Accounts Receivable (Details) (USD $)	Jan. 31, 2013	Jul. 31, 2012
Total accounts receivable	$ 43,283,000	$ 57,830,000
Less allowance for doubtful accounts	1,047,000	1,588,000
Accounts receivable, net	42,236,000	56,242,000
Unbilled receivables on contracts-in-progress due from U.S. government and its agencies	2,338,000	3,320,000
Retainage included in unbilled receivables	0	0
Billed Receivables [Member] | Commercial Customers [Member]
Total accounts receivable	30,082,000	41,139,000
Billed Receivables [Member] | U.S. Government and Its Agencies [Member]
Total accounts receivable	9,094,000	11,927,000
Unbilled Receivables on Contracts-In-Progress [Member]
Total accounts receivable	$ 4,107,000	$ 4,764,000