Employee Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	$ 0	$ 250,000,000	$ 0
Expected future contributions	0
Pension plan assets at fair value	2,833,000,000	2,539,000,000
Special termination benefits	56,000,000
Amount of premium expenses incurred under the plan	40,000,000	35,000,000	32,000,000
Expense associated with savings plans	39,000,000	35,000,000	36,000,000
Change in Assumptions for Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Decrease in net periodic pension expense	25,000,000
Post-retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	0	$ 0	0
Curtailment loss	$ 13,000,000
Discount rate (as a percent)	3.34%	3.71%
Special termination benefits	$ 13,000,000	$ 0	0
Pre-tax losses to be amortized	7,000,000
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value	2,833,000,000	$ 2,539,000,000	2,309,000,000
Curtailment loss	$ 4,000,000
Discount rate (as a percent)	3.56%	4.08%
Decrease to pension liabilities	$ 85,000,000
Special termination benefits	60,000,000	$ 0	$ 7,000,000
Pre-tax losses to be amortized	$ 705,000,000
Equity
Defined Benefit Plan Disclosure [Line Items]
Investment committee equity target allocation percentage of pension assets	70.00%
Targeted allocation of total plan assets in domestic equity (as a percent)	42.00%
Targeted allocation of total plan assets in international equity (as a percent)	28.00%
Percentage within which the planned allocation is managed (as a percent)	3.00%
Pension plan assets at fair value	$ 2,060,000,000	1,806,000,000
Fixed Income
Defined Benefit Plan Disclosure [Line Items]
Investment committee equity target allocation percentage of pension assets	30.00%
Pension plan assets at fair value	$ 729,000,000	665,000,000
Nonqualified Plan | Post-retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	29,000,000	32,000,000
Nonqualified Plan | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	45,000,000	17,000,000
Settlement gain (loss)	12,000,000
Qualified Plan | Post-retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	0	0
Qualified Plan | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Employer Contributions	0	$ 250,000,000
Settlement gain (loss)	$ 11,000,000