Commitments and Contingencies Commitments and Contingencies - Environmental Textuals (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Environmental-related assets	$ 24.5	$ 33.4
Discontinued Operations [Member]
Accrual for Environmental Loss Contingencies, Increase (Decrease) for Revision in Estimates	3.7	(0.7)
Environmental Issue [Member]
Gross Settlement with Insurance Provider for Environmental Matters			$ 34.2
Settlement Agreement with Insurer, Amount Received in Cash		2.0
Settlement Agreement with Insurer, Amount Deposited in Qualified Settlement Fund		32.2
Settlement Agreement with Insurer, Deferred Income		$ 23.0
Reduction to Environmental QSF Asset due to Settlement Agreement	5.2
Recognition of Environmental QSF Deferred Gain due to Amendment	$ 3.8