Income Taxes (Tax Effects of Temporary Differences) (Details) - USD ($)	Jul. 31, 2022	Jul. 31, 2021
Deferred tax assets:
Inventory and warranty reserves	$ 5,970,000	$ 6,774,000
Compensation and commissions	4,376,000	4,338,000
Federal, state and foreign research and experimentation credits	19,476,000	19,324,000
Stock-based compensation	3,950,000	4,979,000
Foreign scientific research and experimental development expenditures	1,890,000	1,496,000
Federal, state and foreign net operating losses	14,481,000	5,413,000
Federal and state capital losses	15,582,000	15,582,000
Lease liabilities	12,595,000	10,980,000
Other	5,919,000	4,550,000
Less: valuation allowance	(31,227,000)	(28,384,000)
Total deferred tax assets	53,012,000	45,052,000
Deferred tax liabilities:
Plant and equipment	(3,489,000)	(1,146,000)
Lease right-of-use assets	(11,801,000)	(10,085,000)
Intangibles	(52,681,000)	(54,635,000)
Total deferred tax liabilities	(67,971,000)	(65,866,000)
Net deferred tax liabilities	$ (14,959,000)	$ (20,814,000)