Basis of Presentation (Details)	3 Months Ended	6 Months Ended	12 Months Ended
Oct. 29, 2016	Oct. 24, 2015	Oct. 29, 2016	Oct. 24, 2015	Apr. 29, 2017	Apr. 30, 2016
Basis of Presentation
Length of fiscal year					364 days	371 days
Improvement in gross margin due to legal settlement (as a percent)	0.10%	0.50%	0.40%	0.50%

Duration of a fiscal period, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but not limited to, weeks in a year or quarter.

No definition available.

Name:	us-gaap_FiscalPeriodDuration
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration