Commitments and Contingencies (Details) (USD $)	12 Months Ended			24 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2013
Future Minimum Lease Payments, Net Of Subleases, Under Operating Leases
2014	$ 5,807,000			$ 5,807,000
2015	4,497,000			4,497,000
2016	4,875,000			4,875,000
2017	3,889,000			3,889,000
2018	3,499,000			3,499,000
Thereafter	3,418,000			3,418,000
Total	25,985,000			25,985,000
Lease Expense
Lease expense charged to operations	5,983,000	7,060,000	6,891,000
Defense Contract Audit Agency (DCAA) Adit
Funded orders received under August 2007 BFT-1 contract	376,246,000			376,246,000
Recommended DCAA Price Adjustment	11,819,000			11,819,000
Employment change of control and indemnification agreement
Legal costs incurred by the Company in response to subpoenas	500,000	1,000,000		1,500,000
Chief Executive Officer [Member]
Related Party Transactions
Related party lease payments made	587,000
New lease expiration date	Dec. 31, 2021
Additional term of related party lease agreement as an option to exercise (in years)	10 years
Rent amount in next calendar year for related party lease agreement	609,000
Mobile Data Communications Segment [Member] | Cost of Sales [Member]
Cost of Revenue [Abstract]
Satellite lease expenditures incurred	$ 2,472,000	$ 40,827,000	$ 46,356,000