Debt (Outstanding Borrowings) (Detail) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Total debt	$ 33,492	$ 33,305
Unamortized debt issuance costs	(221)	(204)
Unamortized discount, net of unamortized premium	(249)	(225)
Amounts due within one year	(128)	(2,371)
Long-term debt	32,894	30,505
MPC:
Finance lease obligations	640	689
Total debt	6,487	7,299
MPC: \| Senior notes
Long-term debt, gross	5,700	6,449
MPC: \| Bonds
Other long-term debt	147	161
MPLX:
Finance lease obligations	5	6
Total debt	27,005	26,006
MPLX: \| Senior notes
Long-term debt, gross	$ 27,000	$ 26,000

Amount of short-term and long-term debt and lease obligation.

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Amount of debt and lease obligation, classified as current.

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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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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Present value of lessee's discounted obligation for lease payments from finance lease.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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