Stock-Based Compensation (Details) (USD $)	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	$ 1,148,000	$ 958,000
Income tax benefits	(412,000)	(340,000)
Total stock-based compensation expense, net of tax	736,000	618,000
Cost of sales
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	62,000	55,000
Operating expenses: Selling
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	110,000	99,000
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	964,000	792,000
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	12,000	12,000
Total operating expenses
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	$ 1,086,000	$ 903,000