Environmental and Other Contingencies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended	45 Months Ended
	Mar. 31, 2018	Sep. 30, 2018	Dec. 31, 2015	Sep. 30, 2018
Environmental and Other Contingencies [Abstract]
Remediation costs	$ 3.8		$ 43.9
Payments for environmental liabilities				$ 43.1
Remediation accrual		$ 4.7		$ 4.7
Proceeds from insurance settlement		$ 25.0