Name:	epsn_LeverageRatio
Namespace Prefix:	epsn_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

The hedging requirement under line of credit facility as percent of projected production volume.

No definition available.

Name:	epsn_LineOfCreditFacilityHedgingRequirementAsPercentOfProjectedProductionVolume
Namespace Prefix:	epsn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The minimum utilization percentage of production for maintaining acceptable commodity hedging agreements.

No definition available.

Name:	epsn_MinimumUtilizationPercentageNaturalGasProduction
Namespace Prefix:	epsn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The threshold percent of utilization of credit facility for cash distributions to parent.

No definition available.

Name:	epsn_ThresholdPercentOfFacilityUtilizationForCashDistributions
Namespace Prefix:	epsn_
Data Type:	dtr-types:percentItemType
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Period Type:	duration

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:	dtr-types: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://fasb.org/us-gaap/role/ref/legacyRef
-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=120391452&loc=d3e13212-122682

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

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
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Period Type: