Description of the Business and Basis of Presentation (Policies)	9 Months Ended
Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Use of estimates	These interim consolidated financial statements are unaudited; however, in the opinion of our management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain information and disclosures derived from our audited annual financial statements, prepared in accordance with GAAP, have been condensed or omitted from these interim financial statements.
Consolidation	These consolidated financial statements include the accounts of our majority-owned, controlled subsidiaries, including MPLX. All significant intercompany transactions and accounts have been eliminated. Due to our ownership of the general partner interest of MPLX, we have determined that we control MPLX and therefore we consolidate MPLX and record a noncontrolling interest for the interest owned by the public. Changes in ownership interest in consolidated subsidiaries that do not result in a change in control are recorded as equity transactions. Investments in entities over which we have significant influence, but not control, are accounted for using the equity method of accounting. This includes entities in which we hold majority ownership but the minority shareholders have substantive participating rights.
Inventories	Inventories are carried at the lower of cost or market value. Costs of crude oil and refined products are aggregated on a consolidated basis for purposes of assessing whether the LIFO cost basis of these inventories may have to be written down to market values.
Derivative instruments	Derivatives that are not designated as accounting hedges may include commodity derivatives used to hedge price risk on (1) inventories, (2) fixed price sales of refined products, (3) the acquisition of foreign-sourced crude oil, (4) the acquisition of ethanol for blending with refined products, (5) the sale of NGLs, (6) the purchase of natural gas, (7) the purchase of soybean oil and (8) the sale of propane under certain percent-of-proceeds and keep-whole arrangements.

Description of the Business and Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

These interim consolidated financial statements are unaudited; however, in the opinion of our management, these statements reflect all adjustments necessary for a fair statement of the results for the periods reported. All such adjustments are of a normal, recurring nature unless otherwise disclosed. These interim consolidated financial statements, including the notes, have been prepared in accordance with the rules of the SEC applicable to interim period financial statements and do not include all of the information and disclosures required by GAAP for complete financial statements. Certain information and disclosures derived from our audited annual financial statements, prepared in accordance with GAAP, have been condensed or omitted from these interim financial statements.

Consolidation

These consolidated financial statements include the accounts of our majority-owned, controlled subsidiaries, including MPLX. All significant intercompany transactions and accounts have been eliminated. Due to our ownership of the general partner interest of MPLX, we have determined that we control MPLX and therefore we consolidate MPLX and record a noncontrolling interest for the interest owned by the public. Changes in ownership interest in consolidated subsidiaries that do not result in a change in control are recorded as equity transactions. Investments in entities over which we have significant influence, but not control, are accounted for using the equity method of accounting. This includes entities in which we hold majority ownership but the minority shareholders have substantive participating rights.

Inventories

Inventories are carried at the lower of cost or market value. Costs of crude oil and refined products are aggregated on a consolidated basis for purposes of assessing whether the LIFO cost basis of these inventories may have to be written down to market values.

Derivative instruments

Derivatives that are not designated as accounting hedges may include commodity derivatives used to hedge price risk on (1) inventories, (2) fixed price sales of refined products, (3) the acquisition of foreign-sourced crude oil, (4) the acquisition of ethanol for blending with refined products, (5) the sale of NGLs, (6) the purchase of natural gas, (7) the purchase of soybean oil and (8) the sale of propane under certain percent-of-proceeds and keep-whole arrangements.

- Definition

Disclosure of inventory accounting policy for inventory classes, including, but not limited to, basis for determining inventory amounts, methods by which amounts are added and removed from inventory classes, loss recognition on impairment of inventories, and situations in which inventories are stated above cost.

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