XML 78 R66.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Equity - Changes in Partners Capital, Unit Rollforward (Details) - shares |  | 6 Months Ended
--- | --- | ---
Mar. 01, 2017 | Jun. 30, 2017
Stockholders Equity [Line Items] |  |  |
Balance at December 31, 2016 |  |  | 368,555,271
Unit-based compensation awards | [1] |  | (172,063)
Balance at June 30, 2017 |  |  | 394,873,292
Limited Partners Common Units [Member] |  |  |
Stockholders Equity [Line Items] |  |  |
Balance at December 31, 2016 |  |  | 357,193,288
Unit-based compensation awards | [1] |  | (168,622)
Balance at June 30, 2017 |  |  | 382,984,949
Class B Units [Member] |  |  |
Stockholders Equity [Line Items] |  |  |
Balance at December 31, 2016 | [2] |  | 3,990,878
Balance at June 30, 2017 |  |  | 3,990,878
General Partner Units [Member] |  |  |
Stockholders Equity [Line Items] |  |  |
Balance at December 31, 2016 |  |  | 7,371,105
Unit-based compensation awards | [1] |  | (3,441)
Balance at June 30, 2017 |  |  | 7,897,465
ATM Program [Member] |  |  |
Stockholders Equity [Line Items] |  |  |
Issuance of units under the ATM Program | [3] |  | 12,921,085
ATM Program [Member] | Limited Partners Common Units [Member] |  |  |
Stockholders Equity [Line Items] |  |  |
Issuance of units under the ATM Program | [3] |  | 12,662,663
ATM Program [Member] | General Partner Units [Member] |  |  |
Stockholders Equity [Line Items] |  |  |
Issuance of units under the ATM Program | [3] |  | 258,422
HST & WHC & MPLXT [Member] |  |  |
Stockholders Equity [Line Items] |  |  |
Contribution of HST/WHC/MPLXT | [4] |  | 13,224,873
HST & WHC & MPLXT [Member] | Limited Partners Common Units [Member] |  |  |
Stockholders Equity [Line Items] |  |  |
Contribution of HST/WHC/MPLXT | [4] |  | 12,960,376
HST & WHC & MPLXT [Member] | General Partner Units [Member] |  |  |
Stockholders Equity [Line Items] |  |  |
Contribution of HST/WHC/MPLXT | [4] | 264,497 | 264,497
[1] | As a result of the unit-based compensation awards issued during the period, MPLX GP contributed less than $1 million in exchange for 3,441 general partner units to maintain its two percent GP Interest.
[2] | On July 1, 2017, 3,990,878 Class B units converted to 4,350,057 common units and will be eligible to receive the second quarter 2017 distribution.
[3] | As a result of common units issued under the ATM Program during the period, MPLX GP contributed $9 million in exchange for 258,422 general partner units to maintain its two percent GP Interest.
[4] | See Note 3 for information regarding the HST, WHC and MPLXT acquisition.

X
- Definition Stockholders Equity [Line Items] + References No definition available. + Details
Name: | mpc_StockholdersEquityLineItems
Namespace Prefix: | mpc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of each class of partnership units outstanding at the balance sheet date. Units represent shares of ownership of the general, limited, and preferred partners. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04.16(b)) -URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04.16(a)) -URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996 Reference 3: 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 + Details
Name: | us-gaap_PartnersCapitalAccountUnits
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

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 number of units converted into shares of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners. + 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 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_PartnersCapitalAccountUnitsConverted
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total units issued during the year due to the sale of units. All partners include general, limited and preferred partners. + References Reference 1: 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 2: 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_PartnersCapitalAccountUnitsSaleOfUnits
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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

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

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=mpc_HSTWHCMPLXTMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |