Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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-Publisher FASB
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Name:	us-gaap_ForeignCurrencyTransactionGainLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Summary of Foreign Currency Exchange Gains (Losses) by Geographic Area (Detail) - USD ($) $ in Thousands	12 Months Ended
	Apr. 28, 2019	Apr. 29, 2018	Apr. 30, 2017
Foreign Currency Exchange Gain And Loss [Line Items]
Foreign currency exchange gains (losses)	$ (62)	$ (306)	$ (9)
China [Member]
Foreign Currency Exchange Gain And Loss [Line Items]
Foreign currency exchange gains (losses)		(298)	111
Canada [Member]
Foreign Currency Exchange Gain And Loss [Line Items]
Foreign currency exchange gains (losses)	2	(8)	(120)
Europe [Member]
Foreign Currency Exchange Gain And Loss [Line Items]
Foreign currency exchange gains (losses)	$ (64)