Financial Instruments - Fair Value of Derivatives Not Designated as Hedge Instruments (Detail) - Not Designated as Hedge Instrument - Foreign Exchange Forward Contracts - USD ($) $ in Thousands	Jan. 31, 2019	Apr. 30, 2018
Derivative assets:
Fair Value of Derivative Assets	$ 1,633	$ 1,778
Derivative liabilities:
Fair Value of Derivative Liabilities	$ 683	$ 1,025

Fair value as of the balance sheet date of all foreign currency derivative liabilities not designated as hedging instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

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