Derivative Financial Instruments (Effect of Derivatives on Income Statement) (Details) (Cash Flow Hedging [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 29, 2013	Jun. 30, 2012	Jun. 29, 2013	Jun. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Before-tax Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	$ 412	$ (1,296)	$ 390	$ (524)
Before-Tax Gain (Loss) Reclassified from AOCI Into Income (Effective Portion)	95	105	212	81
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion)	(5)	0	(4)	0
Diesel Fuel Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Before-tax Gain (Loss) Recognized in AOCI on Derivative (Effective Portion)	412	(1,296)	390	(524)
Diesel Fuel Swap [Member] \| Selling and Administrative Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Before-Tax Gain (Loss) Reclassified from AOCI Into Income (Effective Portion)	95	105	212	81
Gain (Loss) Recognized in Income on Derivative (Ineffective Portion)	$ (5)	$ 0	$ (4)	$ 0

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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

-Paragraph 4C

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4D

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624177-113959

+ Details

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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)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 25

-Section 50

-Paragraph 1

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

-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

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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

+ Details

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