Amount of interest capitalized during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

+ Details

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

- Definition

Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

+ Details

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

- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

+ References

No definition available.

+ Details

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

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
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_VariableInterestEntityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	srt_OwnershipAxis=omp_BobcatDevCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=omp_BobcatDevCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=omp_OasisMidstreamPartnersLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=omp_OasisPetroleumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=omp_BeartoothDevCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=omp_BeartoothDevCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=omp_BighornDevCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=omp_OMPOperatingLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_OwnershipAxis=omp_OMPOperatingLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=omp_BighornDevCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Basis of Presentation (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
Basis of Presentation (Details) - USD ($) $ in Millions	Sep. 25, 2017	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Interest costs capitalized			$ 4.9	$ 1.2	$ 4.4
Weighted average useful life of long-lived assets			30 years
Bobcat DevCo \| Bobcat DevCo
Variable Interest Entity [Line Items]
Ownership interest (percent)	10.00%
Bobcat DevCo \| Oasis Midstream Partners, LP
Variable Interest Entity [Line Items]
Ownership interest (percent)		25.00%
Bobcat DevCo \| Oasis Petroleum
Variable Interest Entity [Line Items]
Non-controlling interest (percent)		75.00%	75.00%
Beartooth DevCo \| Beartooth DevCo
Variable Interest Entity [Line Items]
Ownership interest (percent)	40.00%
Beartooth DevCo \| Oasis Midstream Partners, LP
Variable Interest Entity [Line Items]
Ownership interest (percent)		70.00%
Beartooth DevCo \| Oasis Petroleum
Variable Interest Entity [Line Items]
Non-controlling interest (percent)		30.00%	30.00%
Bighorn DevCo
Variable Interest Entity [Line Items]
Ownership interest (percent)	100.00%
Bighorn DevCo \| OMP Operating, LLC
Variable Interest Entity [Line Items]
Ownership interest (percent)			100.00%
OMP Operating, LLC \| Bighorn DevCo
Variable Interest Entity [Line Items]
Ownership interest (percent)			100.00%