Other Expense, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Income and Expenses [Abstract]
Interest income	$ 0.6	$ 0.3	$ 0.2
Net periodic postretirement benefit cost relating to Salaried VEBA	(6.5)	(6.0)	(4.5)
Realized gain on available for sale securities1	4.4	5.4	3.2
Unrealized gain (loss) on equity securities	0.7	(1.0)	0.0
Loss on extinguishment of debt	(20.3)	0.0	0.0
All other, net	0.4	0.4	1.1
Other expense, net	$ (20.7)	$ (0.9)	0.0
Realized gain related to equity investments			$ 0.3