Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022		Jun. 30, 2021
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 519		$ 649
Net income taxes paid to (received from) taxing authorities	1,123		319
Non-cash investing and financing activities:
Book value of equity method investment	$ 25	[1]	$ 0

[1] Represents the book value of MPC’s equity method investment in Watson Cogeneration Company at June 1, 2022 prior to MPC buying out the remaining interest in Watson Cogeneration Company. See Note 14 for additional information.