Accounts Receivable (Details) (USD $)			3 Months Ended
	Oct. 31, 2013	Jul. 31, 2013	Oct. 31, 2013 Accounts Receivable [Member] Credit Concentration Risk [Member]	Oct. 31, 2013 Billed Receivables [Member] Commercial Customers [Member]	Jul. 31, 2013 Billed Receivables [Member] Commercial Customers [Member]	Oct. 31, 2013 Billed Receivables [Member] U.S. Government and Its Agencies [Member]	Jul. 31, 2013 Billed Receivables [Member] U.S. Government and Its Agencies [Member]	Oct. 31, 2013 Unbilled Receivables on Contracts-In-Progress [Member]	Jul. 31, 2013 Unbilled Receivables on Contracts-In-Progress [Member]
Total accounts receivable	$ 62,727,000	$ 50,518,000		$ 46,722,000	$ 40,005,000	$ 8,353,000	$ 8,114,000	$ 7,652,000	$ 2,399,000
Less allowance for doubtful accounts	707,000	603,000
Accounts receivable, net	62,020,000	49,915,000
Unbilled receivables on contracts-in-progress due from U.S. government and its agencies	2,041,000	699,000
Retainage included in unbilled receivables	$ 0	$ 0
Percentage of total accounts receivable from the prime contractor that we perform work for on our two North African country end-customer contracts			20.30%