Environmental (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Environmental Exit Cost [Line Items]
Environmental Exit Costs, Anticipated Cost	$ 2.4
Environmental Costs Recognized, Capitalized	0.8
Loss Contingency, Settlement Agreement, Date	May 16, 2012
Gain (Loss) Related to Litigation Settlement	3.7
Contribution payable to non profit corporation or trust created by Ute Idian tribe	$ 0.4
Loss Contingency, Settlement Agreement, Counterparty's Name	Ute Indian Tribe of the Uintah and Ouray Reservation