Subsequent Events - MPC Senior Notes Issuance (Details) - Subsequent Event - Senior notes $ in Millions	Apr. 27, 2020 USD ($)
Subsequent Event [Line Items]
Long-term debt, gross	$ 2,500
Senior Notes Due May 2023
Subsequent Event [Line Items]
Long-term debt, gross	1,250
Senior Notes Due May 2025
Subsequent Event [Line Items]
Long-term debt, gross	$ 1,250

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant