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Debt (Senior Notes) (Details) - USD ($)
$ in Millions

12 Months Ended

Aug. 11, 2025

Apr. 09, 2025

Mar. 10, 2025

Feb. 18, 2025

Dec. 01, 2024

May 20, 2024

Dec. 31, 2025

Dec. 31, 2024

Dec. 31, 2023

Series B Preferred Stock [Member]

Debt Instrument [Line Items]

Payments for Repurchase of Preferred Stock and Preference Stock

$ 0

$ 0

$ 600

Senior Notes

Debt Instrument [Line Items]

Debt Instrument, Face Amount

$ 4,500

Senior Notes | Senior Note Due June 2034

Debt Instrument [Line Items]

Interest rate, stated percentage

5.50%

Percent of par

98.778%

Debt Instrument, Face Amount

$ 1,650

Debt Instrument, Issuance Date

May 20, 2024

Senior Notes | Senior Notes Due December 2024 [Member]

Debt Instrument [Line Items]

Repayments of Debt

$ 1,150

Senior Notes | Senior Notes Due February 2031

Debt Instrument [Line Items]

Interest rate, stated percentage

4.80%

Percent of par

99.88%

Debt Instrument, Face Amount

^[1]

$ 1,250

Debt Instrument, Issuance Date

Aug. 11, 2025

Debt Instrument, Maturity Date

Feb. 15, 2031

Senior Notes | Senior Notes Due January 2033

Debt Instrument [Line Items]

Interest rate, stated percentage

5.00%

Percent of par

98.936%

Debt Instrument, Face Amount

^[1]

$ 750

Debt Instrument, Issuance Date

Aug. 11, 2025

Debt Instrument, Maturity Date

Jan. 15, 2033

Senior Notes | Senior Notes Due April 2035

Debt Instrument [Line Items]

Interest rate, stated percentage

5.40%

Percent of par

99.398%

Debt Instrument, Face Amount

^[2]

$ 1,000

Repayments of Debt

$ 1,200

Debt Instrument, Issuance Date

Mar. 10, 2025

Debt Instrument, Maturity Date

Apr. 01, 2035

Senior Notes | Senior Notes Due September 2035

Debt Instrument [Line Items]

Interest rate, stated percentage

5.40%

Percent of par

98.943%

Debt Instrument, Face Amount

^[1]

$ 1,500

Debt Instrument, Issuance Date

Aug. 11, 2025

Debt Instrument, Maturity Date

Sep. 15, 2035

Senior Notes | Senior Notes Due April 2055

Debt Instrument [Line Items]

Interest rate, stated percentage

5.95%

Percent of par

98.331%

Debt Instrument, Face Amount

^[2]

$ 1,000

Debt Instrument, Issuance Date

Mar. 10, 2025

Debt Instrument, Maturity Date

Apr. 01, 2055

Senior Notes | Senior Notes Due September 2055

Debt Instrument [Line Items]

Interest rate, stated percentage

6.20%

Percent of par

98.277%

Debt Instrument, Face Amount

^[1]

$ 1,000

Debt Instrument, Issuance Date

Aug. 11, 2025

Debt Instrument, Maturity Date

Sep. 15, 2055

MPLX LP | Senior Notes | Senior Note Due June 2034

Debt Instrument [Line Items]

Interest rate, stated percentage

5.50%

Debt Instrument, Maturity Date

Jun. 01, 2034

MPLX LP | Senior Notes | Senior Notes Due December 2024 [Member]

Debt Instrument [Line Items]

Interest rate, stated percentage

4.875%

Repayments of Debt

$ 1,149

MPLX LP | Senior Notes | Senior Notes Due February 2025 [Member]

Debt Instrument [Line Items]

Interest rate, stated percentage

4.00%

4.00%

Repayments of Debt

$ 500

Debt Instrument, Maturity Date

Feb. 15, 2025

MPLX LP | Senior Notes | Senior Note Due March 2033

Debt Instrument [Line Items]

Interest rate, stated percentage

5.00%

Debt Instrument, Maturity Date

Mar. 01, 2033

MPLX LP | Senior Notes | Senior Note Due March 2053

Debt Instrument [Line Items]

Interest rate, stated percentage

5.65%

Debt Instrument, Maturity Date

Mar. 01, 2053

MPLX LP | Senior Notes | Senior Notes Due February 2031

Debt Instrument [Line Items]

Interest rate, stated percentage

4.80%

Debt Instrument, Maturity Date

Feb. 15, 2031

MPLX LP | Senior Notes | Senior Notes Due January 2033

Debt Instrument [Line Items]

Interest rate, stated percentage

5.00%

Debt Instrument, Maturity Date

Jan. 15, 2033

MPLX LP | Senior Notes | Senior Notes Due April 2035

Debt Instrument [Line Items]

Interest rate, stated percentage

5.40%

Debt Instrument, Maturity Date

Apr. 01, 2035

MPLX LP | Senior Notes | Senior Notes Due September 2035

Debt Instrument [Line Items]

Interest rate, stated percentage

5.40%

Debt Instrument, Maturity Date

Sep. 15, 2035

MPLX LP | Senior Notes | Senior Notes Due April 2055

Debt Instrument [Line Items]

Interest rate, stated percentage

5.95%

Debt Instrument, Maturity Date

Apr. 01, 2055

MPLX LP | Senior Notes | Senior Notes Due September 2055

Debt Instrument [Line Items]

Interest rate, stated percentage

6.20%

Debt Instrument, Maturity Date

Sep. 15, 2055

MarkWest | Senior Notes

Debt Instrument [Line Items]

Interest rate, stated percentage

4.875%

MarkWest | Senior Notes | Senior Notes Due December 2024 [Member]

Debt Instrument [Line Items]

Interest rate, stated percentage

4.875%

Repayments of Debt

$ 1

[1]

We used a portion of the net proceeds from this offering to fund the Northwind Midstream Acquisition, including the payment of related fees and expenses, and to increase cash and cash equivalents following the recently completed BANGL Acquisition and BANGL Debt Repayment. The remainder of the net proceeds from this offering were used for general partnership purposes.

[2]

On April 9, 2025, MPLX used $1.2 billion of the net proceeds from the issuance of senior notes in March 2025 to redeem all of (i) MPLX’s outstanding $1,189 million aggregate principal amount of 4.875 percent senior notes due June 2025 and (ii) MarkWest’s outstanding $11 million aggregate principal amount of 4.875 percent senior notes due June 2025. The remaining net proceeds from this offering were used for general partnership purposes.

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