Net Earnings (Loss) per Share - Additional Information (Detail) - shares	12 Months Ended
Apr. 28, 2018	Apr. 29, 2017	Apr. 30, 2016
Stock Options and Restricted Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from the calculation of earnings per share	38,584	140,341	129,450
Participating Securities
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from the calculation of earnings per share	127,509		2,163,190

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration