Dividends - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
Apr. 28, 2018	Apr. 29, 2017	Apr. 30, 2016
Dividends Payable [Line Items]
Cash dividends paid to common stockholders	$ 43,638	$ 43,887	$ 46,056

Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration