Marathon Petroleum (MPC) 10-Q 31 Oct 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Oct. 27, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus (Q1,Q2,Q3,FY)	Q3
Trading Symbol	MPC
Entity Registrant Name	Marathon Petroleum Corp
Entity Central Index Key	1,510,295
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		527,815,189

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues and other income:
Sales and other operating revenues (including consumer excise taxes)	$ 16,618	$ 18,716	$ 46,184	$ 56,444
Income (loss) from equity method investments	(208)	23	(236)	58
Net gain on disposal of assets	1	2	26	6
Other income	49	17	106	71
Total revenues and other income	16,460	18,758	46,080	56,579
Costs and expenses:
Cost of revenues (excludes items below)	12,944	14,165	35,475	43,575
Purchases from related parties	128	61	359	219
Inventory market valuation adjustment	0	0	(370)	0
Consumer excise taxes	1,914	1,988	5,633	5,759
Impairment expense	0	144	130	144
Depreciation and amortization	507	364	1,497	1,089
Selling, general and administrative expenses	420	392	1,199	1,143
Other taxes	112	95	332	296
Total costs and expenses	16,025	17,209	44,255	52,225
Income from operations	435	1,549	1,825	4,354
Net interest and other financial income (costs)	(141)	(70)	(420)	(215)
Income before income taxes	294	1,479	1,405	4,139
Provision for income taxes	75	521	481	1,439
Net income	219	958	924	2,700
Less net income (loss) attributable to:
Redeemable noncontrolling interest	16	0	25	0
Noncontrolling interests	58	10	(48)	35
Net income attributable to MPC	$ 145	$ 948	$ 947	$ 2,665
Basic:
Net income attributable to MPC per share	$ 0.28	$ 1.77	$ 1.79	$ 4.93
Weighted average shares outstanding (in shares)	527	535	528	540
Diluted:
Net income attributable to MPC per share	$ 0.27	$ 1.76	$ 1.78	$ 4.90
Weighted average shares outstanding (in shares)	530	538	531	544
Dividends paid (in USD per share)	$ 0.36	$ 0.32	$ 1	$ 0.82

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 219	$ 958	$ 924	$ 2,700
Defined benefit postretirement and post-employment plans:
Actuarial changes, net of tax of $0, $3, $8 and $15	2	5	14	25
Prior service costs, net of tax of ($5), ($5), ($14) and ($14)	(8)	(8)	(23)	(24)
Other comprehensive income (loss)	(6)	(3)	(9)	1
Comprehensive income	213	955	915	2,701
Less comprehensive income (loss) attributable to:
Redeemable noncontrolling interest	16	0	25	0
Noncontrolling interests	58	10	(48)	35
Comprehensive income attributable to MPC	$ 139	$ 945	$ 938	$ 2,666

Consolidated Statements of Com4

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Actuarial changes, tax	$ 0	$ 3	$ 8	$ 15
Prior service costs, tax	$ (5)	$ (5)	$ (14)	$ (14)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents (MPLX: $208 and $43, respectively)	$ 709	$ 1,127
Receivables, less allowance for doubtful accounts of $12 and $12 (MPLX: $295 and $257, respectively)	3,136	2,927
Inventories (MPLX: $50 and $51, respectively)	5,524	5,225
Other current assets (MPLX: $33 and $50, respectively)	176	192
Total current assets	9,545	9,471
Equity method investments (MPLX: $2,475 and $2,458, respectively)	3,554	3,622
Property, plant and equipment, net (MPLX: $10,537 and $9,997, respectively)	25,697	25,164
Goodwill (MPLX: $2,199 and $2,570, respectively)	3,648	4,019
Other noncurrent assets (MPLX: $515 and $478, respectively)	849	839
Total assets	43,293	43,115
Current liabilities:
Accounts payable (MPLX: $472 and $449, respectively)	5,055	4,743
Payroll and benefits payable (MPLX: $1 and $18, respectively)	439	503
Consumer excise taxes payable (MPLX: $2 and $1, respectively)	329	460
Accrued taxes (MPLX: $35 and $26, respectively)	163	184
Debt due within one year (MPLX: $1 and $1, respectively)	28	29
Other current liabilities (MPLX: $72 and $65, respectively)	326	426
Total current liabilities	6,340	6,345
Long-term debt (MPLX: $4,411 and $5,255, respectively)	10,538	11,896
Deferred income taxes (MPLX: $5 and $378, respectively)	3,682	3,285
Defined benefit postretirement plan obligations	1,174	1,179
Deferred credits and other liabilities (MPLX: $163 and $170, respectively)	602	735
Total liabilities	22,336	23,440
Commitments and contingencies (see Note 22)
Redeemable noncontrolling interest	1,000	0
MPC stockholders’ equity:
Preferred stock, no shares issued and outstanding (par value 0.01 per share, 30 million shares authorized)	0	0
Common stock:
Issued – 731 million and 729 million shares (par value 0.01 per share, 1 billion shares authorized)	7	7
Held in treasury, at cost – 203 million and 198 million shares	(7,459)	(7,275)
Additional paid-in capital	11,005	11,071
Retained earnings	10,169	9,752
Accumulated other comprehensive loss	(327)	(318)
Total MPC stockholders’ equity	13,395	13,237
Noncontrolling interests	6,562	6,438
Total equity	19,957	19,675
Total liabilities, redeemable noncontrolling interest and equity	$ 43,293	$ 43,115

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 12	$ 12
Preferred stock:
Shares issued	0	0
Shares outstanding	0	0
Par value	$ 0.01
Shares authorized	30,000,000
Common stock:
Shares issued	731,000,000	729,000,000
Par value	$ 0.01
Shares authorized	1,000,000,000
Treasury stock	(203,000,000)	(198,000,000)

Consolidated Balance Sheets (MP

Consolidated Balance Sheets (MPLX Parenthetical) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 709	$ 1,127
Receivables, less allowance for doubtful accounts	3,136	2,927
Inventories	5,524	5,225
Other current assets	176	192
Equity method investments	3,554	3,622
Property, plant and equipment, net	25,697	25,164
Goodwill	3,648	4,019
Other noncurrent assets	849	839
Liabilities
Accounts payable	5,055	4,743
Payroll and benefits payable	439	503
Consumer excise taxes payable	329	460
Accrued taxes	163	184
Debt due within one year	28	29
Other current liabilities	326	426
Total long-term debt due after one year	10,538	11,896
Defined benefit postretirement plan obligations	1,174	1,179
Deferred credits and other liabilities	602	735
MPLX LP
Assets
Cash and cash equivalents	208	43
Receivables, less allowance for doubtful accounts	295	257
Inventories	50	51
Other current assets	33	50
Equity method investments	2,475	2,458
Property, plant and equipment, net	10,537	9,997
Goodwill	2,199	2,570
Other noncurrent assets	515	478
Liabilities
Accounts payable	472	449
Payroll and benefits payable	1	18
Consumer excise taxes payable	2	1
Accrued taxes	35	26
Debt due within one year	1	1
Other current liabilities	72	65
Total long-term debt due after one year	4,411	5,255
Deferred income taxes	5	378
Defined benefit postretirement plan obligations	0	0
Deferred credits and other liabilities	$ 163	$ 170

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities:
Net income	$ 924	$ 2,700
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of deferred financing costs and debt discount	47	9
Impairment expense	130	144
Depreciation and amortization	1,497	1,089
Inventory market valuation adjustment	(370)	0
Pension and other postretirement benefits, net	(21)	51
Deferred income taxes	335	(6)
Net gain on disposal of assets	(26)	(6)
Equity method investments, net	435	8
Changes in the fair value of derivative instruments	6	9
Changes in:
Current receivables	(209)	931
Inventories	71	86
Current accounts payable and accrued liabilities	237	(1,707)
All other, net	(61)	(55)
Net cash provided by operating activities	2,995	3,253
Investing activities:
Additions to property, plant and equipment	(2,147)	(1,277)
Disposal of assets	88	14
Investments – acquisitions, loans and contributions	(240)	(221)
Investments - redemptions, repayments and return of capital	20	4
All other, net	62	52
Net cash used in investing activities	(2,217)	(1,428)
Financing activities:
Commercial paper – issued	1,063	0
Commercial paper - repayments	(1,063)	0
Long-term debt – borrowings	714	528
Long-term debt – repayments	(2,112)	(433)
Debt issuance costs	(11)	(4)
Issuance of common stock	8	29
Common stock repurchased	(177)	(773)
Dividends paid	(529)	(443)
Issuance of MPLX LP common units	499	0
Issuance of MPLX LP redeemable preferred units	984	0
Distributions to noncontrolling interests	(389)	(29)
Contingent consideration payment	(164)	(175)
All other, net	(19)	25
Net cash used in financing activities	(1,196)	(1,275)
Net increase (decrease) in cash and cash equivalents	(418)	550
Cash and cash equivalents at beginning of period	1,127	1,494
Cash and cash equivalents at end of period	$ 709	$ 2,044

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning balance at Dec. 31, 2014	$ 11,390	$ 7	$ (6,299)	$ 9,841	$ 7,515	$ (313)	$ 639
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	2,700				2,665		35
Dividends declared	(444)				(444)
Distributions to noncontrolling interests	(29)						(29)
Other comprehensive income (loss)	1					1
Shares repurchased	(773)		(773)
Shares returned - stock based compensation			(11)
Shares issued - stock based compensation				29
Net shares issued - stock based compensation	18
Stock-based compensation	60			59			1
Issuance of MPLX LP common units	2						2
Ending balance at Sep. 30, 2015	12,925	7	(7,083)	9,929	9,736	(312)	648
Beginning balance at Dec. 31, 2015	19,675	7	(7,275)	11,071	9,752	(318)	6,438
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	899				947		(48)
Dividends declared	(530)				(530)
Distributions to noncontrolling interests	(380)						(380)
Other comprehensive income (loss)	(9)					(9)
Shares repurchased	(177)		(177)
Shares returned - stock based compensation			(7)
Shares issued - stock based compensation				8
Net shares issued - stock based compensation	1
Stock-based compensation	45			39			6
Issuance of MPLX LP common units	499			(43)			542
Issuance of MPLX LP common units, tax	0			0
Deferred income tax effect from changes in noncontrolling interest - MarkWest Merger	(115)			(115)
Deferred income tax effect from changes in noncontrolling interest - contribution of inland marine	42			42
Tax effect of MPLX reorganization	3			3
Other	4						4
Ending balance at Sep. 30, 2016	$ 19,957	$ 7	$ (7,459)	$ 11,005	$ 10,169	$ (327)	$ 6,562

Consolidated Statement of Equit

Consolidated Statement of Equity - Shares - shares shares in Millions	Total	Common Stock	Treasury Stock
Number of common shares issued (beginning balance) at Dec. 31, 2014		726
Number of shares issued - stock-based compensation		3
Number of common shares issued (ending balance) at Sep. 30, 2015		729
Number of shares held in treasury (beginning balance) at Dec. 31, 2014			(179)
Number of shares repurchased	(15)		(15)
Number of shares returned - stock-based compensation			(1)
Number of shares held in treasury (ending balance) at Sep. 30, 2015			(195)
Number of common shares issued (beginning balance) at Dec. 31, 2015	729	729
Number of shares issued - stock-based compensation		2
Number of common shares issued (ending balance) at Sep. 30, 2016	731	731
Number of shares held in treasury (beginning balance) at Dec. 31, 2015	(198)		(198)
Number of shares repurchased	(4)		(4)
Number of shares returned - stock-based compensation			(1)
Number of shares held in treasury (ending balance) at Sep. 30, 2016	(203)		(203)

Redeemable Noncontrolling Inter

Redeemable Noncontrolling Interest $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Temporary Equity [Abstract]
Beginning balance	$ 0
Net income (loss) attributable to redeemable noncontrolling interest	25
Distributions to noncontrolling interests	(9)
Issuance of MPLX LP redeemable preferred units	984
Ending balance	$ 1,000

Description of the Business and

Description of the Business and Basis of Presentation	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Description of the Business and Basis of Presentation	Description of the Business and Basis of Presentation Description of the Business— Our business consists of refining and marketing, retail and midstream services conducted primarily in the Midwest, Gulf Coast, East Coast, Northeast and Southeast regions of the United States, through subsidiaries, including Marathon Petroleum Company LP, Speedway LLC and its subsidiaries (“Speedway”) and MPLX LP and its subsidiaries (“MPLX”). See Note 9 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 SEC applicable to interim period financial statements and do not include all of the information and disclosures required by 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, 2015 . The results of operations for the three and nine months ended September 30, 2016 are not necessarily indicative of the results to be expected for the full year. Certain prior period financial statement amounts have been reclassified to conform to current period presentation. In the first quarter of 2016, we revised our segment reporting in connection with the contribution of our inland marine business to MPLX. See Note 3 for additional information. The operating results for our inland marine business and our investment in an ocean vessel joint venture, Crowley Ocean Partners LLC (“Crowley Ocean Partners”), are now reported in our Midstream segment. Previously they were reported as part of our Refining & Marketing segment. Comparable prior period information has been recast to reflect our revised segment presentation. See Note 9 for additional information.

Accounting Standards

Accounting Standards	9 Months Ended
	Sep. 30, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recently Adopted Accounting Pronouncements	Accounting Standards Recently Adopted In September 2015, the FASB issued an accounting standard update that eliminates the requirement to restate prior period financial statements for measurement period adjustments related to business combinations. This accounting standard update requires that the cumulative impact of a measurement period adjustment be recognized in the reporting period in which the adjustment is identified. The change was effective for interim and annual periods beginning after December 15, 2015. We recognized measurement period adjustments during the first and second quarters of 2016 on a cumulative prospective basis as additional analysis was completed on the preliminary purchase price allocation for the acquisition of MarkWest Energy Partners, L.P. (“MarkWest”). See Note 4 for further discussion and detail related to these measurement period adjustments. In May 2015, the FASB issued an accounting standard update that eliminates the requirement to categorize investments that are measured at net asset value using the practical expedient in the fair value hierarchy. The change was effective for fiscal years beginning after December 15, 2015 and interim periods within the fiscal year. Retrospective application is required. Adoption of this accounting standard update in the first quarter of 2016 did not have a material impact on our disclosures. In April 2015, the FASB issued an accounting standard update clarifying whether a customer should account for a cloud computing arrangement as an acquisition of a software license or as a service arrangement by providing characteristics that a cloud computing arrangement must have in order to be accounted for as a software license acquisition. The change was effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2015. Retrospective or prospective application is allowed. We adopted this accounting standard update prospectively in the first quarter of 2016 and it did not have a material impact on our consolidated results of operations, financial position or cash flows. In February 2015, the FASB issued an accounting standard update making targeted changes to the current consolidation guidance. The accounting standard update changes the considerations related to substantive rights, related parties, and decision making fees when applying the VIE consolidation model and eliminates certain guidance for limited partnerships and similar entities under the voting interest consolidation model. The change was effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2015. Under the accounting standard update, we continue to consolidate our master limited partnership, MPLX, but it is now considered to be a VIE. The adoption of this accounting standard update in the first quarter of 2016 did impact our disclosures for this consolidated VIE, but did not have a material impact on our results of operations, financial position or cash flows. In June 2014, the FASB issued an accounting standard update for the elimination of the concept of development stage entity (“DSE”) from U.S. GAAP and removes the related incremental reporting. The accounting standard update eliminated the additional financial statement requirements specific to a DSE and was adopted in the first quarter of 2015. In addition, the portion of the accounting standard update that amended the consolidation model to eliminate the special provisions in the VIE rules for assessing the sufficiency of the equity of a DSE was adopted in the first quarter of 2016. Adoption of this accounting standard update in the first quarter of 2015 and 2016 did not have an impact on our consolidated results of operations, financial position or cash flows.
Not Yet Adopted Accounting Pronouncements	Not Yet Adopted In August 2016, the FASB issued an accounting standard update related to the classification of certain cash flows. This accounting standard update provides classification solutions for eight different cash flow items including: debt prepayment/extinguishment costs, settlement of zero-coupon bonds, contingent consideration payments made after a business combination, proceeds from settlement of insurance claims, proceeds from settlement of corporate-owned life insurance policies, distributions received from equity method investees, beneficial interests in securitization transactions, and separately identifiable cash flows and application of the predominance principle. The change is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted. We do not expect application of this accounting standard update to have a material impact on our statement of cash flows. In June 2016, the FASB issued an accounting standard update related to the accounting for credit losses on certain financial instruments. The guidance requires that for most financial assets, losses be based on an expected loss approach which includes estimates of losses over the life of exposure that considers historical, current and forecasted information. Expanded disclosures related to the methods used to estimate the losses as well as a specific disaggregation of balances for financial assets are also required. The change is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with early adoption permitted for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. We do not expect application of this accounting standard update to have a material impact on our consolidated financial statements. In March 2016, the FASB issued an accounting standard update to simplify some provisions in stock compensation accounting. The areas for simplification involve the accounting for share-based payment transactions, including income tax consequences, classification of awards as either equity or liabilities and classification within the statement of cash flows. This change will be effective for fiscal years beginning after December 15, 2016, and interim periods within those years. Early adoption is permitted. We do not expect application of this accounting standard update to have a material impact on our consolidated financial statements. In March 2016, the FASB issued an accounting standard update eliminating the requirement that an investor retrospectively apply equity method accounting when an investment that it had accounted for by another method initially qualifies for the equity method. This change will be effective for fiscal years beginning after December 15, 2016, and interim periods within those years. The guidance will be applied prospectively and early adoption is permitted. We do not expect application of this accounting standard update to have a material impact on our consolidated financial statements. In February 2016, the FASB issued an accounting standard update on lease accounting. This accounting standard update requires lessees to record virtually all leases on their balance sheets. The accounting standard update also requires expanded disclosures to help financial statement users better understand the amount, timing and uncertainty of cash flows arising from leases. The change will be effective on a modified retrospective basis for fiscal years beginning after December 15, 2018, and interim periods within those years, with early adoption permitted. We are in the process of determining the impact of the accounting standard update on our consolidated financial statements. In January 2016, the FASB issued an accounting standard update requiring unconsolidated equity investments, not accounted for under the equity method, to be measured at fair value with changes in fair value recognized in net income. The accounting standard update also requires the use of the exit price notion when measuring the fair value of financial instruments for disclosure purposes and the separate presentation of financial assets and liabilities by measurement category and form on the balance sheet and accompanying notes. The accounting standard update eliminates the requirement to disclose the methods and assumptions used in estimating the fair value of financial instruments measured at amortized cost. Lastly, the accounting standard update requires separate presentation in other comprehensive income of the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when electing to measure the liability at fair value in accordance with the fair value option for financial instruments. The changes are effective for fiscal years and interim periods within those fiscal years beginning after December 15, 2017. Early adoption is permitted only for the guidance regarding presentation of a liability’s credit risk. We do not expect application of this accounting standard update to have a material impact on our consolidated financial statements. In August 2014, the FASB issued an accounting standard update requiring management to assess an entity’s ability to continue as a going concern and to provide related footnote disclosures in certain circumstances. Management will be required to assess if there is substantial doubt about an entity’s ability to continue as a going concern within one year after the issuance of the financial statements. Disclosures will be required if conditions give rise to substantial doubt and the type of disclosure will be determined based on whether management’s plans will be able to alleviate the substantial doubt. The change will be effective for the first fiscal period ending after December 15, 2016, and for fiscal periods and interim periods thereafter with early application permitted. We do not expect application of this accounting standard update to have an impact on our disclosures. In May 2014, the FASB issued an accounting standard update for revenue recognition for contracts with customers. The guidance in the accounting standard update states that revenue is recognized when a customer obtains control of a good or service. Recognition of the revenue will involve a multiple step approach including identifying the contract, identifying the separate performance obligations, determining the transaction price, allocating the price to the performance obligations and then recognizing the revenue as the obligations are satisfied. Additional disclosures will be required to provide adequate information to understand the nature, amount, timing and uncertainty of reported revenues and revenues expected to be recognized. The change will be effective on a retrospective or modified retrospective basis for fiscal years beginning after December 15, 2017, and interim periods within those years, with early adoption permitted, no earlier than January 1, 2017. We are in the process of determining the impact of the accounting standard update on our consolidated financial statements.

MPLX LP

MPLX LP	9 Months Ended
	Sep. 30, 2016
Noncontrolling Interest [Abstract]
MPLX LP	MPLX LP MPLX is a publicly traded master limited partnership formed by us to own, operate, develop and acquire pipelines and other midstream assets related to the transportation and storage of hydrocarbon-based products, including crude oil, refined products, natural gas and NGLs. On December 4, 2015, MPLX and MarkWest completed a merger, whereby MarkWest became a wholly-owned subsidiary of MPLX (the “MarkWest Merger”). MarkWest’s operations include: natural gas gathering, processing and transportation; and NGL gathering, transportation, fractionation, storage and marketing. MPLX’s other assets include a 100 percent interest in MPLX Pipe Line Holdings LLC, which owns a network of common carrier crude oil and product pipeline systems and associated storage assets in the Midwest and Gulf Coast regions of the United States and a 100 percent interest in a butane cavern in Neal, West Virginia. MPLX also owns an inland marine business, which is comprised of 18 tow boats and approximately 200 barges that transports primarily crude oil and refined products principally for MPC in the Midwest and Gulf Coast regions of the United States. See Note 4 for information on MPLX’s anticipated investment in the Bakken Pipeline system. As of September 30, 2016 , we owned a 24 percent interest in MPLX, including a two percent general partner interest. This ownership percentage reflects the conversion of the MPLX Class B Units in July of 2017 at 1.09 to 1.00 and assumes exchange of the MPLX preferred units on a one for one basis. MPLX is a VIE because the limited partners of MPLX do not have substantive kick-out or substantive participating rights over the general partner. We are the primary beneficiary of MPLX because in addition to significant economic interest, we also have the power, through our 100 percent ownership of the general partner, to control the decisions that most significantly impact MPLX. We therefore consolidate MPLX and record a noncontrolling interest for the 76 percent interest owned by the public. The components of our noncontrolling interest consist of equity-based noncontrolling interest and redeemable noncontrolling interest. The redeemable noncontrolling interest relates to MPLX’s preferred units, discussed below. The creditors of MPLX do not have recourse to MPC’s general credit through guarantees or other financial arrangements. The assets of MPLX are the property of MPLX and cannot be used to satisfy the obligations of MPC. Reorganization Transactions On September 1, 2016, MPC, MPLX and various affiliates initiated a series of reorganization transactions in order to simplify MPLX’s ownership structure and its financial and tax reporting. In connection with these transactions, MPC contributed $225 million to MPLX and the issued and outstanding MPLX Class A Units, all of which were held by MarkWest Hydrocarbon L.L.C. (“MarkWest Hydrocarbon”), a subsidiary of MPLX, were exchanged for newly issued common units representing limited partner interests in MPLX. The simple average of the closing prices of MPLX common units for the last 10 trading days prior to September 1, 2016 was used for purposes of these transactions. As a result of these transactions, MPC increased its ownership interest in MPLX by 7 million MPLX common units, or approximately 1 percent . Private Placement of Preferred Units On May 13, 2016, MPLX completed the private placement of approximately 30.8 million 6.5 percent Series A Convertible Preferred Units (the “MPLX Preferred Units”) for a cash price of $32.50 per unit. The aggregate net proceeds of approximately $984 million from the sale of the MPLX Preferred Units was used for capital expenditures, repayment of debt and general partnership purposes. The MPLX Preferred Units rank senior to all MPLX common units with respect to distributions and rights upon liquidation. The holders of the MPLX Preferred Units are entitled to receive quarterly distributions equal to $0.528125 per unit commencing for the quarter ended June 30, 2016, with a prorated amount from the date of issuance. Following the second anniversary of the issuance of the MPLX Preferred Units, the holders of the MPLX Preferred Units will receive as a distribution the greater of $0.528125 per unit or the amount of per unit distributions paid to common units. The MPLX Preferred Units are convertible into MPLX common units on a one for one basis after three years, at the purchasers’ option, and after four years at MPLX’s option, subject to certain conditions. The MPLX Preferred Units are considered redeemable securities due to the existence of redemption provisions upon a deemed liquidation event which is considered outside our control. Therefore, they are presented as temporary equity in the mezzanine section of the consolidated balance sheets. We have recorded the MPLX Preferred Units at their issuance date fair value, net of issuance costs. Since the MPLX Preferred Units are not currently redeemable and not probable of becoming redeemable in the future, adjustment to the initial carrying amount is not necessary and would only be required if it becomes probable that the security would become redeemable. Contribution of Inland Marine Business to MPLX On March 31, 2016, we contributed our inland marine business to MPLX in exchange for 23 million common units and 460 thousand general partner units. The number of units we received from MPLX was determined by dividing $600 million by the volume weighted average NYSE price of MPLX common units for the 10 trading days preceding March 14, 2016, pursuant to the Membership Interests Contribution Agreement. We also agreed to waive first-quarter 2016 common unit distributions, IDRs and general partner distributions with respect to the common units issued in this transaction. The contribution of our inland marine business was accounted for as a transaction between entities under common control and we did not record a gain or loss. ATM Program On August 4, 2016, MPLX entered into a second amended and restated distribution agreement providing for the continuous issuance of up to an aggregate of $1.18 billion of common units, in amounts, at prices and on terms to be determined by market conditions and other factors at the time of any offerings (such continuous offering program, or at-the-market program, referred to as the “ATM Program”). MPLX expects to use the net proceeds from sales under the ATM Program for general partnership purposes including repayment of debt and funding for acquisitions, working capital requirements and capital expenditures. During the nine months ended September 30, 2016 , MPLX issued an aggregate of 18 million common units under the ATM Program, generating net proceeds of approximately $499 million . As a result of common units issued under the ATM Program during the period, we contributed approximately $10 million to MPLX in exchange for general partner units to maintain our two percent general partner interest. Agreements We have various long-term, fee-based transportation and storage services agreements with MPLX. Under these agreements, MPLX provides transportation and storage services to us, and we commit to provide MPLX with minimum quarterly throughput volumes on crude oil and refined products systems and minimum storage volumes of crude oil, refined products and butane. We also have agreements with MPLX that establish fees for operational and management services provided between us and MPLX and for executive management services and certain general and administrative services provided by us to MPLX. These transactions are eliminated in consolidation.

Acquisitions and Investments

Acquisitions and Investments	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Acquisitions and Investments	Acquisitions and Investments Merger with MarkWest Energy Partners, L.P. On December 4, 2015, MPLX completed the MarkWest Merger. The total value of consideration transferred was $8.61 billion , consisting of $7.33 billion in equity and $1.28 billion in cash. At closing, we made a payment of $1.23 billion to MarkWest common unitholders and the remaining $50 million will be paid in equal amounts, the first of which was paid in July 2016 and the second of which will be paid in July 2017, in connection with the conversion of the MPLX Class B Units to MPLX common units. Our financial results and operating statistics reflect the results of MarkWest from the date of the MarkWest Merger. The following table summarizes the final purchase price allocation. Subsequent to December 31, 2015 , additional analysis was completed and adjustments were made to the preliminary purchase price allocation as noted in the table below. The estimated fair value of assets acquired and liabilities and noncontrolling interests assumed at the acquisition date, are as follows: (In millions) As originally reported Adjustments As adjusted Cash and cash equivalents $ 12 $ — $ 12 Receivables 164 — 164 Inventories 33 (1 ) 32 Other current assets 44 — 44 Equity method investments 2,457 143 2,600 Property, plant and equipment, net 8,474 43 8,517 Other noncurrent assets (a) 473 65 538 Total assets acquired 11,657 250 11,907 Accounts payable 322 6 328 Payroll and benefits payable 13 — 13 Accrued taxes 21 — 21 Other current liabilities 44 — 44 Long-term debt 4,567 — 4,567 Deferred income taxes 374 3 377 Deferred credit and other liabilities 151 — 151 Noncontrolling interest 13 — 13 Total liabilities and noncontrolling interest assumed 5,505 9 5,514 Net assets acquired excluding goodwill 6,152 241 6,393 Goodwill 2,454 (241 ) 2,213 Net assets acquired $ 8,606 $ — $ 8,606 (a) The adjustment relates to acquired intangible assets. Adjustments to the preliminary purchase price allocations as of December 31, 2015 stem mainly from additional information obtained by management in the first quarter about facts and circumstances that existed at the acquisition date including updates to forecasted employee benefit costs and capital expenditures, and completion of certain valuations to determine the underlying fair value of certain acquired assets. The adjustment to intangibles mainly relates to a misstatement in the preliminary purchase price allocation as of December 31, 2015. The correction of the error in the first quarter resulted in a $68 million reduction to the carrying value of goodwill and offsetting increases of $64 million in intangibles and $2 million in both equity method investments and property, plant and equipment. Management concluded that the correction of the error is immaterial to the consolidated financial statements for all periods presented. The increases to fair value of equity method investments, property plant and equipment, and other noncurrent assets noted above would not have resulted in a material effect to depreciation and amortization or income from equity method investments in the consolidated statements of income for the year ended December 31, 2015, had the fair value adjustments been recorded as of December 4, 2015. The net fair value of the assets acquired and liabilities assumed in connection with the MarkWest Merger was less than the fair value of the total consideration resulting in the recognition of $2.21 billion of goodwill in three reporting units within our Midstream segment, substantially all of which is not deductible for tax purposes. Goodwill represents the complementary aspects of the highly diverse asset base of MarkWest and MPLX that will provide significant additional opportunities across the hydrocarbon value chain. As further discussed in Note 14 , we recorded a goodwill impairment charge based on the implied fair value of goodwill as of the interim impairment analysis in the first quarter of 2016. During the second quarter of 2016, we finalized the analysis of the purchase price allocation. The completion of the purchase price allocation resulted in a refinement of the impairment expense recorded, as more fully discussed in Note 14 . Unaudited Pro Forma Financial Information The following unaudited pro forma financial information presents consolidated results assuming the MarkWest Merger occurred on January 1, 2014. Three Months Ended Nine Months Ended (In millions, except per share data) 2015 2015 Sales and other operating revenues (including consumer excise taxes) $ 19,186 $ 57,830 Net income attributable to MPC 943 2,600 Net income attributable to MPC per share – basic $ 1.76 $ 4.81 Net income attributable to MPC per share – diluted 1.75 4.78 The unaudited pro forma financial information includes adjustments to align accounting policies, increased depreciation expense to reflect the fair value of property, plant and equipment, increased amortization expense related to identifiable intangible assets, adjustments to amortize the difference between the fair value and the principal amount of the MarkWest debt assumed by MPLX, adjustments to reflect the change in our limited partner interest in MPLX resulting from the MarkWest Merger, as well as the related income tax effects. The unaudited pro forma financial information does not give effect to potential synergies that could result from the transaction and is not necessarily indicative of the results of future operations. Investments in Ocean Vessel Joint Ventures We currently have indirect ownership interests in two ocean vessel joint ventures with Crowley Maritime Corporation (“Crowley”), which were established to own and operate Jones Act vessels in petroleum product service. In September 2015, we acquired a 50 percent ownership interest in a joint venture, Crowley Ocean Partners, with Crowley. The joint venture owns and operates four new Jones Act product tankers, three of which are leased to MPC. Two of the vessels were delivered in 2015, the third was delivered in April 2016 and the fourth was delivered in August 2016. During the nine months ended September 30, 2016 , we contributed $69 million in connection with the delivery of the third and fourth vessels. We have contributed a total of $141 million for the four vessels. In May 2016, MPC and Crowley formed a new ocean vessel joint venture, Crowley Coastal Partners LLC (“Crowley Coastal Partners”), in which MPC has a 50 percent ownership interest. MPC and Crowley each contributed their 50 percent ownership in Crowley Ocean Partners, discussed above, into Crowley Coastal Partners. In addition, we contributed $48 million in cash and Crowley contributed its 100 percent ownership interest in Crowley Blue Water Partners LLC (“Crowley Blue Water Partners”) to Crowley Coastal Partners. Crowley Blue Water Partners is an entity that owns and operates three 750 Series ATB vessels that are leased to MPC. We account for our 50 percent interest in Crowley Coastal Partners as part of our Midstream segment using the equity method of accounting. See Note 5 for information on Crowley Coastal Partners as a VIE and Note 22 for information on our conditional guarantee of the indebtedness of Crowley Ocean Partners and Crowley Blue Water Partners. Investments in Pipeline Companies In November 2013, we agreed to serve as an anchor shipper for the Sandpiper pipeline project and fund 37.5 percent of the construction costs of the project, which was to become part of Enbridge Energy Partners L.P.’s (“Enbridge Energy Partners”) North Dakota System. In exchange for these commitments, we were to earn an approximate 27 percent equity interest in Enbridge Energy Partners’ North Dakota System when the Sandpiper pipeline is placed into service. We made contributions of $14 million to North Dakota Pipeline Company LLC (“North Dakota Pipeline”) during the nine months ended September 30, 2016 and have contributed $301 million since project inception to fund our share of the construction costs for the project. On September 1, 2016, Enbridge Energy Partners announced that its affiliate, North Dakota Pipeline, would withdraw certain pending regulatory applications for the Sandpiper pipeline project and that the project would be deferred indefinitely. These decisions were considered to indicate an impairment of the costs capitalized to date on the project. See Note 15 for information regarding the charge recognized in the third quarter of 2016. MPLX currently expects to participate in a joint venture with Enbridge Energy Partners to acquire a 9.1875 percent equity interest in the Dakota Access Pipeline (“DAPL”) and Energy Transfer Crude Oil Company Pipeline (“ETCOP”) projects, collectively referred to as the Bakken Pipeline system, from Energy Transfer Partners, L.P. (“ETP”) and Sunoco Logistics Partners, L.P. (“SXL”) for $500 million . Furthermore, MPC expects to become a committed shipper on the Bakken Pipeline system under terms of an on-going open season. The acquisition remains subject to certain closing conditions and is expected to close in the fourth quarter of 2016. The Bakken Pipeline system is currently expected to deliver in excess of 470,000 barrels per day of crude oil from the Bakken/Three Forks production area in North Dakota to the Midwest through Patoka, Illinois and ultimately to the Gulf Coast. ETP and SXL collectively own a 75 percent interest in each of the two joint ventures that are developing the Bakken Pipeline system. MPLX and Enbridge Energy Partners will participate in a new joint venture to acquire 49 percent of ETP and SXL’s 75 percent indirect interest in the Bakken Pipeline system. MPLX will own 25 percent of this new joint venture with Enbridge, which results in a 9.1875 percent indirect ownership interest in the Bakken Pipeline system. MPLX expects to account for its investment using the equity method of accounting. Subject to the closing of the transaction with ETP and SXL, Enbridge Energy Partners has agreed to cancel MPC’s transportation services agreement with respect to the Sandpiper pipeline project and release MPC from paying any termination fee per that agreement.

Variable Interest Entity

Variable Interest Entity	9 Months Ended
	Sep. 30, 2016
Variable Interest Entity, Not Primary Beneficiary, Disclosures [Abstract]
Variable Interest Entity	Variable Interest Entities In addition to MPLX, as described in Note 3 , the following entities are also VIEs. Crowley Coastal Partners In May 2016, Crowley Coastal Partners was formed to own the interest in both Crowley Ocean Partners and Crowley Blue Water Partners. We have determined that Crowley Coastal Partners is a VIE based on the terms of the existing financing arrangements for Crowley Blue Water Partners and Crowley Ocean Partners and the associated debt guarantees by MPC and Crowley. Our maximum exposure to loss at September 30, 2016 was $491 million , which includes our equity method investment in Crowley Coastal Partners and the debt guarantees provided to each of the lenders to Crowley Blue Water Partners and Crowley Ocean Partners. We are not the primary beneficiary of this VIE because we do not have the power to control the activities that significantly influence the economic outcomes of the entity and therefore, do not consolidate the entity. MarkWest Utica EMG On January 1, 2012, MarkWest Utica Operating Company, LLC (“Utica Operating”), a wholly-owned and consolidated subsidiary of MarkWest, and EMG Utica, LLC ("EMG Utica") (together the "Members"), executed agreements to form a joint venture, MarkWest Utica EMG LLC (“MarkWest Utica EMG”), to develop significant natural gas gathering, processing and NGL fractionation, transportation and marketing infrastructure in eastern Ohio. MarkWest has a 60 percent legal ownership interest in MarkWest Utica EMG. MarkWest Utica EMG's inability to fund its planned activities without subordinated financial support qualify it as a VIE. Utica Operating is not deemed to be the primary beneficiary due to EMG Utica’s voting rights on significant matters. We account for our ownership interest in MarkWest Utica EMG as an equity method investment. MPLX receives engineering and construction and administrative management fee revenue and reimbursement for other direct personnel costs for operating MarkWest Utica EMG. Our maximum exposure to loss as a result of our involvement with MarkWest Utica EMG includes our equity investment, any additional capital contribution commitments and any operating expenses incurred by the subsidiary operator in excess of compensation received for the performance of the operating services. Our equity investment in MarkWest Utica EMG at September 30, 2016 was $2.25 billion . Ohio Gathering Ohio Gathering Company, L.L.C. (“Ohio Gathering”) is a subsidiary of MarkWest Utica EMG and is engaged in providing natural gas gathering services in the Utica Shale in eastern Ohio. Ohio Gathering is a joint venture between MarkWest Utica EMG and Summit Midstream Partners, LLC. As of September 30, 2016 , we had a 36 percent indirect ownership interest in Ohio Gathering. As this entity is a subsidiary of MarkWest Utica EMG, which is accounted for as an equity method investment, MPLX reports its portion of Ohio Gathering’s net assets as a component of its investment in MarkWest Utica EMG. MPLX receives engineering and construction and administrative management fee revenue and reimbursement for other direct personnel costs for operating Ohio Gathering.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Our related parties include: • Centennial Pipeline LLC (“Centennial”), in which we have a 50 percent noncontrolling interest. Centennial owns a refined products pipeline and storage facility. • Crowley Blue Water Partners, in which we have a 50 percent indirect noncontrolling interest. Crowley Blue Water Partners owns and operates three Jones Act ATB vessels. • Crowley Ocean Partners, in which we have a 50 percent indirect noncontrolling interest. Crowley Ocean Partners owns and operates Jones Act product tankers. • Explorer Pipeline Company (“Explorer”), in which we have a 25 percent interest. Explorer owns and operates a refined products pipeline. • Illinois Extension Pipeline Company, LLC (“Illinois Extension Pipeline”), in which we have a 35 percent noncontrolling interest. Illinois Extension Pipeline owns and operates a crude oil pipeline. • LOCAP LLC (“LOCAP”), in which we have a 59 percent noncontrolling interest. LOCAP owns and operates a crude oil pipeline. • LOOP LLC (“LOOP”), in which we have a 51 percent noncontrolling interest. LOOP owns and operates the only U.S. deepwater oil port. • MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C. (“Jefferson Dry Gas”), in which we have a 67 percent noncontrolling interest. Jefferson Dry Gas is engaged in dry natural gas gathering in the county of Jefferson, Ohio. • MarkWest Utica EMG, in which we have a 60 percent noncontrolling interest. MarkWest Utica EMG owns and operates a NGL pipeline and natural gas gathering system. • Ohio Condensate Company, L.L.C. (“Ohio Condensate”), in which we have a 60 percent noncontrolling interest. Ohio Condensate owns and operates wellhead condensate stabilization and gathering services for certain locations within Ohio. • Ohio Gathering, in which we have a 36 percent indirect noncontrolling interest. Ohio Gathering owns, operates and develops midstream gathering infrastructure in southeastern Ohio. • The Andersons Albion Ethanol LLC (“TAAE”), in which we have a 45 percent noncontrolling interest, The Andersons Clymers Ethanol LLC (“TACE”), in which we have a 60 percent noncontrolling interest and The Andersons Marathon Ethanol LLC (“TAME”), in which we have a 67 percent direct and indirect noncontrolling interest. These companies each own and operate an ethanol production facility. • Other equity method investees. We believe that transactions with related parties were conducted on terms comparable to those with unaffiliated parties. Sales to related parties, which are included in “Sales and other operating revenues (including consumer excise taxes)” on the accompanying consolidated statements of income, were $2 million and $1 million for the three months ended September 30, 2016 and 2015 , respectively, and $5 million and $4 million for the nine months ended September 30, 2016 and 2015 , respectively. Other income from related parties, which is included in “Other income” on the accompanying consolidated statements of income, were $12 million and less than $1 million for the three months ended September 30, 2016 and 2015 , respectively, and $31 million and $1 million for the nine months ended September 30, 2016 and 2015 , respectively. Other income from related parties consists primarily of fees received for operating transportation assets for our related parties. Purchases from related parties were as follows: Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Crowley Blue Water Partners $ 16 $ — $ 22 $ — Crowley Ocean Partners 15 — 32 — Explorer 4 2 12 16 Illinois Extension Pipeline 27 — 82 — LOCAP 6 6 18 17 LOOP 14 12 42 38 Ohio Condensate 2 — 8 — TAAE 9 11 29 39 TACE 10 7 39 38 TAME 23 21 67 64 Other equity method investees 2 2 8 7 Total $ 128 $ 61 $ 359 $ 219 Related party purchases from Crowley Blue Water Partners and Crowley Ocean Partners consist of leasing marine equipment primarily used to transport refined products. Related party purchases from Explorer consist primarily of refined product transportation costs. Related party purchases from Illinois Extension Pipeline, LOCAP, LOOP and other equity method investees consist primarily of crude oil transportation costs. Related party purchases from Ohio Condensate consist of condensate processing fees. Related party purchases from TAAE, TACE and TAME consist of ethanol purchases. Receivables from related parties, which are included in “Receivables, less allowance for doubtful accounts” on the accompanying consolidated balance sheets, were as follows: (In millions) September 30, December 31, Centennial $ 1 $ 1 Jefferson Dry Gas — 2 MarkWest Utica EMG 2 1 Ohio Condensate — 3 Ohio Gathering 2 5 Other equity method investees 2 1 Total $ 7 $ 13 The long-term receivable, which is included in “Other noncurrent assets” on the accompanying consolidated balance sheet, was $1 million at September 30, 2016 and $1 million at December 31, 2015 . Payables to related parties, which are included in “Accounts payable” on the accompanying consolidated balance sheets, were as follows: (In millions) September 30, December 31, Explorer $ 1 $ 1 Illinois Extension Pipeline 9 4 LOCAP 2 2 LOOP 4 5 MarkWest Utica EMG 15 19 Ohio Condensate 1 4 TAAE 1 1 TACE 2 2 TAME 3 3 Other equity method investees 2 1 Total $ 40 $ 42

Income per Common Share

Income per Common Share	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Income per Common Share	Income per Common Share We compute basic earnings per share by dividing net income attributable to MPC by the weighted average number of shares of common stock outstanding. Diluted income per share assumes exercise of certain stock-based compensation awards, provided the effect is not anti-dilutive. MPC grants certain incentive compensation awards to employees and non-employee directors that are considered to be participating securities. Due to the presence of participating securities, we have calculated our earnings per share using the two-class method. Three Months Ended Nine Months Ended (In millions, except per share data) 2016 2015 2016 2015 Basic earnings per share: Allocation of earnings: Net income attributable to MPC $ 145 $ 948 $ 947 $ 2,665 Income allocated to participating securities — 1 1 3 Income available to common stockholders – basic $ 145 $ 947 $ 946 $ 2,662 Weighted average common shares outstanding 527 535 528 540 Basic earnings per share $ 0.28 $ 1.77 $ 1.79 $ 4.93 Diluted earnings per share: Allocation of earnings: Net income attributable to MPC $ 145 $ 948 $ 947 $ 2,665 Income allocated to participating securities — 1 1 3 Income available to common stockholders – diluted $ 145 $ 947 $ 946 $ 2,662 Weighted average common shares outstanding 527 535 528 540 Effect of dilutive securities 3 3 3 4 Weighted average common shares, including dilutive effect 530 538 531 544 Diluted earnings per share $ 0.27 $ 1.76 $ 1.78 $ 4.90 The following table summarizes the shares that were anti-dilutive and, therefore, were excluded from the diluted share calculation. Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Shares issued under stock-based compensation plans 3 1 3 1

Equity

Equity	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Equity	Equity As of September 30, 2016 , we have $2.58 billion of remaining share repurchase authorizations from our board of directors. We may utilize various methods to effect the repurchases, which could include open market repurchases, negotiated block transactions, accelerated share repurchases or open market solicitations for shares, some of which may be affected through Rule 10b5-1 plans. The timing and amount of future repurchases, if any, will depend upon several factors, including market and business conditions, and such repurchases may be discontinued at any time. Total share repurchases were as follows for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended Nine Months Ended (In millions, except per share data) 2016 2015 2016 2015 Number of shares repurchased 1 3 4 15 Cash paid for shares repurchased $ 51 $ 156 $ 177 $ 773 Effective average cost per delivered share $ 42.76 $ 50.86 $ 41.14 $ 49.97

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Segment Information	Segment Information In the first quarter of 2016, we revised our segment reporting in connection with the contribution of our inland marine business to MPLX. The operating results for our inland marine business and our investment in Crowley Ocean Partners are now reported in our Midstream segment. Previously they were reported as part of our Refining & Marketing segment. Comparable prior period information has been recast to reflect our revised segment presentation. We have three reportable segments: Refining & Marketing; Speedway; and Midstream. Each of these segments is organized and managed based upon the nature of the products and services it offers. • Refining & Marketing – refines crude oil and other feedstocks at our refineries in the Gulf Coast and Midwest regions of the United States, purchases ethanol and refined products for resale and distributes refined products through various means, including terminals and trucks that we own or operate. We sell refined products to wholesale marketing customers domestically and internationally, to buyers on the spot market, to our Speedway segment and to independent entrepreneurs who operate Marathon ® retail outlets. • Speedway – sells transportation fuels and convenience merchandise in retail markets in the Midwest, East Coast and Southeast regions of the United States. • Midstream – includes the operations of MPLX and certain other related operations. The Midstream segment gathers, processes and transports natural gas; gathers, transports, fractionates, stores and markets NGLs and transports and stores crude oil and refined products. On December 4, 2015, MPLX completed a merger with MarkWest and its results are included in the Midstream segment. Segment information for periods prior to the MarkWest Merger does not include amounts for these operations. See Note 4 . Segment income represents income from operations attributable to the reportable segments. Corporate administrative expenses and costs related to certain non-operating assets are not allocated to the reportable segments. In addition, certain items that affect comparability (as determined by the chief operating decision maker) are not allocated to the reportable segments. (In millions) Refining & Marketing Speedway Midstream Total Three Months Ended September 30, 2016 Revenues: Customer $ 11,286 $ 4,848 $ 484 $ 16,618 Intersegment (a) 2,798 1 206 3,005 Segment revenues $ 14,084 $ 4,849 $ 690 $ 19,623 Segment income from operations (b) $ 306 $ 209 $ 258 $ 773 Income from equity method investments (d) 8 — 51 59 Depreciation and amortization (d) 277 71 145 493 Capital expenditures and investments (e) 267 71 394 732 (In millions) Refining & Marketing Speedway Midstream Total Three Months Ended September 30, 2015 Revenues: Customer $ 13,441 $ 5,256 $ 19 $ 18,716 Intersegment (a) 3,192 1 198 3,391 Segment revenues $ 16,633 $ 5,257 $ 217 $ 22,107 Segment income from operations (b) $ 1,434 $ 243 $ 93 $ 1,770 Income from equity method investments 6 — 17 23 Depreciation and amortization (d) 262 63 27 352 Capital expenditures and investments (e) 256 130 156 542 (In millions) Refining & Marketing Speedway Midstream Total Nine Months Ended September 30, 2016 Revenues: Customer $ 31,197 $ 13,663 $ 1,324 $ 46,184 Intersegment (a) 7,872 2 595 8,469 Segment revenues $ 39,069 $ 13,665 $ 1,919 $ 54,653 Segment income from operations (b)(c) $ 1,324 $ 569 $ 626 $ 2,519 Income from equity method investments (d) 10 — 110 120 Depreciation and amortization (d) 820 203 429 1,452 Capital expenditures and investments (e) 788 191 1,147 2,126 (In millions) Refining & Marketing Speedway Midstream Total Nine Months Ended September 30, 2015 Revenues: Customer $ 41,277 $ 15,116 $ 51 $ 56,444 Intersegment (a) 9,353 3 587 9,943 Segment revenues $ 50,630 $ 15,119 $ 638 $ 66,387 Segment income from operations (b) $ 3,907 $ 538 $ 286 $ 4,731 Income from equity method investments 20 — 38 58 Depreciation and amortization (d) 784 188 79 1,051 Capital expenditures and investments (e) 686 275 400 1,361 (a) Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties. (b) Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments. (c) The Refining & Marketing and Speedway segments include inventory LCM benefit of $345 million and $25 million , respectively, for the nine months ended September 30, 2016 . (d) Differences between segment totals and MPC totals represent amounts related to unallocated items and are included in “Items not allocated to segments” in the reconciliation below. (e) Capital expenditures include changes in capital accruals, acquisitions (including any goodwill) and investments in affiliates. The following reconciles segment income from operations to income before income taxes as reported in the consolidated statements of income: Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Segment income from operations $ 773 $ 1,770 $ 2,519 $ 4,731 Items not allocated to segments: Corporate and other unallocated items (a)(b) (67 ) (75 ) (201 ) (229 ) Pension settlement expenses (c) (4 ) (2 ) (7 ) (4 ) Impairments (d) (267 ) (144 ) (486 ) (144 ) Net interest and other financial income (costs) (141 ) (70 ) (420 ) (215 ) Income before income taxes $ 294 $ 1,479 $ 1,405 $ 4,139 (a) Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets. (b) Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments. (c) See Note 20 . (d) 2016 relates to impairments of goodwill and equity method investments. 2015 relates to the cancellation of the Residual Oil Upgrader Expansion project. See Notes 14 and 15 , respectively. The following reconciles segment capital expenditures and investments to total capital expenditures: Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Segment capital expenditures and investments $ 732 $ 542 $ 2,126 $ 1,361 Less investments in equity method investees (a) 69 72 383 221 Plus items not allocated to segments: Capital expenditures 14 33 59 95 Capitalized interest 15 10 47 26 Total capital expenditures (b) $ 692 $ 513 $ 1,849 $ 1,261 (a) The nine months ended September 30, 2016 includes an adjustment of $143 million to the fair value of equity investments acquired in connection with the MarkWest Merger. See Note 4 . (b) Capital expenditures include changes in capital accruals. See Note 18 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.

Other Items

Other Items	9 Months Ended
	Sep. 30, 2016
Other Income and Expenses [Abstract]
Other Items	Other Items Net interest and other financial income (costs) was: Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Interest income $ 3 $ 2 $ 5 $ 5 Interest expense (a) (153 ) (77 ) (455 ) (226 ) Interest capitalized 15 11 47 27 Other financial costs (6 ) (6 ) (17 ) (21 ) Net interest and other financial income (costs) $ (141 ) $ (70 ) $ (420 ) $ (215 ) (a) The three and nine months ended September 30, 2016 includes $11 million and $33 million , respectively, for the amortization of the discount related to the difference between the fair value and the principal amount of the assumed MarkWest debt.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The combined federal, state and foreign income tax rate was 26 percent and 35 percent for the three months ended September 30, 2016 and 2015 , respectively and 34 percent and 35 percent for the nine months ended September 30, 2016 and 2015 , respectively. The effective tax rate for the three months ended September 30, 2016 varies from the U.S. statutory rate of 35 percent primarily due to the effects of a lower forecasted annual effective tax rate as compared to the forecasted rate used for the first six months of 2016. The effective tax rate for the nine months ended September 30, 2016 is slightly less than the U.S. statutory rate of 35 percent primarily due to certain permanent tax differences related to the net income attributable to noncontrolling interests (including their proportional share of the goodwill impairment charge recorded by MPLX), the domestic manufacturing deduction and state and local tax expense. The effective tax rate for the three and nine months ended September 30, 2015 is equivalent to the U.S. statutory rate of 35 percent . On March 31, 2016, we contributed our inland marine business to MPLX in exchange for MPLX common units representing limited partner interests and general partner units resulting in an increase in MPC’s controlling interest in MPLX. As a result of the change in our ownership of the underlying assets of MPLX, we recorded a decrease in MPC’s deferred tax liabilities of $42 million with an offsetting increase to additional paid-in capital. During the first quarter of 2016, MPC’s deferred tax liabilities increased $115 million and additional paid-in capital decreased by the same amount for an out of period adjustment to update the preliminary tax effects recorded in 2015 related to the MarkWest Merger. The impact of the out of period adjustment was not material to the consolidated balance sheet as of December 31, 2015. We are continuously undergoing examination of our income tax returns, which have been completed for our U.S. federal and state income tax returns through the 2009 and 2007 tax years, respectively. We had $6 million of unrecognized tax benefits as of September 30, 2016 . Pursuant to our tax sharing agreement with Marathon Oil Corporation (“Marathon Oil”), the unrecognized tax benefits related to pre-spinoff operations for which Marathon Oil was the taxpayer remain the responsibility of Marathon Oil and we have indemnified Marathon Oil accordingly. See Note 22 for indemnification information.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
Inventories	Inventories (In millions) September 30, December 31, Crude oil and refinery feedstocks $ 2,230 $ 2,180 Refined products 2,689 2,804 Materials and supplies 442 438 Merchandise 163 173 LCM reserve — (370 ) Total $ 5,524 $ 5,225 Inventories are carried at the lower of cost or market value. Costs of crude oil, refinery feedstocks and refined products are aggregated on a consolidated basis for purposes of assessing if the LIFO cost basis of these inventories may have to be written down to market values. As of December 31, 2015, costs of inventories exceeded market value by $370 million . As of September 30, 2016 , market value exceeded cost. The effect of the change in LCM reserve was a $370 million benefit to cost of revenues for the nine months ended September 30, 2016 . Based on movements of refined product prices, future inventory valuation adjustments could have a negative effect to earnings. Such losses are subject to reversal in subsequent periods if prices recover. The cost of inventories of crude oil and refinery feedstocks, refined products and merchandise is determined primarily under the LIFO method. During the nine months ended September 30, 2016 and 2015 , we recorded LIFO liquidations caused by permanently decreased levels in refined products inventory volumes. Cost of revenues increased and income from operations decreased by approximately $54 million and $30 million for the nine months ended September 30, 2016 and 2015 , respectively, as a result of the LIFO liquidations.

Property, Plant and Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment (In millions) September 30, December 31, Refining & Marketing $ 19,179 $ 18,396 Speedway 5,224 5,067 Midstream 12,328 11,379 Corporate and Other 795 762 Total 37,526 35,604 Less accumulated depreciation 11,829 10,440 Property, plant and equipment, net $ 25,697 $ 25,164

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	Goodwill Goodwill is tested for impairment on an annual basis and when events or changes in circumstances indicate the fair value of a reporting unit with goodwill has been reduced below the carrying value of the net assets of the reporting unit. During the first quarter of 2016, MPLX, our consolidated subsidiary, determined that an interim impairment analysis of the goodwill recorded in connection with the MarkWest Merger was necessary based on consideration of a number of first quarter events and circumstances, including i) continued deterioration of near term commodity prices as well as longer term pricing trends, ii) recent guidance on reductions to forecasted capital spending, the slowing of drilling activity and the resulting reduced production growth forecasts released or communicated by MPLX’s producer customers and iii) increases in the cost of capital. The combination of these factors was considered to be a triggering event requiring an interim impairment test. Based on the first step of the interim goodwill impairment analysis, the fair value for three of the reporting units to which goodwill was assigned in connection with the MarkWest Merger was less than their respective carrying value. In step two of the impairment analysis, the implied fair values of the goodwill were compared to the carrying values within those reporting units. Based on this assessment, it was determined that goodwill was impaired in two of the reporting units. Accordingly, MPLX recorded an impairment charge of approximately $129 million in the first quarter of 2016. In the second quarter of 2016, we completed our purchase price allocation, which resulted in an additional $1 million of impairment expense that would have been recorded in the first quarter of 2016 had the purchase price allocation been completed as of that date. This adjustment to the impairment expense was the result of completing an evaluation of the deferred tax liabilities associated with the MarkWest Merger and their impact on the resulting goodwill that was recognized. The fair value of the reporting units for the interim goodwill impairment analysis was determined based on applying the discounted cash flow method, which is an income approach, and the guideline public company method, which is a market approach. The discounted cash flow fair value estimate was based on known or knowable information at the interim measurement date. The significant assumptions that were used to develop the estimates of the fair values under the discounted cash flow method include management’s best estimates of the expected future results and discount rates, which ranged from 10.5 percent to 11.5 percent . Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As a result, there can be no assurance that the estimates and assumptions made for purposes of the interim goodwill impairment test will prove to be an accurate prediction of the future. The changes in the carrying amount of goodwill for the nine months ended September 30, 2016 were as follows: (In millions) Refining & Marketing Speedway Midstream Total Balance at December 31, 2015 $ 539 $ 853 $ 2,627 $ 4,019 Purchase price allocation adjustments (a) — — (241 ) (241 ) Impairment — — (130 ) (130 ) Balance at September 30, 2016 $ 539 $ 853 $ 2,256 $ 3,648 (a) See Note 4 for further discussion on purchase price allocation adjustments.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair Values—Recurring The following tables present assets and liabilities accounted for at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 by fair value hierarchy level. We have elected to offset the fair value amounts recognized for multiple derivative contracts executed with the same counterparty, including any related cash collateral as shown below; however, fair value amounts by hierarchy level are presented on a gross basis in the following tables. September 30, 2016 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Commodity derivative instruments, assets $ 277 $ 1 $ — $ (278 ) $ — $ 64 Other assets 2 — — N/A 2 — Total assets at fair value $ 279 $ 1 $ — $ (278 ) $ 2 $ 64 Commodity derivative instruments, liabilities (c) $ 312 $ — $ 4 $ (313 ) $ 3 $ — Embedded derivatives in commodity contracts (c) — — 44 — 44 — Contingent consideration, liability (d) — — 128 N/A 128 — Total liabilities at fair value $ 312 $ — $ 176 $ (313 ) $ 175 $ — December 31, 2015 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Commodity derivative instruments, assets $ 104 $ 2 $ 7 $ (62 ) $ 51 $ — Other assets 2 — — N/A 2 — Total assets at fair value $ 106 $ 2 $ 7 $ (62 ) $ 53 $ — Commodity derivative instruments, liabilities $ 39 $ — $ — $ (39 ) $ — $ — Embedded derivatives in commodity contracts (c) — — 32 — 32 — Contingent consideration, liability (d) — — 317 N/A 317 — Total liabilities at fair value $ 39 $ — $ 349 $ (39 ) $ 349 $ — (a) Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of September 30, 2016 , cash collateral of $35 million was netted with the mark-to-market derivative liabilities. As of December 31, 2015 , $23 million was netted with mark-to-market derivative assets. (b) We have no derivative contracts that are subject to master netting arrangements that are reflected gross on the balance sheet. (c) Level 3 includes $9 million and $5 million classified as current at September 30, 2016 and December 31, 2015 , respectively. (d) Includes $128 million and $196 million classified as current at September 30, 2016 and December 31, 2015 , respectively. Commodity derivatives in Level 1 are exchange-traded contracts for crude oil and refined products measured at fair value with a market approach using the close-of-day settlement prices for the market. Commodity derivatives are covered under master netting agreements with an unconditional right to offset. Collateral deposits in futures commission merchant accounts covered by master netting agreements related to Level 1 commodity derivatives are classified as Level 1 in the fair value hierarchy. Commodity derivatives in Level 2 include crude oil and natural gas swap contracts and are measured at fair value with a market approach. The valuations are based on the appropriate commodity prices and contain no significant unobservable inputs. LIBO Rates are an observable input for the measurement of these derivative contracts. The measurements for commodity contracts contain observable inputs in the form of forward prices based on WTI crude oil prices; and Columbia Appalachia, Henry Hub, PEPL and Houston Ship Channel natural gas prices. Level 3 instruments include OTC NGL contracts and embedded derivatives in commodity contracts. The fair value calculation for these Level 3 instruments used significant unobservable inputs including: (1) NGL prices interpolated and extrapolated due to inactive markets ranging from $0.22 to $3.13 per gallon, (2) electricity prices ranging from $24.66 to $27.11 per megawatt hour and (3) the probability of renewal of 50 percent for the first five -year term and 75 percent for the second five -year term of the gas purchase agreement and the related keep-whole processing agreement. For these contracts, increases in forward NGL prices result in a decrease in the fair value of the derivative assets and an increase in the fair value of the derivative liabilities. The forward prices for the individual NGL products generally increase or decrease in a positive correlation with one another. The embedded derivative liability relates to a natural gas purchase agreement embedded in a keep‑whole processing agreement. Increases or decreases in forward NGL prices result in an increase or decrease in the fair value of the embedded derivative. An increase in the probability of renewal would result in an increase in the fair value of the related embedded derivative liability. The contingent consideration represents the fair value as of September 30, 2016 and December 31, 2015 of the remaining amount we expect to pay to BP related to the earnout provision associated with our 2013 acquisition of BP’s refinery in Texas City, Texas and related logistics and marketing assets. We refer to these assets as the “Galveston Bay Refinery and Related Assets.” The fair value of the remaining contingent consideration was estimated using an income approach and is therefore a Level 3 liability. The amount of cash to be paid under the arrangement is based on both a market-based crack spread and refinery throughput volumes for the months during which the earnout applies, as well as established thresholds that cap the annual and total payment. The earnout payment cannot exceed $250 million per year for the last three years of the arrangement, with the total cumulative payment capped at $700 million over the six-year period commencing in 2014. Any excess or shortfall from the annual cap for a current year’s earnout calculation will not affect subsequent years’ calculations. The fair value calculation used significant unobservable inputs, including: (1) an estimate of forecasted monthly refinery throughput volumes; (2) a range of internal and external monthly crack spread forecasts from approximately $11 to $13 per barrel; and (3) a range of risk-adjusted discount rates from five percent to 10 percent . An increase or decrease in forecasts for the crack spread or refinery throughput volumes may result in a corresponding increase or decrease in the fair value of the contingent consideration liability. Increases to the fair value as a result of increasing forecasts for both of these unobservable inputs, however, are limited as the earnout payment is subject to annual caps. An increase or decrease in the discount rate may result in a decrease or increase to the fair value of the contingent consideration liability, respectively. The fair value of the contingent consideration liability is reassessed each quarter, with changes in fair value recorded in cost of revenues. During the second quarter of 2016, we paid BP $200 million for the third year’s contingent earnout. On the consolidated statements of cash flows for the nine months ended September 30, 2016 , $164 million of the contingent earnout payment is included as a financing activity with the remainder included as an operating activity. Including this second quarter payment, we have paid BP approximately $569 million in total leaving $131 million remaining under the total cap of $700 million . The following is a reconciliation of the beginning and ending balances recorded for liabilities classified as Level 3 in the fair value hierarchy. Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Beginning balance $ 171 $ 307 $ 342 $ 478 Contingent consideration payment — — (200 ) (189 ) Unrealized and realized losses included in net income 6 5 33 23 Settlements of derivative instruments (1 ) — 1 — Ending balance $ 176 $ 312 $ 176 $ 312 The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: Derivative instruments $ 4 $ — $ 19 $ — Contingent consideration agreement 2 5 11 23 Total $ 6 $ 5 $ 30 $ 23 Fair Values - Nonrecurring The following table shows the values of assets, by major category, measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition. Nine Months Ended September 30, 2016 2015 (In millions) Fair Value Impairment Fair Value Impairment Equity method investments $ 42 $ 356 $ — $ — Goodwill — 130 — — Property, plant and equipment, net — — — 144 During the third quarter of 2016, Enbridge Energy Partners announced that its affiliate, North Dakota Pipeline, would withdraw certain pending regulatory applications for the Sandpiper pipeline project and that the project would be deferred indefinitely. These decisions were considered to indicate an impairment of the costs capitalized to date on the project. As the operator of North Dakota Pipeline, which owns the investments made to date in the Sandpiper pipeline project, and the entity responsible for maintaining its financial records, Enbridge completed a fixed asset impairment analysis as of August 31, 2016, in accordance with ASC Topic 360, to determine the fixed asset impairment charge. Based on the estimated liquidation value of the fixed assets, an impairment charge was recorded by North Dakota Pipeline. Based on our 37.5 percent ownership of North Dakota Pipeline, we recognized approximately $267 million of this charge in the third quarter of 2016 through “Income (loss) from equity method investments” on the accompanying consolidated statements of income. Also, in accordance with ASC Topic 323, we completed an assessment to determine any additional equity method impairment charge to be recorded on our consolidated financial statements resulting from an other-than-temporary impairment. The result of this analysis indicated no additional charge was required to be recorded. The fixed assets of North Dakota Pipeline related to the Sandpiper pipeline project consist primarily of project management and engineering costs, pipe, valves, motors and other equipment, land and easements. The fair value of fixed assets was estimated based on a market approach using the estimated price that would be received to sell pipe, land and other related equipment in its current condition, considering the current market conditions for sale of these assets and length of disposal period. The valuation considered a range of potential selling prices from various alternatives that could be used to dispose of these assets. As such, the fair value of the North Dakota Pipeline equity method investment and its underlying assets represents a Level 3 measurement. North Dakota Pipeline expects to dispose of these assets through orderly transactions. During the second quarter of 2016, forecasts for Ohio Condensate, an equity method investment, were reduced in line with updated forecasts for customer requirements. As the operator of that entity responsible for maintaining its financial records, we completed a fixed asset impairment analysis as of June 30, 2016, in accordance with ASC Topic 360, to determine the potential fixed asset impairment charge. The resulting fixed asset impairment charge recorded within Ohio Condensate’s financial statements was $96 million . Based on our 60 percent ownership of Ohio Condensate, approximately $58 million was recorded in the second quarter of 2016 in “Income (loss) from equity method investments” on the accompanying consolidated statements of income. Our investment in Ohio Condensate, which was established at fair value in connection with the MarkWest Merger, exceeded its proportionate share of the underlying net assets. Therefore, in conjunction with the ASC Topic 360 impairment analysis, we completed an equity method impairment analysis in accordance with ASC Topic 323 to determine the potential additional equity method impairment charge to be recorded on our consolidated financial statements resulting from an other-than-temporary impairment. As a result, an additional impairment charge of approximately $31 million was recorded in the second quarter of 2016 in “Income (loss) from equity method investments” on the accompanying consolidated statements of income, which eliminated the basis differential established in connection with the MarkWest Merger. The fair value of Ohio Condensate and its underlying assets was determined based upon applying the discounted cash flow method, which is an income approach, and the guideline public company method, which is a market approach. The discounted cash flow fair value estimate is based on known or knowable information at the interim measurement date. The significant assumptions that were used to develop the estimate of the fair value under the discounted cash flow method include management’s best estimates of the expected future results using a probability weighted average set of cash flow forecasts and a discount rate of 11.2 percent . Fair value determinations require considerable judgment and are sensitive to changes in underlying assumptions and factors. As such, the fair value of the Ohio Condensate equity method investment and its underlying assets represents a Level 3 measurement. As a result, there can be no assurance that the estimates and assumptions made for purposes of the interim impairment test will prove to be an accurate prediction of the future. See Note 14 for additional information on the goodwill impairment. In the third quarter of 2015, we decided to cancel the Residual Oil Upgrader Expansion (“ROUX”) project at our Garyville, LA refinery due to the implications of current market conditions. The project was intended to increase margins by upgrading residual fuel to ultra-low sulfur diesel and gas oil. The work completed on the project through September 30, 2015 had no alternate use or net salvage value; therefore, we fully impaired the $144 million of cost capitalized for the project through that date. This impairment charge is included in “Impairment expense” on the accompanying consolidated statements of income. The fair value of our investment in the project was determined using an income approach and is classified as Level 3. Fair Values – Reported The following table summarizes financial instruments on the basis of their nature, characteristics and risk at September 30, 2016 and December 31, 2015 , excluding the derivative financial instruments and contingent consideration reported above. September 30, 2016 December 31, 2015 (In millions) Fair Value Carrying Value Fair Value Carrying Value Financial assets: Investments $ 27 $ 2 $ 33 $ 2 Other 22 22 35 33 Total financial assets $ 49 $ 24 $ 68 $ 35 Financial liabilities: Long-term debt (a) $ 11,056 $ 10,285 $ 11,366 $ 11,628 Deferred credits and other liabilities 124 111 136 135 Total financial liabilities $ 11,180 $ 10,396 $ 11,502 $ 11,763 (a) Excludes capital leases and debt issuance costs, however, includes amount classified as debt due within one year. Our current assets and liabilities include financial instruments, the most significant of which are trade accounts receivable and payables. We believe the carrying values of our current assets and liabilities approximate fair value. Our fair value assessment incorporates a variety of considerations, including (1) the short-term duration of the instruments, (2) our investment-grade credit rating and (3) our historical incurrence of and expected future insignificance of bad debt expense, which includes an evaluation of counterparty credit risk. Fair values of our financial assets included in investments and other financial assets and of our financial liabilities included in deferred credits and other liabilities are measured primarily using an income approach and most inputs are internally generated, which results in a Level 3 classification. Estimated future cash flows are discounted using a rate deemed appropriate to obtain the fair value. Other financial assets primarily consist of environmental remediation receivables. Deferred credits and other liabilities primarily consist of a liability resulting from a financing arrangement for the construction of MPLX’s steam methane reformer (“SMR”), a payable for merger cash consideration to be paid to MPLX’s Class B unitholders upon conversion to MPLX common units, insurance liabilities and environmental remediation liabilities. Fair value of fixed-rate long-term debt is measured using a market approach, based upon the average of quotes for our debt from major financial institutions and a third-party valuation service. Because these quotes cannot be independently verified to the market, they are considered Level 3 inputs. Fair value of variable-rate long-term debt approximates the carrying value.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives For further information regarding the fair value measurement of derivative instruments, including any effect of master netting agreements or collateral, see Note 15 . We do not designate any of our commodity derivative instruments as hedges for accounting purposes. 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 and (7) the purchase of electricity. The following table presents the gross fair values of derivative instruments, excluding cash collateral, and where they appear on the consolidated balance sheets as of September 30, 2016 and December 31, 2015 : (In millions) September 30, 2016 Balance Sheet Location Asset Liability Commodity derivatives (a) Other current assets $ 278 $ 312 Other current liabilities — 10 Deferred credits and other liabilities — 38 (In millions) December 31, 2015 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 113 $ 39 Other current liabilities — 5 Deferred credits and other liabilities (a) — 27 (a) Includes embedded derivatives. The tables below summarize open commodity derivative contracts for crude oil, natural gas and refined products as of September 30, 2016 . Position Total Barrels (In thousands) Crude Oil (a) Exchange-traded Long 45,660 Exchange-traded Short (47,459 ) OTC Short (92 ) (a ) 91 percent of the exchange-traded contracts expire in the fourth quarter of 2016 . Position MMbtu Natural Gas OTC Long 841,931 Position Total Gallons (In thousands) Refined Products (a) Exchange-traded Long 112,098 Exchange-traded Short (137,634 ) OTC Short (56,108 ) (a ) 100 percent of the exchange-traded contracts expire in the fourth quarter of 2016 . The following table summarizes the effect of all commodity derivative instruments in our consolidated statements of income: Gain (Loss) Gain (Loss) (In millions) Three Months Ended September 30, Nine Months Ended September 30, Income Statement Location 2016 2015 2016 2015 Sales and other operating revenues $ (3 ) $ (1 ) $ (4 ) $ 10 Cost of revenues (19 ) 140 (85 ) 115 Total $ (22 ) $ 139 $ (89 ) $ 125

Debt

Debt	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Debt	Debt Our outstanding borrowings at September 30, 2016 and December 31, 2015 consisted of the following: (In millions) September 30, December 31, Marathon Petroleum Corporation: Commercial paper $ — $ — 364-day bank revolving credit facility due July 2017 — — Bank revolving credit facility due 2020 — — Term loan agreement due 2019 200 700 Senior notes, 2.700% due December 2018 600 600 Senior notes, 3.400% due December 2020 650 650 Senior notes, 5.125% due March 2021 1,000 1,000 Senior notes, 3.625%, due September 2024 750 750 Senior notes, 6.500%, due March 2041 1,250 1,250 Senior notes, 4.750%, due September 2044 800 800 Senior notes, 5.850% due December 2045 250 250 Senior notes, 5.000%, due September 2054 400 400 MPLX LP: MPLX term loan facility due 2019 250 250 MPLX bank revolving credit facility due 2020 — 877 MPLX senior notes, 5.500%, due February 2023 710 710 MPLX senior notes, 4.500%, due July 2023 989 989 MPLX senior notes, 4.875%, due December 2024 1,149 1,149 MPLX senior notes, 4.000%, due February 2025 500 500 MPLX senior notes, 4.875%, due June 2025 1,189 1,189 MarkWest senior notes, 4.500% - 5.500%, due 2023 - 2025 63 63 Capital lease obligations due 2016-2028 327 348 Trade receivables securitization facility due July 2019 — — Total 11,077 12,475 Unamortized debt issuance costs (46 ) (51 ) Unamortized discount (a) (465 ) (499 ) Amounts due within one year (28 ) (29 ) Total long-term debt due after one year $ 10,538 $ 11,896 (a) Includes $431 million and $464 million discount as of September 30, 2016 and December 31, 2015 , respectively, related to the difference between the fair value and the principal amount of the assumed MarkWest debt. Commercial Paper On February 26, 2016, we established a commercial paper program that allows us to have a maximum of $2.0 billion in commercial paper outstanding, with maturities up to 397 days from the date of issuance. We do not intend to have outstanding commercial paper borrowings in excess of available capacity under our bank revolving credit facility. During the nine months ended September 30, 2016 , we borrowed and repaid $1.06 billion under the commercial paper program. At September 30, 2016 , we had no amounts outstanding under the commercial paper program. MPC Bank Revolving Credit Facility On July 20, 2016, we entered into a credit agreement with a syndicate of lenders to replace our existing MPC bank revolving credit facility due in 2017. The new agreement provides for a four -year $2.5 billion bank revolving credit facility maturing on July 20, 2020 . Additionally, we entered into a 364 -day $1.0 billion bank revolving credit facility maturing on July 19, 2017 . The financial covenants contained in these agreements remain the same as under the previous bank revolving credit facility. There were no borrowings or letters of credit outstanding under the MPC bank revolving credit facility at September 30, 2016 . MPC Term Loan Agreement On September 30, 2016, we chose to prepay $500 million under the MPC term loan agreement with available cash on hand. Under the provisions of the MPC term loan agreement, the loan may be prepaid in whole or in part without premium or penalty. The maturity date of the MPC term loan agreement is September 24, 2019. MPLX Bank Revolving Credit Facility During the nine months ended September 30, 2016 , MPLX borrowed $434 million under the MPLX bank revolving credit facility at an average interest rate of 1.9 percent , per annum, and repaid $1.31 billion of the outstanding borrowings. At September 30, 2016 , MPLX had no outstanding borrowings and $3 million letters of credit outstanding under the MPLX bank revolving credit facility, resulting in total availability of $2.0 billion . Trade Receivables Securitization Facility On July 20, 2016, we amended our trade receivables securitization facility (“trade receivables facility”) to, among other things, reduce the capacity from $1.0 billion to $750 million and to extend the maturity date to July 19, 2019 . The reduction in capacity reflects the lower refined product price environment. During the nine months ended September 30, 2016 , we borrowed $280 million under the trade receivables securitization facility at an average interest rate of 1.3 percent and repaid all of these borrowings. At September 30, 2016 , we had no amounts outstanding under our trade receivables securitization facility.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Nine Months Ended (In millions) 2016 2015 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 400 $ 262 Net income taxes paid to taxing authorities 28 1,286 Non-cash investing and financing activities: Property, plant and equipment sold — 5 Property, plant and equipment acquired — 5 The consolidated statements of cash flows exclude changes to the consolidated balance sheets that did not affect cash. The following is a reconciliation of additions to property, plant and equipment to total capital expenditures: Nine Months Ended (In millions) 2016 2015 Additions to property, plant and equipment per consolidated statements of cash flows $ 2,147 $ 1,277 Non-cash additions to property, plant and equipment — 5 Asset retirement expenditures 4 1 Decrease in capital accruals (169 ) (22 ) Total capital expenditures before acquisitions 1,982 1,261 Acquisitions (a) (133 ) — Total capital expenditures $ 1,849 $ 1,261 (a) The nine months ended September 30, 2016 includes adjustments to the fair values of the property, plant and equipment, intangibles and goodwill acquired in connection with the MarkWest Merger. See Note 4 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss The following table shows the changes in accumulated other comprehensive loss by component. Amounts in parentheses indicate debits. (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2014 $ (217 ) $ (104 ) $ 4 $ 4 $ (313 ) Other comprehensive income (loss) before reclassifications (17 ) 14 — (3 ) (6 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (35 ) (3 ) — — (38 ) – actuarial loss (a) 39 6 — — 45 – settlement loss (a) 4 — — — 4 Tax effect (3 ) (1 ) — — (4 ) Other comprehensive income (loss) (12 ) 16 — (3 ) 1 Balance as of September 30, 2015 $ (229 ) $ (88 ) $ 4 $ 1 $ (312 ) (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2015 $ (255 ) $ (70 ) $ 4 $ 3 $ (318 ) Other comprehensive income (loss) before reclassifications (8 ) 1 — — (7 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (35 ) (2 ) — — (37 ) – actuarial loss (a) 28 1 — — 29 – settlement loss (a) 7 — — — 7 Other (b) — — — (1 ) (1 ) Tax effect — — — — — Other comprehensive income (loss) (8 ) — — (1 ) (9 ) Balance as of September 30, 2016 $ (263 ) $ (70 ) $ 4 $ 2 $ (327 ) (a) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 20 . (b) This amount was reclassified out of accumulated other comprehensive loss and is included in selling, general and administrative on the consolidated statements of income.

Defined Benefit Pension and Oth

Defined Benefit Pension and Other Postretirement Plans	9 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Defined Benefit Pension and Other Postretirement Plans	Defined Benefit Pension and Other Postretirement Plans The following summarizes the components of net periodic benefit costs: Three Months Ended September 30, Pension Benefits Other Benefits (In millions) 2016 2015 2016 2015 Components of net periodic benefit cost: Service cost $ 29 $ 25 $ 8 $ 8 Interest cost 18 18 9 8 Expected return on plan assets (24 ) (25 ) — — Amortization – prior service credit (12 ) (12 ) (1 ) (1 ) – actuarial loss 10 13 — 2 – settlement loss 4 2 — — Net periodic benefit cost $ 25 $ 21 $ 16 $ 17 Nine Months Ended September 30, Pension Benefits Other Benefits (In millions) 2016 2015 2016 2015 Components of net periodic benefit cost: Service cost $ 86 $ 76 $ 24 $ 23 Interest cost 55 54 26 24 Expected return on plan assets (73 ) (75 ) — — Amortization – prior service credit (35 ) (35 ) (2 ) (3 ) – actuarial loss 28 39 1 6 – settlement loss 7 4 — — Net periodic benefit cost $ 68 $ 63 $ 49 $ 50 We have no required funding requirements for our funded pension plans for 2016, but during the nine months ended September 30, 2016 , we chose to make a $100 million voluntary contribution. Benefit payments related to unfunded pension and other postretirement benefit plans were $19 million and $19 million , respectively, during the nine months ended September 30, 2016 . During the nine months ended September 30, 2016 and 2015 , we determined that certain of our pension plans’ lump sum payments to employees retiring in the respective years will exceed the plans’ total service and interest costs for the year. Settlement losses are required to be recorded when lump sum payments exceed total service and interest costs. As a result, during the nine months ended September 30, 2016 and 2015 , we recorded pension settlement expenses of $7 million and $4 million .

Stock-Based Compensation Plans

Stock-Based Compensation Plans	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans Stock Option Awards The following table presents a summary of our stock option award activity for the nine months ended September 30, 2016 : Number of Shares Weighted Average Exercise Price Outstanding at December 31, 2015 8,724,631 $ 27.16 Granted 1,474,177 35.27 Exercised (524,458 ) 18.26 Forfeited, canceled or expired (29,607 ) 42.91 Outstanding at September 30, 2016 9,644,743 28.84 The grant date fair value of stock option awards granted during the nine months ended September 30, 2016 was $9.84 per share. The fair value of stock options granted to our employees is estimated on the date of the grant using the Black Scholes option-pricing model, which employs various assumptions. Restricted Stock Awards The following table presents a summary of restricted stock award activity for the nine months ended September 30, 2016 : Shares of Restricted Stock (“RS”) Restricted Stock Units (“RSU”) Number of Shares Weighted Average Grant Date Fair Value Number of Units Weighted Average Grant Date Fair Value Outstanding at December 31, 2015 1,074,543 $ 47.70 513,220 $ 24.59 Granted 722,315 36.10 35,453 40.21 RS’s Vested/RSU’s Issued (463,996 ) 46.42 (190,845 ) 20.60 Forfeited (39,213 ) 44.67 — — Outstanding at September 30, 2016 1,293,649 41.77 357,828 28.26 Performance Unit Awards The following table presents a summary of the activity for performance unit awards to be settled in shares for the nine months ended September 30, 2016 : Number of Units Weighted Average Grant Date Fair Value Outstanding at December 31, 2015 6,145,442 $ 0.92 Granted 2,329,500 0.57 Exercised (1,904,792 ) 0.95 Canceled (314,972 ) 0.93 Outstanding at September 30, 2016 6,255,178 0.78 The performance unit awards granted during the nine months ended September 30, 2016 have a grant date fair value of $0.57 per unit, as calculated using a Monte Carlo valuation model. MPLX Awards During the nine months ended September 30, 2016 , MPLX granted equity-based compensation awards under the MPLX LP 2012 Incentive Compensation Plan. The compensation expense for these awards is not material to our consolidated financial statements.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies We are the subject of, or a party to, a number of pending or threatened legal actions, contingencies and commitments involving a variety of matters, including laws and regulations relating to the environment. Some of these matters are discussed below. For matters for which we have not recorded an accrued liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings and discovery. However, the ultimate resolution of some of these contingencies could, individually or in the aggregate, be material. Environmental matters —We are subject to federal, state, local and foreign laws and regulations relating to the environment. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites and certain other locations including presently or formerly owned or operated retail marketing sites. Penalties may be imposed for noncompliance. At September 30, 2016 and December 31, 2015 , accrued liabilities for remediation totaled $145 million and $163 million , respectively. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties if any that may be imposed. Receivables for recoverable costs from certain states, under programs to assist companies in clean-up efforts related to underground storage tanks at presently or formerly owned or operated retail marketing sites, were $62 million and $70 million at September 30, 2016 and December 31, 2015 , respectively. We are involved in a number of environmental enforcement matters arising in the ordinary course of business. While the outcome and impact on us cannot be predicted with certainty, management believes the resolution of these environmental matters will not, individually or collectively, have a material adverse effect on our consolidated results of operations, financial position or cash flows. Litigation Relating to the MarkWest Merger —In July 2015, a purported class action lawsuit asserting claims challenging the MarkWest Merger was filed in the Court of Chancery of the State of Delaware by a purported unitholder of MarkWest. In August 2015, two similar putative class action lawsuits were filed in the Court of Chancery of the State of Delaware by plaintiffs who purport to be unitholders of MarkWest. On September 9, 2015, these lawsuits were consolidated into one action pending in the Court of Chancery of the State of Delaware, now captioned In re MarkWest Energy Partners, L.P. Unitholder Litigation . On October 1, 2015, the plaintiffs filed a consolidated complaint against the individual members of the board of directors of MarkWest Energy GP, L.L.C. (the “MarkWest GP Board”), MPLX, MPLX GP, MPC and Sapphire Holdco LLC, a wholly-owned subsidiary of MPLX, asserting in connection with the MarkWest Merger and related disclosures that, among other things, (i) the MarkWest GP Board breached its duties in approving the MarkWest Merger with MPLX and (ii) MPC, MPLX, MPLX GP, and Sapphire Holdco LLC aided and abetted such breaches. On February 4, 2016, the Court approved a stipulation and proposed order to dismiss all claims with prejudice as to the named plaintiffs, but the Court retained jurisdiction to adjudicate a fee application by the plaintiffs’ counsel for an award of attorneys’ fees and reimbursement of expenses. On March 28, 2016, the plaintiffs filed an application for reimbursement of approximately $2 million of legal fees and expenses. On May 17, 2016, the plaintiffs withdrew the fee application and the case is now dismissed. MarkWest Environmental Proceeding – In July 2015 representatives from the EPA and the United States Department of Justice conducted a raid on a MarkWest Liberty Midstream pipeline launcher/receiver site utilized for pipeline maintenance operations in Washington County, Pennsylvania pursuant to a search warrant issued by a magistrate of the United States District Court for the Western District of Pennsylvania. As part of this initiative, the U.S. Attorney’s Office for the Western District of Pennsylvania, with the assistance of EPA’s Criminal Investigation Division proceeded with an investigation of MarkWest’s launcher/receiver, pipeline and compressor station operations. In response to the investigation, MarkWest initiated independent studies which demonstrated that there was no risk to worker safety and no threat of public harm associated with MarkWest’s launcher/receiver operations. These findings were supported by a subsequent inspection and review by the Occupational Safety and Health Administration. After providing these studies, and other substantial documentation related to MarkWest's pipeline and compressor stations, and arranging site visits and conducting several meetings with the government’s representatives, on September 13, 2016, the U.S. Attorney’s Office for the Western District of Pennsylvania rendered a declination decision, dropping its criminal investigation and declining to pursue charges in this matter. MarkWest Liberty Midstream continues to discuss with the EPA and the State of Pennsylvania alleged omissions associated with permits or related regulatory obligations for its launcher/receiver and compressor station facilities in the region. It is possible that in connection with any potential or asserted enforcement action associated with this matter, MarkWest Liberty Midstream will incur material assessments, penalties or fines, incur material defense costs and expenses, be required to modify operations or construction activities which could increase operating costs and capital expenditures, or be subject to other obligations or restrictions that could restrict or prohibit our activities, any or all of which could adversely affect our results of operations, financial position or cash flows. The amount of any potential assessments, penalties, fines, restrictions, requirements, modifications, costs or expenses that may be incurred in connection with any potential enforcement action cannot be reasonably estimated or determined at this time. Other Lawsuits —In May 2015, the Kentucky attorney general filed a lawsuit against our wholly-owned subsidiary, Marathon Petroleum Company LP (“MPC LP”) in the United States District Court for the Western District of Kentucky asserting claims under federal and state antitrust statutes, the Kentucky Consumer Protection Act, and state common law. The complaint, as amended in July 2015, alleges that MPC LP used deed restrictions, supply agreements with customers and exchange agreements with competitors to unreasonably restrain trade in areas within Kentucky and seeks declaratory relief, unspecified damages, civil penalties, restitution and disgorgement of profits. At this early stage, the ultimate outcome of this litigation remains uncertain, and neither the likelihood of an unfavorable outcome nor the ultimate liability, if any, can be determined, and we are unable to estimate a reasonably possible loss (or range of loss) for this matter. We intend to vigorously defend ourselves in this matter. In May 2007, the Kentucky attorney general filed a lawsuit against us and Marathon Oil in state court in Franklin County, Kentucky for alleged violations of Kentucky’s emergency pricing and consumer protection laws following Hurricanes Katrina and Rita in 2005. The lawsuit alleges that we overcharged customers by $89 million during September and October 2005 . The complaint seeks disgorgement of these sums, as well as penalties, under Kentucky’s emergency pricing and consumer protection laws. We are vigorously defending this litigation. We believe that this is the first lawsuit for damages and injunctive relief under the Kentucky emergency pricing laws to progress this far and it contains many novel issues. In May 2011, the Kentucky attorney general amended his complaint to include a request for immediate injunctive relief as well as unspecified damages and penalties related to our wholesale gasoline pricing in April and May 2011 under statewide price controls that were activated by the Kentucky governor on April 26, 2011 and which have since expired. The court denied the attorney general’s request for immediate injunctive relief, and the remainder of the 2011 claims likely will be resolved along with those dating from 2005. If the lawsuit is resolved unfavorably in its entirety, it could materially impact our consolidated results of operations, financial position or cash flows. However, management does not believe the ultimate resolution of this litigation will have a material adverse effect. We are also a party to a number of other lawsuits and other proceedings arising in the ordinary course of business. While the ultimate outcome and impact to us cannot be predicted with certainty, we believe that the resolution of these other lawsuits and proceedings will not have a material adverse effect on our consolidated financial position, results of operations or cash flows. Guarantees— We have provided certain guarantees, direct and indirect, of the indebtedness of other companies. Under the terms of most of these guarantee arrangements, we would be required to perform should the guaranteed party fail to fulfill its obligations under the specified arrangements. In addition to these financial guarantees, we also have various performance guarantees related to specific agreements. Guarantees related to indebtedness of equity method investees —We hold interests in an offshore oil port, LOOP, and a crude oil pipeline system, LOCAP. Both LOOP and LOCAP have secured various project financings with throughput and deficiency agreements. Under the agreements, we are required to advance funds if the investees are unable to service their debt. Any such advances are considered prepayments of future transportation charges. The duration of the agreements vary but tend to follow the terms of the underlying debt, which extend through 2037 . Our maximum potential undiscounted payments under these agreements for the debt principal totaled $172 million as of September 30, 2016 . We hold an interest in a refined products pipeline through our investment in Centennial, and have guaranteed our portion of the payment of Centennial’s principal, interest and prepayment costs, if applicable, under a Master Shelf Agreement, which is scheduled to expire in 2024 . The guarantee arose in order for Centennial to obtain adequate financing. Our maximum potential undiscounted payments under this agreement for debt principal totaled $30 million as of September 30, 2016 . In connection with our 50 percent indirect interest in Crowley Ocean Partners, we have agreed to conditionally guarantee our portion of the obligations of the joint venture and its subsidiaries under a senior secured term loan agreement. The term loan agreement provides for loans of up to $325 million to finance the acquisition of four product tankers. MPC’s liability under the guarantee for each vessel is conditioned upon the occurrence of certain events, including if we cease to maintain an investment grade credit rating or the charter for the relevant product tanker ceases to be in effect and is not replaced by a charter with an investment grade company on certain defined commercial terms. As of September 30, 2016 , our maximum potential undiscounted payments under this agreement for debt principal totaled $163 million . In connection with our 50 percent indirect interest in Crowley Blue Water Partners, we have agreed to provide a conditional guarantee of up to 50 percent of its outstanding debt balance in the event there is no charter agreement in place with an investment grade customer for the entity’s three vessels as well as other financial support in certain circumstances. The maximum exposure under these arrangements is 50 percent of the amount of the debt, which was $142 million as of September 30, 2016 . Marathon Oil indemnifications— In conjunction with our spinoff from Marathon Oil, we have entered into arrangements with Marathon Oil providing indemnities and guarantees with recorded values of $3 million as of September 30, 2016 , which consist of unrecognized tax benefits related to MPC, its consolidated subsidiaries and the refining, marketing and transportation business operations prior to our spinoff which are not already reflected in the unrecognized tax benefits described in Note 11 , and other contingent liabilities Marathon Oil may incur related to taxes. Furthermore, the separation and distribution agreement and other agreements with Marathon Oil to effect our spinoff provide for cross-indemnities between Marathon Oil and us. In general, Marathon Oil is required to indemnify us for any liabilities relating to Marathon Oil’s historical oil and gas exploration and production operations, oil sands mining operations and integrated gas operations, and we are required to indemnify Marathon Oil for any liabilities relating to Marathon Oil’s historical refining, marketing and transportation operations. The terms of these indemnifications are indefinite and the amounts are not capped. Other guarantees —We have entered into other guarantees with maximum potential undiscounted payments totaling $83 million as of September 30, 2016 , which primarily consist of a commitment to contribute cash to an equity method investee for certain catastrophic events, up to $50 million per event, in lieu of procuring insurance coverage and leases of assets containing general lease indemnities and guaranteed residual values. General guarantees associated with dispositions – Over the years, we have sold various assets in the normal course of our business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements, and environmental and general indemnifications that require us to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. We are typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based. Contractual commitments and contingencies— At September 30, 2016 , our contractual commitments to acquire property, plant and equipment and advance funds to equity method investees totaled $521 million , which includes $131 million of contingent consideration associated with the acquisition of the Galveston Bay Refinery and Related Assets. See Note 15 for additional information on the contingent consideration. Certain natural gas processing and gathering arrangements require us to construct natural gas processing plants, natural gas gathering pipelines and NGL pipelines and contain certain fees and charges if specified construction milestones are not achieved for reasons other than force majeure. In certain cases, certain producer customers may have the right to cancel the processing arrangements with us if there are significant delays that are not due to force majeure. As of September 30, 2016 , management does not believe there are any indications that we will not be able to meet the construction milestones, that force majeure does not apply, or that such fees and charges will otherwise be triggered.

Supplementary Statistics

Supplementary Statistics	9 Months Ended
	Sep. 30, 2016
Text Block [Abstract]
Supplementary Statistics	Supplementary Statistics (Unaudited) Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Income from Operations by segment Refining & Marketing (a)(b) $ 306 $ 1,434 $ 1,324 $ 3,907 Speedway (b) 209 243 569 538 Midstream (a)(c) 258 93 626 286 Items not allocated to segments: Corporate and other unallocated items (a)(c) (67 ) (75 ) (201 ) (229 ) Pension settlement expenses (4 ) (2 ) (7 ) (4 ) Impairments (d) (267 ) (144 ) (486 ) (144 ) Income from operations $ 435 $ 1,549 $ 1,825 $ 4,354 Capital Expenditures and Investments (e) Refining & Marketing (a) $ 267 $ 256 $ 788 $ 686 Speedway 71 130 191 275 Midstream (a) 394 156 1,147 400 Corporate and Other (f) 29 43 106 121 Total $ 761 $ 585 $ 2,232 $ 1,482 (a) We revised our operating segment presentation in the first quarter of 2016 in connection with the contribution of our inland marine business to MPLX; our inland marine business, which was previously included in Refining & Marketing, is now included in Midstream. Comparable prior period information has been recast to reflect our revised segment presentation. (b) The Refining & Marketing and Speedway segments include inventory LCM benefit of $345 million and $25 million , respectively, for the nine months ended September 30, 2016 . (c) Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments. (d) 2016 relates to impairments of goodwill and equity method investments. 2015 relates to the cancellation of the Residual Oil Upgrader Expansion project. See Notes 14 and 15 , respectively, to the unaudited consolidated financial statements. (e) Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates. (f) Includes capitalized interest of $15 million and $10 million for the three months ended September 30, 2016 and 2015 , respectively, and $47 million and $26 million for the nine months ended September 30, 2016 and 2015 , respectively. Supplementary Statistics (Unaudited) Three Months Ended Nine Months Ended 2016 2015 2016 2015 MPC Consolidated Refined Product Sales Volumes (mbpd) (a) 2,316 2,359 2,274 2,316 Refining & Marketing Operating Statistics Refining & Marketing refined product sales volume (mbpd) (b) 2,307 2,345 2,265 2,303 Refining & Marketing gross margin (dollars per barrel) (c)(d) $ 10.75 $ 17.27 $ 11.20 $ 16.08 Crude oil capacity utilization percent (e) 100 101 95 100 Refinery throughputs (mbpd): (f) Crude oil refined 1,791 1,744 1,708 1,735 Other charge and blendstocks 135 168 156 170 Total 1,926 1,912 1,864 1,905 Sour crude oil throughput percent 59 56 60 55 WTI-priced crude oil throughput percent 20 20 20 20 Refined product yields (mbpd): (f) Gasoline 907 911 908 906 Distillates 647 611 616 598 Propane 38 33 35 36 Feedstocks and special products 253 292 245 307 Heavy fuel oil 43 32 36 30 Asphalt 70 66 58 58 Total 1,958 1,945 1,898 1,935 Refinery direct operating costs (dollars per barrel): (g) Planned turnaround and major maintenance $ 1.62 $ 1.37 $ 1.72 $ 0.94 Depreciation and amortization 1.42 1.36 1.46 1.37 Other manufacturing (h) 4.01 4.17 4.03 4.12 Total $ 7.05 $ 6.90 $ 7.21 $ 6.43 Refining & Marketing Operating Statistics By Region - Gulf Coast Refinery throughputs (mbpd): (i) Crude oil refined 1,073 1,072 1,057 1,065 Other charge and blendstocks 185 180 199 177 Total 1,258 1,252 1,256 1,242 Sour crude oil throughput percent 72 68 73 68 WTI-priced crude oil throughput percent 8 6 7 6 Refined product yields (mbpd): (i) Gasoline 511 544 530 526 Distillates 411 408 407 386 Propane 27 25 26 26 Feedstocks and special products 289 271 283 299 Heavy fuel oil 30 16 24 14 Asphalt 17 19 15 16 Total 1,285 1,283 1,285 1,267 Refinery direct operating costs (dollars per barrel): (g) Planned turnaround and major maintenance $ 2.05 $ 0.80 $ 1.87 $ 0.70 Depreciation and amortization 1.14 1.07 1.13 1.09 Other manufacturing (h) 3.70 4.00 3.62 3.92 Total $ 6.89 $ 5.87 $ 6.62 $ 5.71 Supplementary Statistics (Unaudited) Three Months Ended Nine Months Ended 2016 2015 2016 2015 Refining & Marketing Operating Statistics By Region – Midwest Refinery throughputs (mbpd): (i) Crude oil refined 718 672 651 670 Other charge and blendstocks 39 28 37 33 Total 757 700 688 703 Sour crude oil throughput percent 39 36 39 35 WTI-priced crude oil throughput percent 39 43 41 42 Refined product yields (mbpd): (i) Gasoline 396 367 378 380 Distillates 236 203 209 212 Propane 13 10 11 11 Feedstocks and special products 51 59 40 46 Heavy fuel oil 13 16 12 17 Asphalt 53 47 43 42 Total 762 702 693 708 Refinery direct operating costs (dollars per barrel): (g) Planned turnaround and major maintenance $ 0.72 $ 2.30 $ 1.26 $ 1.32 Depreciation and amortization 1.72 1.80 1.90 1.79 Other manufacturing (h) 4.04 4.25 4.29 4.24 Total $ 6.48 $ 8.35 $ 7.45 $ 7.35 Speedway Operating Statistics Convenience stores at period-end 2,773 2,756 Gasoline and distillate sales (millions of gallons) 1,575 1,555 4,605 4,501 Gasoline and distillate gross margin (dollars per gallon) (d)(j) $ 0.1773 $ 0.2146 $ 0.1668 $ 0.1822 Merchandise sales (in millions) $ 1,338 $ 1,294 $ 3,777 $ 3,669 Merchandise gross margin (in millions) $ 386 $ 358 $ 1,085 $ 1,028 Merchandise gross margin percent 28.9 % 27.7 % 28.7 % 28.0 % Same store gasoline sales volume (period over period) (0.6 %) 0.5 % 0.2 % (0.3 %) Same store merchandise sales (period over period) (k) 4.0 % 3.6 % 3.0 % 4.7 % Midstream Operating Statistics Crude oil and refined product pipeline throughputs (mbpd) (l) 2,433 2,259 2,298 2,231 Gathering system throughput (MMcf/d) (m) 3,306 3,313 Natural gas processed (MMcf/d) (m) 5,906 5,691 C2 (ethane) + NGLs (natural gas liquids) fractionated (mbpd) (m) 348 330 (a) Total average daily volumes of refined product sales to wholesale, branded and retail (Speedway segment) customers. (b) Includes intersegment sales. (c) Sales revenue less cost of refinery inputs and purchased products, divided by total refinery throughputs. (d) Excludes LCM inventory valuation adjustments. (e) Based on calendar day capacity, which is an annual average that includes downtime for planned maintenance and other normal operating activities. (f) Excludes inter-refinery volumes of 89 mbpd and 40 mbpd for the three months ended September 30, 2016 and 2015 , respectively, and 80 mbpd and 40 mbpd for the nine months ended September 30, 2016 and 2015 , respectively. (g) Per barrel of total refinery throughputs. (h) Includes utilities, labor, routine maintenance and other operating costs. (i) Includes inter-refinery transfer volumes. (j) The price paid by consumers less the cost of refined products, including transportation, consumer excise taxes and bankcard processing fees, divided by gasoline and distillate sales volume. (k) Excludes cigarettes. Same store sales comparison includes only locations owned at least 13 months. (l) On owned common-carrier pipelines, excluding equity method investments. (m) Includes amounts related to unconsolidated equity method investments. Includes the results of the MarkWest assets beginning on the Dec. 4, 2015 acquisition date.

Description of the Business a35

Description of the Business and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [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 U.S. GAAP for complete financial statements.
Inventories	Inventories are carried at the lower of cost or market value. Costs of crude oil, refinery feedstocks and refined products are aggregated on a consolidated basis for purposes of assessing if the LIFO cost basis of these inventories may have to be written down to market values. As of December 31, 2015, costs of inventories exceeded market value by $370 million . As of September 30, 2016 , market value exceeded cost. The effect of the change in LCM reserve was a $370 million benefit to cost of revenues for the nine months ended September 30, 2016 . Based on movements of refined product prices, future inventory valuation adjustments could have a negative effect to earnings. Such losses are subject to reversal in subsequent periods if prices recover. The cost of inventories of crude oil and refinery feedstocks, refined products and merchandise is determined primarily under the LIFO method.
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 and (7) the purchase of electricity.
Stock-based compensation arrangements	The fair value of stock options granted to our employees is estimated on the date of the grant using the Black Scholes option-pricing model, which employs various assumptions.

Acquisitions and Investments (

Acquisitions and Investments (Tables)	9 Months Ended
	Sep. 30, 2016
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes the final purchase price allocation. Subsequent to December 31, 2015 , additional analysis was completed and adjustments were made to the preliminary purchase price allocation as noted in the table below. The estimated fair value of assets acquired and liabilities and noncontrolling interests assumed at the acquisition date, are as follows: (In millions) As originally reported Adjustments As adjusted Cash and cash equivalents $ 12 $ — $ 12 Receivables 164 — 164 Inventories 33 (1 ) 32 Other current assets 44 — 44 Equity method investments 2,457 143 2,600 Property, plant and equipment, net 8,474 43 8,517 Other noncurrent assets (a) 473 65 538 Total assets acquired 11,657 250 11,907 Accounts payable 322 6 328 Payroll and benefits payable 13 — 13 Accrued taxes 21 — 21 Other current liabilities 44 — 44 Long-term debt 4,567 — 4,567 Deferred income taxes 374 3 377 Deferred credit and other liabilities 151 — 151 Noncontrolling interest 13 — 13 Total liabilities and noncontrolling interest assumed 5,505 9 5,514 Net assets acquired excluding goodwill 6,152 241 6,393 Goodwill 2,454 (241 ) 2,213 Net assets acquired $ 8,606 $ — $ 8,606 (a) The adjustment relates to acquired intangible assets.
Business Acquisition, Pro Forma Information	The following unaudited pro forma financial information presents consolidated results assuming the MarkWest Merger occurred on January 1, 2014. Three Months Ended Nine Months Ended (In millions, except per share data) 2015 2015 Sales and other operating revenues (including consumer excise taxes) $ 19,186 $ 57,830 Net income attributable to MPC 943 2,600 Net income attributable to MPC per share – basic $ 1.76 $ 4.81 Net income attributable to MPC per share – diluted 1.75 4.78

Related Party Transactions (Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Purchases From Related Parties	Purchases from related parties were as follows: Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Crowley Blue Water Partners $ 16 $ — $ 22 $ — Crowley Ocean Partners 15 — 32 — Explorer 4 2 12 16 Illinois Extension Pipeline 27 — 82 — LOCAP 6 6 18 17 LOOP 14 12 42 38 Ohio Condensate 2 — 8 — TAAE 9 11 29 39 TACE 10 7 39 38 TAME 23 21 67 64 Other equity method investees 2 2 8 7 Total $ 128 $ 61 $ 359 $ 219
Receivables From Related Parties	Receivables from related parties, which are included in “Receivables, less allowance for doubtful accounts” on the accompanying consolidated balance sheets, were as follows: (In millions) September 30, December 31, Centennial $ 1 $ 1 Jefferson Dry Gas — 2 MarkWest Utica EMG 2 1 Ohio Condensate — 3 Ohio Gathering 2 5 Other equity method investees 2 1 Total $ 7 $ 13
Payables To Related Parties	Payables to related parties, which are included in “Accounts payable” on the accompanying consolidated balance sheets, were as follows: (In millions) September 30, December 31, Explorer $ 1 $ 1 Illinois Extension Pipeline 9 4 LOCAP 2 2 LOOP 4 5 MarkWest Utica EMG 15 19 Ohio Condensate 1 4 TAAE 1 1 TACE 2 2 TAME 3 3 Other equity method investees 2 1 Total $ 40 $ 42

Income per Common Share (Tables

Income per Common Share (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Summary of Earnings Per Common Share	MPC grants certain incentive compensation awards to employees and non-employee directors that are considered to be participating securities. Due to the presence of participating securities, we have calculated our earnings per share using the two-class method. Three Months Ended Nine Months Ended (In millions, except per share data) 2016 2015 2016 2015 Basic earnings per share: Allocation of earnings: Net income attributable to MPC $ 145 $ 948 $ 947 $ 2,665 Income allocated to participating securities — 1 1 3 Income available to common stockholders – basic $ 145 $ 947 $ 946 $ 2,662 Weighted average common shares outstanding 527 535 528 540 Basic earnings per share $ 0.28 $ 1.77 $ 1.79 $ 4.93 Diluted earnings per share: Allocation of earnings: Net income attributable to MPC $ 145 $ 948 $ 947 $ 2,665 Income allocated to participating securities — 1 1 3 Income available to common stockholders – diluted $ 145 $ 947 $ 946 $ 2,662 Weighted average common shares outstanding 527 535 528 540 Effect of dilutive securities 3 3 3 4 Weighted average common shares, including dilutive effect 530 538 531 544 Diluted earnings per share $ 0.27 $ 1.76 $ 1.78 $ 4.90
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table summarizes the shares that were anti-dilutive and, therefore, were excluded from the diluted share calculation. Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Shares issued under stock-based compensation plans 3 1 3 1

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Share Repurchases	Total share repurchases were as follows for the three and nine months ended September 30, 2016 and 2015 : Three Months Ended Nine Months Ended (In millions, except per share data) 2016 2015 2016 2015 Number of shares repurchased 1 3 4 15 Cash paid for shares repurchased $ 51 $ 156 $ 177 $ 773 Effective average cost per delivered share $ 42.76 $ 50.86 $ 41.14 $ 49.97

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2016
Segment Reporting [Abstract]
Income From Operations Attributable To Operating Segments	(In millions) Refining & Marketing Speedway Midstream Total Three Months Ended September 30, 2016 Revenues: Customer $ 11,286 $ 4,848 $ 484 $ 16,618 Intersegment (a) 2,798 1 206 3,005 Segment revenues $ 14,084 $ 4,849 $ 690 $ 19,623 Segment income from operations (b) $ 306 $ 209 $ 258 $ 773 Income from equity method investments (d) 8 — 51 59 Depreciation and amortization (d) 277 71 145 493 Capital expenditures and investments (e) 267 71 394 732 (In millions) Refining & Marketing Speedway Midstream Total Three Months Ended September 30, 2015 Revenues: Customer $ 13,441 $ 5,256 $ 19 $ 18,716 Intersegment (a) 3,192 1 198 3,391 Segment revenues $ 16,633 $ 5,257 $ 217 $ 22,107 Segment income from operations (b) $ 1,434 $ 243 $ 93 $ 1,770 Income from equity method investments 6 — 17 23 Depreciation and amortization (d) 262 63 27 352 Capital expenditures and investments (e) 256 130 156 542 (In millions) Refining & Marketing Speedway Midstream Total Nine Months Ended September 30, 2016 Revenues: Customer $ 31,197 $ 13,663 $ 1,324 $ 46,184 Intersegment (a) 7,872 2 595 8,469 Segment revenues $ 39,069 $ 13,665 $ 1,919 $ 54,653 Segment income from operations (b)(c) $ 1,324 $ 569 $ 626 $ 2,519 Income from equity method investments (d) 10 — 110 120 Depreciation and amortization (d) 820 203 429 1,452 Capital expenditures and investments (e) 788 191 1,147 2,126 (In millions) Refining & Marketing Speedway Midstream Total Nine Months Ended September 30, 2015 Revenues: Customer $ 41,277 $ 15,116 $ 51 $ 56,444 Intersegment (a) 9,353 3 587 9,943 Segment revenues $ 50,630 $ 15,119 $ 638 $ 66,387 Segment income from operations (b) $ 3,907 $ 538 $ 286 $ 4,731 Income from equity method investments 20 — 38 58 Depreciation and amortization (d) 784 188 79 1,051 Capital expenditures and investments (e) 686 275 400 1,361 (a) Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties. (b) Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments. (c) The Refining & Marketing and Speedway segments include inventory LCM benefit of $345 million and $25 million , respectively, for the nine months ended September 30, 2016 . (d) Differences between segment totals and MPC totals represent amounts related to unallocated items and are included in “Items not allocated to segments” in the reconciliation below. (e) Capital expenditures include changes in capital accruals, acquisitions (including any goodwill) and investments in affiliates.
Reconciliation Of Segment Income From Operations To Income Before Income Taxes	The following reconciles segment income from operations to income before income taxes as reported in the consolidated statements of income: Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Segment income from operations $ 773 $ 1,770 $ 2,519 $ 4,731 Items not allocated to segments: Corporate and other unallocated items (a)(b) (67 ) (75 ) (201 ) (229 ) Pension settlement expenses (c) (4 ) (2 ) (7 ) (4 ) Impairments (d) (267 ) (144 ) (486 ) (144 ) Net interest and other financial income (costs) (141 ) (70 ) (420 ) (215 ) Income before income taxes $ 294 $ 1,479 $ 1,405 $ 4,139 (a) Corporate and other unallocated items consists primarily of MPC’s corporate administrative expenses and costs related to certain non-operating assets. (b) Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments. (c) See Note 20 . (d) 2016 relates to impairments of goodwill and equity method investments. 2015 relates to the cancellation of the Residual Oil Upgrader Expansion project. See Notes 14 and 15 , respectively.
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures	The following reconciles segment capital expenditures and investments to total capital expenditures: Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Segment capital expenditures and investments $ 732 $ 542 $ 2,126 $ 1,361 Less investments in equity method investees (a) 69 72 383 221 Plus items not allocated to segments: Capital expenditures 14 33 59 95 Capitalized interest 15 10 47 26 Total capital expenditures (b) $ 692 $ 513 $ 1,849 $ 1,261 (a) The nine months ended September 30, 2016 includes an adjustment of $143 million to the fair value of equity investments acquired in connection with the MarkWest Merger. See Note 4 . (b) Capital expenditures include changes in capital accruals. See Note 18 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.

Other Items (Tables)

Other Items (Tables)	9 Months Ended
	Sep. 30, 2016
Other Income and Expenses [Abstract]
Net Interest And Other Financial Income (Costs)	Net interest and other financial income (costs) was: Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Interest income $ 3 $ 2 $ 5 $ 5 Interest expense (a) (153 ) (77 ) (455 ) (226 ) Interest capitalized 15 11 47 27 Other financial costs (6 ) (6 ) (17 ) (21 ) Net interest and other financial income (costs) $ (141 ) $ (70 ) $ (420 ) $ (215 ) (a) The three and nine months ended September 30, 2016 includes $11 million and $33 million , respectively, for the amortization of the discount related to the difference between the fair value and the principal amount of the assumed MarkWest debt.

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2016
Inventory Disclosure [Abstract]
Summary Of Inventories	(In millions) September 30, December 31, Crude oil and refinery feedstocks $ 2,230 $ 2,180 Refined products 2,689 2,804 Materials and supplies 442 438 Merchandise 163 173 LCM reserve — (370 ) Total $ 5,524 $ 5,225

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Summary Of Property, Plant And Equipment	(In millions) September 30, December 31, Refining & Marketing $ 19,179 $ 18,396 Speedway 5,224 5,067 Midstream 12,328 11,379 Corporate and Other 795 762 Total 37,526 35,604 Less accumulated depreciation 11,829 10,440 Property, plant and equipment, net $ 25,697 $ 25,164

Goodwill (Tables)

Goodwill (Tables)	9 Months Ended
	Sep. 30, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The changes in the carrying amount of goodwill for the nine months ended September 30, 2016 were as follows: (In millions) Refining & Marketing Speedway Midstream Total Balance at December 31, 2015 $ 539 $ 853 $ 2,627 $ 4,019 Purchase price allocation adjustments (a) — — (241 ) (241 ) Impairment — — (130 ) (130 ) Balance at September 30, 2016 $ 539 $ 853 $ 2,256 $ 3,648 (a) See Note 4 for further discussion on purchase price allocation adjustments.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Assets and Liabilities Accounted for at Fair Value on Recurring Basis	The following tables present assets and liabilities accounted for at fair value on a recurring basis as of September 30, 2016 and December 31, 2015 by fair value hierarchy level. We have elected to offset the fair value amounts recognized for multiple derivative contracts executed with the same counterparty, including any related cash collateral as shown below; however, fair value amounts by hierarchy level are presented on a gross basis in the following tables. September 30, 2016 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Commodity derivative instruments, assets $ 277 $ 1 $ — $ (278 ) $ — $ 64 Other assets 2 — — N/A 2 — Total assets at fair value $ 279 $ 1 $ — $ (278 ) $ 2 $ 64 Commodity derivative instruments, liabilities (c) $ 312 $ — $ 4 $ (313 ) $ 3 $ — Embedded derivatives in commodity contracts (c) — — 44 — 44 — Contingent consideration, liability (d) — — 128 N/A 128 — Total liabilities at fair value $ 312 $ — $ 176 $ (313 ) $ 175 $ — December 31, 2015 Fair Value Hierarchy (In millions) Level 1 Level 2 Level 3 Netting and Collateral (a) Net Carrying Value on Balance Sheet (b) Collateral Pledged Not Offset Commodity derivative instruments, assets $ 104 $ 2 $ 7 $ (62 ) $ 51 $ — Other assets 2 — — N/A 2 — Total assets at fair value $ 106 $ 2 $ 7 $ (62 ) $ 53 $ — Commodity derivative instruments, liabilities $ 39 $ — $ — $ (39 ) $ — $ — Embedded derivatives in commodity contracts (c) — — 32 — 32 — Contingent consideration, liability (d) — — 317 N/A 317 — Total liabilities at fair value $ 39 $ — $ 349 $ (39 ) $ 349 $ — (a) Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of September 30, 2016 , cash collateral of $35 million was netted with the mark-to-market derivative liabilities. As of December 31, 2015 , $23 million was netted with mark-to-market derivative assets. (b) We have no derivative contracts that are subject to master netting arrangements that are reflected gross on the balance sheet. (c) Level 3 includes $9 million and $5 million classified as current at September 30, 2016 and December 31, 2015 , respectively. (d) Includes $128 million and $196 million classified as current at September 30, 2016 and December 31, 2015 , respectively.
Reconciliation of Net Beginning and Ending Balances Recorded for Net Assets and Liabilities Classified as Level 3	The following is a reconciliation of the beginning and ending balances recorded for liabilities classified as Level 3 in the fair value hierarchy. Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Beginning balance $ 171 $ 307 $ 342 $ 478 Contingent consideration payment — — (200 ) (189 ) Unrealized and realized losses included in net income 6 5 33 23 Settlements of derivative instruments (1 ) — 1 — Ending balance $ 176 $ 312 $ 176 $ 312 The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period: Derivative instruments $ 4 $ — $ 19 $ — Contingent consideration agreement 2 5 11 23 Total $ 6 $ 5 $ 30 $ 23
Fair Value Measurements, Nonrecurring	The following table shows the values of assets, by major category, measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition. Nine Months Ended September 30, 2016 2015 (In millions) Fair Value Impairment Fair Value Impairment Equity method investments $ 42 $ 356 $ — $ — Goodwill — 130 — — Property, plant and equipment, net — — — 144
Financial Instruments at Fair Value, Excluding Derivative Financial Instruments and Contingent Consideration	The following table summarizes financial instruments on the basis of their nature, characteristics and risk at September 30, 2016 and December 31, 2015 , excluding the derivative financial instruments and contingent consideration reported above. September 30, 2016 December 31, 2015 (In millions) Fair Value Carrying Value Fair Value Carrying Value Financial assets: Investments $ 27 $ 2 $ 33 $ 2 Other 22 22 35 33 Total financial assets $ 49 $ 24 $ 68 $ 35 Financial liabilities: Long-term debt (a) $ 11,056 $ 10,285 $ 11,366 $ 11,628 Deferred credits and other liabilities 124 111 136 135 Total financial liabilities $ 11,180 $ 10,396 $ 11,502 $ 11,763 (a) Excludes capital leases and debt issuance costs, however, includes amount classified as debt due within one year.

Derivatives (Tables)

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Classification of Fair Values of Derivative Instruments, Excluding Cash Collateral	The following table presents the gross fair values of derivative instruments, excluding cash collateral, and where they appear on the consolidated balance sheets as of September 30, 2016 and December 31, 2015 : (In millions) September 30, 2016 Balance Sheet Location Asset Liability Commodity derivatives (a) Other current assets $ 278 $ 312 Other current liabilities — 10 Deferred credits and other liabilities — 38 (In millions) December 31, 2015 Balance Sheet Location Asset Liability Commodity derivatives Other current assets $ 113 $ 39 Other current liabilities — 5 Deferred credits and other liabilities (a) — 27 (a) Includes embedded derivatives.
Open Commodity Derivative Contracts	The tables below summarize open commodity derivative contracts for crude oil, natural gas and refined products as of September 30, 2016 . Position Total Barrels (In thousands) Crude Oil (a) Exchange-traded Long 45,660 Exchange-traded Short (47,459 ) OTC Short (92 ) (a ) 91 percent of the exchange-traded contracts expire in the fourth quarter of 2016 . Position MMbtu Natural Gas OTC Long 841,931 Position Total Gallons (In thousands) Refined Products (a) Exchange-traded Long 112,098 Exchange-traded Short (137,634 ) OTC Short (56,108 ) (a ) 100 percent of the exchange-traded contracts expire in the fourth quarter of 2016 .
Effect of Commodity Derivative Instruments in Statements of Income	The following table summarizes the effect of all commodity derivative instruments in our consolidated statements of income: Gain (Loss) Gain (Loss) (In millions) Three Months Ended September 30, Nine Months Ended September 30, Income Statement Location 2016 2015 2016 2015 Sales and other operating revenues $ (3 ) $ (1 ) $ (4 ) $ 10 Cost of revenues (19 ) 140 (85 ) 115 Total $ (22 ) $ 139 $ (89 ) $ 125

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Outstanding Borrowings	Our outstanding borrowings at September 30, 2016 and December 31, 2015 consisted of the following: (In millions) September 30, December 31, Marathon Petroleum Corporation: Commercial paper $ — $ — 364-day bank revolving credit facility due July 2017 — — Bank revolving credit facility due 2020 — — Term loan agreement due 2019 200 700 Senior notes, 2.700% due December 2018 600 600 Senior notes, 3.400% due December 2020 650 650 Senior notes, 5.125% due March 2021 1,000 1,000 Senior notes, 3.625%, due September 2024 750 750 Senior notes, 6.500%, due March 2041 1,250 1,250 Senior notes, 4.750%, due September 2044 800 800 Senior notes, 5.850% due December 2045 250 250 Senior notes, 5.000%, due September 2054 400 400 MPLX LP: MPLX term loan facility due 2019 250 250 MPLX bank revolving credit facility due 2020 — 877 MPLX senior notes, 5.500%, due February 2023 710 710 MPLX senior notes, 4.500%, due July 2023 989 989 MPLX senior notes, 4.875%, due December 2024 1,149 1,149 MPLX senior notes, 4.000%, due February 2025 500 500 MPLX senior notes, 4.875%, due June 2025 1,189 1,189 MarkWest senior notes, 4.500% - 5.500%, due 2023 - 2025 63 63 Capital lease obligations due 2016-2028 327 348 Trade receivables securitization facility due July 2019 — — Total 11,077 12,475 Unamortized debt issuance costs (46 ) (51 ) Unamortized discount (a) (465 ) (499 ) Amounts due within one year (28 ) (29 ) Total long-term debt due after one year $ 10,538 $ 11,896 (a) Includes $431 million and $464 million discount as of September 30, 2016 and December 31, 2015 , respectively, related to the difference between the fair value and the principal amount of the assumed MarkWest debt.

Supplemental Cash Flow Inform48

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Summary of Supplemental Cash Flow Information	Nine Months Ended (In millions) 2016 2015 Net cash provided by operating activities included: Interest paid (net of amounts capitalized) $ 400 $ 262 Net income taxes paid to taxing authorities 28 1,286 Non-cash investing and financing activities: Property, plant and equipment sold — 5 Property, plant and equipment acquired — 5
Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures	The consolidated statements of cash flows exclude changes to the consolidated balance sheets that did not affect cash. The following is a reconciliation of additions to property, plant and equipment to total capital expenditures: Nine Months Ended (In millions) 2016 2015 Additions to property, plant and equipment per consolidated statements of cash flows $ 2,147 $ 1,277 Non-cash additions to property, plant and equipment — 5 Asset retirement expenditures 4 1 Decrease in capital accruals (169 ) (22 ) Total capital expenditures before acquisitions 1,982 1,261 Acquisitions (a) (133 ) — Total capital expenditures $ 1,849 $ 1,261 (a) The nine months ended September 30, 2016 includes adjustments to the fair values of the property, plant and equipment, intangibles and goodwill acquired in connection with the MarkWest Merger. See Note 4 .

Accumulated Other Comprehensi49

Accumulated Other Comprehensive Loss (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Changes in Accumulated Other Comprehensive Loss by Component	The following table shows the changes in accumulated other comprehensive loss by component. Amounts in parentheses indicate debits. (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2014 $ (217 ) $ (104 ) $ 4 $ 4 $ (313 ) Other comprehensive income (loss) before reclassifications (17 ) 14 — (3 ) (6 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (35 ) (3 ) — — (38 ) – actuarial loss (a) 39 6 — — 45 – settlement loss (a) 4 — — — 4 Tax effect (3 ) (1 ) — — (4 ) Other comprehensive income (loss) (12 ) 16 — (3 ) 1 Balance as of September 30, 2015 $ (229 ) $ (88 ) $ 4 $ 1 $ (312 ) (In millions) Pension Benefits Other Benefits Gain on Cash Flow Hedge Workers Compensation Total Balance as of December 31, 2015 $ (255 ) $ (70 ) $ 4 $ 3 $ (318 ) Other comprehensive income (loss) before reclassifications (8 ) 1 — — (7 ) Amounts reclassified from accumulated other comprehensive loss: Amortization – prior service credit (a) (35 ) (2 ) — — (37 ) – actuarial loss (a) 28 1 — — 29 – settlement loss (a) 7 — — — 7 Other (b) — — — (1 ) (1 ) Tax effect — — — — — Other comprehensive income (loss) (8 ) — — (1 ) (9 ) Balance as of September 30, 2016 $ (263 ) $ (70 ) $ 4 $ 2 $ (327 ) (a) These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 20 . (b) This amount was reclassified out of accumulated other comprehensive loss and is included in selling, general and administrative on the consolidated statements of income.

Defined Benefit Pension and O50

Defined Benefit Pension and Other Postretirement Plans (Tables)	9 Months Ended
	Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Costs	The following summarizes the components of net periodic benefit costs: Three Months Ended September 30, Pension Benefits Other Benefits (In millions) 2016 2015 2016 2015 Components of net periodic benefit cost: Service cost $ 29 $ 25 $ 8 $ 8 Interest cost 18 18 9 8 Expected return on plan assets (24 ) (25 ) — — Amortization – prior service credit (12 ) (12 ) (1 ) (1 ) – actuarial loss 10 13 — 2 – settlement loss 4 2 — — Net periodic benefit cost $ 25 $ 21 $ 16 $ 17 Nine Months Ended September 30, Pension Benefits Other Benefits (In millions) 2016 2015 2016 2015 Components of net periodic benefit cost: Service cost $ 86 $ 76 $ 24 $ 23 Interest cost 55 54 26 24 Expected return on plan assets (73 ) (75 ) — — Amortization – prior service credit (35 ) (35 ) (2 ) (3 ) – actuarial loss 28 39 1 6 – settlement loss 7 4 — — Net periodic benefit cost $ 68 $ 63 $ 49 $ 50

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Stock Option Award Activity	The following table presents a summary of our stock option award activity for the nine months ended September 30, 2016 : Number of Shares Weighted Average Exercise Price Outstanding at December 31, 2015 8,724,631 $ 27.16 Granted 1,474,177 35.27 Exercised (524,458 ) 18.26 Forfeited, canceled or expired (29,607 ) 42.91 Outstanding at September 30, 2016 9,644,743 28.84
Summary of Restricted Stock Award Activity	The following table presents a summary of restricted stock award activity for the nine months ended September 30, 2016 : Shares of Restricted Stock (“RS”) Restricted Stock Units (“RSU”) Number of Shares Weighted Average Grant Date Fair Value Number of Units Weighted Average Grant Date Fair Value Outstanding at December 31, 2015 1,074,543 $ 47.70 513,220 $ 24.59 Granted 722,315 36.10 35,453 40.21 RS’s Vested/RSU’s Issued (463,996 ) 46.42 (190,845 ) 20.60 Forfeited (39,213 ) 44.67 — — Outstanding at September 30, 2016 1,293,649 41.77 357,828 28.26
Schedule of Performance Unit Awards	The following table presents a summary of the activity for performance unit awards to be settled in shares for the nine months ended September 30, 2016 : Number of Units Weighted Average Grant Date Fair Value Outstanding at December 31, 2015 6,145,442 $ 0.92 Granted 2,329,500 0.57 Exercised (1,904,792 ) 0.95 Canceled (314,972 ) 0.93 Outstanding at September 30, 2016 6,255,178 0.78

Supplementary Statistics (Table

Supplementary Statistics (Tables)	9 Months Ended
	Sep. 30, 2016
Text Block [Abstract]
Supplementary Statistics	Supplementary Statistics (Unaudited) Three Months Ended Nine Months Ended (In millions) 2016 2015 2016 2015 Income from Operations by segment Refining & Marketing (a)(b) $ 306 $ 1,434 $ 1,324 $ 3,907 Speedway (b) 209 243 569 538 Midstream (a)(c) 258 93 626 286 Items not allocated to segments: Corporate and other unallocated items (a)(c) (67 ) (75 ) (201 ) (229 ) Pension settlement expenses (4 ) (2 ) (7 ) (4 ) Impairments (d) (267 ) (144 ) (486 ) (144 ) Income from operations $ 435 $ 1,549 $ 1,825 $ 4,354 Capital Expenditures and Investments (e) Refining & Marketing (a) $ 267 $ 256 $ 788 $ 686 Speedway 71 130 191 275 Midstream (a) 394 156 1,147 400 Corporate and Other (f) 29 43 106 121 Total $ 761 $ 585 $ 2,232 $ 1,482 (a) We revised our operating segment presentation in the first quarter of 2016 in connection with the contribution of our inland marine business to MPLX; our inland marine business, which was previously included in Refining & Marketing, is now included in Midstream. Comparable prior period information has been recast to reflect our revised segment presentation. (b) The Refining & Marketing and Speedway segments include inventory LCM benefit of $345 million and $25 million , respectively, for the nine months ended September 30, 2016 . (c) Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments. (d) 2016 relates to impairments of goodwill and equity method investments. 2015 relates to the cancellation of the Residual Oil Upgrader Expansion project. See Notes 14 and 15 , respectively, to the unaudited consolidated financial statements. (e) Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates. (f) Includes capitalized interest of $15 million and $10 million for the three months ended September 30, 2016 and 2015 , respectively, and $47 million and $26 million for the nine months ended September 30, 2016 and 2015 , respectively.
Operating Statistics	Supplementary Statistics (Unaudited) Three Months Ended Nine Months Ended 2016 2015 2016 2015 MPC Consolidated Refined Product Sales Volumes (mbpd) (a) 2,316 2,359 2,274 2,316 Refining & Marketing Operating Statistics Refining & Marketing refined product sales volume (mbpd) (b) 2,307 2,345 2,265 2,303 Refining & Marketing gross margin (dollars per barrel) (c)(d) $ 10.75 $ 17.27 $ 11.20 $ 16.08 Crude oil capacity utilization percent (e) 100 101 95 100 Refinery throughputs (mbpd): (f) Crude oil refined 1,791 1,744 1,708 1,735 Other charge and blendstocks 135 168 156 170 Total 1,926 1,912 1,864 1,905 Sour crude oil throughput percent 59 56 60 55 WTI-priced crude oil throughput percent 20 20 20 20 Refined product yields (mbpd): (f) Gasoline 907 911 908 906 Distillates 647 611 616 598 Propane 38 33 35 36 Feedstocks and special products 253 292 245 307 Heavy fuel oil 43 32 36 30 Asphalt 70 66 58 58 Total 1,958 1,945 1,898 1,935 Refinery direct operating costs (dollars per barrel): (g) Planned turnaround and major maintenance $ 1.62 $ 1.37 $ 1.72 $ 0.94 Depreciation and amortization 1.42 1.36 1.46 1.37 Other manufacturing (h) 4.01 4.17 4.03 4.12 Total $ 7.05 $ 6.90 $ 7.21 $ 6.43 Refining & Marketing Operating Statistics By Region - Gulf Coast Refinery throughputs (mbpd): (i) Crude oil refined 1,073 1,072 1,057 1,065 Other charge and blendstocks 185 180 199 177 Total 1,258 1,252 1,256 1,242 Sour crude oil throughput percent 72 68 73 68 WTI-priced crude oil throughput percent 8 6 7 6 Refined product yields (mbpd): (i) Gasoline 511 544 530 526 Distillates 411 408 407 386 Propane 27 25 26 26 Feedstocks and special products 289 271 283 299 Heavy fuel oil 30 16 24 14 Asphalt 17 19 15 16 Total 1,285 1,283 1,285 1,267 Refinery direct operating costs (dollars per barrel): (g) Planned turnaround and major maintenance $ 2.05 $ 0.80 $ 1.87 $ 0.70 Depreciation and amortization 1.14 1.07 1.13 1.09 Other manufacturing (h) 3.70 4.00 3.62 3.92 Total $ 6.89 $ 5.87 $ 6.62 $ 5.71 Supplementary Statistics (Unaudited) Three Months Ended Nine Months Ended 2016 2015 2016 2015 Refining & Marketing Operating Statistics By Region – Midwest Refinery throughputs (mbpd): (i) Crude oil refined 718 672 651 670 Other charge and blendstocks 39 28 37 33 Total 757 700 688 703 Sour crude oil throughput percent 39 36 39 35 WTI-priced crude oil throughput percent 39 43 41 42 Refined product yields (mbpd): (i) Gasoline 396 367 378 380 Distillates 236 203 209 212 Propane 13 10 11 11 Feedstocks and special products 51 59 40 46 Heavy fuel oil 13 16 12 17 Asphalt 53 47 43 42 Total 762 702 693 708 Refinery direct operating costs (dollars per barrel): (g) Planned turnaround and major maintenance $ 0.72 $ 2.30 $ 1.26 $ 1.32 Depreciation and amortization 1.72 1.80 1.90 1.79 Other manufacturing (h) 4.04 4.25 4.29 4.24 Total $ 6.48 $ 8.35 $ 7.45 $ 7.35 Speedway Operating Statistics Convenience stores at period-end 2,773 2,756 Gasoline and distillate sales (millions of gallons) 1,575 1,555 4,605 4,501 Gasoline and distillate gross margin (dollars per gallon) (d)(j) $ 0.1773 $ 0.2146 $ 0.1668 $ 0.1822 Merchandise sales (in millions) $ 1,338 $ 1,294 $ 3,777 $ 3,669 Merchandise gross margin (in millions) $ 386 $ 358 $ 1,085 $ 1,028 Merchandise gross margin percent 28.9 % 27.7 % 28.7 % 28.0 % Same store gasoline sales volume (period over period) (0.6 %) 0.5 % 0.2 % (0.3 %) Same store merchandise sales (period over period) (k) 4.0 % 3.6 % 3.0 % 4.7 % Midstream Operating Statistics Crude oil and refined product pipeline throughputs (mbpd) (l) 2,433 2,259 2,298 2,231 Gathering system throughput (MMcf/d) (m) 3,306 3,313 Natural gas processed (MMcf/d) (m) 5,906 5,691 C2 (ethane) + NGLs (natural gas liquids) fractionated (mbpd) (m) 348 330 (a) Total average daily volumes of refined product sales to wholesale, branded and retail (Speedway segment) customers. (b) Includes intersegment sales. (c) Sales revenue less cost of refinery inputs and purchased products, divided by total refinery throughputs. (d) Excludes LCM inventory valuation adjustments. (e) Based on calendar day capacity, which is an annual average that includes downtime for planned maintenance and other normal operating activities. (f) Excludes inter-refinery volumes of 89 mbpd and 40 mbpd for the three months ended September 30, 2016 and 2015 , respectively, and 80 mbpd and 40 mbpd for the nine months ended September 30, 2016 and 2015 , respectively. (g) Per barrel of total refinery throughputs. (h) Includes utilities, labor, routine maintenance and other operating costs. (i) Includes inter-refinery transfer volumes. (j) The price paid by consumers less the cost of refined products, including transportation, consumer excise taxes and bankcard processing fees, divided by gasoline and distillate sales volume. (k) Excludes cigarettes. Same store sales comparison includes only locations owned at least 13 months. (l) On owned common-carrier pipelines, excluding equity method investments. (m) Includes amounts related to unconsolidated equity method investments. Includes the results of the MarkWest assets beginning on the Dec. 4, 2015 acquisition date.

MPLX LP (Detail)

MPLX LP (Detail) - MPLX LP	Dec. 04, 2015	Sep. 30, 2016BargeTow_Boat
Noncontrolling Interest [Line Items]
Number of tow boats | Tow_Boat		18
Number of barges | Barge		200
Ownership percentage of general partner interest		100.00%
Public's ownership interest in MPLX		76.00%
MarkWest
Noncontrolling Interest [Line Items]
Common units conversion ratio	1.09
General Partner and Limited Partner
Noncontrolling Interest [Line Items]
MPC's partnership interest in MPLX (in percentage)		24.00%
General Partner
Noncontrolling Interest [Line Items]
MPC's partnership interest in MPLX (in percentage)		2.00%
Storage Services Butane Cavern
Noncontrolling Interest [Line Items]
Ownership interest		100.00%
MPLX Pipe Line Holdings LP | General Partner
Noncontrolling Interest [Line Items]
Ownership interest		100.00%

MPLX LP MPLX LP (Reorganization

MPLX LP MPLX LP (Reorganization Transactions) (Details) - MPLX LP - USD ($) shares in Millions, $ in Millions	Sep. 01, 2016	Mar. 31, 2016
General partners' contributed capital	$ 225
Limited Partner
Units issued, number of units	7	23
General Partner and Limited Partner
Increase in ownership percentage by MPC	1.00%

MPLX LP (Private Placement of P

MPLX LP (Private Placement of Preferred Units) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	May 13, 2016	Sep. 30, 2016	Sep. 30, 2015
Noncontrolling Interest [Line Items]
Issuance of MPLX LP redeemable preferred units		$ 984	$ 0
MPLX LP | Series A Convertible Preferred Units
Noncontrolling Interest [Line Items]
Sale of units (in number of preferred units)	30.8
Preferred units, dividend rate, percentage	6.50%
Issuance of MPLX LP redeemable preferred units	$ 984
Preferred units, distribution rate, per-dollar-amount	$ 0.528125
Preferred units, description	The MPLX Preferred Units are convertible into MPLX common units on a one for one basis after three years, at the purchasers’ option, and after four years at MPLX’s option, subject to certain conditions.
MPLX LP | Series A Convertible Preferred Units | Preferred Units
Noncontrolling Interest [Line Items]
Units issued, price per unit	$ 32.50

MPLX LP (Contribution of Inland

MPLX LP (Contribution of Inland Marine Business to MPLX) (Details) - MPLX LP - USD ($) shares in Thousands, $ in Millions	Sep. 01, 2016	Mar. 31, 2016
Limited Partner
Noncontrolling Interest [Line Items]
Units issued, number of units	7,000	23,000
Equity interest issued, value assigned		$ 600
General Partner
Noncontrolling Interest [Line Items]
Units issued, number of units		460

MPLX LP (ATM Program) (Details)

MPLX LP (ATM Program) (Details) - USD ($) shares in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 01, 2016	Aug. 04, 2016
Noncontrolling Interest [Line Items]
Net proceeds from issuance of MPLX LP common limited partners units	$ 499	$ 0
MPLX LP
Noncontrolling Interest [Line Items]
General partners' contributed capital			$ 225
MPLX LP | General Partner
Noncontrolling Interest [Line Items]
MPC's partnership interest in MPLX (in percentage)	2.00%
MPLX LP | ATM Program
Noncontrolling Interest [Line Items]
Common units aggregate value				$ 1,180
Net proceeds from issuance of MPLX LP common limited partners units	$ 499
General partners' contributed capital	$ 10
MPLX LP | ATM Program | Limited Partners Common Units [Member]
Noncontrolling Interest [Line Items]
Sale of units (in number of common units)	18
MPLX LP | ATM Program | General Partner
Noncontrolling Interest [Line Items]
MPC's partnership interest in MPLX (in percentage)	2.00%

Acquisitions and Investments (M

Acquisitions and Investments (Merger with MarkWest Energy Partners, L.P.) (Details) $ in Millions		Dec. 04, 2015USD ($)reporting_unit	Dec. 31, 2015USD ($)	Sep. 30, 2016USD ($)reporting_unit
Business Acquisition [Line Items]
Purchase price adjustments	[1]			$ 241
Goodwill			$ 4,019	$ 3,648
Number of reporting units | reporting_unit				3
Midstream
Business Acquisition [Line Items]
Purchase price adjustments	[1]			$ 241
Goodwill			2,627	$ 2,256
Number of reporting units | reporting_unit		3
MarkWest
Business Acquisition [Line Items]
Total fair value of consideration transferred		$ 8,610
Fair value of MPLX units issued		7,330
Cash payment to MarkWest unitholders		1,230	$ 1,280
Payable to MarkWest Class B unitholders		50
Equity method investments		2,600
Property, plant and equipment, net		8,517
Goodwill		2,213
MarkWest | Misstatement of Original Purchase Price Allocation
Business Acquisition [Line Items]
Purchase price adjustments		(68)
Equity method investments		2
Property, plant and equipment, net		2
MarkWest | Misstatement of Original Purchase Price Allocation | Customer Relationships
Business Acquisition [Line Items]
Other noncurrent assets		$ 64
[1]	See Note 4 for further discussion on purchase price allocation adjustments.

Acquisitions and Investments 59

Acquisitions and Investments (MarkWest - Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015	Dec. 04, 2015
Business Acquisition [Line Items]
Goodwill		$ 3,648	$ 4,019
MarkWest
Business Acquisition [Line Items]
Cash and cash equivalents				$ 12
Receivables				164
Inventories				32
Other current assets				44
Equity method investments				2,600
Property, plant and equipment, net				8,517
Other noncurrent assets(a)				538
Total assets acquired				11,907
Accounts payable				328
Payroll and benefits payable				13
Accrued taxes				21
Other current liabilities				44
Long-term debt				4,567
Deferred income taxes				377
Deferred credit and other liabilities				151
Noncontrolling interest				13
Total liabilities and noncontrolling interest assumed				5,514
Net assets acquired excluding goodwill				6,393
Goodwill				2,213
Net assets acquired				8,606
MarkWest | As originally reported
Business Acquisition [Line Items]
Cash and cash equivalents				12
Receivables				164
Inventories				33
Other current assets				44
Equity method investments				2,457
Property, plant and equipment, net				8,474
Other noncurrent assets(a)				473
Total assets acquired				11,657
Accounts payable				322
Payroll and benefits payable				13
Accrued taxes				21
Other current liabilities				44
Long-term debt				4,567
Deferred income taxes				374
Deferred credit and other liabilities				151
Noncontrolling interest				13
Total liabilities and noncontrolling interest assumed				5,505
Net assets acquired excluding goodwill				6,152
Goodwill				2,454
Net assets acquired				8,606
MarkWest | Adjustments
Business Acquisition [Line Items]
Cash and cash equivalents				0
Receivables				0
Inventories				(1)
Other current assets				0
Equity method investments				143
Property, plant and equipment, net				43
Other noncurrent assets(a)	[1]			65
Total assets acquired				250
Accounts payable				6
Payroll and benefits payable				0
Accrued taxes				0
Other current liabilities				0
Long-term debt				0
Deferred income taxes				3
Deferred credit and other liabilities				0
Noncontrolling interest				0
Total liabilities and noncontrolling interest assumed				9
Net assets acquired excluding goodwill				241
Goodwill				(241)
Net assets acquired				$ 0
[1]	The adjustment relates to acquired intangible assets.

Acquisitions and Investments (U

Acquisitions and Investments (Unaudited Pro Forma Financial Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2015
Business Combinations [Abstract]
Sales and other operating revenues (including consumer excise taxes)	$ 19,186	$ 57,830
Net income attributable to MPC	$ 943	$ 2,600
Net income attributable to MPC per share – basic	$ 1.76	$ 4.81
Net income attributable to MPC per share – diluted	$ 1.75	$ 4.78

Acquisitions and Investments (I

Acquisitions and Investments (Investment in Ocean Vessel Joint Venture) (Details) $ in Millions	1 Months Ended	9 Months Ended	12 Months Ended	13 Months Ended
	May 31, 2016	Sep. 30, 2016USD ($)Joint_venturevessel	Dec. 31, 2015vessel	Sep. 30, 2016USD ($)Joint_venturevessel	Sep. 30, 2015
Crowley Ocean Partners
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		50.00%		50.00%	50.00%
Number of vessels | vessel			2	4
Cash paid to acquire equity method investments | $		$ 69		$ 141
Crowley Coastal Partners
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		50.00%		50.00%
Cash paid to acquire equity method investments | $		$ 48
Crowley Blue Water Partners
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		50.00%		50.00%
Number of vessels | vessel		3
Crowley Maritime Corporation
Schedule of Equity Method Investments [Line Items]
Number of joint ventures | Joint_venture		2		2
Crowley Maritime Corporation | Crowley Blue Water Partners
Schedule of Equity Method Investments [Line Items]
Percentage of partners interest contributed	100.00%

Acquisitions and Investments 62

Acquisitions and Investments (Investments in Pipeline Company) (Details) $ in Millions		Aug. 02, 2016USD ($)bbl / d	Sep. 30, 2016USD ($)Joint_venture	Sep. 30, 2016USD ($)Joint_venture	Jan. 01, 2019
Energy Transfer Partners and Sunoco Logistics Partners
Schedule of Equity Method Investments [Line Items]
Number of joint ventures | Joint_venture			2	2
North Dakota Pipeline
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage			37.50%	37.50%
Cash paid to acquire equity method investments			$ 14	$ 301
Bakken Pipeline System
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		9.1875%
Cash paid to acquire equity method investments		$ 500
Crude oil throughput | bbl / d	[1]	470,000
Bakken Pipeline System | Energy Transfer Partners and Sunoco Logistics Partners
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		75.00%
Bakken Pipeline System | MPC & Enbridge Energy Partners
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in joint venture acquired		49.00%
MPC & Enbridge Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage		25.00%
Scenario, Forecast | North Dakota Pipeline Class A Units
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage					27.00%
[1]	On owned common-carrier pipelines, excluding equity method investments.

Variable Interest Entities (Det

Variable Interest Entities (Details) $ in Millions	Sep. 30, 2016USD ($)
Crowley Coastal Partners
Variable Interest Entity [Line Items]
VIE, maximum loss exposure, amount	$ 491
Equity method investments, ownership percentage	50.00%
MarkWest Utica EMG
Variable Interest Entity [Line Items]
VIE, maximum loss exposure, amount	$ 2,250
Equity method investments, ownership percentage	60.00%
Ohio Gathering
Variable Interest Entity [Line Items]
Equity method investments, ownership percentage	36.00%

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Related Party Transaction [Line Items]
Sales to related parties	$ 2	$ 1	$ 5	$ 4
Other income from related parties	12	$ 1	31	$ 1
Due from related parties, noncurrent	$ 1		$ 1		$ 1
Centennial
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	50.00%		50.00%
Crowley Blue Water Partners
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	50.00%		50.00%
Crowley Ocean Partners
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	50.00%	50.00%	50.00%	50.00%
Explorer
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	25.00%		25.00%
Illinois Extension Pipeline
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	35.00%		35.00%
LOCAP
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	59.00%		59.00%
LOOP
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	51.00%		51.00%
Jefferson Dry Gas
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	67.00%		67.00%
MarkWest Utica EMG
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	60.00%		60.00%
Ohio Condensate
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	60.00%		60.00%
Ohio Gathering
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	36.00%		36.00%
TAAE
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	45.00%		45.00%
TACE
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	60.00%		60.00%
TAME
Related Party Transaction [Line Items]
Equity method investments, ownership percentage	67.00%		67.00%

Related Party Transactions - Pu

Related Party Transactions - Purchases from Related Parties (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Related Party Transaction [Line Items]
Purchases from related parties	$ 128	$ 61	$ 359	$ 219
Crowley Blue Water Partners
Related Party Transaction [Line Items]
Purchases from related parties	16	0	22	0
Crowley Ocean Partners
Related Party Transaction [Line Items]
Purchases from related parties	15	0	32	0
Explorer
Related Party Transaction [Line Items]
Purchases from related parties	4	2	12	16
Illinois Extension Pipeline
Related Party Transaction [Line Items]
Purchases from related parties	27	0	82	0
LOCAP
Related Party Transaction [Line Items]
Purchases from related parties	6	6	18	17
LOOP
Related Party Transaction [Line Items]
Purchases from related parties	14	12	42	38
Ohio Condensate
Related Party Transaction [Line Items]
Purchases from related parties	2	0	8	0
TAAE
Related Party Transaction [Line Items]
Purchases from related parties	9	11	29	39
TACE
Related Party Transaction [Line Items]
Purchases from related parties	10	7	39	38
TAME
Related Party Transaction [Line Items]
Purchases from related parties	23	21	67	64
Other equity method investees
Related Party Transaction [Line Items]
Purchases from related parties	$ 2	$ 2	$ 8	$ 7

Related Party Transactions - Re

Related Party Transactions - Receivables From Related Parties (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Current receivables from related parties	$ 7	$ 13
Centennial
Related Party Transaction [Line Items]
Current receivables from related parties	1	1
Jefferson Dry Gas
Related Party Transaction [Line Items]
Current receivables from related parties	0	2
MarkWest Utica EMG
Related Party Transaction [Line Items]
Current receivables from related parties	2	1
Ohio Condensate
Related Party Transaction [Line Items]
Current receivables from related parties	0	3
Ohio Gathering
Related Party Transaction [Line Items]
Current receivables from related parties	2	5
Other equity method investees
Related Party Transaction [Line Items]
Current receivables from related parties	$ 2	$ 1

Related Party Transactions - Pa

Related Party Transactions - Payables To Related Parties (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Payables to related parties	$ 40	$ 42
Explorer
Related Party Transaction [Line Items]
Payables to related parties	1	1
Illinois Extension Pipeline
Related Party Transaction [Line Items]
Payables to related parties	9	4
LOCAP
Related Party Transaction [Line Items]
Payables to related parties	2	2
LOOP
Related Party Transaction [Line Items]
Payables to related parties	4	5
MarkWest Utica EMG
Related Party Transaction [Line Items]
Payables to related parties	15	19
Ohio Condensate
Related Party Transaction [Line Items]
Payables to related parties	1	4
TAAE
Related Party Transaction [Line Items]
Payables to related parties	1	1
TACE
Related Party Transaction [Line Items]
Payables to related parties	2	2
TAME
Related Party Transaction [Line Items]
Payables to related parties	3	3
Other equity method investees
Related Party Transaction [Line Items]
Payables to related parties	$ 2	$ 1

Income Per Common Share - Summa

Income Per Common Share - Summary of Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Basic earnings per share:
Net income attributable to MPC	$ 145	$ 948	$ 947	$ 2,665
Income allocated to participating securities	0	1	1	3
Income available to common stockholders – basic	$ 145	$ 947	$ 946	$ 2,662
Weighted average common shares outstanding (in shares)	527	535	528	540
Basic (in USD per share)	$ 0.28	$ 1.77	$ 1.79	$ 4.93
Diluted earnings per share:
Net income attributable to MPC	$ 145	$ 948	$ 947	$ 2,665
Income allocated to participating securities	0	1	1	3
Income available to common stockholders – diluted	$ 145	$ 947	$ 946	$ 2,662
Weighted average common shares outstanding (in shares)	527	535	528	540
Effect of dilutive securities (in shares)	3	3	3	4
Weighted average common shares, including dilutive effect (in shares)	530	538	531	544
Diluted (in USD per share)	$ 0.27	$ 1.76	$ 1.78	$ 4.90

Income Per Common Share - Anti-

Income Per Common Share - Anti-dilutive Shares (Details) - shares shares in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Stock Based Compensation Expense [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares issued under stock-based compensation plans	3	1	3	1

Equity - Additional Information

Equity - Additional Information (Detail) $ in Millions	Sep. 30, 2016USD ($)
Equity [Abstract]
Stock repurchase program, remaining authorized repurchase amount	$ 2,580

Equity - Share Repurchases (Det

Equity - Share Repurchases (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Equity [Abstract]
Number of shares repurchased	1	3	4	15
Cash paid for shares repurchased	$ 51	$ 156	$ 177	$ 773
Effective average cost per delivered share	$ 42.76	$ 50.86	$ 41.14	$ 49.97

Segment Information - Additiona

Segment Information - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2016Segment
Segment Reporting [Abstract]
Number of reportable segments	3

Segment Information - Income Fr

Segment Information - Income From Operations Attributable To Operating Segments (Detail) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Segment Reporting Information [Line Items]
Revenues		$ 16,618		$ 18,716	$ 46,184		$ 56,444
Income from operations		435		1,549	1,825		4,354
Income from equity method investments		(208)		23	(236)		58
Depreciation and amortization		507		364	1,497		1,089
Capital expenditures and investments	[1]	761		585	2,232		1,482
Inventory market valuation adjustment		0		0	(370)		0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	[2]	3,005		3,391	8,469		9,943
Operating Segments
Segment Reporting Information [Line Items]
Revenues		19,623		22,107	54,653		66,387
Income from operations		773		1,770	2,519		4,731
Income from equity method investments		59	[3]	23	120	[3]	58
Depreciation and amortization	[3]	493		352	1,452		1,051
Capital expenditures and investments	[4]	732		542	2,126		1,361
Refining & Marketing
Segment Reporting Information [Line Items]
Revenues		11,286		13,441	31,197		41,277
Inventory market valuation adjustment					(345)
Refining & Marketing | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues		2,798		3,192	7,872		9,353
Refining & Marketing | Operating Segments
Segment Reporting Information [Line Items]
Revenues		14,084		16,633	39,069		50,630
Income from operations	[5]	306		1,434	1,324	[6]	3,907
Income from equity method investments		8		6	10		20
Depreciation and amortization		277		262	820		784
Capital expenditures and investments	[5]	267		256	788		686
Speedway
Segment Reporting Information [Line Items]
Revenues		4,848		5,256	13,663		15,116
Inventory market valuation adjustment					(25)
Speedway | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues		1		1	2		3
Speedway | Operating Segments
Segment Reporting Information [Line Items]
Revenues		4,849		5,257	13,665		15,119
Income from operations		209		243	569	[6]	538
Income from equity method investments		0		0	0		0
Depreciation and amortization		71		63	203		188
Capital expenditures and investments		71		130	191		275
Midstream
Segment Reporting Information [Line Items]
Revenues		484		19	1,324		51
Midstream | Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues		206		198	595		587
Midstream | Operating Segments
Segment Reporting Information [Line Items]
Revenues		690		217	1,919		638
Income from operations	[5],[7]	258		93	626		286
Income from equity method investments		51		17	110		38
Depreciation and amortization		145		27	429		79
Capital expenditures and investments	[5]	394		156	1,147		400
Reportable Segment
Segment Reporting Information [Line Items]
Revenues		$ 16,618		$ 18,716	$ 46,184		$ 56,444
[1]	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
[2]	Management believes intersegment transactions were conducted under terms comparable to those with unaffiliated parties
[3]	Differences between segment totals and MPC totals represent amounts related to unallocated items and are included in “Items not allocated to segments” in the reconciliation below.
[4]	Capital expenditures include changes in capital accruals, acquisitions (including any goodwill) and investments in affiliates.
[5]	We revised our operating segment presentation in the first quarter of 2016 in connection with the contribution of our inland marine business to MPLX; our inland marine business, which was previously included in Refining & Marketing, is now included in Midstream. Comparable prior period information has been recast to reflect our revised segment presentation.
[6]	The Refining & Marketing and Speedway segments include inventory LCM benefit of $345 million and $25 million, respectively, for the nine months ended September 30, 2016.
[7]	Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.

Segment Information - Reconcili

Segment Information - Reconciliation Of Segment Income From Operations To Income Before Income Taxes (Detail) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations		$ 435		$ 1,549	$ 1,825		$ 4,354
Impairment expense		0		144	130		144
Net interest and other financial income (costs)		141		70	420		215
Income before income taxes		294		1,479	1,405		4,139
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations		773		1,770	2,519		4,731
Corporate and Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Income from operations	[1],[2]	(67)		(75)	(201)		(229)
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Pension settlement expenses	[3]	(4)		(2)	(7)		(4)
Impairment expense		$ (267)	[4]	$ (144)	$ (486)	[4]	$ (144)
[1]	Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
[2]	We revised our operating segment presentation in the first quarter of 2016 in connection with the contribution of our inland marine business to MPLX; our inland marine business, which was previously included in Refining & Marketing, is now included in Midstream. Comparable prior period information has been recast to reflect our revised segment presentation.
[3]	See Note 20.
[4]	elates to impairments of goodwill and equity method investments. 2015 relates to the cancellation of the Residual Oil Upgrader Expansion project. See Notes 14 and 15, respectively.

Segment Information - Reconci75

Segment Information - Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]
Capital expenditures and investments	[1]	$ 761	$ 585	$ 2,232		$ 1,482
Plus items not allocated to segments:
Capital expenditures	[2]	692	513	1,849		1,261
MarkWest | Adjustments
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]
Less: Investments in equity method investees				143
Operating Segments
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]
Capital expenditures and investments	[3]	732	542	2,126		1,361
Less: Investments in equity method investees		69	72	383	[4]	221
Corporate and Other
Reconciliation Of Segment Capital Expenditures And Investments To Total Capital Expenditures [Line Items]
Capital expenditures and investments	[5]	29	43	106		121
Plus items not allocated to segments:
Capital expenditures		14	33	59		95
Capitalized interest		$ 15	$ 10	$ 47		$ 26
[1]	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
[2]	Capital expenditures include changes in capital accruals. See Note 18 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.
[3]	Capital expenditures include changes in capital accruals, acquisitions (including any goodwill) and investments in affiliates.
[4]	The nine months ended September 30, 2016 includes an adjustment of $143 million to the fair value of equity investments acquired in connection with the MarkWest Merger. See Note 4.
[5]	Includes capitalized interest of $15 million and $10 million for the three months ended September 30, 2016 and 2015, respectively, and $47 million and $26 million for the nine months ended September 30, 2016 and 2015, respectively.

Other Items - Net Interest And

Other Items - Net Interest And Other Financial Income (Costs) (Detail) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Interest income	$ 3		$ 2	$ 5		$ 5
Interest expense	(153)	[1]	(77)	(455)	[1]	(226)
Interest capitalized	15		11	47		27
Other financial costs	(6)		(6)	(17)		(21)
Net interest and other financial income (costs)	(141)		$ (70)	(420)		$ (215)
MPLX LP | MarkWest | Senior Notes
Amortization of debt discount	$ 11			$ 33
[1]	The three and nine months ended September 30, 2016 includes $11 million and $33 million, respectively, for the amortization of the discount related to the difference between the fair value and the principal amount of the assumed MarkWest debt.

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating Loss Carryforwards [Line Items]
Combined federal, state and foreign income tax rate	26.00%	35.00%	34.00%	35.00%
Statutory rate applied to income before income taxes			35.00%	35.00%
Deferred income tax effect from changes in noncontrolling interest - contribution of inland marine			$ 42
Deferred income tax effect from changes in noncontrolling interest - MarkWest Merger			115
Unrecognized benefits	$ 6		6
Additional Paid-in Capital
Operating Loss Carryforwards [Line Items]
Deferred income tax effect from changes in noncontrolling interest - contribution of inland marine			42
Deferred income tax effect from changes in noncontrolling interest - MarkWest Merger			$ 115

Inventories - Summary Of Invent

Inventories - Summary Of Inventories (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Crude oil and refinery feedstocks	$ 2,230	$ 2,180
Refined products	2,689	2,804
Materials and supplies	442	438
Merchandise	163	173
LCM reserve	0	(370)
Total	$ 5,524	$ 5,225

Inventories - Additional Inform

Inventories - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Inventory Disclosure [Abstract]
LCM reserve	$ 0		$ 0		$ (370)
Inventory market valuation adjustment	$ 0	$ 0	370	$ 0
Impact on income as a result of LIFO liquidations			$ (54)	$ (30)

Property, Plant And Equipment -

Property, Plant And Equipment - Summary Of Property, Plant And Equipment (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 37,526	$ 35,604
Less accumulated depreciation	11,829	10,440
Net property, plant and equipment	25,697	25,164
Operating Segments | Refining & Marketing
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	19,179	18,396
Operating Segments | Speedway
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	5,224	5,067
Operating Segments | Midstream
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,328	11,379
Corporate and Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 795	$ 762

Goodwill (Details)

Goodwill (Details) $ in Millions	Dec. 04, 2015reporting_unit	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)reporting_unit	Sep. 30, 2015USD ($)
Goodwill [Line Items]
Number of reporting units						3
Number of reporting units impaired						2
Impairment expense | $		$ 0			$ 144	$ 130	$ 144
Midstream
Goodwill [Line Items]
Number of reporting units	3
Impairment expense | $			$ 1	$ 129		$ 130
Midstream | Goodwill | Minimum
Goodwill [Line Items]
Discount rate						10.50%
Midstream | Goodwill | Maximum
Goodwill [Line Items]
Discount rate						11.50%

Goodwill - Changes in Carrying

Goodwill - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Goodwill [Line Items]
Goodwill, beginning balance				$ 4,019		$ 4,019
Purchase price adjustments	[1]					(241)
Impairment loss		$ 0			$ (144)	(130)	$ (144)
Goodwill, ending balance		3,648				3,648
Refining & Marketing
Goodwill [Line Items]
Goodwill, beginning balance				539		539
Purchase price adjustments						0
Impairment loss						0
Goodwill, ending balance		539				539
Speedway
Goodwill [Line Items]
Goodwill, beginning balance				853		853
Purchase price adjustments						0
Impairment loss						0
Goodwill, ending balance		853				853
Midstream
Goodwill [Line Items]
Goodwill, beginning balance				2,627		2,627
Purchase price adjustments	[1]					(241)
Impairment loss			$ (1)	$ (129)		(130)
Goodwill, ending balance		$ 2,256				$ 2,256
[1]	See Note 4 for further discussion on purchase price allocation adjustments.

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Accounted for at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Sep. 30, 2016		Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash collateral netted with derivative liabilities		$ 35
Cash collateral netted with derivative assets				$ (23)
Contingent consideration, current		128		196
Embedded derivatives in commodity contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Embedded derivatives, current		9		5
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - netting and collateral		(278)		(62)
Commodity derivative instruments, assets - collateral pledged not offset		64		0
Other assets		2		2
Total assets at fair value		2		53
Commodity derivative instruments, liabilities - netting and collateral		(313)		(39)
Commodity derivative instruments, liabilities - collateral pledged not offset		0		0
Contingent consideration, liability		128		317
Total liabilities at fair value		175		349
Fair Value, Measurements, Recurring | Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - netting and collateral	[1]	(278)		(62)
Commodity derivative instruments, assets - net carrying value on balance sheet	[2]	0		51
Commodity derivative instruments, assets - collateral pledged not offset		64		0
Commodity derivative instruments, liabilities - netting and collateral	[1]	(313)		(39)
Commodity derivative instruments, liabilities - net carrying value on balance sheet	[2]	3		0
Commodity derivative instruments, liabilities - collateral pledged not offset		0		0
Fair Value, Measurements, Recurring | Embedded derivatives in commodity contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - netting and collateral		0		0
Commodity derivative instruments, liabilities - net carrying value on balance sheet	[2]	44		32
Commodity derivative instruments, liabilities - collateral pledged not offset		0		0
Fair Value, Measurements, Recurring | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets		2		2
Total assets at fair value		279		106
Contingent consideration, liability		0		0
Total liabilities at fair value		312		39
Fair Value, Measurements, Recurring | Level 1 | Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - gross		277		104
Commodity derivative instruments, liabilities - gross		312		39
Fair Value, Measurements, Recurring | Level 1 | Embedded derivatives in commodity contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - gross		0		0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets		0		0
Total assets at fair value		1		2
Contingent consideration, liability		0		0
Total liabilities at fair value		0		0
Fair Value, Measurements, Recurring | Level 2 | Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - gross		1		2
Commodity derivative instruments, liabilities - gross		0		0
Fair Value, Measurements, Recurring | Level 2 | Embedded derivatives in commodity contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - gross		0		0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other assets		0		0
Total assets at fair value		0		7
Contingent consideration, liability	[3]	128		317
Total liabilities at fair value		176		349
Fair Value, Measurements, Recurring | Level 3 | Commodity derivatives
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, assets - gross		0		7
Commodity derivative instruments, liabilities - gross		4	[4]	0
Fair Value, Measurements, Recurring | Level 3 | Embedded derivatives in commodity contracts
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Commodity derivative instruments, liabilities - gross	[4]	$ 44		$ 32
[1]	Represents the impact of netting assets, liabilities and cash collateral when a legal right of offset exists. As of September 30, 2016, cash collateral of $35 million was netted with the mark-to-market derivative liabilities. As of December 31, 2015, $23 million was netted with mark-to-market derivative assets.
[2]	We have no derivative contracts that are subject to master netting arrangements that are reflected gross on the balance sheet.
[3]	Includes $128 million and $196 million classified as current at September 30, 2016 and December 31, 2015, respectively.
[4]	ncludes $9 million and $5 million classified as current at September 30, 2016 and December 31, 2015, respectively.

Fair Value Measurements - Recur

Fair Value Measurements - Recurring Narrative (Detail)	9 Months Ended		27 Months Ended
	Sep. 30, 2016USD ($)$ / bbl	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)	Feb. 01, 2013USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration payment included as financing on statements of cash flows	$ 164,000,000	$ 175,000,000
Remaining commitment for contingent consideration	521,000,000
Galveston Bay Refinery and Related Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maximum earnout payment, year four				$ 250,000,000
Maximum earnout payment, year five				250,000,000
Maximum earnout payment, year six				250,000,000
Total cumulative payment capped over six-year period				$ 700,000,000
Contingent consideration payment	200,000,000		$ 569,000,000
Remaining commitment for contingent consideration	$ 131,000,000		131,000,000
Embedded derivatives in commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Embedded derivative renewal term	5 years
Level 3 | Minimum | Galveston Bay Refinery and Related Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range of internal and external crack spread forecast per barrel | $ / bbl	11
Discount rate	5.00%
Level 3 | Maximum | Galveston Bay Refinery and Related Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range of internal and external crack spread forecast per barrel | $ / bbl	13
Discount rate	10.00%
Level 3 | Commodity derivatives | Minimum | Ethanol prices
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward commodity price	$ 0.22		0.22
Level 3 | Commodity derivatives | Maximum | Ethanol prices
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Forward commodity price	$ 3.13		3.13
Level 3 | Embedded derivatives in commodity contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Probability of renewal first term	50.00%
Probability of renewal second term	75.00%
Level 3 | Embedded derivatives in commodity contracts | Minimum | ERCOT Pricing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity price	$ 24.66		24.66
Level 3 | Embedded derivatives in commodity contracts | Maximum | ERCOT Pricing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Commodity price	$ 27.11		$ 27.11

Fair Value Measurements - Recon

Fair Value Measurements - Reconciliation of Net Beginning and Ending Balances Recorded for Net Assets and Liabilities Classified as Level 3 (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 171	$ 307	$ 342	$ 478
Contingent consideration payment	0	0	(200)	(189)
Unrealized and realized losses included in net income	6	5	33	23
Settlements of derivative instruments	(1)	0	1	0
Ending balance	$ 176	$ 312	$ 176	$ 312

Fair Value Measurements - Losse

Fair Value Measurements - Losses Included in Earnings Relating to Assets Still Held at End of Period (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period:	$ 6	$ 5	$ 30	$ 23
Derivative
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period:	4	0	19	0
Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
The amount of total losses for the period included in earnings attributable to the change in unrealized losses relating to assets still held at the end of period:	$ 2	$ 5	$ 11	$ 23

Fair Value Measurements - Nonre

Fair Value Measurements - Nonrecurring Table (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, impairment expense	$ 0	$ 144	$ 130	$ 144
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments, fair value disclosure	42	0	42	0
Equity method investment, impairment expense			356	0
Goodwill, fair value disclosure	0	0	0	0
Goodwill, impairment expense			130	0
Property, plant and equipment, fair value disclosure	$ 0	$ 0	0	0
Property, plant and equipment, impairment expense			$ 0	$ 144

Fair Value Measurements - Non88

Fair Value Measurements - Nonrecurring Narrative (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investment, impairment expense	$ 356	$ 0
Property, plant and equipment, impairment expense	$ 0	$ 144
North Dakota Pipeline
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments, ownership percentage	37.50%
Income (loss) from equity method investments from asset impairment	$ (267)
Ohio Condensate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity method investments, ownership percentage	60.00%
Income (loss) from equity method investments from asset impairment	$ (58)
Equity method investment, impairment expense	96
Income (loss) from equity method investments from elimination of basis differential	$ (31)
Ohio Condensate | Equity Method Investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rate	11.20%

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments at Fair Value, Excluding Derivative Financial Instruments and Contingent Consideration (Detail) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Fair Value
Financial assets:
Investments		$ 27	$ 33
Other		22	35
Total financial assets		49	68
Financial liabilities:
Long-term debt	[1]	11,056	11,366
Deferred credits and other liabilities		124	136
Total financial liabilities		11,180	11,502
Carrying Value
Financial assets:
Investments		2	2
Other		22	33
Total financial assets		24	35
Financial liabilities:
Long-term debt	[1]	10,285	11,628
Deferred credits and other liabilities		111	135
Total financial liabilities		$ 10,396	$ 11,763
[1]	Excludes capital leases and debt issuance costs, however, includes amount classified as debt due within one year.

Derivatives - Classification of

Derivatives - Classification of Gross Fair Values of Derivative Instruments, Excluding Cash Collateral (Detail) - Commodity derivatives - USD ($) $ in Millions		Sep. 30, 2016		Dec. 31, 2015
Other current assets
Derivatives, Fair Value [Line Items]
Asset		$ 278	[1]	$ 113
Liability		312	[1]	39
Other current liabilities
Derivatives, Fair Value [Line Items]
Asset		0		0
Liability		10	[1]	5
Deferred credits and other liabilities
Derivatives, Fair Value [Line Items]
Asset		0		0
Liability	[1]	$ 38		$ 27
[1]	Includes embedded derivatives.

Derivatives - Open Commodity De

Derivatives - Open Commodity Derivative Contracts - Crude Oil (Details) - Crude Oil bbl in Thousands	3 Months Ended
	Sep. 30, 2016bbl
Exchange Traded
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	91.00%
Derivative contract expiration date	Dec. 31, 2016
Exchange Traded | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	45,660	[1]
Exchange Traded | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	47,459	[1]
Over the Counter | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Barrels)	92
[1]	of the exchange-traded contracts expire in the fourth quarter of 2016.

Derivatives - Open Commodity 92

Derivatives - Open Commodity Derivative Contracts - Natural Gas (Details)	Sep. 30, 2016MMBTU
Over the Counter | Long
Derivative [Line Items]
Notional contracts (in MMbtu)	841,931

Derivatives - Open Commodity 93

Derivatives - Open Commodity Derivative Contracts - Refined Products (Detail) - Refined Products gal in Thousands	3 Months Ended
	Sep. 30, 2016gal
Exchange Traded
Derivative [Line Items]
Percentage of derivative contracts expiring in the period	100.00%
Derivative contract expiration date	Dec. 31, 2016
Exchange Traded | Long
Derivative [Line Items]
Notional contracts (in thousands of Total Gallons)	112,098	[1]
Exchange Traded | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Gallons)	137,634	[1]
Over the Counter | Short
Derivative [Line Items]
Notional contracts (in thousands of Total Gallons)	56,108
[1]	of the exchange-traded contracts expire in the fourth quarter of 2016.

Derivatives - Effect of Commodi

Derivatives - Effect of Commodity Derivative Instruments in Statements of Income (Detail) - Commodity derivatives - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (22)	$ 139	$ (89)	$ 125
Sales and other operating revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	(3)	(1)	(4)	10
Cost of revenues
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss)	$ (19)	$ 140	$ (85)	$ 115

Debt - Outstanding Borrowings (

Debt - Outstanding Borrowings (Detail) - USD ($) $ in Millions		Jul. 20, 2016	Sep. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Commercial paper			$ 0	$ 0
Total			11,077	12,475
Unamortized debt issuance costs			(46)	(51)
Unamortized discount	[1]		(465)	(499)
Amounts due within one year			(28)	(29)
Total long-term debt due after one year			10,538	11,896
MPLX LP
Debt Instrument [Line Items]
Amounts due within one year			(1)	(1)
Total long-term debt due after one year			4,411	5,255
Senior Notes | MPLX LP | MarkWest
Debt Instrument [Line Items]
Long-term debt, gross			63	63
Unamortized discount			(431)	(464)
Capital Lease Obligations | Subsidiaries
Debt Instrument [Line Items]
Capital lease obligations			$ 327	348
Debt instrument maturity year, start			Jan. 1, 2016
Debt instrument maturity year, end			Dec. 31, 2028
364-day bank revolving credit facility due July 2017
Debt Instrument [Line Items]
Line of credit facility, expiration date		Jul. 19, 2017
364-day bank revolving credit facility due July 2017 | Line of Credit
Debt Instrument [Line Items]
Long-term debt, gross			$ 0	0
Line of credit facility, expiration date			Jul. 19, 2017
Bank revolving credit facility due 2020
Debt Instrument [Line Items]
Line of credit facility, expiration date		Jul. 20, 2020
Bank revolving credit facility due 2020 | Line of Credit
Debt Instrument [Line Items]
Long-term debt, gross			$ 0	0
Line of credit facility, expiration date			Jul. 20, 2020
Term loan agreement due 2019 | Unsecured Debt
Debt Instrument [Line Items]
Long-term debt, gross			$ 200	700
Line of credit facility, expiration date			Sep. 24, 2019
Senior notes, 2.700% due December 2018 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross			$ 600	600
Debt instrument, maturity date			Dec. 14, 2018
Debt instrument, interest rate			2.70%
Senior notes, 3.400% due December 2020 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross			$ 650	650
Debt instrument, maturity date			Dec. 15, 2020
Debt instrument, interest rate			3.40%
Senior notes, 5.125% due March 2021 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross			$ 1,000	1,000
Debt instrument, maturity date			Mar. 1, 2021
Debt instrument, interest rate			5.125%
Senior notes, 3.625%, due September 2024 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross			$ 750	750
Debt instrument, maturity date			Sep. 15, 2024
Debt instrument, interest rate			3.625%
Senior notes, 6.500%, due March 2041 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross			$ 1,250	1,250
Debt instrument, maturity date			Mar. 1, 2041
Debt instrument, interest rate			6.50%
Senior notes, 4.750%, due September 2044 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross			$ 800	800
Debt instrument, maturity date			Sep. 15, 2044
Debt instrument, interest rate			4.75%
Senior notes, 5.850% due December 2045 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross			$ 250	250
Debt instrument, maturity date			Dec. 15, 2045
Debt instrument, interest rate			5.85%
Senior notes, 5.000%, due September 2054 | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross			$ 400	400
Debt instrument, maturity date			Sep. 15, 2054
Debt instrument, interest rate			5.00%
MPLX term loan facility due 2019 | Unsecured Debt | MPLX LP
Debt Instrument [Line Items]
Long-term debt, gross			$ 250	250
Line of credit facility, expiration date			Nov. 20, 2019
MPLX bank revolving credit facility due 2020 | Line of Credit | MPLX LP
Debt Instrument [Line Items]
Long-term debt, gross			$ 0	877
Line of credit facility, expiration date			Dec. 4, 2020
MPLX senior notes, 5.500%, due February 2023 | Senior Notes | MPLX LP
Debt Instrument [Line Items]
Long-term debt, gross			$ 710	710
Debt instrument, maturity date			Feb. 15, 2023
Debt instrument, interest rate			5.50%
MPLX senior notes, 5.500%, due February 2023 | Senior Notes | MPLX LP | MarkWest
Debt Instrument [Line Items]
Debt instrument, maturity date			Feb. 15, 2023
Debt instrument, interest rate			5.50%
MPLX senior notes, 4.500%, due July 2023 | Senior Notes | MPLX LP
Debt Instrument [Line Items]
Long-term debt, gross			$ 989	989
Debt instrument, maturity date			Jul. 15, 2023
Debt instrument, interest rate			4.50%
MPLX senior notes, 4.500%, due July 2023 | Senior Notes | MPLX LP | MarkWest
Debt Instrument [Line Items]
Debt instrument, maturity date			Jul. 15, 2023
Debt instrument, interest rate			4.50%
MPLX senior notes, 4.875%, due December 2024 | Senior Notes | MPLX LP
Debt Instrument [Line Items]
Long-term debt, gross			$ 1,149	1,149
Debt instrument, maturity date			Dec. 1, 2024
Debt instrument, interest rate			4.875%
MPLX senior notes, 4.875%, due December 2024 | Senior Notes | MPLX LP | MarkWest
Debt Instrument [Line Items]
Debt instrument, maturity date			Dec. 1, 2024
Debt instrument, interest rate			4.875%
MPLX senior notes, 4.000%, due February 2025 | Senior Notes | MPLX LP
Debt Instrument [Line Items]
Long-term debt, gross			$ 500	500
Debt instrument, maturity date			Feb. 15, 2025
Debt instrument, interest rate			4.00%
MPLX senior notes, 4.875%, due June 2025 | Senior Notes | MPLX LP
Debt Instrument [Line Items]
Long-term debt, gross			$ 1,189	1,189
Debt instrument, maturity date			Jun. 1, 2025
Debt instrument, interest rate			4.875%
MPLX senior notes, 4.875%, due June 2025 | Senior Notes | MPLX LP | MarkWest
Debt Instrument [Line Items]
Debt instrument, maturity date			Jun. 1, 2025
Debt instrument, interest rate			4.875%
Trade receivables securitization facility due July 2019
Debt Instrument [Line Items]
Long-term debt, gross			$ 0
Line of credit facility, expiration date		Jul. 19, 2019
Trade receivables securitization facility due July 2019 | Secured Debt | Subsidiaries
Debt Instrument [Line Items]
Long-term debt, gross			$ 0	$ 0
Line of credit facility, expiration date			Jul. 19, 2019
[1]	Includes $431 million and $464 million discount as of September 30, 2016 and December 31, 2015, respectively, related to the difference between the fair value and the principal amount of the assumed MarkWest debt.

Debt - Commercial Paper (Detail

Debt - Commercial Paper (Details) - USD ($) $ in Millions	Feb. 26, 2016	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Debt Instrument [Line Items]
Commercial paper – issued		$ 1,063	$ 0
Commercial paper - repayments		1,063	$ 0
Commercial paper		$ 0		$ 0
Commercial Paper
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 2,000
Debt instrument, term	397 days

Debt - MPC Bank Revolving Credi

Debt - MPC Bank Revolving Credit Facility (Details) - USD ($) $ in Millions	Jul. 20, 2016	Sep. 30, 2016	Dec. 31, 2015
Bank revolving credit facility due 2020
Debt Instrument [Line Items]
Debt instrument, term	4 years
Maximum borrowing capacity	$ 2,500
Line of credit facility, expiration date	Jul. 20, 2020
Bank revolving credit facility due 2020 | Letter of Credit
Debt Instrument [Line Items]
Long-term line of credit		$ 0
Bank revolving credit facility due 2020 | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, expiration date		Jul. 20, 2020
Long-term debt, gross		$ 0	$ 0
364-day bank revolving credit facility due July 2017
Debt Instrument [Line Items]
Debt instrument, term	364 days
Maximum borrowing capacity	$ 1,000
Line of credit facility, expiration date	Jul. 19, 2017
364-day bank revolving credit facility due July 2017 | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, expiration date		Jul. 19, 2017
Long-term debt, gross		$ 0	$ 0

Debt - MPC Term Loan Agreement

Debt - MPC Term Loan Agreement (Details) $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Term loan agreement due 2019
Debt Instrument [Line Items]
Repayments of long-term debt	$ 500

Debt - MPLX Bank Revolving Cred

Debt - MPLX Bank Revolving Credit Facility (Detail) - MPLX LP - MPLX bank revolving credit facility due 2020 - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Line of Credit Facility [Line Items]
Borrowings during period	$ 434
Interest rate during period	1.90%
Repayments during period	$ 1,310
Remaining borrowing capacity	2,000
Letter of Credit
Line of Credit Facility [Line Items]
Long-term line of credit	3
Line of Credit
Line of Credit Facility [Line Items]
Long-term debt, gross	$ 0	$ 877

Debt - Trade Receivables Securi

Debt - Trade Receivables Securitization Facility (Details) - Trade receivables securitization facility due July 2019 - USD ($) $ in Millions	Jul. 20, 2016	Sep. 30, 2016	Jun. 30, 2016
Debt Instrument [Line Items]
Current borrowing capacity	$ 750		$ 1,000
Line of credit facility, expiration date	Jul. 19, 2019
Borrowings during period		$ 280
Interest rate during period		1.30%
Repayments during period		$ 280
Long-term debt, gross		$ 0

Supplemental Cash Flow Infor101

Supplemental Cash Flow Information - Summary of Supplemental Cash Flow Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 400	$ 262
Net income taxes paid to taxing authorities	28	1,286
Non-cash investing and financing activities:
Property, plant and equipment sold	0	5
Property, plant and equipment acquired	$ 0	$ 5

Supplemental Cash Flow Infor102

Supplemental Cash Flow Information - Reconciliation of Additions to Property, Plant and Equipment to Total Capital Expenditures (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Supplemental Cash Flow Elements [Abstract]
Additions to property, plant and equipment per consolidated statements of cash flows				$ 2,147		$ 1,277
Non-cash additions to property, plant and equipment				0		5
Asset retirement expenditures				4		1
Decrease in capital accruals				(169)		(22)
Total capital expenditures before acquisitions				1,982		1,261
Acquisitions				(133)	[1]	0
Capital expenditures	[2]	$ 692	$ 513	$ 1,849		$ 1,261
[1]	The nine months ended September 30, 2016 includes adjustments to the fair values of the property, plant and equipment, intangibles and goodwill acquired in connection with the MarkWest Merger. See Note 4.
[2]	Capital expenditures include changes in capital accruals. See Note 18 for a reconciliation of total capital expenditures to additions to property, plant and equipment as reported in the consolidated statements of cash flows.

Accumulated Other Comprehens103

Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss by Component (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				$ (318)	$ (313)
Other comprehensive loss before reclassifications				(7)	(6)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit				(37)	(38)
Amortization - actuarial loss				29	45
Amortization - settlement loss				7	4
Other				(1)
Tax effect				0	(4)
Other comprehensive income (loss)		$ (6)	$ (3)	(9)	1
Ending balance		(327)	(312)	(327)	(312)
Accumulated Defined Benefit Plans Adjustment | Pension Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				(255)	(217)
Other comprehensive loss before reclassifications				(8)	(17)
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]			(35)	(35)
Amortization - actuarial loss	[1]			28	39
Amortization - settlement loss	[1]			7	4
Tax effect				0	(3)
Other comprehensive income (loss)				(8)	(12)
Ending balance		(263)	(229)	(263)	(229)
Accumulated Defined Benefit Plans Adjustment | Other Benefits
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				(70)	(104)
Other comprehensive loss before reclassifications				1	14
Amounts reclassified from accumulated other comprehensive loss:
Amortization - prior service credit	[1]			(2)	(3)
Amortization - actuarial loss	[1]			1	6
Amortization - settlement loss				0	0
Tax effect				0	(1)
Other comprehensive income (loss)				0	16
Ending balance		(70)	(88)	(70)	(88)
Gain on Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				4	4
Other comprehensive loss before reclassifications				0	0
Amounts reclassified from accumulated other comprehensive loss:
Tax effect				0	0
Other comprehensive income (loss)				0	0
Ending balance		4	4	4	4
Workers Compensation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance				3	4
Other comprehensive loss before reclassifications				0	(3)
Amounts reclassified from accumulated other comprehensive loss:
Other	[2]			(1)
Tax effect				0	0
Other comprehensive income (loss)				(1)	(3)
Ending balance		$ 2	$ 1	$ 2	$ 1
[1]	These accumulated other comprehensive loss components are included in the computation of net periodic benefit cost. See Note 20.
[2]	This amount was reclassified out of accumulated other comprehensive loss and is included in selling, general and administrative on the consolidated statements of income.

Defined Benefit Pension and 104

Defined Benefit Pension and Other Postretirement Plans - Components of Net Periodic Benefit Costs (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Benefits
Components of net periodic benefit cost:
Service cost	$ 29	$ 25	$ 86	$ 76
Interest cost	18	18	55	54
Expected return on plan assets	(24)	(25)	(73)	(75)
Amortization – prior service credit	(12)	(12)	(35)	(35)
Amortization – actuarial loss	10	13	28	39
Amortization - settlement loss	4	2	7	4
Net periodic benefit cost	25	21	68	63
Other Benefits
Components of net periodic benefit cost:
Service cost	8	8	24	23
Interest cost	9	8	26	24
Expected return on plan assets	0	0	0	0
Amortization – prior service credit	(1)	(1)	(2)	(3)
Amortization – actuarial loss	0	2	1	6
Amortization - settlement loss	0	0	0	0
Net periodic benefit cost	$ 16	$ 17	$ 49	$ 50

Defined Benefit Pension and 105

Defined Benefit Pension and Other Postretirement Plans - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions			$ 100
Pension settlement expenses	$ 4	$ 2	7	$ 4
Other Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefits paid			19
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Benefits paid			19
Pension settlement expenses	$ 0	$ 0	$ 0	$ 0

Stock-Based Compensation Pla106

Stock-Based Compensation Plans - Summary of Stock Option Award Activity (Detail) - Stock Options	9 Months Ended
	Sep. 30, 2016$ / sharesshares
Number of Shares
Outstanding, beginning balance | shares	8,724,631
Granted | shares	1,474,177
Exercised | shares	(524,458)
Forfeited, canceled or expired | shares	(29,607)
Outstanding, ending balance | shares	9,644,743
Weighted Average Exercise Price
Outstanding, beginning balance (in USD per share) | $ / shares	$ 27.16
Granted (in USD per share) | $ / shares	35.27
Exercised (in USD per share) | $ / shares	18.26
Forfeited, canceled or expired (in USD per share) | $ / shares	42.91
Outstanding, ending balance (in USD per share) | $ / shares	$ 28.84

Stock-Based Compensation Pla107

Stock-Based Compensation Plans - Narrative (Detail)	9 Months Ended
	Sep. 30, 2016$ / shares
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value (in USD per share)	$ 9.84
Performance Unit Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in USD per share)	$ 0.57

Stock-Based Compensation Pla108

Stock-Based Compensation Plans - Summary of Restricted Stock Award Activity (Detail)	9 Months Ended
	Sep. 30, 2016$ / sharesshares
Restricted Stock
Number of Shares
Outstanding, beginning balance | shares	1,074,543
Granted | shares	722,315
RS’s Vested/RSU’s Issued | shares	(463,996)
Forfeited | shares	(39,213)
Outstanding, ending balance | shares	1,293,649
Weighted Average Grant Date Fair Value
Outstanding, beginning balance (in USD per share) | $ / shares	$ 47.70
Granted (in USD per share) | $ / shares	36.10
RS's Vested/RSU's Issued (in USD per share) | $ / shares	46.42
Forfeited (in USD per share) | $ / shares	44.67
Outstanding, ending balance (in USD per share) | $ / shares	$ 41.77
Restricted Stock Units
Number of Shares
Outstanding, beginning balance | shares	513,220
Granted | shares	35,453
RS’s Vested/RSU’s Issued | shares	(190,845)
Forfeited | shares	0
Outstanding, ending balance | shares	357,828
Weighted Average Grant Date Fair Value
Outstanding, beginning balance (in USD per share) | $ / shares	$ 24.59
Granted (in USD per share) | $ / shares	40.21
RS's Vested/RSU's Issued (in USD per share) | $ / shares	20.60
Forfeited (in USD per share) | $ / shares	0
Outstanding, ending balance (in USD per share) | $ / shares	$ 28.26

Stock-Based Compensation Pla109

Stock-Based Compensation Plans - Summary of Performance Unit Awards (Detail) - Performance Unit Awards	9 Months Ended
	Sep. 30, 2016$ / sharesshares
Number of Units
Outstanding, beginning balance | shares	6,145,442
Granted | shares	2,329,500
Exercised | shares	(1,904,792)
Canceled | shares	(314,972)
Outstanding, ending balance | shares	6,255,178
Weighted Average Grant Date Fair Value
Outstanding, beginning balance (in USD per share) | $ / shares	$ 0.92
Granted (in USD per share) | $ / shares	0.57
Exercised (in USD per share) | $ / shares	0.95
Canceled (in USD per share) | $ / shares	0.93
Outstanding, ending balance (in USD per share) | $ / shares	$ 0.78

Commitments and Contingencies (

Commitments and Contingencies (Detail)	9 Months Ended
	Sep. 30, 2016
Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, inestimable loss	For matters for which we have not recorded an accrued liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings and discovery.

Commitments and Contingencie111

Commitments and Contingencies (Environmental Matters) (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Accrued liabilities for remediation	$ 145	$ 163
Receivables for recoverable costs	$ 62	$ 70

Commitments and Contingencie112

Commitments and Contingencies (Litigation Relating to the MarkWest Merger) (Details) $ in Millions	Mar. 28, 2016USD ($)
MarkWest Merger
Loss Contingencies [Line Items]
Legal Fees	$ 2

Commitments and Contingencie113

Commitments and Contingencies (Other Lawsuits) (Details) - Emergency Pricing And Consumer Protection Laws - Pending Litigation $ in Millions	9 Months Ended
	Sep. 30, 2016USD ($)
Loss Contingencies [Line Items]
Plaintiff	Commonwealth of Kentucky
Alleged amount overcharged from customers	$ 89
Loss contingency, period of occurrence	during September and October 2005

Commitments and Contingencie114

Commitments and Contingencies (Guarantees) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Centennial
Loss Contingencies [Line Items]
Equity method investments, ownership percentage	50.00%
Crowley Ocean Partners
Loss Contingencies [Line Items]
Equity method investments, ownership percentage	50.00%	50.00%
Crowley Blue Water Partners
Loss Contingencies [Line Items]
Equity method investments, ownership percentage	50.00%
Financial Guarantee | LOOP and LOCAP LLC | Guarantee of Indebtedness of Others
Loss Contingencies [Line Items]
Line of credit facility, expiration date	Dec. 31, 2037
Financial Guarantee | Centennial | Master Shelf Agreement
Loss Contingencies [Line Items]
Line of credit facility, expiration date	Dec. 31, 2024
Indemnification Agreement | Marathon Oil Companies
Loss Contingencies [Line Items]
Guarantee obligation current carrying value	$ 3
Other Guarantees
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	83
Guarantee obligations maximum exposure per event	50
Guarantee of Indebtedness of Others | Financial Guarantee | LOOP and LOCAP LLC
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	172
Guarantee of Indebtedness of Others | Financial Guarantee | Centennial
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	30
Guarantee of Indebtedness of Others | Financial Guarantee | Crowley Ocean Partners
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	163
Guarantee of Indebtedness of Others | Financial Guarantee | Crowley Ocean Partners | Crowley Term Loan
Loss Contingencies [Line Items]
Maximum borrowing capacity	325
Guarantee of Indebtedness of Others | Financial Guarantee | Crowley Blue Water Partners
Loss Contingencies [Line Items]
Maximum potential undiscounted payments	$ 142

Commitments and Contingencie115

Commitments and Contingencies (Contractual Commitments and Contingencies) (Details) - USD ($) $ in Millions	9 Months Ended	27 Months Ended
	Sep. 30, 2016	Sep. 30, 2016
Loss Contingencies [Line Items]
Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees	$ 521
Galveston Bay Refinery and Related Assets
Loss Contingencies [Line Items]
Contractual commitments to acquire property, plant and equipment and advance funds to equity method investees	$ 131	$ 131

Supplementary Statistics - Supp

Supplementary Statistics - Supplementary Statistics (Detail) - USD ($) $ in Millions		3 Months Ended					9 Months Ended
		Sep. 30, 2016		Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015
Supplementary Statistics [Line Items]
Income from operations		$ 435				$ 1,549	$ 1,825		$ 4,354
Impairment expense		0				144	130		144
Capital expenditures and investments	[1]	761				585	2,232		1,482
Inventory market valuation adjustment		0				0	(370)		0
Refining & Marketing
Supplementary Statistics [Line Items]
Impairment expense							0
Inventory market valuation adjustment							(345)
Speedway
Supplementary Statistics [Line Items]
Impairment expense							0
Inventory market valuation adjustment							(25)
Midstream
Supplementary Statistics [Line Items]
Impairment expense				$ 1	$ 129		130
Operating Segments
Supplementary Statistics [Line Items]
Income from operations		773				1,770	2,519		4,731
Capital expenditures and investments	[2]	732				542	2,126		1,361
Operating Segments | Refining & Marketing
Supplementary Statistics [Line Items]
Income from operations	[3]	306				1,434	1,324	[4]	3,907
Capital expenditures and investments	[3]	267				256	788		686
Operating Segments | Speedway
Supplementary Statistics [Line Items]
Income from operations		209				243	569	[4]	538
Capital expenditures and investments		71				130	191		275
Operating Segments | Midstream
Supplementary Statistics [Line Items]
Income from operations	[3],[5]	258				93	626		286
Capital expenditures and investments	[3]	394				156	1,147		400
Corporate and Other
Supplementary Statistics [Line Items]
Income from operations	[3],[6]	(67)				(75)	(201)		(229)
Capital expenditures and investments	[7]	29				43	106		121
Capitalized interest		15				10	47		26
Segment Reconciling Items
Supplementary Statistics [Line Items]
Pension settlement expenses	[8]	(4)				(2)	(7)		(4)
Impairment expense		$ (267)	[9]			$ (144)	$ (486)	[9]	$ (144)
[1]	Capital expenditures include changes in capital accruals, acquisitions and investments in affiliates.
[2]	Capital expenditures include changes in capital accruals, acquisitions (including any goodwill) and investments in affiliates.
[3]	We revised our operating segment presentation in the first quarter of 2016 in connection with the contribution of our inland marine business to MPLX; our inland marine business, which was previously included in Refining & Marketing, is now included in Midstream. Comparable prior period information has been recast to reflect our revised segment presentation.
[4]	The Refining & Marketing and Speedway segments include inventory LCM benefit of $345 million and $25 million, respectively, for the nine months ended September 30, 2016.
[5]	Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
[6]	Corporate overhead expenses attributable to MPLX are included in the Midstream segment. Corporate overhead expenses are not allocated to the Refining & Marketing and Speedway segments.
[7]	Includes capitalized interest of $15 million and $10 million for the three months ended September 30, 2016 and 2015, respectively, and $47 million and $26 million for the nine months ended September 30, 2016 and 2015, respectively.
[8]	See Note 20.
[9]	elates to impairments of goodwill and equity method investments. 2015 relates to the cancellation of the Residual Oil Upgrader Expansion project. See Notes 14 and 15, respectively.

Supplementary Statistics - Oper

Supplementary Statistics - Operating Statistics (Detail) bbl / d in Thousands, gal in Millions, CFPD in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016USD ($)bbl / dStoreCFPD$ / bbl$ / galgal	Sep. 30, 2015USD ($)bbl / dStore$ / bbl$ / galgal	Sep. 30, 2016USD ($)bbl / dStoreCFPD$ / bbl$ / galgal		Sep. 30, 2015USD ($)bbl / dStore$ / bbl$ / galgal
Operating Statistics [Line Items ]
MPC Consolidated Refined Product Sales Volumes (thousands of barrels per day)	[1]	2,316	2,359	2,274		2,316
Refining & Marketing
Refining & Marketing Operating Statistics
Refining & Marketing refined product sales volume (thousands of barrels per day)	[2]	2,307	2,345	2,265		2,303
Refining & Marketing gross margin (dollars per barrel) | $ / bbl	[3]	10.75	17.27	11.20	[4]	16.08
Crude oil capacity utilization percent	[5]	100.00%	101.00%	95.00%		100.00%
Refinery throughputs (thousands of barrels per day)	[6]	1,926	1,912	1,864		1,905
Sour crude oil throughput percent		59.00%	56.00%	60.00%		55.00%
WTI-priced crude oil throughput percent		20.00%	20.00%	20.00%		20.00%
Refined product yields (thousands of barrels per day)	[6]	1,958	1,945	1,898		1,935
Inter-refinery transfers		89	40	80		40
Refinery direct operating costs (dollars per barrel):
Planned turnaround and major maintenance | $ / bbl	[7]	1.62	1.37	1.72		0.94
Depreciation and amortization | $ / bbl	[7]	1.42	1.36	1.46		1.37
Other manufacturing | $ / bbl	[7],[8]	4.01	4.17	4.03		4.12
Total | $ / bbl	[7]	7.05	6.90	7.21		6.43
Refining & Marketing | Crude oil refined
Refining & Marketing Operating Statistics
Refinery throughputs (thousands of barrels per day)	[6]	1,791	1,744	1,708		1,735
Refining & Marketing | Other charge and blendstocks
Refining & Marketing Operating Statistics
Refinery throughputs (thousands of barrels per day)	[6]	135	168	156		170
Refining & Marketing | Gasoline
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[6]	907	911	908		906
Refining & Marketing | Distillates
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[6]	647	611	616		598
Refining & Marketing | Propane
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[6]	38	33	35		36
Refining & Marketing | Feedstocks and special products
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[6]	253	292	245		307
Refining & Marketing | Heavy fuel oil
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[6]	43	32	36		30
Refining & Marketing | Asphalt
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[6]	70	66	58		58
Refining & Marketing | Gulf Coast:
Refining & Marketing Operating Statistics
Refinery throughputs (thousands of barrels per day)	[9]	1,258	1,252	1,256		1,242
Sour crude oil throughput percent		72.00%	68.00%	73.00%		68.00%
WTI-priced crude oil throughput percent		8.00%	6.00%	7.00%		6.00%
Refined product yields (thousands of barrels per day)	[9]	1,285	1,283	1,285		1,267
Refinery direct operating costs (dollars per barrel):
Planned turnaround and major maintenance | $ / bbl	[7]	2.05	0.80	1.87		0.70
Depreciation and amortization | $ / bbl	[7]	1.14	1.07	1.13		1.09
Other manufacturing | $ / bbl	[7],[8]	3.70	4	3.62		3.92
Total | $ / bbl	[7]	6.89	5.87	6.62		5.71
Refining & Marketing | Gulf Coast: | Crude oil refined
Refining & Marketing Operating Statistics
Refinery throughputs (thousands of barrels per day)	[9]	1,073	1,072	1,057		1,065
Refining & Marketing | Gulf Coast: | Other charge and blendstocks
Refining & Marketing Operating Statistics
Refinery throughputs (thousands of barrels per day)	[9]	185	180	199		177
Refining & Marketing | Gulf Coast: | Gasoline
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	511	544	530		526
Refining & Marketing | Gulf Coast: | Distillates
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	411	408	407		386
Refining & Marketing | Gulf Coast: | Propane
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	27	25	26		26
Refining & Marketing | Gulf Coast: | Feedstocks and special products
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	289	271	283		299
Refining & Marketing | Gulf Coast: | Heavy fuel oil
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	30	16	24		14
Refining & Marketing | Gulf Coast: | Asphalt
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	17	19	15		16
Refining & Marketing | Midwest:
Refining & Marketing Operating Statistics
Refinery throughputs (thousands of barrels per day)	[9]	757	700	688		703
Sour crude oil throughput percent		39.00%	36.00%	39.00%		35.00%
WTI-priced crude oil throughput percent		39.00%	43.00%	41.00%		42.00%
Refined product yields (thousands of barrels per day)	[9]	762	702	693		708
Refinery direct operating costs (dollars per barrel):
Planned turnaround and major maintenance | $ / bbl	[7]	0.72	2.30	1.26		1.32
Depreciation and amortization | $ / bbl	[7]	1.72	1.80	1.90		1.79
Other manufacturing | $ / bbl	[7],[8]	4.04	4.25	4.29		4.24
Total | $ / bbl	[7]	6.48	8.35	7.45		7.35
Refining & Marketing | Midwest: | Crude oil refined
Refining & Marketing Operating Statistics
Refinery throughputs (thousands of barrels per day)	[9]	718	672	651		670
Refining & Marketing | Midwest: | Other charge and blendstocks
Refining & Marketing Operating Statistics
Refinery throughputs (thousands of barrels per day)	[9]	39	28	37		33
Refining & Marketing | Midwest: | Gasoline
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	396	367	378		380
Refining & Marketing | Midwest: | Distillates
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	236	203	209		212
Refining & Marketing | Midwest: | Propane
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	13	10	11		11
Refining & Marketing | Midwest: | Feedstocks and special products
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	51	59	40		46
Refining & Marketing | Midwest: | Heavy fuel oil
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	13	16	12		17
Refining & Marketing | Midwest: | Asphalt
Refining & Marketing Operating Statistics
Refined product yields (thousands of barrels per day)	[9]	53	47	43		42
Speedway
Speedway Operating Statistics
Convenience stores at period-end | Store		2,773	2,756	2,773		2,756
Gasoline and distillate sales (millions of gallons) | gal		1,575	1,555	4,605		4,501
Gasoline and distillate gross margin (dollars per gallon) | $ / gal	[4],[10]	0.1773	0.2146	0.1668		0.1822
Merchandise sales (in millions) | $		$ 1,338	$ 1,294	$ 3,777		$ 3,669
Merchandise gross margin (in millions) | $		$ 386	$ 358	$ 1,085		$ 1,028
Merchandise margin percent		28.90%	27.70%	28.70%		28.00%
Same store gasoline sales volume (period over period) percentage		(0.60%)	0.50%	0.20%		(0.30%)
Merchandise sales excluding cigarettes (period over period) percentage	[11]	4.00%	3.60%	3.00%		4.70%
Midstream
Midstream Operating Statistics
Crude oil and refined product pipeline throughputs (thousands of barrels per day)	[12]	2,433	2,259	2,298		2,231
Gathering system throughput (MMcf/d) | CFPD	[13]	3,306		3,313
Natural gas processed (MMcf/d) | CFPD	[13]	5,906		5,691
C2 and NGLs fractionated (thousands barrels per day)	[13]	348		330
[1]	Total average daily volumes of refined product sales to wholesale, branded and retail (Speedway segment) customers.
[2]	Includes intersegment sales.
[3]	Sales revenue less cost of refinery inputs and purchased products, divided by total refinery throughputs.
[4]	Excludes LCM inventory valuation adjustments.
[5]	Based on calendar day capacity, which is an annual average that includes downtime for planned maintenance and other normal operating activities.
[6]	Excludes inter-refinery volumes of 89 mbpd and 40 mbpd for the three months ended September 30, 2016 and 2015, respectively, and 80 mbpd and 40 mbpd for the nine months ended September 30, 2016 and 2015, respectively.
[7]	Per barrel of total refinery throughputs.
[8]	Includes utilities, labor, routine maintenance and other operating costs.
[9]	Includes inter-refinery transfer volumes.
[10]	The price paid by consumers less the cost of refined products, including transportation, consumer excise taxes and bankcard processing fees, divided by gasoline and distillate sales volume.
[11]	Excludes cigarettes. Same store sales comparison includes only locations owned at least 13 months.
[12]	On owned common-carrier pipelines, excluding equity method investments.
[13]	Includes amounts related to unconsolidated equity method investments. Includes the results of the MarkWest assets beginning on the Dec. 4, 2015 acquisition date.