Acquisitions - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Business Acquisition Actual Revenue And Pre Tax Income Loss [Line Items]
Interest expense	$ 5,504	$ 7,824	$ 11,156
Income tax expense (benefit)	30,987	29,235	20,093
Pre-tax amortization of intangible assets	$ 7,113	$ 9,056	$ 12,103