Contingent Liability Contingent Liability (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Dec. 31, 2015
Loss Contingencies [Line Items]
Environmental Remediation Term	10 years
Environmental Exit Costs, Reasonably Possible Additional Losses, Low Estimate	$ 0.9
Capitalizable Environmental Exit Costs	0.3
Environmental Exit Costs, Liability for Remediation	1.0	$ 0.3
Minimum [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Anticipated Cost	0.3
Maximum [Member]
Loss Contingencies [Line Items]
Environmental Exit Costs, Anticipated Cost	$ 1.4