Commitments and Contingencies	9 Months Ended
Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Legal Matters: Energen and its subsidiaries are, from time to time, parties to various pending or threatened legal proceedings and we have accrued a provision for our estimated liability. Certain of these lawsuits include claims for punitive damages in addition to other specified relief. We recognize a liability for contingencies, including an estimate of legal costs to be incurred, when information available indicates both a loss is probable and the amount of the loss can be reasonably estimated. Based upon information presently available, and in light of available legal and other defenses, contingent liabilities arising from threatened and pending litigation are not considered material in relation to the respective financial positions of Energen and its subsidiaries. It should be noted, however, that there is uncertainty in the valuation of pending claims and prediction of litigation results. On November 4, 2015, Energen Resources filed a quiet title action against Endeavor Energy Resources, L.P. (Endeavor) in the District Court of Howard County, Texas, to remove a cloud on the title to approximately 10,000 acres leased by Energen Resources in that county. Energen Resources believes the cloud on title arises from a prior, unreleased but partially terminated oil and gas lease covering the leased lands. The trial judge ruled with respect to the acreage not held by production that Endeavor’s lease terminated prior to the date Energen Resources entered into its lease. In November 2016, the trial judge entered a final judgment to that effect and that judgment was appealed by Endeavor in April 2017. On October 25, 2018, the Texas Eleventh Circuit Court of Appeals entered a judgment affirming the trial court’s final judgment in favor of Energen Resources. The judgment is subject to rehearing before the Eleventh Circuit Court of Appeals and may be appealed to the Supreme Court of Texas. In connection with the Merger Agreement and the transactions contemplated thereby, two purported class action lawsuits and an individual lawsuit have been filed. Two of the complaints, captioned Melvin Gross v. Energen Corporation, et al., Case No. 2:18-cv-01711-RDP (filed October 17, 2018) and Shiva Stein v. Energen Corporation, et al., Case 2:18-cv-01746-JHE (filed October 22, 2018), were filed in the United States District Court for the Northern District of Alabama. One complaint, captioned Jordan Rosenblatt v. Energen Corporation, et al., Case No. 01-CV-2018-9043232100 (filed October 26, 2018), was filed in the Circuit Court of Jefferson County, Alabama. The complaints assert claims against Energen and its directors. In general, the complaints allege that the defendants violated Sections 14(a) and 20(a) of the Exchange Act because the joint proxy statement/prospectus with respect to the Merger filed with the SEC allegedly misrepresents or omits material information or assert state law breaches of fiduciary duty based on such alleged misrepresentations or omissions. The complaints generally seek, among other things, injunctive relief preventing the consummation of the Merger, rescission in the event the Merger is consummated, and damages. The defendants believe that the actions are without merit. Environmental Matters: Various environmental laws and regulations apply to the operations of Energen and Energen Resources. Historically, the cost of environmental compliance has not materially affected our financial position, results of operations or cash flows. New regulations, enforcement policies, claims for damages or other events could result in significant unanticipated costs. During January 2014, Energen Resources responded to a General Notice and Information Request from the Environmental Protection Agency regarding the Reef Environmental Site (the Site) in Sylacauga, Talladega County, Alabama. The letter identifies Energen Resources as a potentially responsible party under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 for the cleanup of the Site. In 2008, Energen hired a third party to transport approximately 3,000 gallons of non-hazardous wastewater to Reef Environmental for wastewater treatment. Reef Environmental ceased operating its wastewater treatment system in 2010. Because it used Reef Environmental only one time for a small volume of non-hazardous wastewater, Energen Resources has not accrued a liability for cleanup of the Site. New Mexico Audits: In 2011, Energen Resources received an Order to Perform Restructured Accounting and Pay Additional Royalties (the Order), following an audit performed by the Taxation and Revenue Department (the Department) of the State of New Mexico on behalf of the Office of Natural Resources Revenue (ONRR), of federal oil and gas leases in New Mexico. The audit covered periods from January 2004 through December 2008 and included a review of the computation and payment of royalties due on minerals removed from specified U.S. federal leases. The Order addressed ONRR’s efforts to change accounting and reporting practices, and to unbundle fees charged by third parties that gather, compress and transport natural gas production. ONRR now maintains that all or some of such fees are not deductible. Energen Resources appealed the Order in 2011, and in July 2012, on a motion from ONRR, the Order was remanded. In August 2014, ONRR issued its Revised Order and Energen Resources appealed the Revised Order. In the Revised Order, ONRR ordered that Energen pay additional royalties on production from certain federal leases in the amount of $129,700. At ONRR’s request, the Revised Order was also remanded in August 2015. On April 15, 2016, ONRR issued its Second Revised Order. The Second Revised Order directs Energen Resources to pay additional royalties of $189,000, replacing the previous demand of $129,700. Energen estimates that application of the ONRR position to all of the Company’s federal leases would result in ONRR claims up to approximately $24 million, plus interest and penalties from 2004 forward. ONRR began implementing its unbundling initiative in 2010, but seeks to implement its revisions retroactively, despite the fact that they conflict with previous audits, allowances and industry practice. Energen is contesting the Second Revised Order, the predecessor orders and the findings. Management is unable, at this time, to determine a range of reasonably possible losses, and no amount has been accrued as of September 30, 2018. Income Taxes: In March 2018, the Company executed a statute of limitation extension for its 2014 federal consolidated income tax return until September 10, 2019. This extension was granted as part of the Company’s ongoing IRS examination of its 2014 and 2016 federal consolidated income tax returns. In June 2018, the Company received notice that the state of Alabama initiated an income tax audit for the 2014 tax year for all subsidiaries. Under SEC Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118), provisional amounts must be recorded for certain income tax effects of the 2017 Tax Cuts and Jobs Act for which the accounting under ASC 740 is incomplete, but a reasonable estimate can be determined. Energen recorded a provisional estimate of $0.4 million deferred income tax expense at December 31, 2017 with respect to the IRC Section 162(m) limitation and associated compensation-related deferred tax assets. As of September 30, 2018, the accounting for this income tax effect has been completed and no changes have been made to the provisional estimate recorded at December 31, 2017.

COMMITMENTS AND CONTINGENCIES

Legal Matters: Energen and its subsidiaries are, from time to time, parties to various pending or threatened legal proceedings and we have accrued a provision for our estimated liability. Certain of these lawsuits include claims for punitive damages in addition to other specified relief. We recognize a liability for contingencies, including an estimate of legal costs to be incurred, when information available indicates both a loss is probable and the amount of the loss can be reasonably estimated. Based upon information presently available, and in light of available legal and other defenses, contingent liabilities arising from threatened and pending litigation are not considered material in relation to the respective financial positions of Energen and its subsidiaries. It should be noted, however, that there is uncertainty in the valuation of pending claims and prediction of litigation results.

On November 4, 2015, Energen Resources filed a quiet title action against Endeavor Energy Resources, L.P. (Endeavor) in the District Court of Howard County, Texas, to remove a cloud on the title to approximately 10,000 acres leased by Energen Resources in that county. Energen Resources believes the cloud on title arises from a prior, unreleased but partially terminated oil and gas lease covering the leased lands. The trial judge ruled with respect to the acreage not held by production that Endeavor’s lease terminated prior to the date Energen Resources entered into its lease. In November 2016, the trial judge entered a final judgment to that effect and that judgment was appealed by Endeavor in April 2017. On October 25, 2018, the Texas Eleventh Circuit Court of Appeals entered a judgment affirming the trial court’s final judgment in favor of Energen Resources. The judgment is subject to rehearing before the Eleventh Circuit Court of Appeals and may be appealed to the Supreme Court of Texas.

In connection with the Merger Agreement and the transactions contemplated thereby, two purported class action lawsuits and an individual lawsuit have been filed. Two of the complaints, captioned Melvin Gross v. Energen Corporation, et al., Case No. 2:18-cv-01711-RDP (filed October 17, 2018) and Shiva Stein v. Energen Corporation, et al., Case 2:18-cv-01746-JHE (filed October 22, 2018), were filed in the United States District Court for the Northern District of Alabama. One complaint, captioned Jordan Rosenblatt v. Energen Corporation, et al., Case No. 01-CV-2018-9043232100 (filed October 26, 2018), was filed in the Circuit Court of Jefferson County, Alabama. The complaints assert claims against Energen and its directors. In general, the complaints allege that the defendants violated Sections 14(a) and 20(a) of the Exchange Act because the joint proxy statement/prospectus with respect to the Merger filed with the SEC allegedly misrepresents or omits material information or assert state law breaches of fiduciary duty based on such alleged misrepresentations or omissions. The complaints generally seek, among other things, injunctive relief preventing the consummation of the Merger, rescission in the event the Merger is consummated, and damages. The defendants believe that the actions are without merit.

Environmental Matters: Various environmental laws and regulations apply to the operations of Energen and Energen Resources. Historically, the cost of environmental compliance has not materially affected our financial position, results of operations or cash flows. New regulations, enforcement policies, claims for damages or other events could result in significant unanticipated costs.

During January 2014, Energen Resources responded to a General Notice and Information Request from the Environmental Protection Agency regarding the Reef Environmental Site (the Site) in Sylacauga, Talladega County, Alabama. The letter identifies Energen Resources as a potentially responsible party under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 for the cleanup of the Site. In 2008, Energen hired a third party to transport approximately 3,000 gallons of non-hazardous wastewater to Reef Environmental for wastewater treatment. Reef Environmental ceased operating its wastewater treatment system in 2010. Because it used Reef Environmental only one time for a small volume of non-hazardous wastewater, Energen Resources has not accrued a liability for cleanup of the Site.

New Mexico Audits: In 2011, Energen Resources received an Order to Perform Restructured Accounting and Pay Additional Royalties (the Order), following an audit performed by the Taxation and Revenue Department (the Department) of the State of New Mexico on behalf of the Office of Natural Resources Revenue (ONRR), of federal oil and gas leases in New Mexico. The audit covered periods from January 2004 through December 2008 and included a review of the computation and payment of royalties due on minerals removed from specified U.S. federal leases. The Order addressed ONRR’s efforts to change accounting and reporting practices, and to unbundle fees charged by third parties that gather, compress and transport natural gas production. ONRR now maintains that all or some of such fees are not deductible.

Energen Resources appealed the Order in 2011, and in July 2012, on a motion from ONRR, the Order was remanded. In August 2014, ONRR issued its Revised Order and Energen Resources appealed the Revised Order. In the Revised Order, ONRR ordered that Energen pay additional royalties on production from certain federal leases in the amount of $129,700. At ONRR’s request, the Revised Order was also remanded in August 2015. On April 15, 2016, ONRR issued its Second Revised Order. The Second Revised Order directs Energen Resources to pay additional royalties of $189,000, replacing the previous demand of $129,700. Energen estimates that application of the ONRR position to all of the Company’s federal leases would result in ONRR claims up to approximately $24 million, plus interest and penalties from 2004 forward. ONRR began implementing its unbundling initiative in 2010, but seeks to implement its revisions retroactively, despite the fact that they conflict with previous audits, allowances and industry practice. Energen is contesting the Second Revised Order, the predecessor orders and the findings. Management is unable, at this time, to determine a range of reasonably possible losses, and no amount has been accrued as of September 30, 2018.

Income Taxes: In March 2018, the Company executed a statute of limitation extension for its 2014 federal consolidated income tax return until September 10, 2019. This extension was granted as part of the Company’s ongoing IRS examination of its 2014 and 2016 federal consolidated income tax returns. In June 2018, the Company received notice that the state of Alabama initiated an income tax audit for the 2014 tax year for all subsidiaries.

Under SEC Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118), provisional amounts must be recorded for certain income tax effects of the 2017 Tax Cuts and Jobs Act for which the accounting under ASC 740 is incomplete, but a reasonable estimate can be determined. Energen recorded a provisional estimate of $0.4 million deferred income tax expense at December 31, 2017 with respect to the IRC Section 162(m) limitation and associated compensation-related deferred tax assets. As of September 30, 2018, the accounting for this income tax effect has been completed and no changes have been made to the provisional estimate recorded at December 31, 2017.