Debt To EBITDA Ratio

No definition available.

Name:	bpmp_DebtToEBITDARatio
Namespace Prefix:	bpmp_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Indebtedness Threshold

+ References

No definition available.

+ Details

Name:	bpmp_IndebtednessThreshold
Namespace Prefix:	bpmp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Limited Partners' Capital Account, Units Issued Under Over-Allotment Option

+ References

No definition available.

+ Details

Name:	bpmp_LimitedPartnersCapitalAccountUnitsIssuedUnderOverAllotmentOption
Namespace Prefix:	bpmp_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Line Of Credit Facility, Utilization Fee Percentage

+ References

No definition available.

+ Details

Name:	bpmp_LineOfCreditFacilityUtilizationFeePercentage
Namespace Prefix:	bpmp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Required Consolidated Leverage Ratio

+ References

No definition available.

+ Details

Name:	bpmp_RequiredConsolidatedLeverageRatio
Namespace Prefix:	bpmp_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Required Consolidated Leverage Ratio, Potential Temporary Increase

+ References

No definition available.

+ Details

Name:	bpmp_RequiredConsolidatedLeverageRatioPotentialTemporaryIncrease
Namespace Prefix:	bpmp_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of limited partner units authorized to be issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70434-108055

+ Details

Name:	us-gaap_LimitedPartnersCapitalAccountUnitsAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of limited partner units issued.

+ References

+ Details

Name:	us-gaap_LimitedPartnersCapitalAccountUnitsIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

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.

+ References

+ Details

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

- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

Name:	us-gaap_SharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Definition

The number of units or percentage investment held in the subsidiary by the limited liability company or limited partnership.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611443-123010

+ Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConsolidatedEntitiesAxis=bpmp_BPMidstreamPartnersLPPredecessorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConsolidatedEntitiesAxis=bpmp_MarsOilPipelineCompanyLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConsolidatedEntitiesAxis=bpmp_MardiGrasTransportationSystemCompanyLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Events (Details)	Oct. 30, 2017 USD ($) $ / shares shares	Nov. 06, 2017 USD ($)	Sep. 30, 2017 USD ($)
Subsequent Event [Line Items]
Outstanding borrowing			$ 0
Subsequent Event
Subsequent Event [Line Items]
Units authorized (in shares) \| shares	42,500,000
Share price (in dollars per share) \| $ / shares	$ 18.00
Units issued under over-allotment option (in shares) \| shares	5,294,358
Units issued (in shares) \| shares	47,794,358
Line of credit facility maximum borrowing capacity	$ 600,000,000
Required consolidated leverage ratio	5
Required consolidated leverage ratio, potential temporary increase	5.5
Debt to EBITDA ratio	4.5
Indebtedness threshold	$ 75,000,000
Commitment fee percentage	0.10%
Utilization fee percentage	0.20%
Outstanding borrowing		$ 15,000,000
Subsequent Event \| London Interbank Offered Rate (LIBOR)
Subsequent Event [Line Items]
Basis spread on variable rate	0.85%
Subsequent Event \| BP Midstream Partners LP Predecessor
Subsequent Event [Line Items]
Subsidiary of limited partnership, ownership interest	100.00%
Subsequent Event \| Mars Oil Pipeline Company LLC
Subsequent Event [Line Items]
Subsidiary of limited partnership, ownership interest	28.50%
Subsequent Event \| Mardi Gras Transportation System Company LLC
Subsequent Event [Line Items]
Subsidiary of limited partnership, ownership interest	20.00%