Pension and Retiree Medical Benefits Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 23, 2019	Mar. 24, 2018
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer, Discretionary	$ 150	$ 1,400
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Contributions by Employer, Discretionary	$ 17	$ 17