v3.26.3
Debt (MPLX Senior Notes) (Details) - Senior notes - USD ($)
$ in Millions
Sep. 23, 2026
Aug. 24, 2026
Mar. 02, 2026
Feb. 12, 2026
Aug. 11, 2025
Senior Notes Due April 2036          
Debt Instrument [Line Items]          
Debt Instrument, Issuance Date       Feb. 12, 2026  
Debt Instrument, Interest Rate, Stated Percentage       5.30%  
Percent of Par       99.678%  
Debt Instrument, Maturity Date       Apr. 01, 2036  
Senior Notes Due April 2056          
Debt Instrument [Line Items]          
Debt Instrument, Issuance Date       Feb. 12, 2026  
Debt Instrument, Interest Rate, Stated Percentage       6.10%  
Percent of Par       98.453%  
Debt Instrument, Maturity Date       Apr. 01, 2056  
Senior Notes, 4.700% due November 2029          
Debt Instrument [Line Items]          
Debt Instrument, Issuance Date   Aug. 24, 2026      
Debt Instrument, Interest Rate, Stated Percentage   4.70%      
Percent of Par   99.312%      
Debt Instrument, Maturity Date   Nov. 01, 2029      
Senior Notes, 5.000% due May 2032          
Debt Instrument [Line Items]          
Debt Instrument, Issuance Date   Aug. 24, 2026      
Debt Instrument, Interest Rate, Stated Percentage   5.00%      
Percent of Par   98.972%      
Debt Instrument, Maturity Date   May 01, 2032      
Senior Notes, 5.500% due November 2036          
Debt Instrument [Line Items]          
Debt Instrument, Issuance Date   Aug. 24, 2026      
Debt Instrument, Interest Rate, Stated Percentage   5.50%      
Percent of Par   98.066%      
Debt Instrument, Maturity Date   Nov. 01, 2036      
MPLX:          
Debt Instrument [Line Items]          
Debt instrument, face amount         $ 4,500
MPLX: | Senior Notes Due April 2036          
Debt Instrument [Line Items]          
Debt instrument, face amount [1]       $ 1,000  
MPLX: | Senior Notes Due April 2056          
Debt Instrument [Line Items]          
Debt instrument, face amount [1]       $ 500  
MPLX: | Senior Notes, 4.700% due November 2029          
Debt Instrument [Line Items]          
Debt instrument, face amount [2]   $ 1,250      
MPLX: | Senior Notes, 5.000% due May 2032          
Debt Instrument [Line Items]          
Debt instrument, face amount [2]   500      
MPLX: | Senior Notes, 5.500% due November 2036          
Debt Instrument [Line Items]          
Debt instrument, face amount [2]   $ 500      
MPLX: | Senior Notes Due March 2026          
Debt Instrument [Line Items]          
Repayments of debt     $ 1,500    
MPLX: | Senior Notes Due March 2027, 4.125%          
Debt Instrument [Line Items]          
Repayments of debt $ 1,250        
[1]
In March 2026, MPLX used the proceeds from the issuance of senior notes in February 2026 to repay all of MPLX’s outstanding $1.5 billion aggregate principal amount of 1.750 percent senior notes at maturity.
[2] MPLX used a portion of the proceeds from the issuance of senior notes in August 2026 to redeem the outstanding $1.25 billion aggregate principal amount of 4.125 percent senior notes due March 2027.