Environmental and Legal Contingencies (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Hamilton Plant [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	$ 0.7
Mansfield Works [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	1.1
Proposed civil penalty related to environmental issue	0.3
Ashland coke plant [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	0.4
Ambridge Works [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	2.2
Dicks Creek [Member]
Site Contingency [Line Items]
Site contingency accrual, undiscounted amount	15.0
Middletown Works [Member]
Site Contingency [Line Items]
Proposed civil penalty related to environmental issue	$ 0.3