Schedule of Foreign Currency Forward Contracts (Detail) - Level 2 - USD ($) $ in Millions	Apr. 30, 2018	Jul. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign currency forward contracts (liability) asset	$ (0.1)
Foreign currency forward contracts (liability) asset		$ 0.6
Total	$ (0.1)	$ 0.6

Fair value portion of liability contracts related to the exchange of different currencies, including, but not limited to, foreign currency options, forward (delivery or nondelivery) contracts, and swaps entered into.

No definition available.

Name:	us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant