Summary of Significant Accounting Policies - Warranties (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017
Product Warranty Liability [Line Items]
Warranty reserves	$ 3,280	$ 2,328
Most products
Product Warranty Liability [Line Items]
Warranty period	1 year
Endoscopy, Water Purification and Filtration products
Product Warranty Liability [Line Items]
Warranty period	24 months
Consumables, accessories and parts
Product Warranty Liability [Line Items]
Warranty period	90 days