Stock-Based Compensation - Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	$ 3,587	$ 2,739	$ 6,163	$ 4,590
Cost of sales
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	287	181	524	296
Total operating expenses
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	3,300	2,558	5,639	4,294
Selling
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	575	264	1,146	629
General and administrative
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	2,665	2,257	4,375	3,590
Research and development
Income statement components of stock-based compensation expense recognized in Consolidated Statements of Income
Stock-based compensation expense	$ 60	$ 37	$ 118	$ 75