Employee Benefit Plans (Benefit obligation, Plan Assets and Funded Status) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 27, 2013	Dec. 28, 2012	Dec. 30, 2011
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at End of Plan Year	$ 2,500	$ 2,294
Pension Plan, Defined Benefit [Member]
Actuarial Present Value of Benefit Obligation [Abstract]
Accumulated Benefit Obligation	2,538	2,806
Projected Benefit Obligation	2,679	2,954	2,668
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected Benefit Obligation at Beginning of Year	2,954	2,668
Service Cost	49	44	40
Interest Cost	108	123	121
Plan Participants Contributions	0	0
Plan Amendments	0	0
Actuarial Net (Gains) Losses	(275)	274
Benefits Paid	(157)	(155)
Benefit Obligation at End of Plan Year	2,679	2,954	2,668
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Plan Year	2,294	1,850
Actual Return on Plan Assets	350	311
Plan Participants Contributions	0	0
Benefits Paid	(157)	(155)
Fair Value of Plan Assets at End of Plan Year	2,500	2,294	1,850
Funded Status at End of Plan Year	(179)	(660)
Other Postretirement Benefit Plan, Defined Benefit [Member]
Actuarial Present Value of Benefit Obligation [Abstract]
Projected Benefit Obligation	350	415	388
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected Benefit Obligation at Beginning of Year	415	388
Service Cost	3	4	2
Interest Cost	13	16	11
Plan Participants Contributions	8	8
Plan Amendments	0	(1)
Actuarial Net (Gains) Losses	(49)	43
Benefits Paid	(40)	(43)
Benefit Obligation at End of Plan Year	350	415	388
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Plan Year	0	0
Actual Return on Plan Assets	0	0
Plan Participants Contributions	8	8
Benefits Paid	(40)	(43)
Fair Value of Plan Assets at End of Plan Year	0	0	0
Funded Status at End of Plan Year	(350)	(415)
Qualified Employer Contributions [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Employer Contributions	0	275
Qualified Employer Contributions [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Employer Contributions	0	0
Non-qualified Employer Contributions [Member] | Pension Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Employer Contributions	13	13
Non-qualified Employer Contributions [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Employer Contributions	$ 32	$ 35