Valuation and Qualifying Accounts and Reserves (Details) - USD ($)		12 Months Ended
		Jul. 31, 2018	Jul. 31, 2017		Jul. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Charged to cost and expenses		$ 573,000	$ 497,000		$ 907,000
Charged to cost and expenses		5,628,000	2,900,000		2,780,000
Allowance for doubtful accounts receivable:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period		1,300,000	1,029,000		1,206,000
Charged to cost and expenses	[1]	573,000	497,000		907,000
Charged to other accounts - describe		0	0		0
Transfers (deductions) - describe	[2]	(112,000)	(226,000)		(1,084,000)
Balance at end of period		1,761,000	1,300,000		1,029,000
Inventory reserves:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period		16,019,000	16,198,000		16,904,000
Charged to cost and expenses	[3]	5,628,000	2,900,000		2,780,000
Charged to other accounts - describe		0	0		0
Transfers (deductions) - describe	[4]	(4,220,000)	(3,079,000)		(3,486,000)
Balance at end of period		17,427,000	16,019,000		16,198,000
Valuation allowance for deferred tax assets:
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period		8,633,000	9,624,000		4,442,000
Charged to cost and expenses	[5]	3,221,000	324,000		524,000
Charged to other accounts - describe		0	121,000	[6]	4,658,000	[6]
Transfers (deductions) - describe		0	(1,436,000)	[6]	0
Balance at end of period		$ 11,854,000	$ 8,633,000		$ 9,624,000

[1] Provision for doubtful accounts.

[2] Write-off of uncollectible receivables.

[3] Provision for excess and obsolete inventory.

[4] Write-off of inventory.

[5] Change in valuation allowance.

[6] Acquisition related valuation allowance charged to (deducted from) goodwill.