Acquisitions and Other Transacations	6 Months Ended
Acquisitions and Other Transacations	Jun. 30, 2025
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]
Acquisitions and Other Transactions	Acquisitions and Other Transactions Whiptail Midstream Acquisition On March 11, 2025, MPLX acquired gathering businesses from Whiptail Midstream, LLC for $237 million in cash. These San Juan basin assets consist primarily of crude and natural gas gathering systems in the Four Corners region. The acquisition was accounted for as a business combination, which requires all the identifiable assets acquired and liabilities assumed to be remeasured to fair value at the date of acquisition. The preliminary determination of the fair value includes $172 million of property, plant and equipment, $41 million of intangibles and $24 million of net working capital. The allocation is subject to revision, as certain data necessary to complete the purchase price allocation is not yet available, including, but not limited to, the final valuation of assets acquired and liabilities assumed. The final valuation will be completed no later than one year from the acquisition date. The results for the acquired business are reported within our Midstream segment. Whistler Joint Venture Transaction On May 29, 2024, MPLX and its joint venture partner contributed their respective membership interest in Whistler Pipeline, LLC to a newly formed joint venture, WPC Parent, LLC, and issued a 19 percent voting interest in WPC Parent, LLC to an affiliate of Enbridge Inc. in exchange for the contribution of cash and the Rio Bravo Pipeline project (collectively the “Whistler Joint Venture Transaction”). As a result of the transaction, MPLX’s voting interest in the joint venture was reduced from 37.5 percent to 30.4 percent. MPLX recognized a gain of $151 million at closing and received a cash distribution of $134 million, recorded as a return of capital, related to the dilution of the ownership interest. The gain is included in income from equity method investments on the accompanying consolidated statements of income and the return of capital is included in investments - redemptions, repayments, return of capital and sales proceeds within the investing section of the accompanying consolidated statements of cash flows. Utica Midstream Acquisition On March 22, 2024, MPLX used $625 million of cash to purchase additional ownership interest in existing joint ventures and gathering assets, which will enhance MPLX’s position in the Utica basin. Prior to the acquisition, MPLX owned an indirect interest in Ohio Gathering Company, L.L.C. (“OGC”) and a direct interest in Ohio Condensate Company, L.L.C. (“OCC”). After giving effect to the acquisition, MPLX owns a combined direct and indirect 73 percent interest in OGC and a 100 percent interest in OCC. In addition, MPLX acquired a 100 percent interest in a dry gas gathering system in the Utica basin. OGC continues to be accounted for as an equity method investment as MPLX did not obtain control of OGC as a result of the transaction. OGC is considered a VIE and MPLX is not deemed to be the primary beneficiary due to voting rights on significant matters. The acquisition date fair value of our investment in OGC exceeded our portion of the underlying net assets of the joint venture by approximately $75 million. This basis difference is being amortized into net income over the remaining estimated useful lives of the underlying net assets. OCC was previously accounted for as an equity method investment, and it is now consolidated and included in our consolidated financial results. The acquisition was accounted for as a business combination requiring all the acquired assets and liabilities to be remeasured to fair value resulting in a consolidated fair value of net assets and liabilities of $625 million. The fair value includes $507 million related to acquired interests in the joint ventures and the remaining balance related to other acquired assets and liabilities. The revaluation of MPLX’s existing 62 percent equity method investment in OCC resulted in a $20 million gain, which is included in net gain on disposal of assets on the accompanying consolidated statements of income. The fair value of equity method investments was based on a discounted cash flow model.