Retirement Plans (Summary of Changes in Fair Value of Level 3 Assets) (Details) (USD $)	12 Months Ended
Dec. 27, 2014	Dec. 28, 2013	Dec. 29, 2012
Fair Value of Level 3 Assets [Roll Forward]
Fair value of plan assets at end of year	$ 267,635,000	$ 260,917,000
Pensions [Member]
Fair Value of Level 3 Assets [Roll Forward]
Fair value of plan assets at beginning of year			231,897,000
Fair value of plan assets at end of year	267,635,000	260,917,000	231,897,000
Alternative investments [Member] \| Pensions [Member]
Fair Value of Level 3 Assets [Roll Forward]
Fair value of plan assets at end of year	58,643,000	53,116,000
Level 3 [Member] \| Pensions [Member]
Fair Value of Level 3 Assets [Roll Forward]
Fair value of plan assets at end of year	58,643,000	53,116,000
Level 3 [Member] \| Alternative investments [Member] \| Pensions [Member]
Fair Value of Level 3 Assets [Roll Forward]
Fair value of plan assets at beginning of year	53,116,000	46,297,000
Purchases, sales and settlements		0
Asset sales	(2,884,000)
Asset purchases	2,884,000
Unrealized gains	5,527,000	6,819,000
Fair value of plan assets at end of year	58,643,000	53,116,000
Realized losses on asset sales	$ 100,000

Defined Benefit Plan, Fair Value of Plan Assets, Asset Purchases

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- Definition

Defined Benefit Plan, Fair Value of Plan Assets, Asset Sales

+ References

No definition available.

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Defined Benefit Plan, Fair Value of Plan Assets, Realized Gains (Losses)

+ References

No definition available.

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Defined Benefit Plan, Fair Value of Plan Assets, Unrealized Gains

+ References

No definition available.

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- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 30

-Section 35

-Paragraph 50

-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930

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- Definition

Amount of increase (decrease) in plan assets from purchases, sales and settlement of plan obligations.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(iv)(02)(B)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)(iv)(02)(B)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e2446-114920

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