Employee Benefit Plans (Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 26, 2014	Dec. 27, 2013
Defined Benefit Plan Disclosure [Line Items]
Distribution of pension plan assets	$ 2,504	$ 2,500
Equity, Percent of Total Assets	100.00%	100.00%
Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Targeted and established equity allocation (in hundredths)	70.00%
Targeted allocation of total plan assets in domestic equity (in hundredths)	42.00%
Targeted allocation of total plan assets in international equity (in hundredths)	28.00%
Percentage within which the planned allocation is managed (in hundredths)	3.00%
Distribution of pension plan assets	1,715	1,619
Equity, Percent of Total Assets	68.00%	65.00%
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Targeted and established equity allocation (in hundredths)	30.00%
Distribution of pension plan assets	740	795
Equity, Percent of Total Assets	30.00%	32.00%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Distribution of pension plan assets	$ 49	$ 86
Equity, Percent of Total Assets	2.00%	3.00%

Target allocation percentage of investments in equity securities to total plan assets in domestic equity.

No definition available.

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- Definition

Target allocation percentage of investments in equity securities to total plan assets in international equity.

+ References

No definition available.

+ Details

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- Definition

Target allocation percentage of investments in within which plan assets investment are managed.

+ References

No definition available.

+ Details

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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=35743120&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

Target allocation of investments of this type to total plan assets presented on a weighted average basis.

+ 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)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&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)(i)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

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- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e2446-114920

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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