Basis of Presentation, Significant Accounting Policies, and Recently Issued Accounting Standards	9 Months Ended
Sep. 30, 2012
Accounting Policies [Abstract]
Basis of Presentation, Significant Accounting Policies, and Recently Issued Accounting Standards	Note 2 - Basis of Presentation, Significant Accounting Policies, and Recently Issued Accounting Standards Basis of Presentation The accompanying unaudited condensed consolidated financial statements of SM Energy have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and the instructions to Form 10-Q and Regulation S-X. They do not include all information and notes required by GAAP for complete financial statements. However, except as disclosed herein, there has been no material change in the information disclosed in the notes to consolidated financial statements included in SM Energy’s Annual Report on Form 10-K for the year ended December 31, 2011 (the “2011 Form 10-K”). In the opinion of management, all adjustments, consisting of normal recurring accruals that are considered necessary for a fair presentation of interim financial information, have been included. Operating results for the periods presented are not necessarily indicative of expected results for the full year. In connection with the preparation of its unaudited condensed consolidated financial statements, the Company evaluated events subsequent to the balance sheet date of September 30, 2012, through the filing date of this report. Other Significant Accounting Policies The accounting policies followed by the Company are set forth in Note 1 to the Company’s consolidated financial statements in the 2011 Form 10-K, and are supplemented throughout the notes to the unaudited condensed consolidated financial statements in this report. It is suggested that these unaudited condensed consolidated financial statements be read in conjunction with the consolidated financial statements and notes included in the 2011 Form 10-K. Recently Issued and Adopted Accounting Standards On January 1, 2012, the Company adopted new fair value measurement authoritative accounting guidance issued by the Financial Accounting Standards Board (the “FASB”), that clarifies the application of fair value measurement and disclosure requirements and changing particular principles and requirements for measuring fair value. For each class of assets and liabilities not measured at fair value in the Company's financial statements but for which fair value is disclosed, this guidance requires the Company to disclose the nature, characteristics, and risks of the asset or liability and the level of the fair value hierarchy within which the fair value measurement is categorized. Please refer to Note 11 - Fair Value Measurements in which the changes to the Company's financial statements resulting from the new authoritative guidance are presented. On January 1, 2012, the Company adopted new authoritative accounting guidance issued by the FASB stating an entity that reports items of other comprehensive income has the option to present the components of comprehensive income in either one continuous financial statement or two consecutive financial statements, including reclassification adjustments. Subsequent to the issuance of this authoritative guidance, the FASB issued additional authoritative accounting guidance that effectively deferred the requirement to present the reclassification adjustments on the face of the financial statements, as well as the requirement to present the individual components of other comprehensive income for interim periods. The adoption of this statement did not have a material impact on the Company. The Company has elected to present a separate statement of comprehensive income, including the individual components, titled condensed consolidated statements of comprehensive income (loss), as part of Item 1 to this report. On September 30, 2012, the Company elected to early adopt new authoritative accounting guidance issued by the FASB, which provided that an entity that tests indefinite-lived intangible assets for impairment has the option to assess qualitative factors to determine whether it is more likely than not that an asset is impaired as a basis for determining whether a quantitative test is necessary. The adoption of this statement did not have a material impact on the Company's financial statements. There are no new significant accounting standards applicable to the Company that have been issued but not yet adopted by the Company as of September 30, 2012.

Note 2 - Basis of Presentation, Significant Accounting Policies, and Recently Issued Accounting Standards

Basis of Presentation

The accompanying unaudited condensed consolidated financial statements of SM Energy have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and the instructions to Form 10-Q and Regulation S-X. They do not include all information and notes required by GAAP for complete financial statements. However, except as disclosed herein, there has been no material change in the information disclosed in the notes to consolidated financial statements included in SM Energy’s Annual Report on Form 10-K for the year ended December 31, 2011 (the “2011 Form 10-K”). In the opinion of management, all adjustments, consisting of normal recurring accruals that are considered necessary for a fair presentation of interim financial information, have been included. Operating results for the periods presented are not necessarily indicative of expected results for the full year. In connection with the preparation of its unaudited condensed consolidated financial statements, the Company evaluated events subsequent to the balance sheet date of September 30, 2012, through the filing date of this report.

Other Significant Accounting Policies

The accounting policies followed by the Company are set forth in Note 1 to the Company’s consolidated financial statements in the 2011 Form 10-K, and are supplemented throughout the notes to the unaudited condensed consolidated financial statements in this report. It is suggested that these unaudited condensed consolidated financial statements be read in conjunction with the consolidated financial statements and notes included in the 2011 Form 10-K.

Recently Issued and Adopted Accounting Standards

On January 1, 2012, the Company adopted new fair value measurement authoritative accounting guidance issued by the Financial Accounting Standards Board (the “FASB”), that clarifies the application of fair value measurement and disclosure requirements and changing particular principles and requirements for measuring fair value. For each class of assets and liabilities not measured at fair value in the Company's financial statements but for which fair value is disclosed, this guidance requires the Company to disclose the nature, characteristics, and risks of the asset or liability and the level of the fair value hierarchy within which the fair value measurement is categorized. Please refer to Note 11 - Fair Value Measurements in which the changes to the Company's financial statements resulting from the new authoritative guidance are presented.

On January 1, 2012, the Company adopted new authoritative accounting guidance issued by the FASB stating an entity that reports items of other comprehensive income has the option to present the components of comprehensive income in either one continuous financial statement or two consecutive financial statements, including reclassification adjustments. Subsequent to the issuance of this authoritative guidance, the FASB issued additional authoritative accounting guidance that effectively deferred the requirement to present the reclassification adjustments on the face of the financial statements, as well as the requirement to present the individual components of other comprehensive income for interim periods. The adoption of this statement did not have a material impact on the Company. The Company has elected to present a separate statement of comprehensive income, including the individual components, titled condensed consolidated statements of comprehensive income (loss), as part of Item 1 to this report.

On September 30, 2012, the Company elected to early adopt new authoritative accounting guidance issued by the FASB, which provided that an entity that tests indefinite-lived intangible assets for impairment has the option to assess qualitative factors to determine whether it is more likely than not that an asset is impaired as a basis for determining whether a quantitative test is necessary. The adoption of this statement did not have a material impact on the Company's financial statements.

There are no new significant accounting standards applicable to the Company that have been issued but not yet adopted by the Company as of September 30, 2012.