Pension and Post-Retirement Plans (Components of Net Pension Expense and Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 14, 2014	Jun. 15, 2013	Jun. 14, 2014	Jun. 15, 2013
Pension [Member]
Components of net pension expense:
Estimated return on assets	$ (27.5)	$ (24.9)	$ (55.0)	$ (49.8)
Service cost	9.7	9.7	19.5	19.5
Interest cost	22.3	19.7	44.5	39.4
Amortization of prior service cost (credit)	2.3	3.0	4.5	5.9
Amortization of unrecognized losses	9.8	18.0	19.6	35.9
Total	16.6	25.5	33.1	50.9
Other Post-Retirement Benefits [Member]
Components of net pension expense:
Estimated return on assets	0	0	0	0
Service cost	0.2	0.1	0.4	0.3
Interest cost	0.8	0.7	1.6	1.4
Amortization of prior service cost (credit)	(0.1)	0	(0.1)	(0.1)
Amortization of unrecognized losses	0.1	0.2	0.2	0.5
Total	$ 1.0	$ 1.0	$ 2.1	$ 2.1