Valuation and Qualifying Accounts and Reserves (Details) - USD ($)	12 Months Ended
	Jul. 31, 2023	Jul. 31, 2022	Jul. 31, 2021	Jul. 31, 2020
Allowance for doubtful accounts receivable
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 2,089,000	$ 2,337,000	$ 1,648,000	$ 1,769,000
Charged to cost and expenses	261,000	838,000	(18,000)
Charged to other accounts	0	0	215,000
Transfers (deductions)	(509,000)	(149,000)	(318,000)
Balance at end of period	2,089,000	2,337,000	1,648,000
Inventory reserves
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	24,659,000	23,121,000	20,229,000	19,076,000
Charged to cost and expenses	4,871,000	4,447,000	4,364,000
Charged to other accounts	0	0	0
Transfers (deductions)	(3,333,000)	(1,555,000)	(3,211,000)
Balance at end of period	24,659,000	23,121,000	20,229,000
Valuation allowance for deferred tax assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	34,478,000	31,227,000	28,384,000	$ 11,471,000
Charged to cost and expenses	4,617,000	2,947,000	17,750,000
Charged to other accounts	0	0	0
Transfers (deductions)	(1,366,000)	(104,000)	(837,000)
Balance at end of period	$ 34,478,000	$ 31,227,000	$ 28,384,000