Equity Method Investments (MarkWest Torñado GP, L.L.C.) (Details) - USD ($) $ in Millions		12 Months Ended
	Dec. 15, 2023	Dec. 31, 2024	Dec. 31, 2023		Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Book value of equity method investment		$ 50	$ 311	[1]	$ 150
Net gain on disposal of assets		$ 28	$ 217		$ 1,061
Markwest Tornado GP, L.L.C.
Schedule of Equity Method Investments [Line Items]
Payments to acquire additional interest in subsidiaries	$ 303
Equity method investment, remaining ownership interest purchased	40.00%
Cash payment for acquisition	$ 270
Contract with customer, asset, before allowance for credit loss, noncurrent	$ 33
Equity method investments, ownership percentage	60.00%
Book value of equity method investment	$ 311
Net gain on disposal of assets	92
Recognized identifiable assets acquired and liabilities assumed, net	$ 673

[1] 2024 represents the book value of Coastal Holdings prior to MPC buying out the remaining 50 percent interest from our joint venture partner. 2023 represents the book value of MPLX’s equity method investment in Torñado, prior to MPLX buying out the remaining interest in this entity. 2022 represents the book value of MPC’s equity method investment in Watson Cogeneration Company and Tanker Holdings of $25 million and $125 million, respectively, prior to MPC buying out the remaining interest in these entities. See Note 14 for additional information.