Inventories (Details) - USD ($)	Jul. 31, 2020	Jul. 31, 2019
Inventory Disclosure [Abstract]
Raw materials and components	$ 59,175,000	$ 53,959,000
Work-in-process and finished goods	42,203,000	40,576,000
Total inventories	101,378,000	94,535,000
Less reserve for excess and obsolete inventories	19,076,000	19,696,000
Inventories, net	82,302,000	74,839,000
Inventory directly related to long-term contracts	7,215,000	4,053,000
Inventory related to contracts from third party commercial customers who outsource their manufacturing to us	$ 1,387,000	$ 1,513,000