Name:	epm_DebtInstrumentCovenantConsolidatedInterestCoverageRatio
Namespace Prefix:	epm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

Represents the ratio of consolidated total funded indebtedness to consolidated earnings before, interest, taxes, depreciation and amortization allowed under the covenants of the credit facility.

No definition available.

Name:	epm_DebtInstrumentCovenantConsolidatedLeverageRatio
Namespace Prefix:	epm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

Represents the current ratio allowed under the covenants of the credit facility.

No definition available.

Name:	epm_DebtInstrumentCovenantCurrentRatio
Namespace Prefix:	epm_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

Represents the term of interest period four of a debt instrument.

No definition available.

Name:	epm_DebtInstrumentInterestPeriodFourTerm
Namespace Prefix:	epm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the term of interest period one of a debt instrument.

No definition available.

Name:	epm_DebtInstrumentInterestPeriodOneTerm
Namespace Prefix:	epm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the term covered by an interest payment for a debt instrument interest period.

No definition available.

Name:	epm_DebtInstrumentInterestPeriodPaymentTerm
Namespace Prefix:	epm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the term of interest period three of a debt instrument.

No definition available.

Name:	epm_DebtInstrumentInterestPeriodThreeTerm
Namespace Prefix:	epm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the term of interest period two of a debt instrument.

No definition available.

Name:	epm_DebtInstrumentInterestPeriodTwoTerm
Namespace Prefix:	epm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the amount to be compensated to the lender for incurred loan costs upon closing of Credit Agreement.

No definition available.

Name:	epm_LineOfCreditFacilityLoanCostsToBeCompensatedToLender
Namespace Prefix:	epm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Represents the percentage of the value of the oil and gas properties as a limitation of borrowing amount.

No definition available.

Name:	epm_LineOfCreditFacilityPercentageOfValueOfOilAndGasPropertiesAsBorrowingLimitation
Namespace Prefix:	epm_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

No definition available.

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

No definition available.

Name:	us-gaap_DebtIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

No definition available.

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

Name:	us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

No definition available.

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.