Accounts Receivable (Details)	12 Months Ended
	Jul. 31, 2016 USD ($) contract	Jul. 31, 2015 USD ($)
Total accounts receivable	$ 151,996,000	$ 70,461,000
Less: Allowance for doubtful accounts	1,029,000	1,206,000
Accounts receivable, net	$ 150,967,000	$ 69,255,000
Percent of unbilled receivables estimated to be billed and collected within one year	92.60%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | U.S. government
Percentage of total accounts receivable	27.90%	13.50%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | U.S. Prime Contractor
Percentage of total accounts receivable	10.50%	36.30%
Number Of Customer		1
Billed Receivables [Member] | Commercial and International Customers [Member]
Total accounts receivable	$ 90,185,000	$ 39,062,000
Billed Receivables [Member] | U.S. Government and Its Agencies [Member]
Total accounts receivable	21,465,000	8,375,000
Unbilled Revenues [Member]
Retainage included in unbilled receivables	118,000	0
Unbilled Revenues [Member] | Customer Concentration Risk [Member] | U.S. Prime Contractor
Unbilled receivable related to our large over-the-horizon microwave system contracts	$ 6,070,000	20,256,000
Number of our large over-the-horizon microwave system contracts | contract	2
Unbilled Revenues [Member] | Commercial and International Customers [Member]
Total accounts receivable	$ 19,333,000	21,898,000
Unbilled Revenues [Member] | U.S. Government and Its Agencies [Member]
Total accounts receivable	$ 21,013,000	$ 1,126,000