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Investments and Noncontrolling Interest (Equity Method Investments) (Details) - USD ($)
$ in Millions

12 Months Ended

May 29, 2024

Dec. 31, 2025

Dec. 31, 2024

Dec. 31, 2023

Jul. 31, 2024

Schedule of Equity Method Investments [Line Items]

Equity method investments

$ 4,798

$ 4,531

Investments - redemptions, repayments, return of capital and sales proceeds

293

146

$ 3

BANGL, LLC

Schedule of Equity Method Investments [Line Items]

Ownership percentage

45.00%

Equity Method Investment, Additional Ownership Acquired

20.00%

MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(4)

Schedule of Equity Method Investments [Line Items]

Contribution of Property

125

Investments - redemptions, repayments, return of capital and sales proceeds

42

WPC Parent, LLC

Schedule of Equity Method Investments [Line Items]

Investments - redemptions, repayments, return of capital and sales proceeds

$ 134

Crude Oil and Products Logistics [Member]

Schedule of Equity Method Investments [Line Items]

Equity method investments

$ 1,581

1,595

Crude Oil and Products Logistics [Member] | Illinois Extension Pipeline Company, L.L.C.

Schedule of Equity Method Investments [Line Items]

Ownership percentage

35.00%

Equity method investments

$ 208

218

Crude Oil and Products Logistics [Member] | LOOP LLC

Schedule of Equity Method Investments [Line Items]

Ownership percentage

41.00%

Equity method investments

$ 313

310

Crude Oil and Products Logistics [Member] | MarEn Bakken Company LLC(1)

Schedule of Equity Method Investments [Line Items]

Ownership percentage

25.00%

Equity method investments

^[1]

$ 502

526

Crude Oil and Products Logistics [Member] | Other VIEs and Non-VIEs [Member]

Schedule of Equity Method Investments [Line Items]

Equity method investments

^[2]

$ 558

541

Crude Oil and Products Logistics [Member] | Bakken Pipeline System | Indirect Ownership Interest

Schedule of Equity Method Investments [Line Items]

Ownership percentage

9.19%

Natural Gas & NGL Services [Member]

Schedule of Equity Method Investments [Line Items]

Equity method investments

$ 3,217

2,936

Natural Gas & NGL Services [Member] | Rockies Operations

Schedule of Equity Method Investments [Line Items]

Equity method investments

129

Natural Gas & NGL Services [Member] | Other VIEs and Non-VIEs [Member]

Schedule of Equity Method Investments [Line Items]

Equity method investments

^[2]

565

$ 418

Natural Gas & NGL Services [Member] | BANGL, LLC

Schedule of Equity Method Investments [Line Items]

Ownership percentage

^[3]

45.00%

Equity method investments

^[3]

$ 0

$ 281

Natural Gas & NGL Services [Member] | MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.(4)

Schedule of Equity Method Investments [Line Items]

Ownership percentage

67.00%

Equity method investments

$ 407

^[4]

329

Natural Gas & NGL Services [Member] | MarkWest Utica EMG, L.L.C.

Schedule of Equity Method Investments [Line Items]

Ownership percentage

61.00%

Equity method investments

$ 890

742

Natural Gas & NGL Services [Member] | Ohio Gathering Company L.L.C.

Schedule of Equity Method Investments [Line Items]

Ownership percentage

32.00%

Equity method investments

^[5]

$ 444

470

Natural Gas & NGL Services [Member] | Ohio Gathering Company L.L.C. | Indirect Ownership Interest

Schedule of Equity Method Investments [Line Items]

Ownership percentage

41.00%

Natural Gas & NGL Services [Member] | Sherwood Midstream LLC

Schedule of Equity Method Investments [Line Items]

Ownership percentage

50.00%

Equity method investments

$ 475

488

Natural Gas & NGL Services [Member] | WPC Parent, LLC

Schedule of Equity Method Investments [Line Items]

Ownership percentage

30.00%

Equity method investments

$ 273

208

Natural Gas & NGL Services [Member] | Texas City Logistics LLC

Schedule of Equity Method Investments [Line Items]

Ownership percentage

50.00%

Equity method investments

$ 163

$ 0

[1]	The investment in MarEn Bakken Company LLC includes our 9.19 percent indirect interest in a joint venture (“Dakota Access”) that owns and operates the Dakota Access Pipeline and Energy Transfer Crude Oil Pipeline projects (collectively, the “Bakken Pipeline system”).
[2]	Included within Other are certain equity method investments that have been deemed to be VIEs. The December 31, 2024 Natural Gas and NGL Services value includes $129 million in investments associated with the Rockies, which were divested in the fourth quarter 2025.
[3]	At December 31, 2024, we owned a 45 percent interest in BANGL. On July 1, 2025, we acquired the remaining 55 percent interest in BANGL. As a result of acquiring the remaining interest, we obtained control and now consolidate BANGL.
[4]	On March 31, 2025, MPLX contributed a wholly-owned subsidiary with a fair value of $125 million to MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. As a result of the transaction, MPLX received special distributions of $42 million in 2025, which are reflected as a return of capital on the Consolidated Statement of Cash Flows.
[5]	MPLX also holds a 41 percent indirect interest in OGC through our ownership interest in MarkWest Utica EMG, L.L.C.

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