Employee Benefit Plans (Pension and Other Post-Employment Benefits Adjustments) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 26, 2014		Dec. 27, 2013		Dec. 28, 2012
Pension Benefits [Member]
Components of other comprehensive loss (income) [Abstract]
Losses (Gains)	$ 305		$ (462)
Expense (Income) recognized in income statement [Abstract]
Amortization of net losses	57	[1]	100	[1]	82
Settlement gain	(1)		(2)		(2)	[2]
Amortization of prior service cost	0	[3]	0	[3]	0
Estimated amount to be expensed in the future period	70
Remaining prior service costs to be expensed in future period	1
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Losses	908
Prior Service Costs (Credits)	0
Total	908
Post-retirement Benefits [Member]
Components of other comprehensive loss (income) [Abstract]
Losses (Gains)	(8)		(48)
Expense (Income) recognized in income statement [Abstract]
Amortization of net losses	5	[1]	14	[1]	9
Settlement gain	0		0		0	[2]
Amortization of prior service cost	(1)	[3]	(1)	[3]	(1)
Estimated amount to be expensed in the future period	5
Remaining prior service costs to be expensed in future period	1
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Losses	59
Prior Service Costs (Credits)	(1)
Total	$ 58

[1] Amortization of net losses estimated to be expensed for 2015 is approximately $70 million and $5 million for pension benefits and post-retirement benefits, respectively. The increase in amortization is largely related to the impact of lower discount rates and adoption of new mortality tables, partially offset by favorable pension asset experience.

[2] Settlement gains were recognized as one of the pension plan's lump-sum payments exceeded the sum of the service cost and interest cost recognized. The gain is the recognition of a portion of its accumulated other comprehensive income related to that plan.

[3] Amortization of prior service costs estimated to be expensed in 2015 is less than $1 million for pension benefits. The estimated post-retirement benefits amount to be credited to expense for 2015 is $1 million.