Equity Method Investments	6 Months Ended
Jun. 30, 2022
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	EQUITY METHOD INVESTMENTSOn June 1, 2022, MPC purchased the remaining 49 percent interest in Watson Cogeneration Company from NRG Energy, Inc. for approximately $59 million. This entity will now be consolidated and included in our consolidated results. It was previously accounted for as an equity method investment.The excess of the estimated $62 million fair value over the $25 million book value of our 51 percent ownership interest in Watson Cogeneration Company resulted in a $37 million non-cash gain, which is included in the net gain on disposal of assets line of the accompanying consolidated statements of income.

The entire disclosure for equity method investments and joint ventures. Equity method investments are investments that give the investor the ability to exercise significant influence over the operating and financial policies of an investee. Joint ventures are entities owned and operated by a small group of businesses as a separate and specific business or project for the mutual benefit of the members of the group.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-URI https://asc.fasb.org/topic&trid=2196965

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