Other (Expense) Income, Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other Income and Expenses [Abstract]
Interest income	$ 0.1	$ 0.0	$ 0.3	$ 0.1
Net periodic postretirement benefit cost relating to Salaried VEBA	(1.6)	(1.6)	(3.3)	(3.1)
Realized gain on available for sale securities	1.2	1.5	2.4	3.1
Unrealized (loss) gain on equity securities	0.0	(0.4)	0.5	(0.4)
All other income (expense), net	0.2	0.0	0.5	(0.1)
Other (expense) income, net	$ (0.1)	$ (0.5)	$ 0.4	$ (0.4)