Revenue (Receivables) (Details) $ in Millions	Dec. 31, 2021 USD ($)
Revenue from Contract with Customer [Abstract]
Matching buy/sell receivables	$ 5,230

Carrying amounts due as of the balance sheet date of the amounts receivable from matching buy/sell transactions.

No definition available.

Name:	mpc_MatchingBuySellReceivables
Namespace Prefix:	mpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant