Leases Leases Narrative (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Lessor, Sales-type Lease, Assumptions and Judgments, Value of Underlying Asset, Amount			$ 171
Sales-type Lease, Lease Receivable			370
Sales-type Lease, Selling Profit (Loss)			209
MPC
Operating Lease, Lease Income	[1]	$ 208		$ 248	$ 589	$ 773
Sales-type Lease, Lease Receivable		419			419
Sales-type Lease, Unguaranteed Residual Asset		22			22		$ 7
Refining Logistics [Member] | MPC
Sales-type Lease, Unguaranteed Residual Asset			$ 10
Third Party [Member]
Operating Lease, Lease Income	[1]	70		$ 63	199	$ 196
Sales-type Lease, Lease Receivable		1			1
Sales-type Lease, Selling Profit (Loss)		$ 0			$ 0

[1] These amounts are presented net of executory costs.