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Subsequent Event Subsequent Event (Detail) - Subsequent Event - USD ($) | Apr. 29, 2018 | Apr. 27, 2018
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Subsequent Event [Line Items] |  |
Equity value |  | $ 23,300,000,000
Enterprise value |  | $ 35,600,000,000
Share price |  | $ 81.43
Share conversion rate | 1.87 |
Cash consideration to unitholders | $ 152.27 |
Percent paid in common stock | 85.00% |
Percent paid in cash | 15.00% |
MPC |  |
Subsequent Event [Line Items] |  |
Ownership of combined company | 66.00% |
Andeavor |  |
Subsequent Event [Line Items] |  |
Ownership of combined company | 34.00% |

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- Definition Business Combinations, Cost of Acquired Entity, Cash, Percentage of Acquisition Price + References No definition available. + Details
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- Definition Business Combinations, Cost of Acquired Entity, Common Stock, Percentage of Acquisition Price + References No definition available. + Details
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- Definition Enterprise Value + References No definition available. + Details
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- Definition Ownership of combined company + References No definition available. + Details
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- 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
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- Definition Number of shares of equity interests issued or issuable to acquire 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
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- Definition Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=84160947&loc=d3e2207-128464 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472 + Details
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- Definition Price of a single share of a number of saleable stocks of a company. + References No definition available. + Details
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- 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
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- Details
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- Details
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- Details
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