Environmental and Legal Contingencies (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
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
Ashland Works [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	$ 15.2

Estimated undiscounted amount of the accrual for the environmental loss contingencies at an individual site as of the balance sheet date.

Reference 1: 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 96-1

-Paragraph 132, 161, 163

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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