Commitments and Contingencies (Details) - New Mexico Audits (Unfavorable Regulatory Action, USD $)	9 Months Ended
	Sep. 30, 2012
Unfavorable Regulatory Action
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Minimum	$ 142,000
Loss Contingency, Range of Possible Loss, Maximum	$ 23,000,000
Loss Contingency, Inestimable Loss	The preliminary findings and subsequent Order (issued April 25, 2011) are contrary to deductions allowed under previous audits, retroactive in application and inconsistent with the Company’s understanding of industry practice. The Company is vigorously contesting the Order and has requested additional information from the ONRR and the Department to assist the Company in evaluating the ONRR Order and the Department's findings. Management is unable, at this time, to determine a range of reasonably possible losses as a result of this Order, and no amount has been accrued as of June 30, 2012.