Derivative Financial Instruments (Summary of Fair Value of Derivative Instruments on Consolidated Balance Sheet) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets, Fair Value	$ 14.1	$ 8.9
Derivative Liabilities, Fair Value	0.2	1.4
Other Current Assets [Member] | Natural Gas Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Fair Value	0.1
Other Current Assets [Member] | Foreign Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Fair Value	0.3
Other Current Assets [Member] | Interest Rate Swap Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Fair Value		0.2
Other Non-Current Assets [Member] | Interest Rate Swap Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets, Fair Value	13.7	8.7
Accounts Payable And Accrued Expenses [Member] | Natural Gas Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Fair Value	0.1	0.5
Accounts Payable And Accrued Expenses [Member] | Foreign Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Fair Value	$ 0.1	0.7
Other Long-Term Liabilities [Member] | Natural Gas Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Fair Value		0.1
Other Long-Term Liabilities [Member] | Foreign Exchange Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities, Fair Value		$ 0.1