Stock-Based Compensation - Expense (Details) - USD ($)	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	$ 8,361,000	$ 5,867,000	$ 5,409,000
Income tax benefits	(2,956,000)	(2,026,000)	(1,909,000)
Total stock-based compensation expense, net of tax	5,405,000	3,841,000	3,500,000
Total unrecognized stock-based compensation expense, before income taxes, related to total nonvested stock options and stock awards (in dollars)	$ 8,960,000
Remaining weighted average period over which unrecognized stock-based compensation expense is expected to be recognized	15 months
Cost of sales
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	$ 438,000	270,000	337,000
Operating expenses: Selling
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	929,000	608,000	665,000
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	6,881,000	4,897,000	4,339,000
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	113,000	92,000	68,000
Total operating expenses
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation before income taxes	$ 7,923,000	$ 5,597,000	$ 5,072,000