Business Combinations and Asset Acquisitions	9 Months Ended
Sep. 30, 2024
Business Combination, Asset Acquisition, and Joint Venture Formation [Abstract]
Mergers, Acquisitions and Dispositions Disclosures	Acquisitions and Other Transactions BANGL, LLC Acquisition On July 31, 2024, MPLX exercised its right of first offer under the BANGL, LLC joint venture agreement to purchase an additional 20 percent ownership interest in BANGL, LLC, for $210 million cash, increasing total ownership interest to 45 percent (the “BANGL Transaction”). BANGL is a natural gas liquids pipeline system connecting the Delaware and Midland basins to the fractionation market in Sweeny, Texas. The purchase price of the additional 20 percent ownership interest in BANGL, LLC exceeded our portion of the underlying net assets of the joint venture by approximately $156 million. This basis difference is being amortized into net income over the remaining estimated useful lives of the underlying net assets. Following the BANGL Transaction, our investment in BANGL, LLC continues to be accounted for as an equity method investment. 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. 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 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 on hand to purchase additional ownership interest in existing joint ventures and gathering assets (the “Utica Midstream Acquisition”), which will enhance our position in the Utica basin. Prior to the acquisition, we owned an indirect interest in Ohio Gathering Company L.L.C. (“OGC”) and a direct interest in Ohio Condensate Company L.L.C. (“OCC”) and now own a combined 73 percent interest in OGC, a 100 percent interest in OCC, and a 100 percent interest in a dry gas gathering system in the Utica basin, including 53 miles of gathering pipeline and three dehydration units with a combined capacity of approximately 620 MMcf/d. 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. The acquisition date fair value of our investment in OGC exceeded our portion of the underlying net assets of the joint venture by approximately $86 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 reflected as a consolidated subsidiary within our consolidated financial results. The results for the acquired business are reported within our G&P segment. The Utica Midstream 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 $518 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 Other income within the accompanying consolidated statements of income. The fair value of equity method investments was based on a discounted cash flow model.

On July 31, 2024, MPLX exercised its right of first offer under the BANGL, LLC joint venture agreement to purchase an additional 20 percent ownership interest in BANGL, LLC, for $210 million cash, increasing total ownership interest to 45 percent (the “BANGL Transaction”). BANGL is a natural gas liquids pipeline system connecting the Delaware and Midland basins to the fractionation market in Sweeny, Texas. The purchase price of the additional 20 percent ownership interest in BANGL, LLC exceeded our portion of the underlying net assets of the joint venture by approximately $156 million. This basis difference is being amortized into net income over the remaining estimated useful lives of the underlying net assets. Following the BANGL Transaction, our investment in BANGL, LLC continues to be accounted for as an equity method investment.

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. 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 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.

On March 22, 2024, MPLX used $625 million of cash on hand to purchase additional ownership interest in existing joint ventures and gathering assets (the “Utica Midstream Acquisition”), which will enhance our position in the Utica basin. Prior to the acquisition, we owned an indirect interest in Ohio Gathering Company L.L.C. (“OGC”) and a direct interest in Ohio Condensate Company L.L.C. (“OCC”) and now own a combined 73 percent interest in OGC, a 100 percent interest in OCC, and a 100 percent interest in a dry gas gathering system in the Utica basin, including 53 miles of gathering pipeline and three dehydration units with a combined capacity of approximately 620 MMcf/d. 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. The acquisition date fair value of our investment in OGC exceeded our portion of the underlying net assets of the joint venture by approximately $86 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 reflected as a consolidated subsidiary within our consolidated financial results. The results for the acquired business are reported within our G&P segment.

The Utica Midstream 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 $518 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 Other income within the accompanying consolidated statements of income. The fair value of equity method investments was based on a discounted cash flow model.