Pension Plans and Postretirement Benefits (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Pension Plan
Components of net period pension benefit expense
Service cost — benefits earned during the period	$ 2.7	$ 2.7	$ 8.1	$ 8.1
Interest cost on benefit obligation	8.2	9.1	24.5	27.4
Expected return on plan assets	(17.9)	(18.3)	(53.7)	(54.9)
Amortization of prior service cost	(1.5)	(1.5)	(4.5)	(4.5)
Amortization of net actuarial loss (gain)	7.8	7.3	23.6	21.9
Net periodic (income) expense	(3.4)	(3.4)	(10.1)	(10.1)
Other Postretirement Benefits Plan
Components of net period pension benefit expense
Interest cost on benefit obligation	0.1	0.1	0.3	0.3
Amortization of net actuarial loss (gain)	(0.1)	(0.1)	(0.3)	(0.3)
Net periodic (income) expense	$ 0.0	$ 0.0	$ 0.0	$ 0.0