenue from External Customers [Line Items]
Percentage of consolidated net sales	15.40%