Pension, Retiree Medical and Savings Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period of active plan participants, pension expense		11
Defined Benefit Plan, Average remaining life expectancy of Inactive Plan Participants, Pension Expense		27
Average remaining service period of active plan participants, retiree medical expense		7
Pension strategy investment term, years		5 years
Defined Contribution Plan, Cost		$ 176	$ 164	$ 148
Pre-tax non-cash settlement charge, after-tax			162
Change in accounting estimate			125
Change in Accounting Estimate after Tax			$ 81
Change in Accounting Estimate per Share			$ 0.06
Cost Savings Related to Reorganization of U.S. Pension Plans		42
Cost Savings Related to Reorganization of U.S. Pension Plans Net of Tax		$ 27
Cost Savings Related to Reorganization of U.S. Pension Plans Net of Tax, Earnings per Share		$ 0.02
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets		7.50%	7.50%	7.50%
Discretionary contribution to fund pension settlement			$ 452
Pre-tax non-cash settlement charge			$ 242
Pre-tax non-cash settlement charge, net of tax, per share			$ 0.11
Retiree Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets		7.50%	7.50%	7.50%
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 175
Scenario, Forecast [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	7.20%
Scenario, Forecast [Member] | Retiree Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 75
Subsequent Event [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	1,400
Subsequent Event [Member] | Funded Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	$ 800