Retirement Plans (Schedule of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 27, 2019	Dec. 28, 2018	Dec. 29, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.1	$ 0.2	$ 1.4
Interest cost	0.7	0.6	2.3
Expected return on plan assets	0.0	0.0	(1.3)
Amortization of net actuarial loss	0.5	0.5	2.7
Amortization of prior service cost	0.2	0.1	0.2
Loss (gain) on plan settlements	0.0	0.1	71.1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	0.0	0.0	1.0
Net period benefit cost (credit)	1.5	1.5	75.4
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.0	0.0	0.0
Interest cost	1.6	1.5	1.7
Expected return on plan assets	0.0	0.0	0.0
Amortization of net actuarial loss	0.0	0.1	0.0
Amortization of prior service cost	(2.1)	(2.1)	(2.0)
Loss (gain) on plan settlements	0.0	(0.7)	(0.9)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	0.0	0.0	0.0
Net period benefit cost (credit)	$ (0.5)	$ (1.2)	$ (1.2)