Fair Value - Impairment of Long-Lived Assets (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of Long-Lived Assets to be Disposed of	$ 225.0
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	$ 0.0
Impairment of Long-Lived Assets to be Disposed of		0.0	28.8
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	0.0
Impairment of Long-Lived Assets to be Disposed of		$ 0.0	$ 1.2