Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income (loss)	$ 11,001	$ (9,977)	$ 3,255
Other comprehensive income (loss)	445	(192)	(176)
Comprehensive income (loss)	11,446	(10,169)	3,079
Less comprehensive income (loss) attributable to:
Redeemable noncontrolling interest	100	81	81
Noncontrolling interests	1,163	(232)	537
Comprehensive income (loss) attributable to MPC	10,183	(10,018)	2,461
Actuarial changes
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss)	276	(157)	(147)
Prior service
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss)	175	(34)	(27)
Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss)	$ (6)	$ (1)	$ (2)