Retirement Plans (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 24, 2016	Jun. 30, 2017	Jun. 24, 2016
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.2	$ 0.4	$ 1.5	$ 0.8
Interest cost	0.4	3.5	2.1	7.0
Expected return on plan assets	0.0	(4.2)	(1.3)	(8.4)
Amortization of net actuarial loss	0.4	2.6	2.6	5.2
Amortization of prior service cost	0.1	0.0	0.2	0.0
Plan settlements	0.5	3.3	69.7	7.0
Net periodic benefit cost	1.6	5.6	74.8	11.6
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 0.0	$ 0.0	$ 0.0	$ 0.1