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The net cash impact recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

No definition available.

Name:	epm_DepreciationDepletionAndAmortizationCashFlowsImpact
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Represents the change in amount that is due from joint interest partner during the reporting period.

No definition available.

Name:	epm_IncreaseDecreaseInAmountDueFromJointInterestPartner
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Represents the change in the amount of receivables during the reporting period from the sale of oil and natural gas of the reporting entity.

No definition available.

Name:	epm_IncreaseDecreaseInReceivablesFromOilAndNaturalGasSales
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Represents the cash outflow in relation to the acquisition of oil and gas properties during the reporting period.

No definition available.

Name:	epm_PaymentForAcquisitionOfOilAndGasProperties
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Represents the cash outflow in relation to the development of oil and gas properties during the reporting period.

No definition available.

Name:	epm_PaymentForDevelopmentOfOilAndGasProperties
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The cash outflow resulting from purchase of the treasury stock under the cost method.

No definition available.

Name:	epm_PaymentsForPurchaseOfTreasuryStockCostMethod
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Represents the cash outflow during the reporting period for asset retirement obligations.

No definition available.

Name:	epm_PaymentsOnAssetRetirementObligations
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This element depicts the amount that the reporting entity received when certificates of deposit matured on their specified due date during the reporting period.

No definition available.

Name:	epm_ProceedsFromMaturitiesOfCertificatesOfDeposit
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Share Based Compensation, Restructuring Expense

No definition available.

Name:	epm_ShareBasedCompensationRestructuringExpense
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Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Amount of deferred income tax expense (benefit) pertaining to income (loss) from continuing operations.

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Amount of cash inflow from realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes.

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The increase (decrease) during the reporting period in the amounts payable to vendors for goods and services received and the amount of obligations and expenses incurred but not paid.

Name:	us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

The increase (decrease) during the reporting period of all taxes owed but not paid, including income, property and other taxes.

No definition available.

Name:	us-gaap_IncreaseDecreaseInAccruedTaxesPayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

The increase (decrease) during the reporting period in income taxes receivable, which represents the amount due from tax authorities for refunds of overpayments or recoveries of income taxes paid.

Name:	us-gaap_IncreaseDecreaseInIncomeTaxesReceivable
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Balance Type:	credit
Period Type:	duration

Name:	us-gaap_IncreaseDecreaseInOperatingCapitalAbstract
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Period Type:	duration

The increase (decrease) during the reporting period in the value of prepaid expenses and other assets not separately disclosed in the statement of cash flows, for example, deferred expenses, intangible assets, or income taxes.

Name:	us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets
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Balance Type:	credit
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The increase (decrease) in cash associated with the entity's continuing operating, investing, and financing activities. While for technical reasons this element has no balance attribute, the default assumption is a debit balance consistent with its label.

No definition available.

Name:	us-gaap_NetCashProvidedByUsedInContinuingOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Amount of cash inflow (outflow) of financing activities, excluding discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Name:	us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperations
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Name:	us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Amount of cash inflow (outflow) of investing activities, excluding discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

Name:	us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Name:	us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract
Namespace Prefix:	us-gaap_
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Period Type:	duration

Amount of cash inflow (outflow) from operating activities, excluding discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

Name:	us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract
Namespace Prefix:	us-gaap_
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Period Type:	duration

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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-Glossary Other Comprehensive Income

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-Glossary Net Income

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-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.18)

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-Section S99

-Paragraph 1

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-Name Regulation S-X (SX)

-Number 210

-Section 03

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-Article 5

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Name:	us-gaap_NetIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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The net cash outflow or inflow from other investing activities. This element is used when there is not a more specific and appropriate element in the taxonomy.

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-Glossary Investing Activities

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Name:	us-gaap_PaymentsForProceedsFromOtherInvestingActivities
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The cash outflow paid to third parties in connection with debt origination, which will be amortized over the remaining maturity period of the associated long-term debt.

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Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

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Amount of cash outflow in the form of ordinary dividends to preferred shareholders of the parent entity.

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The cash outflow associated with the investment in or advances to an entity in which the reporting entity shares control of the entity with another party or group.

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Name:	us-gaap_PaymentsToAcquireInterestInJointVenture
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The cash outflow for acquisition of or capital improvements of property, plant and equipment, used to produce goods or deliver services, and not otherwise defined in the taxonomy.

Name:	us-gaap_PaymentsToAcquireOtherPropertyPlantAndEquipment
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Proceeds from issuance of capital stock which provides for a specific dividend that is paid to the shareholders before any dividends to common stockholders and which takes precedence over common stockholders in the event of liquidation.

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The net cash inflow or outflow from other financing activities. This element is used when there is not a more specific and appropriate element in the taxonomy.

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-Glossary Financing Activities

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Name:	us-gaap_ProceedsFromPaymentsForOtherFinancingActivities
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The cash inflow from the sale of property, plant and equipment (capital expenditures), software, and other intangible assets.

Name:	us-gaap_ProceedsFromSaleOfProductiveAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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-Name Accounting Standards Codification

-Glossary Financing Activities

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Name:	us-gaap_ProceedsFromStockOptionsExercised
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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.