Investments - Summary of Investments (Details) (USD $) In Thousands, unless otherwise specified	Jan. 25, 2015	Jan. 26, 2014
Schedule of Available-for-sale Securities [Line Items]
Market Value	$ 23,271us-gaap_AvailableForSaleSecurities	$ 18,258us-gaap_AvailableForSaleSecurities
Adjusted Cost	23,271	18,257
Gross Unrealized Gain	0	1
Agency securities
Schedule of Available-for-sale Securities [Line Items]
Market Value	23,271	18,258
Adjusted Cost	23,271	18,257
Gross Unrealized Gain	0	1
Bank time deposits
Schedule of Available-for-sale Securities [Line Items]
Market Value	0	0
Adjusted Cost	0	0
Gross Unrealized Gain	$ 0	$ 0

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in equity securities classified as available-for-sale.

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 50

-Paragraph 2

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

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