Income Taxes (Provision for Income Taxes Differed from Amounts Computed by the U.S. Federal Income Tax Rate) (Details) (USD $)	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Income Tax Disclosure [Abstract]
Computed expected tax expense	$ 13,477,000	$ 9,623,000	$ 15,414,000
Computed expected tax rate	35.00%	35.00%	35.00%
State and local income taxes, net of Federal benefit	1,172,000	782,000	995,000
State and local income taxes, net of Federal benefit effective tax rate	3.10%	2.80%	2.30%
Nondeductible stock-based compensation	70,000	71,000	86,000
Effective income tax rate reconciliation, nondeductible expense, share-based compensation cost	0.20%	0.30%	0.20%
Domestic production activities deduction	(912,000)	(1,344,000)	(1,436,000)
Effective income tax rate reconciliation, deductions, qualified production activities	(2.40%)	(4.90%)	(3.30%)
Research and experimentation credits	(506,000)	(888,000)	(241,000)
Effective income tax rate reconciliation, tax credits, research	(1.30%)	(3.20%)	(0.50%)
Change in the beginning of the year valuation allowance for deferred tax assets	0	693,000	0
Effective income tax rate reconciliation, change in deferred tax assets valuation allowance	0.00%	2.50%	0.00%
Income tax reconciliation, tax settlements	0	(141,000)	(2,841,000)
Effective income tax rate reconciliation, tax settlements	0.00%	(0.50%)	(6.50%)
Foreign income taxes	(62,000)	640,000	99,000
Effective income tax rate reconciliation, foreign income tax rate differential	(0.20%)	2.30%	0.20%
Other	117,000	249,000	(452,000)
Effective income tax rate reconciliation, other adjustments	0.30%	0.90%	(1.00%)
Total provision for income taxes	$ 13,356,000	$ 9,685,000	$ 11,624,000
Income tax effective tax rate, continuing operations	34.70%	35.20%	26.40%