Employee Benefit Plans (Benefit Obligation and Fair Value of Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 25, 2015	Dec. 26, 2014	Dec. 27, 2013	Dec. 25, 2015	Dec. 26, 2014
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Plan Year	$ 2,504
Fair Value of Plan Assets at End of Plan Year	2,309	$ 2,504
Pension Benefits [Member]
Actuarial Present Value of Benefit Obligation [Abstract]
Accumulated Benefit Obligation				$ 2,672	$ 2,849
Projected Benefit Obligation	3,002	2,679	$ 2,679	2,860	3,002
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected Benefit Obligation at Beginning of Plan Year	3,002	2,679
Service Cost	45	44	49
Interest Cost	116	123	108
Plan Participants' Contributions	0	0
Workforce Reduction Program/Curtailment	7	27
Actuarial Loss (Gain)	(110)	333
Benefits Paid	(200)	(204)
Benefit Obligation at End of Plan Year	2,860	3,002	2,679
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Plan Year	2,504	2,500
Actual Return on Plan Assets	(9)	195
Plan Participants' Contributions	0	0
Benefits Paid	(200)	(204)
Fair Value of Plan Assets at End of Plan Year	2,309	2,504	2,500
Funded Status at End of Plan Year				(551)	(498)
Post-retirement Benefits [Member]
Actuarial Present Value of Benefit Obligation [Abstract]
Projected Benefit Obligation	340	350	350	314	340
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected Benefit Obligation at Beginning of Plan Year	340	350
Service Cost	2	3	3
Interest Cost	12	13	13
Plan Participants' Contributions	7	7
Workforce Reduction Program/Curtailment	0	8
Actuarial Loss (Gain)	(7)	(8)
Benefits Paid	(40)	(33)
Benefit Obligation at End of Plan Year	314	340	350
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	7	7
Benefits Paid	(40)	(33)
Fair Value of Plan Assets at End of Plan Year	0	0	$ 0
Funded Status at End of Plan Year				$ (314)	$ (340)
Non-qualified Employer Contributions [Member] | Pension Benefits [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Non-qualified Employer Contributions	14	13
Non-qualified Employer Contributions [Member] | Post-retirement Benefits [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Non-qualified Employer Contributions	$ 33	$ 26