Investments - Schedule Of Interest Income Generated From Investments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Apr. 26, 2015	Apr. 27, 2014
Investments [Abstract]
Interest income	$ 5us-gaap_InvestmentIncomeInterest	$ 8us-gaap_InvestmentIncomeInterest

Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7(b))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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