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Related Party Agreements and Transaction - Summary of Charges for Omnibus Agreement (Detail) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2018 | Mar. 31, 2017
MPC |  |
Related Party Transaction [Line Items] |  |
Charges for services under an omnibus agreement | $ 52 | $ 23
MPC | Purchases - related parties |  |
Related Party Transaction [Line Items] |  |
Charges for services under an omnibus agreement | 36 | 15
MPC | General and administrative expenses |  |
Related Party Transaction [Line Items] |  |
Charges for services under an omnibus agreement | 16 | $ 8
Related Party Revolving Credit Agreement | MPC Investment |  |
Related Party Transaction [Line Items] |  |
Current borrowing capacity | $ 500 |

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- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + 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 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 + Details
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- 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
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- Details
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- Details
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- Details
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- Details
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- Details
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