Fair Value of Impaired Assets (Details) $ in Millions	6 Months Ended
	Jun. 30, 2018 USD ($)
Property, Plant and Equipment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Long Lived Assets, Fair Value	$ 0.0
Impairment of Long-Lived Assets to be Disposed of	23.6
Other Assets and Deferred Charges [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Long Lived Assets, Fair Value	0.0
Impairment of Long-Lived Assets to be Disposed of	$ 0.3