Environmental and Legal Contingencies (Details 2) $ in Millions	6 Months Ended
Jun. 30, 2017 USD ($)
Hamilton Plant [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	$ 0.7
Mansfield OH Works [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	1.1
Ashland coke plant [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	1.4
Ambridge Works [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	5.6
Middletown Works RCRA Site [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	13.6
Zanesville Works RCRA [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	0.7
CivilPenalty [Member] \| Middletown Works [Member]
Site Contingency [Line Items]
Site Contingency, Loss Exposure Not Accrued, Best Estimate	$ 0.1

Undiscounted amount of the accrual for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.Y.Q1)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

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+ References

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- Definition

Best estimate of the loss exposure for reasonably possible environmental contingencies at an individual site for which no accrual has been recorded.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 10
-Subparagraph (c),(d)(2)
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13237-110859

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