Environmental and Legal Contingencies (Details 2) $ in Millions	Sep. 30, 2019 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	0.4
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	4.8
Middletown Works RCRA Site [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	13.2
Zanesville Works RCRA [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	$ 0.8