Postretirement Benefits Assumed Health Care Trend Rates (Details)	12 Months Ended
	Dec. 31, 2017 Rate	Jan. 01, 2017 Rate	Jan. 03, 2016 Rate	Dec. 28, 2014 Rate
Compensation and Retirement Disclosure [Abstract]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year, pre-65	7.25%	7.50%		7.75%
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year, post-65	6.25%	6.50%		6.75%
Prescription drug benefit cost trend rate assumed for the following year	10.50%	10.50%		11.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	3.89%	3.89%	3.89%
Year that the rate reaches the ultimate trend rate	2075	2075		2075