Inventories (Details) - USD ($)	Jan. 31, 2021	Jul. 31, 2020
Inventory Disclosure [Abstract]
Raw materials and components	$ 62,194,000	$ 59,175,000
Work-in-process and finished goods	39,569,000	42,203,000
Total inventories	101,763,000	101,378,000
Less reserve for excess and obsolete inventories	20,133,000	19,076,000
Inventories, net	81,630,000	82,302,000
Inventory directly related to long-term contracts	5,535,000	7,215,000
Inventory related to contracts from third party commercial customers who outsource their manufacturing to us	$ 1,597,000	$ 1,387,000