Stock-Based Compensation (Details) - USD ($)	3 Months Ended
	Oct. 31, 2015	Oct. 31, 2014
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	$ 1,720,000	$ 1,581,000
Income tax benefits	(613,000)	(539,000)
Total stock-based compensation expense, net of tax	1,107,000	1,042,000
Cost of sales
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	79,000	99,000
Operating expenses: Selling
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	190,000	186,000
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	1,425,000	1,279,000
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	26,000	17,000
Total operating expenses
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	$ 1,641,000	$ 1,482,000