Stock-Based Compensation (Details) (USD $)	3 Months Ended		9 Months Ended
	Apr. 30, 2015	Apr. 30, 2014	Apr. 30, 2015	Apr. 30, 2014
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	$ 1,353,000	$ 1,422,000	$ 4,354,000	$ 3,978,000
Income tax benefits	(479,000)	(499,000)	(1,525,000)	(1,404,000)
Total stock-based compensation expense, net of tax	874,000	923,000	2,829,000	2,574,000
Cost of sales
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	64,000	109,000	226,000	280,000
Operating expenses: Selling
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	138,000	190,000	444,000	491,000
Operating expenses: General and administrative
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	1,137,000	1,104,000	3,639,000	3,158,000
Operating expenses: Research and development
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	14,000	19,000	45,000	49,000
Total operating expenses
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	$ 1,289,000	$ 1,313,000	$ 4,128,000	$ 3,698,000