Debt (MPC Bank Revolving Credit Facility) (Details) $ in Millions	Jul. 07, 2022 USD ($) Period	Dec. 31, 2022 USD ($)
MPC revolving credit facility due October 2023
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 5,000
MPC bank revolving credit facility due July 2027
Line of Credit Facility [Line Items]
Total capacity		$ 5,000
Marathon Petroleum Corporation | MPC bank revolving credit facility due July 2027
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 5,000
Number of renewal periods | Period	2
Debt instrument, description of variable rate basis	at either the Adjusted Term SOFR or the Alternate Base Rate, both as defined in the MPC Credit Agreement, plus an applicable margin
Marathon Petroleum Corporation | MPC bank revolving credit facility due July 2027 | Letter of Credit
Line of Credit Facility [Line Items]
Total capacity	$ 2,200
Marathon Petroleum Corporation | MPC bank revolving credit facility due July 2027 | Maximum
Line of Credit Facility [Line Items]
Line of credit facility additional borrowing capacity	$ 1,000
Ratio of indebtedness to net capital	0.65
Marathon Petroleum Corporation | MPC bank revolving credit facility due July 2027 | Maximum | Bridge Loan
Line of Credit Facility [Line Items]
Total capacity	$ 250
Marathon Petroleum Corporation | MPC bank revolving credit facility due July 2027 | Maximum | Letter of Credit
Line of Credit Facility [Line Items]
Total capacity	$ 3,000