XML 66 R49.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Acquisitions Joint-Interest Acquisition (Details) $ in Millions |  |  | 3 Months Ended |
--- | --- | --- | --- | ---
Sep. 01, 2017 USD ($) in mi shares | Mar. 01, 2017 USD ($) | Mar. 31, 2018 USD ($) shares | Sep. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2017 USD ($)
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Units acquired | shares | [1] |  |  | 113,888,889 |  |  |
General partner ownership interest |  | 2.00% | 2.00% | 2.00% |  |  |
Distributions of cash received from joint-interest acquisition entities to MPC |  |  |  | $ 11 |  | $ 0 |
Income from equity method investments | [2] |  |  | 61 |  | 5 |
Equity method investments |  |  |  | 4,033 |  |  | $ 4,010
Contribution from MPC |  |  |  | 1,046 |  | $ 12 |
LOOP LOCAP SAX and Explorer Llc |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Payments to acquire interest in joint venture |  | $ 420 |  |  |  |  |
Equity interest issued or issuable, value assigned |  | 630 |  |  |  |  |
Total consideration, value assigned |  | 1,050 |  |  |  |  |
Equity interest issued or issuable, fair value assigned |  | 653 |  |  |  |  |
Total consideration, fair value assigned |  | $ 1,070 |  |  |  |  |
Income from equity method investments |  |  |  | 37 |  |  |
Equity method investments |  |  |  | $ 635 |  |  |
Illinois Extension |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Equity method investment, ownership percentage |  | 35.00% |  | 35.00% |  |  |
Pipeline length | mi |  | 168 |  |  |  |  |
Pipeline diameter | in |  | 24 |  |  |  |  |
Number of pump stations |  | 2 |  |  |  |  |
Equity method investments |  |  |  | $ 288 |  |  | 284
LOOP |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Equity method investment, ownership percentage |  | 41.00% |  | 41.00% |  |  |
Equity method investments |  |  |  | $ 225 |  |  | 225
LOCAP |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Equity method investment, ownership percentage |  | 59.00% |  | 59.00% |  |  |
Equity method investments |  |  |  | $ 26 |  |  | 24
Explorer |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Equity method investment, ownership percentage |  | 25.00% |  | 25.00% |  |  |
Pipeline length | mi |  | 1,830 |  |  |  |  |
Equity method investments |  |  |  | $ 97 |  |  | $ 89
Limited Partners Common Units |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Units acquired | shares | [1] |  |  | 111,611,111 |  |  |
General Partner Units |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Units acquired | shares | [1] |  |  | 2,277,778 |  |  |
General Partner Units | LOOP LOCAP SAX and Explorer Llc |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Units acquired | shares | [1] | 377,778 |  |  |  |  |
General Partner Common Units | LOOP LOCAP SAX and Explorer Llc |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Units acquired | shares | [1] | 13,719,017 |  |  |  |  |
MPLX Logistics LLC | Limited Partners Common Units | LOOP LOCAP SAX and Explorer Llc |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Units acquired | shares | [1] | 3,350,893 |  |  |  |  |
MPLX Holdings Inc | Limited Partners Common Units | LOOP LOCAP SAX and Explorer Llc |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Units acquired | shares | [1] | 1,441,224 |  |  |  |  |
MPC |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Contribution from MPC |  |  | $ 6 |  | $ 10 |  |
General Partner | MPC | LOOP LOCAP SAX and Explorer Llc |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Distributions of cash received from joint-interest acquisition entities to MPC |  |  |  | $ 32 |  |  |
[1] | MPC agreed to waive approximately one-third of the first quarter 2018 distributions on the common units issued in connection with this transaction. As a result of this waiver, MPC will not receive $23.7 million of the distributions that would have otherwise accrued on such common units with respect to the first quarter 2018. See Note 4 for information regarding this acquisition.
[2] | “Income (loss) from equity method investments” includes the impact of any basis differential amortization or accretion.

X
- Definition Fair value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity. + References No definition available. + Details
Name: | mpc_BusinessAcquisitionEquityInterestIssuedorIssuableFairValueAssigned
Namespace Prefix: | mpc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable and cash paid to acquire the entity. + References No definition available. + Details
Name: | mpc_BusinessAcquisitionTotalConsiderationFairValueAssigned
Namespace Prefix: | mpc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable and cash to acquire the entity. + References No definition available. + Details
Name: | mpc_BusinessAcquisitionTotalConsiderationValueAssigned
Namespace Prefix: | mpc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Capital Contribution By Related Party + References No definition available. + Details
Name: | mpc_CapitalContributionByRelatedParty
Namespace Prefix: | mpc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of Pump Stations + References No definition available. + Details
Name: | mpc_NumberofPumpStations
Namespace Prefix: | mpc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Pipeline diameter + References No definition available. + Details
Name: | mpc_Pipelinediameter
Namespace Prefix: | mpc_
Data Type: | num:lengthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Pipeline length + References No definition available. + Details
Name: | mpc_Pipelinelength
Namespace Prefix: | mpc_
Data Type: | num:lengthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b)(4) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 + Details
Name: | us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_EquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(12)) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(10)) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(f)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
Name: | us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPManagingMemberOrGeneralPartnerOwnershipInterest
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Change in the number of units for each class of partners' capital accounts during the year due to acquisitions. Partners include general, limited and preferred partners. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 50 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=66023778&loc=d3e9334-128500 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 50 -Section 30 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=66023778&loc=d3e9337-128500 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 50 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=66023778&loc=d3e9298-128500 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 50 -Section 05 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=66006417&loc=d3e8580-128490 + Details
Name: | us-gaap_PartnersCapitalAccountUnitsAcquisitions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The distributions of earnings to an entity that is affiliated with the reporting entity by means of direct or indirect ownership. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfDistributionsToAffiliates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow associated with the investment in or advances to an entity in which the reporting entity shares control of the entity with another party or group. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireInterestInJointVenture
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- 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_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mpc_LOOPLOCAPSAXandExplorerLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mpc_IllinoisExtensionPipelineCompanyLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mpc_LoopLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mpc_LocapLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mpc_ExplorerPipelineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=mpc_LimitedPartnersCommonUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=mpc_GeneralPartnerUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=mpc_GeneralPartnerCommonUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mpc_MPLXLogisticsLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=mpc_MPLXHoldingsIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=mpc_MarathonPetroleumCorporationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_GeneralPartnerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |