Income Taxes - Deferred Income Tax Assets, Liabilities and Related Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance [Line Items]
Provisional net tax benefit			$ (156.5)
Deferred Income Tax Assets:
Compensation Based Accruals				$ 3.7	$ 2.8
Net Operating Loss Carryforwards				30.5	29.4
Postretirement Benefits				0.7	0.8
Tax Credits				0.7	1.5
Other				1.9	1.9
Valuation Allowance	$ (31.8)	$ (31.2)	(45.5)	(31.8)	(26.1)
Total Deferred Income Tax Assets				5.7	10.3
Deferred Income Tax Liabilities:
Property, Plant and Equipment				(16.3)	(14.8)
Goodwill				(1.8)	(1.5)
Other Intangibles				(12.1)	(12.2)
Other				(0.3)	0.0
Net Noncurrent Deferred Income Tax Liabilities				(30.5)	(28.5)
Net Deferred Income Tax Liability				(24.8)	$ (18.2)
Summary of Valuation Allowances
Balance at End of Period	31.8	26.1	31.2
Balance Beginning of Period	26.1	31.2	45.5
International
Deferred Income Tax Assets:
Valuation Allowance	(31.8)			$ (31.8)
Summary of Valuation Allowances
Balance at End of Period	31.8
Deferred Tax Assets
Summary of Valuation Allowances
Charges to Costs and Expenses	(5.6)	2.9	14.8
Deductions	$ 0.1	$ (2.2)
Additions			$ 0.5