Pension, Retiree Medical and Savings Plans (Level 3 Assets) (Details) (Level 3 [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 29, 2012
Change in fair value of plan assets
Fair value at beginning of year	$ 110
Return on Assets Held at Year End	24
Return on Assets Sold	1
Purchases and Sales, Net	318
Fair value at end of year	453
Real Estate [Member]
Change in fair value of plan assets
Fair value at beginning of year	56
Return on Assets Held at Year End	15
Return on Assets Sold	1
Purchases and Sales, Net	319
Fair value at end of year	391
Contracts With Insurance Companies [Member]
Change in fair value of plan assets
Fair value at beginning of year	54
Return on Assets Held at Year End	9
Return on Assets Sold	0
Purchases and Sales, Net	(1)
Fair value at end of year	$ 62

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.

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