Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Equity [Abstract]
Foreign currency translation, net of income tax benefit of $2.5 million and $2.8 million at June 30, 2018 and December 31, 2017, respectively	$ (3.1)	$ 4.4
Derivative instrument fair market value, net of income tax expense of $1.8 million at June 30, 2018 and December 31, 2017	4.4	3.6
Employee pension and postretirement benefit adjustments, net of income tax benefit of $6.3 million and $6.5 million at June 30, 2018 and December 31, 2017, respectively	(39.0)	(40.0)
Accumulated other comprehensive loss	(37.7)	(32.0)
Foreign currency translation tax effect	2.5	2.8
Derivative instrument fair market value tax effect	1.8	1.8
Employee pension and postretirement benefit adjustments tax effect	$ 6.3	$ 6.5