Employee Benefit Plans (Health Care Cost Trend Rates) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 26, 2014	Dec. 27, 2013
Maximum [Member]
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect of a one percent increase on service and interest costs	1
Effect of a one percent increase on postretirement benefit obligation	1
Post-retirement Benefits [Member]
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Expected rates assumed in health care costs trend rates for medical plans (in hundreds)	4.75%
Components of Benefit Cost: Non-Medicare Eligible	8.00%	8.50%
Components of Benefit Cost: Medicare Eligible	7.50%	8.00%
Benefit Obligations: Non-Medicare Eligible	8.00%	8.00%
Benefit Obligations: Medicare Eligible	7.50%	7.50%