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 term of the debt agreement.

No definition available.

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

The amount that is to be reduced by the Lender's Regulation D reserve requirement, used to determine the adjusted variable rate to the debt instrument.

No definition available.

Name:	epm_DebtInstrumentVariableRateBasisAmountToBeReducedByLenderRegulationDReserveRequirement
Namespace Prefix:	epm_
Data Type:	xbrli:integerItemType
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 number of loans that can be outstanding at any time.

No definition available.

Name:	epm_LineOfCreditFacilityNumberOfLoansOutstanding
Namespace Prefix:	epm_
Data Type:	xbrli:integerItemType
Balance Type:	na
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

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

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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

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

Amount borrowed under the credit facility as of the balance sheet date.

Reference 1: 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_LineOfCreditFacilityAmountOutstanding
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.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: 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 3: 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_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.