Stock-Based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2018	Oct. 31, 2017
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	$ 2,576	$ 1,851
Cost of sales
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	237	115
Total operating expenses
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	2,339	1,736
Selling
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	571	365
General and administrative
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	1,710	1,333
Research and development
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	$ 58	$ 38