Employee Benefit Plans - Schedule of Changes in Benefit Obligation and Fair Value of Plan Assets (Details) - USD ($)	12 Months Ended
Dec. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Change in Plan Assets:
Fair Value of Plan Assets at Beginning of Plan Year	$ 2,539,000,000
Employer Contributions	0	$ 250,000,000	$ 0
Fair Value of Plan Assets at End of Plan Year	2,833,000,000	2,539,000,000
Pension Plans
Actuarial Present Value of Benefit Obligation
Accumulated Benefit Obligation	2,873,000,000	2,717,000,000
Change in Projected Benefit Obligation:
Projected Benefit Obligation at Beginning of Plan Year	2,871,000,000	2,860,000,000
Service Cost	36,000,000	48,000,000	45,000,000
Interest Cost	92,000,000	119,000,000	116,000,000
Plan Participants' Contributions	0	0
Workforce Reduction Program/Curtailment	58,000,000	0
Actuarial Loss (Gain)	163,000,000	20,000,000
Benefits Paid	(218,000,000)	(176,000,000)
Benefit Obligation at End of Plan Year	3,002,000,000	2,871,000,000	2,860,000,000
Change in Plan Assets:
Fair Value of Plan Assets at Beginning of Plan Year	2,539,000,000	2,309,000,000
Actual Return on Plan Assets	467,000,000	139,000,000
Plan Participants' Contributions	0	0
Benefits Paid	(218,000,000)	(176,000,000)
Fair Value of Plan Assets at End of Plan Year	2,833,000,000	2,539,000,000	2,309,000,000
Funded Status at End of Plan Year	(169,000,000)	(332,000,000)
Curtailment gain (loss)	4,000,000
Pension Plans \| Qualified Plan
Change in Plan Assets:
Employer Contributions	0	250,000,000
Pension Plans \| Nonqualified Plan
Change in Plan Assets:
Employer Contributions	45,000,000	17,000,000
Post-retirement Benefits
Change in Projected Benefit Obligation:
Projected Benefit Obligation at Beginning of Plan Year	274,000,000	314,000,000
Service Cost	2,000,000	2,000,000	2,000,000
Interest Cost	7,000,000	12,000,000	12,000,000
Plan Participants' Contributions	7,000,000	6,000,000
Workforce Reduction Program/Curtailment	13,000,000	0
Actuarial Loss (Gain)	(17,000,000)	(22,000,000)
Benefits Paid	(36,000,000)	(38,000,000)
Benefit Obligation at End of Plan Year	250,000,000	274,000,000	314,000,000
Change in Plan Assets:
Fair Value of Plan Assets at Beginning of Plan Year	0	0
Actual Return on Plan Assets	0	0
Plan Participants' Contributions	7,000,000	6,000,000
Benefits Paid	(36,000,000)	(38,000,000)
Fair Value of Plan Assets at End of Plan Year	0	0	$ 0
Funded Status at End of Plan Year	(250,000,000)	(274,000,000)
Curtailment gain (loss)	13,000,000
Post-retirement Benefits \| Qualified Plan
Change in Plan Assets:
Employer Contributions	0	0
Post-retirement Benefits \| Nonqualified Plan
Change in Plan Assets:
Employer Contributions	$ 29,000,000	$ 32,000,000

-- None. No documentation exists for this element. --

No definition available.

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Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

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- Definition

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of contributions received by defined benefit plan from participant which increase benefit obligation.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Amount of (increase) decrease in benefit obligation of defined benefit plan from event reducing expected years of future service of present employees or eliminating accrual of benefits for some or all future services of present employees.

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- Definition

Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

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- Definition

Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of contributions received by defined benefit plan from participant which increases plan assets.

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Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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