Inventories (Details) - USD ($)	Jul. 31, 2019	Jul. 31, 2018
Inventory Disclosure [Abstract]
Raw materials and components	$ 53,959,000	$ 53,649,000
Work-in-process and finished goods	40,576,000	38,854,000
Total inventories	94,535,000	92,503,000
Less reserve for excess and obsolete inventories	19,696,000	17,427,000
Inventories, net	74,839,000	75,076,000
Inventory directly related to long-term contracts	4,053,000	1,249,000
Inventory related to contracts from third party commercial customers who outsource their manufacturing to us	$ 1,513,000	$ 1,310,000