Litigation Settlement, Amount Awarded To Other Party, Portion Due On Effective Date of Plan

No definition available.

Name:	omp_LitigationSettlementAmountAwardedToOtherPartyPortionDueOnEffectiveDateOfPlan
Namespace Prefix:	omp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Quantity of oil and gas subject to delivery commitment.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1207
-Paragraph (a)
-Subparagraph (2)

+ Details

Name:	srt_OilAndGasDeliveryCommitmentsAndContractsRemainingContractualVolume
Namespace Prefix:	srt_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount awarded to other party in judgment or settlement of litigation.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementAmountAwardedToOtherParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

+ Details

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

- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

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

- Definition

Term of the unrecognized unconditional purchase obligation, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121559207&loc=d3e25336-109308

+ Details

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

- Details

Name:	srt_LitigationCaseAxis=omp_MiradaLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LitigationStatusAxis=us-gaap_SettledLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=omp_SolomonLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=omp_WaterVolumeCommitmentAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OtherCommitmentsAxis=omp_CrudeOilCommitmentsMember
Namespace Prefix:
Data Type:	na
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Period Type:

Commitments and Contingencies (Details) $ in Thousands, bbl in Millions					9 Months Ended
	Sep. 28, 2020 USD ($)	Sep. 14, 2020 USD ($)	Nov. 01, 2019 USD ($)	Mar. 23, 2017 USD ($)	Sep. 30, 2020 USD ($) bbl
Loss Contingencies [Line Items]
Delivery commitment					$ 19,700
Mirada Litigation
Loss Contingencies [Line Items]
Monetary damages sought (in excess of)			$ 200,000	$ 100,000
Mirada Litigation \| Settled
Loss Contingencies [Line Items]
Payment to be made under settlement agreement	$ 42,800
Payment due on the effective date of the restructuring plan	$ 20,000
Solomon Litigation \| Settled
Loss Contingencies [Line Items]
Payment due on the effective date of the restructuring plan		$ 15
Water Volume Commitment Agreements
Loss Contingencies [Line Items]
Minimum quantity to be delivered (barrels) \| bbl					9.8
Purchase and delivery commitment period					10 years
Crude Oil Commitments
Loss Contingencies [Line Items]
Minimum quantity to be delivered (barrels) \| bbl					24.8
Purchase and delivery commitment period					10 years