Pension Benefits - Schedule of Assumptions Used (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 25, 2016	Dec. 27, 2015	Dec. 28, 2014
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Calculation term, market-related value	3 years
Increase (decrease) to pension obligation due to change in mortality table assumptions	$ (34.7)		$ 117.0
Decrease in service costs and interest costs	$ (18.0)
Non-Qualified Plans [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.17%	4.40%
Estimated increase in compensation level used to calculate benefit obligation	2.50%	2.50%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate for determining projected benefit obligation	4.40%	3.90%	4.60%
Discount rate in effect for determining interest cost	3.44%	3.90%	4.60%
Rate of increase in compensation levels	2.50%	2.50%	2.50%
Qualified Plans [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.31%	4.60%
Estimated increase in compensation level used to calculate benefit obligation	2.95%	2.96%
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Discount rate for determining projected benefit obligation	4.60%	4.05%	4.90%
Discount rate in effect for determining service cost	5.78%	4.05%	4.90%
Discount rate in effect for determining interest cost	3.68%	4.05%	4.90%
Rate of increase in compensation levels	2.91%	2.89%	2.87%
Expected long-term rate of return on assets	7.01%	7.01%	7.02%
Minimum [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Spot rate used in calculation of service and interest costs	1.32%
Maximum [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]
Spot rate used in calculation of service and interest costs	4.79%