Accounting Changes and Error Corrections Accounting Changes and Error Corrections (Policies)	12 Months Ended
Dec. 31, 2013
Accounting Changes and Error Corrections [Abstract]
Restatement, Policy	Restatement of Previously Issued Consolidated Financial Statements Overview. In connection with the preparation of our financial statements for the quarter ended September 30, 2014, we determined that the ceiling test calculation we had prepared at December 31, 2013, March 31, 2009 and December 31, 2008, to determine whether the net book value of the Company's oil and gas properties exceed the ceiling, incorrectly included the deferred income tax effect of the Company's asset retirement obligations when computing the ceiling test limitation of its oil and natural gas properties under the full-cost method of accounting. The Company determined that the error caused a material overstatement of its full-cost ceiling test write-down of oil and gas properties in periods prior to 2014, more specifically in the fourth quarter of 2013, in the first quarter of 2009 and the fourth quarter of 2008, including associated depletion for all periods presented. As a result of this error, we are restating our audited consolidated financial statements for the years ended December 31, 2013, 2012 and 2011 and our unaudited condensed consolidated financial information for the quarters ended March 31, 2013, June 30, 2013, September 30, 2013, and December 31, 2013. As of December 31, 2013, the correction of this error increased the Company's net oil and gas property balances by approximately $49 million, increased net deferred tax liabilities by approximately $18 million, and increased retained earnings by approximately $31 million. Approximately $15 million of the increase in retained earnings is related to periods prior to 2013, more specifically to the first quarter of 2009 and the fourth quarter of 2008. For the year ended December 31, 2013, the correction of the ceiling test error resulted in a decrease in our ceiling-test write-down for the year ended December 31, 2013 of approximately $27 million, which was partially offset by an increase in our depreciation, depletion and amortization expense for full year 2013 of approximately $1 million. These corrections increased net income for the year ended December 31, 2013 by approximately $16 million (net of an increase to the income tax benefit of approximately $9 million for the period). Along with restating our financial statements to correct the error discussed above, we have recorded adjustments for certain previously identified immaterial accounting errors related to the periods covered by this Form 10-K/A. When these financial statements were originally issued, we assessed the impact of these errors and concluded that they were not material to our financial statements for the each of the years ended December 31, 2013, 2012, and 2011, and reported fiscal quarters within each of these years. However, in conjunction with our need to restate our financial statements as a result of the error noted above, we have determined that it would be appropriate to make adjustments for all such previously unrecorded adjustments in this Form 10-K/A.

Restatement of Previously Issued Consolidated Financial Statements

Overview. In connection with the preparation of our financial statements for the quarter ended September 30, 2014, we determined that the ceiling test calculation we had prepared at December 31, 2013, March 31, 2009 and December 31, 2008, to determine whether the net book value of the Company's oil and gas properties exceed the ceiling, incorrectly included the deferred income tax effect of the Company's asset retirement obligations when computing the ceiling test limitation of its oil and natural gas properties under the full-cost method of accounting. The Company determined that the error caused a material overstatement of its full-cost ceiling test write-down of oil and gas properties in periods prior to 2014, more specifically in the fourth quarter of 2013, in the first quarter of 2009 and the fourth quarter of 2008, including associated depletion for all periods presented. As a result of this error, we are restating our audited consolidated financial statements for the years ended December 31, 2013, 2012 and 2011 and our unaudited condensed consolidated financial information for the quarters ended March 31, 2013, June 30, 2013, September 30, 2013, and December 31, 2013.

As of December 31, 2013, the correction of this error increased the Company's net oil and gas property balances by approximately $49 million, increased net deferred tax liabilities by approximately $18 million, and increased retained earnings by approximately $31 million. Approximately $15 million of the increase in retained earnings is related to periods prior to 2013, more specifically to the first quarter of 2009 and the fourth quarter of 2008. For the year ended December 31, 2013, the correction of the ceiling test error resulted in a decrease in our ceiling-test write-down for the year ended December 31, 2013 of approximately $27 million, which was partially offset by an increase in our depreciation, depletion and amortization expense for full year 2013 of approximately $1 million. These corrections increased net income for the year ended December 31, 2013 by approximately $16 million (net of an increase to the income tax benefit of approximately $9 million for the period).

Along with restating our financial statements to correct the error discussed above, we have recorded adjustments for certain previously identified immaterial accounting errors related to the periods covered by this Form 10-K/A. When these financial statements were originally issued, we assessed the impact of these errors and concluded that they were not material to our financial statements for the each of the years ended December 31, 2013, 2012, and 2011, and reported fiscal quarters within each of these years. However, in conjunction with our need to restate our financial statements as a result of the error noted above, we have determined that it would be appropriate to make adjustments for all such previously unrecorded adjustments in this Form 10-K/A.