Inventories (Details) - USD ($)	Jul. 31, 2018	Jul. 31, 2017
Inventory Disclosure [Abstract]
Raw materials and components	$ 53,649,000	$ 50,569,000
Work-in-process and finished goods	38,854,000	26,053,000
Total inventories	92,503,000	76,622,000
Less reserve for excess and obsolete inventories	17,427,000	16,019,000
Inventories, net	75,076,000	60,603,000
Inventory directly related to long-term contracts	1,249,000	2,148,000
Inventory related to contracts from third party commercial customers who outsource their manufacturing to us	$ 1,310,000	$ 1,718,000