Pension, Retiree Medical and Savings Plans (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	4 Months Ended	12 Months Ended
	Dec. 29, 2012	Dec. 27, 2014	Dec. 28, 2013	Dec. 28, 2013 Pension Plans, Defined Benefit	Dec. 29, 2012 Pension Plans, Defined Benefit	Dec. 31, 2011 Pension Plans, Defined Benefit	Dec. 27, 2014 Retiree Medical Plan	Dec. 28, 2013 Retiree Medical Plan	Dec. 29, 2012 Retiree Medical Plan	Dec. 31, 2011 Retiree Medical Plan	Dec. 27, 2014 United States Pension Plan of US Entity, Defined Benefit	Dec. 28, 2013 United States Pension Plan of US Entity, Defined Benefit	Dec. 29, 2012 United States Pension Plan of US Entity, Defined Benefit	Dec. 31, 2011 United States Pension Plan of US Entity, Defined Benefit	Dec. 28, 2013 U.S. Savings Plan	Dec. 29, 2012 U.S. Savings Plan	Dec. 31, 2011 U.S. Savings Plan	Dec. 28, 2013 2020 And Thereafter	Dec. 28, 2013 Discretionary Pension Plans, Defined Benefit	Dec. 29, 2012 Discretionary Pension Plans, Defined Benefit	Dec. 31, 2011 Discretionary Pension Plans, Defined Benefit	Dec. 29, 2012 Discretionary Retiree Medical Plan	Dec. 28, 2013 Nondiscretionary Retiree Medical Plan	Dec. 29, 2012 Nondiscretionary Retiree Medical Plan	Dec. 31, 2011 Nondiscretionary Retiree Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Contribution															$ 122	$ 109	$ 144
Lower limit of net accumulated gain or loss			10.00%
Average remaining service period of active plan participants, pension expense			11 years
Average remaining service period of active plan participants, retiree medical expense			9 years
Unfunded plans included in total projected benefit liability			700
Expected future employer contributions in 2013		260					70
Expected return on plan assets								7.80%	7.80%	7.80%	7.50%	7.80%	7.80%	7.80%
Pension strategy investment term, years			5 years
Employer contributions				200	1,614	239		62	251			63	1,368						23	1,375	61	140	62	111	110
Average increase in the cost of covered retiree medical benefits			6.00%
Average increase is then projected to decline																		5.00%
Discretionary contribution to fund pension settlement	405
Pre-tax non-cash settlement charge	195
Pre-tax non-cash settlement charge, after-tax	$ 131
Pre-tax non-cash settlement charge, net of tax, per share	$ 0.08