Summary of Significant Accounting Policies - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation	$ 17,473	$ 15,045	$ 11,989
Furniture, equipment and software | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Furniture, equipment and software | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	15 years
Buildings and improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years
Buildings and improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	40 years