Pension, Retiree Medical and Savings Plans (Weighted-Average Assumptions to Determine Projected Benefit Liability and Benefit Expense for Pension and Retiree Medical Plans) (Details)		12 Months Ended
		Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
United States Pension Plan of US Entity, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Liability discount rate		3.70%	4.40%	4.50%
Interest cost discount rate	[1]	3.70%	3.80%
Service Cost Discount Rate	[1]	4.50%	4.60%
Expense discount rate (a)	[1]			4.20%
Expected return on plan assets		7.50%	7.50%	7.50%
Liability rate of salary increases		3.10%	3.10%	3.10%
Expense rate of salary increases		3.10%	3.10%	3.50%
International
Defined Benefit Plan Disclosure [Line Items]
Liability discount rate		3.00%	3.10%	4.00%
Interest cost discount rate	[1]	2.80%	3.50%
Service Cost Discount Rate	[1]	3.60%	4.10%
Expense discount rate (a)	[1]			3.80%
Expected return on plan assets		6.00%	6.20%	6.50%
Liability rate of salary increases		3.70%	3.60%	3.60%
Expense rate of salary increases		3.60%	3.60%	3.60%
Retiree Medical Plan
Defined Benefit Plan Disclosure [Line Items]
Liability discount rate		3.50%	4.00%	4.20%
Interest cost discount rate	[1]	3.20%	3.30%
Service Cost Discount Rate	[1]	4.00%	4.30%
Expense discount rate (a)	[1]			3.80%
Expected return on plan assets		7.50%	7.50%	7.50%

[1] Effective as of the beginning of 2016, we prospectively changed the method we use to estimate the service and interest cost components of pension and retiree medical expense. See additional unaudited information in “Our Critical Accounting Policies” in Management’s Discussion and Analysis of Financial Condition and Results of Operations.