v3.26.1
Debt (Available Capacity under our Facilities) (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Apr. 30, 2026
Apr. 07, 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 1,626    
MPC Revolving Credit Facility due April 2031      
Debt Instrument [Line Items]      
Maximum borrowing capacity     $ 5,000
MPC Revolving Credit Facility due April 2031 | Letter of Credit      
Debt Instrument [Line Items]      
Maximum borrowing capacity     2,000
MPC Revolving Credit Facility due April 2031 | Swing-line Loan      
Debt Instrument [Line Items]      
Maximum borrowing capacity     300
Trade Receivables Securitization due April 2029      
Debt Instrument [Line Items]      
Total Capacity [1]   $ 100  
Trade Receivables Securitization due April 2029 | Uncommitted Amount      
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 2,500    
Outstanding Borrowings 0    
Outstanding Letters of Credit 0    
Available Capacity $ 2,500    
Weighted Average Interest Rate 0.00%    
Maximum borrowing capacity     2,000
MPLX LP | MPLX Revolving Credit Facility Due April 2031      
Debt Instrument [Line Items]      
Maximum borrowing capacity     2,500
MPLX LP | MPLX Revolving Credit Facility Due April 2031 | Letter of Credit      
Debt Instrument [Line Items]      
Maximum borrowing capacity     150
MPLX LP | MPLX Revolving Credit Facility Due April 2031 | Swing-line Loan      
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 June 30, 2026, letters of credit in the total amount of $1.626 billion 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.