Postretirement Benefits Other Than Pensions (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) employees	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Income (Loss) from Continuing Operations before Income Taxes	$ 44.2	$ 68.3	$ 52.1	$ (3.5)	$ 40.6	$ (33.2)	$ 2.6	$ (6.5)	$ 161.1	$ 3.5	$ 100.3
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of retired employees covered | employees									475
Number of active employees covered | employees									200
Plan Amendments									$ 0.0	(11.0)
Effect of one percentage point increase on accumulated postretirement benefit obligation									0.6	$ 0.6
Amounts that will be amortized from AOCI in next Fiscal Year									3.0
Estimated future employer contributions in next fiscal year									$ 1.6
Medical Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year									7.50%	6.80%
Health care cost trend rate assumed for future years									4.80%	5.00%
Prescription Drug Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next fiscal year									10.00%	10.30%
Health care cost trend rate assumed for future years									4.80%	5.00%