Description of the Business and Basis of Presentation	6 Months Ended
Jun. 30, 2014
Accounting Policies [Abstract]
Description of the Business and Basis of Presentation	Description of the Business and Basis of Presentation Description of the Business—As used in this report, the terms “MPC,” “we,” “us,” “the Company” or “our” may refer to Marathon Petroleum Corporation, one or more of its consolidated subsidiaries or all of them taken as a whole. Our business consists of refining and marketing, retail marketing and pipeline transportation operations conducted primarily in the Midwest, Gulf Coast and Southeast regions of the United States, through subsidiaries, including Marathon Petroleum Company LP, Speedway LLC and MPLX LP and its subsidiaries (“MPLX”). See Note 8 for additional information about our operations. Basis of Presentation—All significant intercompany transactions and accounts have been eliminated. 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 Securities and Exchange Commission applicable to interim period financial statements and do not include all of the information and disclosures required by United States generally accepted accounting principles (“U.S. GAAP”) for complete financial statements. These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2013. The results of operations for the three and six months ended June 30, 2014 are not necessarily indicative of the results to be expected for the full year. During the first quarter of 2014, we recorded an out-of-period adjustment for additional expenses related to the prior year's bonus programs of $29 million, included in total costs and expenses on the consolidated statements of income. The impact to our consolidated results of operations for the six months ended June 30, 2014 and for the year ended December 31, 2013 was immaterial. We do not expect this adjustment to have a material impact to our results of operations for the year ended December 31, 2014.

Description of the Business and Basis of Presentation

Description of the Business—As used in this report, the terms “MPC,” “we,” “us,” “the Company” or “our” may refer to Marathon Petroleum Corporation, one or more of its consolidated subsidiaries or all of them taken as a whole.

Our business consists of refining and marketing, retail marketing and pipeline transportation operations conducted primarily in the Midwest, Gulf Coast and Southeast regions of the United States, through subsidiaries, including Marathon Petroleum Company LP, Speedway LLC and MPLX LP and its subsidiaries (“MPLX”).

See Note 8 for additional information about our operations.

Basis of Presentation—All significant intercompany transactions and accounts have been eliminated.

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 Securities and Exchange Commission applicable to interim period financial statements and do not include all of the information and disclosures required by United States generally accepted accounting principles (“U.S. GAAP”) for complete financial statements.

These interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2013. The results of operations for the three and six months ended June 30, 2014 are not necessarily indicative of the results to be expected for the full year.

During the first quarter of 2014, we recorded an out-of-period adjustment for additional expenses related to the prior year's bonus programs of $29 million, included in total costs and expenses on the consolidated statements of income. The impact to our consolidated results of operations for the six months ended June 30, 2014 and for the year ended December 31, 2013 was immaterial. We do not expect this adjustment to have a material impact to our results of operations for the year ended December 31, 2014.