Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Postemployment Benefits [Abstract]
Employer match and administrative fees for 401(k) plan	$ 1,797	$ 917	$ 565
Investments under employees deferred compensation plan	$ 28,095	$ 15,529

Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant