Environmental and Legal Contingencies (Details 4) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Schumacher [Member]
Loss Contingencies [Line Items]
Loss Contingency, Number of Plaintiffs		92
Potential exposure of increase to defined benefit plan obligation	$ 3,000,000	$ 3,000,000
Patrick [Member]
Loss Contingencies [Line Items]
Potential exposure of increase to defined benefit plan obligation	28,900,000	28,900,000
Lipker [Member]
Loss Contingencies [Line Items]
Monthly benefit payment, individual arrangement	463	463
Consolidation Coal [Member]
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought, Value		30,000,000
Loss Contingency Damages Sought Value Codefendant		20,000,000
Other Postretirement Benefit Plans, Defined Benefit [Member] | Zanesville Works Retiree Healthcare Benefits Litigation [Member]
Loss Contingencies [Line Items]
Amount of combined lump sum payments to VEBA and plaintiff's counsel	10,600,000
Amount of cash contributions to the VEBA trust in the second fiscal year following the latest fiscal year	3,100,000	3,100,000
Amount Of Cash Contributions To Veba Trust In Third Fiscal Year Following Latest Fiscal Year	3,100,000	3,100,000
Amount of Cash Contributions to VEBA Trust in Fourth Fiscal Year Following Latest Fiscal Year	3,100,000	3,100,000
Increase in benefit obligation from litigation settlement		3,000,000
Reversal of Prior Amortization Related to Retiree Settlement and Legal Fees	$ 3,800,000	$ 3,800,000
Amortization Period On Remaining Portion Of Reversed Prior Amortization Recorded In Other Comprehensive Income In Number Of Years		2 years