Business and Summary of Significant Accounting Principles (Asset Retirement Obligations Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Additional capitalized costs	$ 4.7	$ 4.9

The amount of asset retirement costs previously incurred and capitalized separately from the capitalized amount of the associated long-lived assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61901-109447

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant