Impairment of Long-Lived Assets	3 Months Ended
Mar. 31, 2013
Impairment of Long-Lived Assets	6. Impairment of Long-Lived Assets The Company reviews the carrying values of its long-lived assets annually or whenever events or changes in circumstances indicate that such carrying values may not be recoverable. If, upon review, the sum of the undiscounted pretax cash flows is less than the carrying value of the asset group, the carrying value is written down to estimated fair value. Individual assets are grouped for impairment purposes at the lowest level for which there are identifiable cash flows that are largely independent of the cash flows of other groups of assets, generally on a field-by-field basis. The fair value of impaired assets is determined based on quoted market prices in active markets, if available, or upon the present values of expected future cash flows using discount rates commensurate with the risks involved in the asset group. The impairment analysis performed by the Company may utilize Level 3 inputs. The long-lived assets of the Company consist primarily of proved oil and gas properties and undeveloped leaseholds. The Company completed an exploration well targeting the Niobrara, Dakota and Frontier formations in 2012. Upon completion, the Company determined that it did not expect to recover the full amount of capitalized costs associated with this exploration well, and wrote-off a portion of the capitalized costs in the fourth quarter of 2012. The Company incurred $1,039 of additional costs related to this well in the first quarter of 2013, which were charged to impairment expense consistent with the Company’s 2012 year-end assessment. In the three months ended March 31, 2012, the Company recorded impairment expense of $301 related to wells that were plugged and abandoned at a non-operated property. The Company also wrote off $25 and $4 during the three months ended March 31, 2013 and 2012, respectively, related to expired undeveloped leaseholds.

6. Impairment of Long-Lived Assets

The Company reviews the carrying values of its long-lived assets annually or whenever events or changes in circumstances indicate that such carrying values may not be recoverable. If, upon review, the sum of the undiscounted pretax cash flows is less than the carrying value of the asset group, the carrying value is written down to estimated fair value. Individual assets are grouped for impairment purposes at the lowest level for which there are identifiable cash flows that are largely independent of the cash flows of other groups of assets, generally on a field-by-field basis. The fair value of impaired assets is determined based on quoted market prices in active markets, if available, or upon the present values of expected future cash flows using discount rates commensurate with the risks involved in the asset group. The impairment analysis performed by the Company may utilize Level 3 inputs. The long-lived assets of the Company consist primarily of proved oil and gas properties and undeveloped leaseholds.

The Company completed an exploration well targeting the Niobrara, Dakota and Frontier formations in 2012. Upon completion, the Company determined that it did not expect to recover the full amount of capitalized costs associated with this exploration well, and wrote-off a portion of the capitalized costs in the fourth quarter of 2012. The Company incurred $1,039 of additional costs related to this well in the first quarter of 2013, which were charged to impairment expense consistent with the Company’s 2012 year-end assessment. In the three months ended March 31, 2012, the Company recorded impairment expense of $301 related to wells that were plugged and abandoned at a non-operated property. The Company also wrote off $25 and $4 during the three months ended March 31, 2013 and 2012, respectively, related to expired undeveloped leaseholds.