Employee Benefit Plans (Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 27, 2013	Dec. 28, 2012
Defined Benefit Plan Disclosure [Line Items]
Distribution of pension plan assets	$ 2,500	$ 2,294
Equity, Percent of Total Assets	100.00%	100.00%
Equity [Member]
Defined Benefit Plan Disclosure [Line Items]
Targeted and established equity allocation (in hundredths)	60.00%
Targeted allocation of total plan assets in domestic equity (in hundredths)	40.00%
Targeted allocation of total plan assets in international equity (in hundredths)	20.00%
Percentage within which the planned allocation is managed (in hundredths)	3.00%
Distribution of pension plan assets	1,619	1,408
Equity, Percent of Total Assets	65.00%	61.00%
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Targeted and established equity allocation (in hundredths)	40.00%
Distribution of pension plan assets	795	829
Equity, Percent of Total Assets	32.00%	36.00%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Distribution of pension plan assets	$ 86	$ 57
Equity, Percent of Total Assets	3.00%	3.00%