Contingent Liabilities (Narrative) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Contingent Liabilities [Abstract]
Undiscounted remediation liability associated with environmentally contaminated non-operating facility	$ 5.8	$ 7.2

Total costs accrued as of the balance sheet date for environmental loss contingencies.

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Name:	us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant