v3.26.1
Debt (Available Capacity under our Facilities) (Details) - USD ($)
$ in Millions
Apr. 30, 2026
Apr. 07, 2026
Mar. 31, 2026
MPC bank revolving credit facility due July 2027      
Debt Instrument [Line Items]      
Total Capacity     $ 5,000
Outstanding Borrowings     0
Outstanding Letters of Credit     1
Available Capacity     $ 4,999
Weighted Average Interest Rate     0.00%
MPC trade receivables securitization facility due September 2027      
Debt Instrument [Line Items]      
Total Capacity [1]     $ 100
Outstanding Borrowings     0
Outstanding Letters of Credit [1]     100
Available Capacity     $ 0
Weighted Average Interest Rate     0.00%
Maximum borrowing capacity     $ 100
MPC trade receivables securitization facility due September 2027 | Purchase crude oil from Strategic Petroleum Reserve      
Debt Instrument [Line Items]      
Outstanding Letters of Credit     726
MPC Revolving Credit Facility due April 2031 | Subsequent Event      
Debt Instrument [Line Items]      
Maximum borrowing capacity   $ 5,000  
MPC Revolving Credit Facility due April 2031 | Letter of Credit | Subsequent Event      
Debt Instrument [Line Items]      
Maximum borrowing capacity   2,000  
MPC Revolving Credit Facility due April 2031 | Swing-line Loan | Subsequent Event      
Debt Instrument [Line Items]      
Maximum borrowing capacity   300  
Trade Receivables Securitization due April 2029 | Subsequent Event      
Debt Instrument [Line Items]      
Total Capacity [1] $ 100    
Trade Receivables Securitization due April 2029 | Uncommitted Amount | Subsequent Event      
Debt Instrument [Line Items]      
Available Capacity [1] $ 1,900    
MPLX LP | MPLX bank revolving credit facility due July 2027      
Debt Instrument [Line Items]      
Total Capacity     2,000
Outstanding Borrowings     0
Outstanding Letters of Credit     0
Available Capacity     $ 2,000
Weighted Average Interest Rate     0.00%
Maximum borrowing capacity     $ 2,000
MPLX LP | MPLX Revolving Credit Facility Due April 2031 | Subsequent Event      
Debt Instrument [Line Items]      
Maximum borrowing capacity   2,500  
MPLX LP | MPLX Revolving Credit Facility Due April 2031 | Letter of Credit | Subsequent Event      
Debt Instrument [Line Items]      
Maximum borrowing capacity   150  
MPLX LP | MPLX Revolving Credit Facility Due April 2031 | Swing-line Loan | Subsequent Event      
Debt Instrument [Line Items]      
Maximum borrowing capacity   $ 150  
[1] The committed borrowing and letter of credit issuance capacity under the trade receivables securitization facility is $100 million. In addition, the facility allows for the issuance of letters of credit in excess of the committed capacity at the discretion of the issuing banks. As of March 31, 2026, letters of credit in the total amount of $726 million were issued and outstanding under the facility to secure contracts awarded by the U.S. Department of Energy to purchase crude oil from the SPR.