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Debt - MPC Trade Receivables Securitization Facility (Details) - USD ($)
$ in Millions
Jul. 19, 2019
Jun. 30, 2019
Debt Instrument [Line Items]    
Current borrowing capacity   $ 11,100
Subsequent Event | Trade receivables securitization facility due July 2021 [Member]    
Debt Instrument [Line Items]    
Current borrowing capacity $ 750