Contingent Liabilities and Commitments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2016
Other Commitments [Abstract]
Commitments for construction and acquisition of property, plant, and equipment	$ 137.0
Accrued Liabilities [Member]
Site Contingency [Line Items]
Notice of Penalty	1.4		$ 1.6
Environmental assessment and remediation
Site Contingency [Line Items]
Accrued environmental assessment and remediation costs, total	3.5	$ 4.0
Accrued environmental assessment and remediation costs, current	1.5	1.8
Accrued environmental assessment and remediation costs, noncurrent	2.0	$ 2.2
Environmental assessment and remediation | Minimum
Site Contingency [Line Items]
Environmental assessment and remediation costs, best estimate	$ 5.0
Expected duration of environmental assessment and remediation spending	4 years
Environmental assessment and remediation | Maximum
Site Contingency [Line Items]
Environmental assessment and remediation costs, best estimate	$ 7.0
Expected duration of environmental assessment and remediation spending	6 years
Potentially responsible party at various Superfund and state waste disposal sites | Maximum
Site Contingency [Line Items]
Environmental assessment and remediation costs, best estimate	$ 0.5