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v3.25.4

Debt (Senior Notes - Issuances) (Details) - Senior Notes - USD ($) $ in Millions |  |  |  | 12 Months Ended
--- | --- | --- | --- | ---
Aug. 11, 2025 | Apr. 09, 2025 | Mar. 10, 2025 | Dec. 31, 2025
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Face Amount |  | $ 4,500 |  |  |
MarkWest |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 4.875%
Senior Notes Due April 2035 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Issuance Date |  |  |  | Mar. 10, 2025 |
Debt Instrument, Face Amount | [1] |  |  | $ 1,000 |
Interest rate, stated percentage |  |  |  | 5.40% |
Percent of par |  |  |  | 99.398% |
Debt Instrument, Maturity Date |  |  |  | Apr. 01, 2035 |
Repayments of Debt |  |  | $ 1,200 |  |
Senior Notes Due April 2035 | MPLX LP [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 5.40%
Debt Instrument, Maturity Date |  |  |  |  | Apr. 01, 2035
Senior Notes Due April 2055 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Issuance Date |  |  |  | Mar. 10, 2025 |
Debt Instrument, Face Amount | [1] |  |  | $ 1,000 |
Interest rate, stated percentage |  |  |  | 5.95% |
Percent of par |  |  |  | 98.331% |
Debt Instrument, Maturity Date |  |  |  | Apr. 01, 2055 |
Senior Notes Due April 2055 | MPLX LP [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 5.95%
Debt Instrument, Maturity Date |  |  |  |  | Apr. 01, 2055
Senior Notes Due February 2031 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Issuance Date |  | Aug. 11, 2025 |  |  |
Debt Instrument, Face Amount | [2] | $ 1,250 |  |  |
Interest rate, stated percentage |  | 4.80% |  |  |
Percent of par |  | 99.88% |  |  |
Debt Instrument, Maturity Date |  | Feb. 15, 2031 |  |  |
Senior Notes Due February 2031 | MPLX LP [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 4.80%
Debt Instrument, Maturity Date |  |  |  |  | Feb. 15, 2031
Senior Notes Due January 2033 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Issuance Date |  | Aug. 11, 2025 |  |  |
Debt Instrument, Face Amount | [2] | $ 750 |  |  |
Interest rate, stated percentage |  | 5.00% |  |  |
Percent of par |  | 98.936% |  |  |
Debt Instrument, Maturity Date |  | Jan. 15, 2033 |  |  |
Senior Notes Due January 2033 | MPLX LP [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 5.00%
Debt Instrument, Maturity Date |  |  |  |  | Jan. 15, 2033
Senior Notes Due September 2035 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Issuance Date |  | Aug. 11, 2025 |  |  |
Debt Instrument, Face Amount | [2] | $ 1,500 |  |  |
Interest rate, stated percentage |  | 5.40% |  |  |
Percent of par |  | 98.943% |  |  |
Debt Instrument, Maturity Date |  | Sep. 15, 2035 |  |  |
Senior Notes Due September 2035 | MPLX LP [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 5.40%
Debt Instrument, Maturity Date |  |  |  |  | Sep. 15, 2035
Senior Notes Due September 2055 |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Debt Instrument, Issuance Date |  | Aug. 11, 2025 |  |  |
Debt Instrument, Face Amount | [2] | $ 1,000 |  |  |
Interest rate, stated percentage |  | 6.20% |  |  |
Percent of par |  | 98.277% |  |  |
Debt Instrument, Maturity Date |  | Sep. 15, 2055 |  |  |
Senior Notes Due September 2055 | MPLX LP [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate, stated percentage |  |  |  |  | 6.20%
Debt Instrument, Maturity Date |  |  |  |  | Sep. 15, 2055
Senior Notes Due June 2025 [Member] | MPLX LP [Member] |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate, stated percentage |  |  | 4.875% |  | 4.875%
Debt Instrument, Maturity Date |  |  |  |  | Jun. 01, 2025
Repayments of Debt |  |  | $ 1,189 |  |
Senior Notes Due June 2025 [Member] | MarkWest |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |
Interest rate, stated percentage |  |  | 4.875% |  |
Repayments of Debt |  |  | $ 11 |  |
[1] | 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.
[2] | 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.

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