Summary of Significant Accounting Policies (Correction for Immaterial Prior Period Misstatements) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Sep. 28, 2013	Dec. 27, 2014	Dec. 28, 2013	Dec. 29, 2012
SERP investment		$ 9,121wmk_SerpInvestment	$ 8,752wmk_SerpInvestment	$ 6,900wmk_SerpInvestment
Gain on disposition of fixed assets		2,630	2,033	1,407
Impairment of fixed assets	2,100	0	2,088	0
Opening cash impact of reclassification of fixed asset gains (losses) and associated impairment			0
Scenario, Previously Reported [Member]
Gain/loss on disposition/impairment of fixed assets			$ (55)

Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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- Definition

Amount of gain (loss) from the difference between the sale price or salvage price and the book value of an asset that was sold or retired, and gain (loss) from the write down of assets from their carrying value to fair value.

+ References

No definition available.

+ Details

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- Definition

The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 958

-SubTopic 225

-Section 45

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-Subparagraph (a)

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Impairment

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+ Details

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- Definition

The adjustment made to the opening cash balance due to a reclassification of the gains (losses) and impairment associated with fixed assets.

+ References

No definition available.

+ Details

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- Definition

Amount of investments in level 1 mutual funds related to a non-qualified supplemental executive retirement plan and a non-qualified pharmacist deferred compensation plan for certain of its associates.

+ References

No definition available.

+ Details

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