v3.24.3
Credit Agreement (Detail) - USD ($)
$ in Millions
9 Months Ended
Sep. 30, 2024
Dec. 31, 2023
Debt Instrument [Line Items]    
Long-term Line of Credit $ 0 $ 0
MPLX Revolving Credit Facility due June 2027    
Debt Instrument [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity 2,000  
Letter of Credit, Issuing Capacity $ 150  
Debt Instrument, Description of Variable Rate Basis Adjusted Term SOFR or the Alternate Base Rate, both as defined in the MPLX Credit Agreement, plus an applicable margin.