Employee Benefit Plans - Schedule of Changes in Benefit Obligation and Fair Value of Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 30, 2016	Dec. 25, 2015	Dec. 26, 2014	Dec. 30, 2016	Dec. 25, 2015
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Plan Year	$ 2,309
Non-qualified Employer Contributions	250
Fair Value of Plan Assets at End of Plan Year	2,539	$ 2,309
Pension Plans
Actuarial Present Value of Benefit Obligation
Accumulated Benefit Obligation				$ 2,717	$ 2,672
Projected Benefit Obligation	2,860	3,002	$ 3,002	2,871	2,860
Change in Projected Benefit Obligation:
Projected Benefit Obligation at Beginning of Plan Year	2,860	3,002
Service Cost	48	45	44
Interest Cost	119	116	123
Plan Participants' Contributions	0	0
Workforce Reduction Program/Curtailment	0	7
Actuarial Loss (Gain)	20	(110)
Benefits Paid	(176)	(200)
Benefit Obligation at End of Plan Year	2,871	2,860	3,002
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair Value of Plan Assets at Beginning of Plan Year	2,309	2,504
Actual Return on Plan Assets	139	(9)
Non-qualified Employer Contributions	250	0
Plan Participants' Contributions	0	0
Benefits Paid	(176)	(200)
Fair Value of Plan Assets at End of Plan Year	2,539	2,309	2,504
Funded Status at End of Plan Year				(332)	(551)
Pension Plans | Non-qualified Employer Contributions
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Non-qualified Employer Contributions	17	14
Post-retirement Medical Plan
Actuarial Present Value of Benefit Obligation
Projected Benefit Obligation	314	340	340	274	314
Change in Projected Benefit Obligation:
Projected Benefit Obligation at Beginning of Plan Year	314	340
Service Cost	2	2	3
Interest Cost	12	12	13
Plan Participants' Contributions	6	7
Workforce Reduction Program/Curtailment	0	0
Actuarial Loss (Gain)	(22)	(7)
Benefits Paid	(38)	(40)
Benefit Obligation at End of Plan Year	274	314	340
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
Non-qualified Employer Contributions	0	0
Plan Participants' Contributions	6	7
Benefits Paid	(38)	(40)
Fair Value of Plan Assets at End of Plan Year	0	0	$ 0
Funded Status at End of Plan Year				$ (274)	$ (314)
Post-retirement Medical Plan | Non-qualified Employer Contributions
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Non-qualified Employer Contributions	$ 32	$ 33