Master Limited Partnership (Unit Repurchase Program) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2023		Mar. 31, 2022	Aug. 02, 2022	Nov. 02, 2020
Units acquired, average cost per unit	$ 126.56	[1]	$ 75.88
Stock repurchase program, remaining authorized repurchase amount	$ 5,130
Share Repurchase Authorization August 2022
Stock repurchase program, authorized amount				$ 5,000
MPLX LP
Units repurchased, units	0		3
Units repurchased, value	$ 0		$ 100
Units acquired, average cost per unit	$ 0		$ 32.06
Stock repurchase program, remaining authorized repurchase amount	$ 846
MPLX LP | Share Repurchase Authorization November 2020
Stock repurchase program, authorized amount					$ 1,000
MPLX LP | Share Repurchase Authorization August 2022
Stock repurchase program, authorized amount				$ 1,000

[1] The average cost per share for the 2023 period includes a 1% excise tax on share repurchases resulting from the Inflation Reduction Act of 2022.