Inventories (Details) - USD ($)	Apr. 30, 2017	Jul. 31, 2016
Inventory Disclosure [Abstract]
Raw materials and components	$ 54,551,000	$ 54,723,000
Work-in-process and finished goods	28,672,000	32,829,000
Total inventories	83,223,000	87,552,000
Less reserve for excess and obsolete inventories	15,886,000	16,198,000
Inventories, net	67,337,000	71,354,000
Inventory directly related to long-term contracts	2,170,000	2,896,000
Inventory related to contracts from third party commercial customers who outsource their manufacturing to us	$ 1,896,000	$ 1,428,000