Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Equity [Abstract]
Foreign currency translation, net of income tax benefit of $2.8 and zero, respectively	$ 4.4	$ (9.8)
Derivative instrument fair market value, net of income tax expense of $1.8 and zero, respectively	3.6	0.8
Employee pension and postretirement benefit adjustments, net of income tax benefit of $6.5 and $6.3, respectively	(40.0)	(34.4)
Accumulated other comprehensive loss	(32.0)	(43.4)
Taxes on foreign currency translation	2.8	0.0
Taxes on derivative instruments	1.8	0.0
Income taxes pension and postretirement benefit adjustments	$ (6.5)	$ (6.3)