Note 5 - Short-Term Investments (Details) - Short-Term Investments (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 28, 2014	Dec. 28, 2014	Dec. 29, 2013
Note 5 - Short-Term Investments (Details) - Short-Term Investments [Line Items]
Amortized Cost	$ 46,660		$ 49,099
Fair Value	46,638us-gaap_AvailableForSaleSecurities		49,099us-gaap_AvailableForSaleSecurities
Unrealized Gain (Loss)	(22)	(100)	0
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Note 5 - Short-Term Investments (Details) - Short-Term Investments [Line Items]
Amortized Cost	23,982		21,986
Fair Value	23,984		21,993
Unrealized Gain (Loss)	2		7
Corporate Bond Securities [Member]
Note 5 - Short-Term Investments (Details) - Short-Term Investments [Line Items]
Amortized Cost	21,717		27,113
Fair Value	21,693		27,106
Unrealized Gain (Loss)	(24)		(7)
Certificates of Deposit [Member]
Note 5 - Short-Term Investments (Details) - Short-Term Investments [Line Items]
Amortized Cost	961
Fair Value	$ 961

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

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

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-Subparagraph (SX 210.5-02.2)

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Amount of unrealized gain (loss) on investments in debt and equity securities classified as available-for-sale securities.

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-Name Accounting Standards Codification

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