Debt and Credit Arrangements (Details 3) (USD $)	12 Months Ended
Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012
Debt and Credit Arrangements
Weighted average interest rate for credit facility borrowings, including the impact of interest rate swaps	1.70%	1.40%	1.30%
Interest paid	$ 3,700,000us-gaap_InterestPaidNet	$ 2,000,000us-gaap_InterestPaidNet	$ 967,000us-gaap_InterestPaidNet
Interest rate swap
Debt and Credit Arrangements
Amount of Gain or (Loss) Recognized in Accumulated OCI on Derivative (Effective Portion)	(164,000)	(32,000)	(72,000)
Interest rate swap liabilities	376,000
Interest expense \| Interest rate swap
Debt and Credit Arrangements
Amount of Gain or (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(996,000)	(501,000)	(150,000)
Amount of Gain or (Loss) Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing)	0	0	0
Portion of derivative liability that would be reclassified into earnings	$ 113,000
Estimate of period of time over which portion of derivative liability would be reclassified into earnings	12 months

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The estimated value of gains (losses), net anticipated to be transferred in the future from accumulated other comprehensive income into earnings.

+ References

No definition available.

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Estimated period for the anticipated transfer of gain (loss), net, from accumulated other comprehensive income into earnings, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

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-Subparagraph (c)

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-Topic 815

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- Definition

The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (d)

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-Name Accounting Standards Codification

-Topic 815

-SubTopic 25

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-Subparagraph (a)(1),(2)

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- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

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- Definition

The amount of cash paid for interest during the period net of cash paid for interest that is capitalized.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 2

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- Definition

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

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- Definition

The effective interest rate during the reporting period.

+ References

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 210.5-02.19(b),22(b))

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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