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- References

No definition available.

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The cash inflow from the issuance of common limited partners units during the period, net of offering costs.

No definition available.

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Namespace Prefix:	energy12_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

Number of oil-producing wells and oil wells capable of production representing summation of fractional ownership working interest to whole.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Regulation S-K (SK)
-Number 229
-Section 1208
-Paragraph a
-Publisher SEC

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Data Type:	xbrli:integerItemType
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Number of oil and gas wells in process of being drilled.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name Regulation S-K (SK)
-Number 229
-Section 1206
-Paragraph a
-Publisher SEC

Name:	srt_WellsInProcessOfDrilling
Namespace Prefix:	srt_
Data Type:	xbrli:decimalItemType
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State in which the limited liability company or limited partnership was organized.

No definition available.

Name:	us-gaap_LimitedLiabilityCompanyOrLimitedPartnershipBusinessFormationState
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Data Type:	xbrli:stringItemType
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Total contributions made by each class of partners (i.e., general, limited and preferred partners).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 4.F)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

Name:	us-gaap_PartnersCapitalAccountContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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Total units issued during the year due to the sale of units. All partners include general, limited and preferred partners.

Name:	us-gaap_PartnersCapitalAccountUnitsSaleOfUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

The cash inflow from the issuance of common limited partners units during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 14
-Subparagraph (a)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-14

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

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Name:	us-gaap_BusinessAcquisitionAxis=energy12_BakkenAssetsMember
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Data Type:	na
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