Equity Method Investments (Impairments) (Details) - MPLX $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments from asset impairment and elimination of basis differential	$ 28
Equity Method Investment - Basis Difference
Schedule of Equity Method Investments [Line Items]
Income (loss) from equity method investments from asset impairment and elimination of basis differential	$ 14