Marathon Oil (MRO) 10-Q 6 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	9 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2013	Oct. 31, 2013	Jun. 29, 2012
Document and Entity Information [Abstract]	'	'	'
Document Type	'10-Q	'	'
Document Period End Date	30-Sep-13	'	'
Document Fiscal Period Focus	'Q3	'	'
Document Fiscal Year Focus	'2013	'	'
Amendment Flag	'false	'	'
Entity Registrant Name	'Marathon Oil Corp	'	'
Entity Central Index Key	'0000101778	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Well Known Seasoned Issuer	'Yes	'	'
Entity Common Stock Shares Outstanding	'	696,634,081	'
Entity Public Float	'	'	$17,991

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues and other income:	'	'	'	'
Sales and other operating revenues, including related party	$3,119	$3,405	$9,978	$9,324
Marketing revenues	668	631	1,597	2,237
Income from equity method investments	114	122	309	260
Net gain (loss) on disposal of assets	-6	-12	-4	126
Other income	19	15	38	38
Total revenues and other income	3,914	4,161	11,918	11,985
Costs and expenses:	'	'	'	'
Production	575	601	1,767	1,581
Marketing, including purchases from related parties	664	629	1,588	2,238
Other operating	126	112	323	311
Exploration	153	170	751	477
Depreciation, depletion and amortization	720	625	2,205	1,779
Impairments	11	8	49	271
Taxes other than income	91	55	268	178
General and administrative	152	179	490	499
Total costs and expenses	2,492	2,379	7,441	7,334
Income from operations	1,422	1,782	4,477	4,651
Net interest and other	-66	-53	-209	-160
Income before income taxes	1,356	1,729	4,268	4,491
Provision for income taxes	787	1,279	2,890	3,231
Net income	$569	$450	$1,378	$1,260
Basic:	'	'	'	'
Net income, per basic share	$0.80	$0.64	$1.95	$1.79
Diluted:	'	'	'	'
Net income, per diluted share	$0.80	$0.63	$1.94	$1.78
Dividends paid, per share	$0.19	$0.17	$0.53	$0.51
Weighted average common shares outstanding, basic	707	706	708	705
Weighted average common shares outstanding, diluted	711	709	712	709

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Comprehensive Income [Abstract]	'	'	'	'
Net income	$569	$450	$1,378	$1,260
Postretirement and postemployment plans	'	'	'	'
Change in actuarial loss and other	34	-90	180	-80
Income tax (provision) benefit on postretirement and postemployment plans	-13	32	-67	28
Postretirement and postemployment plans, net of tax	21	-58	113	-52
Derivative hedges	'	'	'	'
Net unrecognized gain	0	1	0	1
Income tax provision on derivatives	0	0	0	0
Derivative hedges, net of tax	0	1	0	1
Foreign currency translation and other	'	'	'	'
Net unrecognized gain	1	0	-3	0
Income tax benefit on foreign currency translation and other	0	0	1	0
Foreign currency translation and other, net of tax	1	0	-2	0
Other comprehensive income (loss)	22	-57	111	-51
Comprehensive income	$591	$393	$1,489	$1,209

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$354	$684
Receivables	2,562	2,418
Inventories	360	361
Other current assets	179	299
Total current assets	3,455	3,762
Equity method investments	1,216	1,279
Property, plant and equipment, less accumulated depreciation, depletion and amortization of $21,171 and $19,266	27,822	28,272
Goodwill	499	525
Other noncurrent assets	2,784	1,468
Total assets	35,776	35,306
Current liabilities:	'	'
Commercial paper	200	200
Accounts payable	2,406	2,324
Payroll and benefits payable	162	217
Accrued taxes	1,511	1,983
Other current liabilities	326	173
Long-term debt due within one year	68	184
Total current liabilities	4,673	5,081
Long-term debt	6,433	6,512
Deferred tax liabilities, noncurrent	2,481	2,432
Defined benefit postretirement plan obligations	713	856
Asset retirement obligations	2,027	1,749
Deferred credits and other liabilities, noncurrent	455	393
Total liabilities	16,782	17,023
Commitments and contingencies	'	'
Stockholders' Equity	'	'
Preferred stock - no shares issued and outstanding (no par value, 26 million shares authorized)	0	0
Common stock issued - 770 million and 770 million shares (par value $1 per share, 1.1 billion shares authorized)	770	770
Common stock, securities exchangeable into common stock - no shares issued or outstanding (no par value, 29 million shares authorized)	0	0
Held in treasury, at cost - 74 million and 63 million shares	-2,949	-2,560
Additional paid-in capital	6,603	6,616
Retained earnings	14,892	13,890
Accumulated other comprehensive loss	-322	-433
Total equity	18,994	18,283
Total liabilities and stockholders' equity	$35,776	$35,306

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets Parentheticals (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, except Share data, unless otherwise specified
Consolidated Balance Sheets Parenthetical [Abstract]	'	'
Less accumulated depreciation, depletion and amortization	($21,171)	($19,266)
Preferred stock, no par value	$0	$0
Preferred stock shares authorized	26,000,000	26,000,000
Preferred stock shares issued	0	0
Preferred stock shares outstanding	0	0
Common stock, par value per share	$1	$1
Common stock shares authorized	1,100,000,000	1,100,000,000
Common stock, shares issued	770,000,000	770,000,000
Common stock, securities exchangeable, no par value	$0	$0
Common stock, securities exchangeable, shares authorized	29,000,000	29,000,000
Common stock, securities exchangeable, shares issued	0	0
Common stock, securities exchangeable, shares outstanding	0	0
Held in treasury, shares	74,000,000	63,000,000

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Operating activities:	'	'
Net income	$1,378	$1,260
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Deferred income taxes	17	-27
Depreciation, depletion and amortization	2,205	1,779
Impairments	49	271
Pension and other postretirement benefits, net	41	-56
Exploratory dry well costs and unproved property impairments	619	287
Net gain on disposal of assets	4	-126
Equity method investments, net	12	-14
Changes in:	'	'
Current receivables, changes in	-151	-646
Inventories, changes in	-8	-6
Current accounts payable and accrued liabilities, changes in	-286	156
All other operating, net	161	-66
Net cash provided by operating activities	4,041	2,812
Investing activities:	'	'
Acquisitions, net of cash acquired	-74	-806
Additions to property, plant and equipment	-3,818	-3,509
Disposal of assets	402	193
Investments - return of capital	45	42
All other investing, net	34	49
Net cash used in investing activities	-3,411	-4,031
Financing activities:	'	'
Commercial paper, net	0	1,839
Debt issuance costs	0	9
Debt repayments	-148	-111
Purchases of common stock	-500	0
Dividends paid	-376	-360
All other financing, net	70	26
Net cash (used in) provided by financing activities	-954	1,385
Effect of exchange rate changes on cash	-6	12
Net decrease in cash and cash equivalents	-330	178
Cash and cash equivalents at beginning of period	684	493
Cash and cash equivalents at end of period	$354	$671

Basis_of_Presentation_Basis_of

Basis of Presentation Basis of Presentation	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Basis of Presentation [Text Block]	'
	Basis of Presentation
	These consolidated financial statements are unaudited; however, in the opinion of 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 disclosed otherwise.  These consolidated financial statements, including notes, have been prepared in accordance with the applicable rules of the Securities and Exchange Commission ("SEC") and do not include all of the information and disclosures required by accounting principles generally accepted in the United States of America for complete financial statements.
	Beginning in the first quarter of 2013, we changed the presentation of our consolidated statements of income, primarily to present additional details of revenues and expenses and to classify certain expenses more consistently with our peer group of independent exploration and production companies. To effect these changes, reclassifications of previously reported amounts were made and are reflected in these consolidated financial statements. As a result of the reclassifications, general and administrative expenses for the third quarter and first nine months of 2012 increased by $40 million and $110 million which primarily includes certain costs associated with operations support and operations management. Offsetting reductions are reflected in production, other operating and exploration expenses and taxes other than income.
	These interim financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Marathon Oil Corporation 2012 Annual Report on Form 10-K.  The results of operations for the third quarter and first nine months of 2013 are not necessarily indicative of the results to be expected for the full year.

Accounting_Standards

Accounting Standards	9 Months Ended
	Sep. 30, 2013
Accounting Standards Disclosure [Abstract]	'
Accounting Standards [Text Block]	'
	Accounting Standards
	Not Yet Adopted
	In June 2013, the Financial Accounting Standards Board ("FASB") ratified the Emerging Issues Task Force consensus on Issue 13-C, which requires that an unrecognized tax benefit or a portion of an unrecognized tax benefit be presented as a reduction to a deferred tax asset for an available net operating loss carryforward, a similar tax loss or tax credit carryforward. This accounting standards update is effective for us beginning in the first quarter of 2014 and should be applied prospectively to unrecognized tax benefits that exist as of the effective date. Early adoption and retrospective application are permitted. We do not expect this accounting standards update to have a significant impact on our consolidated results of operations, financial position or cash flows.
	In February 2013, an accounting standards update was issued to provide guidance for the recognition, measurement, and disclosure of obligations resulting from joint and several liability arrangements for which the total amount of the obligation is fixed at the reporting date, except for obligations such as asset retirement and environmental obligations, contingencies, guarantees, income taxes and retirement benefits, which are separately addressed within United States generally accepted accounting principles ("U.S. GAAP"). An entity is required to measure obligations resulting from joint and several liability arrangements for which the total amount of the obligation is fixed at the reporting date as the sum of 1) the amount the entity agreed to pay on the basis of its arrangement among its co-obligors and 2) any amount the entity expects to pay on behalf of its co-obligors. Disclosure of the nature of the obligation, including how the liability arose, the relationship with other co-obligors and the terms and conditions of the arrangement is required. In addition, the total outstanding amount under the arrangement, not reduced by the effect of any amounts that may be recoverable from other entities, plus the carrying amount of any liability or receivable recognized must be disclosed. This accounting standards update is effective for us beginning in the first quarter of 2014 and should be applied retrospectively for those in-scope obligations resulting from joint and several liability arrangements that exist at the beginning of 2014. Early adoption is permitted. We do not expect this accounting standards update to have a significant impact on our consolidated results of operations, financial position or cash flows.
	Recently Adopted
	In February 2013, an accounting standards update was issued to improve the reporting of reclassifications out of accumulated other comprehensive income. This standard requires an entity to provide information about the amounts reclassified out of accumulated other comprehensive income by component. In addition, an entity is required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income by the respective line items of net income but only if the amount reclassified is required under U.S. GAAP to be reclassified to net income in its entirety in the same reporting period. For other amounts that are not required under U.S. GAAP to be reclassified in their entirety to net income, an entity is required to cross-reference to other disclosures required under U.S. GAAP that provide additional detail about those amounts. This accounting standards update was effective for us beginning the first quarter of 2013 and we present the required disclosures in Note 16. Adoption of this standard did not have a significant impact on our consolidated results of operations, financial position or cash flows.
	In December 2011, an accounting standards update designed to enhance disclosures about offsetting assets and liabilities was issued. Further clarification limiting the scope of these disclosures to derivatives, repurchase agreements and reverse repurchase agreements, and securities borrowing and securities lending transactions was issued in January 2013. The disclosures are intended to enable financial statement users to evaluate the effect or potential effect of netting arrangements on an entity’s financial position. Entities are required to disclose both gross information and net information about in-scope financial instruments that are either offset in the statement of financial position or subject to an enforceable master netting arrangement or similar agreement, irrespective of whether they are offset. The accounting standards update was effective for us beginning the first quarter of 2013 and we include the required disclosures in Note 14. Adoption of this standard did not have a significant impact on our consolidated results of operations, financial position or cash flows.

Variable_Interest_Entity

Variable Interest Entity	9 Months Ended
	Sep. 30, 2013
Variable Interest Entities Disclosure [Abstract]	'
Variable Interest Entity [Text Block]	'
	Variable Interest Entity
	The owners of the Athabasca Oil Sands Project (“AOSP”), in which we hold a 20 percent undivided interest, contracted with a wholly-owned subsidiary of a publicly traded Canadian limited partnership (“Corridor Pipeline”) to provide materials transportation capabilities among the Muskeg River and Jackpine mines, the Scotford upgrader and markets in Edmonton.  The contract, originally signed in 1999 by a company we acquired, allows each holder of an undivided interest in the AOSP to ship materials in accordance with its undivided interest.  Costs under this contract are accrued and recorded on a monthly basis, with current liabilities of $3 million recorded at September 30, 2013, consistent with December 31, 2012.  Under this agreement, the AOSP absorbs all of the operating and capital costs of the pipeline.  Currently, no third-party shippers use the pipeline.  Should shipments be suspended, by choice or due to force majeure, we remain responsible for the portion of the payments related to our undivided interest for all remaining periods.  The contract expires in 2029; however, the shippers can extend its term perpetually.  This contract qualifies as a variable interest contractual arrangement and the Corridor Pipeline qualifies as a variable interest entity (“VIE”).  We hold a variable interest but are not the primary beneficiary because our shipments are only 20 percent of the total; therefore the Corridor Pipeline is not consolidated by us.  Our maximum exposure to loss as a result of our involvement with this VIE is the amount we expect to pay over the contract term, which was $707 million as of September 30, 2013.  The liability on our books related to this contract at any given time will reflect amounts due for the immediately previous month’s activity, which is substantially less than the maximum exposure over the contract term.  We have not provided financial assistance to Corridor Pipeline and we do not have any guarantees of such assistance in the future.

Income_per_Common_Share

Income per Common Share	9 Months Ended
	Sep. 30, 2013
Income Per Common Share Disclosure [Abstract]	'
Income per Common Share [Text Block]	'
	Income per Common Share
	Basic income per share is based on the weighted average number of common shares outstanding.  Diluted income per share assumes exercise of stock options and stock appreciation rights, provided the effect is not antidilutive.
		Three Months Ended September 30,
		2013				2012
	(In millions, except per share data)	Basic		Diluted		Basic		Diluted
	Net income	$	569	$	569	$	450	$	450
	Weighted average common shares outstanding	707		707		706		706
	Effect of dilutive securities	—		4		—		3
	Weighted average common shares, including
	dilutive effect	707		711		706		709
	Per share:
	Net income		$0.80		$0.80		$0.64		$0.63
		Nine Months Ended September 30,
		2013				2012
	(In millions, except per share data)	Basic		Diluted		Basic		Diluted
	Net income	$	1,378	$	1,378	$	1,260	$	1,260
	Weighted average common shares outstanding	708		708		705		705
	Effect of dilutive securities	—		4		—		4
	Weighted average common shares, including
	dilutive effect	708		712		705		709
	Per share:
	Net income	$1.95		$1.94		$1.79		$1.78
	The per share calculations above exclude 4 million and 5 million stock options for the third quarter and first nine months of 2013, as they were antidilutive. Excluded for the third quarter and first nine months of 2012 were 10 million stock options.

Dispositions

Dispositions	9 Months Ended
	Sep. 30, 2013
Dispositions Disclosure [Abstract]	'
Dispositions [Text Block]	'
	Dispositions
	2013 - North America Exploration and Production ("E&P") Segment
	In June 2013, we closed the sale of our interests in the DJ Basin for proceeds of $19 million. A loss of $114 million was recorded in the second quarter of 2013.
	In February 2013, we conveyed our interests in the Marcellus natural gas shale play to the operator. A $43 million loss on this transaction was recorded in the first quarter of 2013.
	In February 2013, we closed the sale of our interest in the Neptune gas plant, located onshore Louisiana, for proceeds of $166 million. A $98 million gain was recorded in the first quarter of 2013.
	In January 2013, we closed the sale of our remaining assets in Alaska, for proceeds of $195 million, subject to a six-month escrow of $50 million which was collected in July 2013. After closing adjustments made in the second quarter of 2013, the gain on this sale was $55 million.
	2013 - International E&P Segment
	In June 2013, we entered into an agreement to sell our non-operated 10 percent working interest in the Production Sharing Contract and Joint Operating Agreement in Block 31 offshore Angola. This transaction, valued at $1.5 billion before closing adjustments, is expected to close in the fourth quarter of 2013, subject to government and regulatory approvals. Angola Block 31 is reflected as held for sale in the September 30, 2013 consolidated balance sheet as follows:
	(In millions)
	Other current assets	$	15
	Other noncurrent assets	1,598
	Total assets	1,613
	Other current liabilities	42
	Deferred credits and other liabilities	41
	Total liabilities	$	83
	2012 - North America E&P Segment
	In the third quarter of 2012, we sold approximately 5,800 net undeveloped acres located outside the core of the Eagle Ford shale for proceeds of $9 million. A net loss of $18 million was recorded.
	In January 2012, we closed on the sale of our interests in several Gulf of Mexico crude oil pipeline systems for proceeds of $206 million.  This included our equity method interests in Poseidon Oil Pipeline Company, L.L.C. and Odyssey Pipeline L.L.C., as well as certain other oil pipeline interests including the Eugene Island pipeline system.  A gain of $166 million was recorded in the first quarter of 2012.
	2012 - International E&P Segment
	In May 2012, we reached an agreement to relinquish our operatorship of and interests in the Bone Bay and Kumawa exploration licenses in Indonesia. A $36 million payment to settle all of our obligations related to these licenses, including well commitments, was accrued and reported as a loss on disposal of assets in the second quarter of 2012 and we paid the accrued amount in the third quarter of 2012.

Acquisitions_Notes

Acquisitions (Notes)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Business Combination Disclosure [Text Block]	'
	Acquisitions
	During the third quarters and first nine months of 2013 and 2012, our business combinations related to properties acquired by our North America E&P segment in the Eagle Ford shale in south Texas. The pro forma impact of these transactions, individually and in the aggregate, is not material to our consolidated statements of income for any periods presented.
	The fair values of assets acquired and liabilities assumed in each of these business combinations were measured primarily using an income approach, specifically utilizing a discounted cash flow analysis. The estimated fair values were based on significant inputs not observable in the market, and therefore represent Level 3 measurements. Significant inputs included estimated reserve volumes, the expected future production profile, estimated commodity prices and assumptions regarding future operating and development costs. The discount rates used in the discounted cash flow analyses were approximately 10 percent for the both the 2013 and 2012 transactions.
	2013
	In July 2013, we acquired 4,800 net undeveloped acres in the core of the Eagle Ford shale in a transaction valued at $97 million, including carried interest of $23 million. The transaction was accounted for as a business combination, with the entire up-front cash consideration of $74 million allocated to property, plant and equipment at the acquisition date.
	2012
	We acquired approximately 20,000 net acres in the core of the Eagle Ford shale during the first nine months of 2012. The largest transaction was the acquisition of Paloma Partners II, LLC, which closed during the third quarter for cash consideration of $768 million. This transaction was accounted for as a business combination. Smaller transactions closed during the second quarter of 2012.
	The following table summarizes the amounts allocated to the assets acquired and liabilities assumed for Paloma Partners II, LLC based upon their fair values at the acquisition date:
	(In millions)
	Assets:
	Cash	$	8
	Receivables	22
	Inventories	1
	Total current assets acquired	31
	Property, plant and equipment	822
	Total assets acquired	$	853
	Liabilities:
	Accounts payable	78
	Asset retirement obligations	7
	Total liabilities assumed	85
	Net assets acquired	$	768

Segment_Information

Segment Information	9 Months Ended
	Sep. 30, 2013
Segment Information Disclosure [Abstract]	'
Segment Information [Text Block]	'
	Segment Information
	Beginning in 2013, we changed our reportable segments and revised our management reporting to better reflect the growing importance of United States unconventional resource plays to our business. All prior-year periods presented have been recast to reflect these new segments.
	We have three reportable operating segments.  Each of these segments is organized and managed based upon both geographic location and the nature of the products and services it offers.
	•	North America E&P ("N.A. E&P") – explores for, produces and markets liquid hydrocarbons and natural gas in North America;
	•	International E&P ("Int'l E&P") – explores for, produces and markets liquid hydrocarbons and natural gas outside of North America and produces and markets products manufactured from natural gas, such as liquefied natural gas ("LNG")and methanol, in Equatorial Guinea; and
	•	Oil Sands Mining (“OSM”) – mines, extracts and transports bitumen from oil sands deposits in Alberta, Canada, and upgrades the bitumen to produce and market synthetic crude oil and vacuum gas oil.
	Information regarding assets by segment is not presented because it is not reviewed by the chief operating decision maker (“CODM”).  Segment income represents income from continuing operations excluding certain items not allocated to segments as discussed below, net of income taxes, attributable to the operating segments. Our corporate and operations support general and administrative costs are not allocated to the operating segments. These costs primarily consist of employment costs (including pension effects), professional services, facilities and other costs associated with corporate and operations support activities, net of associated income tax effects.  Unrealized gains or losses on crude oil derivative instruments, impairments, gains or losses on dispositions or other items that affect comparability (as determined by the CODM) also are not allocated to operating segments.
	Differences between segment totals and our consolidated totals for income taxes and depreciation, depletion and amortization represent amounts related to corporate administrative activities and other unallocated items which are included in “Items not allocated to segments, net of income taxes” in the reconciliation below. Total capital expenditures include accruals but not corporate activities.
		Three Months Ended September 30, 2013
	(In millions)	N.A. E&P				Int'l E&P				OSM				Total
	Revenues:
	Sales and other operating revenues	$	1,321			$	1,396			$	463			$	3,180
	Marketing revenues	607				58				3				668
	Segment revenues	$	1,928			$	1,454			$	466			3,848
	Unrealized loss on crude oil derivative instruments													(61		)
	Total revenues													$	3,787
	Segment income	$	242			$	321			$	106			$	669
	Income from equity method investments	—				114				—				114
	Depreciation, depletion and amortization	490				179				54				723
	Income tax provision	143				714				35				892
	Capital expenditures	831				254				65				1,150
		Three Months Ended September 30, 2012
	(In millions)	N.A. E&P				Int'l E&P				OSM				Total
	Revenues:
	Sales and other operating revenues	$	993			$	1,907			$	460			$	3,360
	Marketing revenues	548				73				10				631
	Segment revenues	$	1,541			$	1,980			$	470			3,991
	Unrealized gain on crude oil derivative instruments													45
	Total revenues													$	4,036
	Segment income	$	107			$	405			$	66			$	578
	Income from equity method investments	1				121				—				122
	Depreciation, depletion and amortization	360				194				60				614
	Income tax provision	66				1,219				20				1,305
	Capital expenditures	1,045				229				41				1,315
		Nine Months Ended September 30, 2013
	(In millions)	N.A. E&P				Int'l E&P				OSM				Total
	Revenues:
	Sales and other operating revenues	$	3,820			$	5,015			$	1,204			$	10,039
	Marketing revenues	1,391				194				12				1,597
	Segment revenues	$	5,211			$	5,209			$	1,216			11,636
	Unrealized loss on crude oil derivative instruments													(61		)
	Total revenues													$	11,575
	Segment income	$	404			$	1,156			$	164			$	1,724
	Income from equity method investments	—				309				—				309
	Depreciation, depletion and amortization	1,458				575				154				2,187
	Income tax provision	242				2,860				55				3,157
	Capital expenditures	2,705				720				207				3,632
		Nine Months Ended September 30, 2012
	(In millions)	N.A. E&P				Int'l E&P				OSM				Total
	Revenues:
	Sales and other operating revenues	$	2,738			$	5,383			$	1,158			$	9,279
	Marketing revenues	2,019				193				25				2,237
	Segment revenues	$	4,757			$	5,576			$	1,183			11,516
	Unrealized gain on crude oil derivative instruments													45
	Total revenues													$	11,561
	Segment income	$	281			$	1,185			$	154			$	1,620
	Income from equity method investments	2				258				—				260
	Depreciation, depletion and amortization	964				622				159				1,745
	Income tax provision	166				3,260				50				3,476
	Capital expenditures	2,887				569				136				3,592
	The following reconciles total revenues to sales and other operating revenues as reported in the consolidated statements of income:
		Three Months Ended September 30,						Nine Months Ended September 30,
	(In millions)	2013			2012			2013			2012
Total revenues	$	3,787		$	4,036		$	11,575		$	11,561
Less:  Marketing revenues	668			631			1,597			2,237
Sales and other operating revenues, including related party	$	3,119		$	3,405		$	9,978		$	9,324
The following reconciles segment income to net income as reported in the consolidated statements of income:
	Three Months Ended September 30,						Nine Months Ended September 30,
(In millions)	2013			2012			2013			2012
Segment income	$	669		$	578		$	1,724		$	1,620
Items not allocated to segments, net of income taxes:
Corporate and other unallocated items	(61		)	(146		)	(288		)	(294		)
Unrealized gain (loss) on crude oil derivative instruments	(39		)	29			(39		)	29
Net gain (loss) on dispositions	—			(11		)	(9		)	72
Impairments	—			—			(10		)	(167		)
Net income	$	569		$	450		$	1,378		$	1,260

Defined_Benefit_Postretirement

Defined Benefit Postretirement Plans	9 Months Ended
	Sep. 30, 2013
Defined Benefit Postretirement Plans Disclosure [Abstract]	'
Defined Benefit Postretirement Plans [Text Block]	'
	Defined Benefit Postretirement Plans
	The following summarizes the components of net periodic benefit cost:
		Three Months Ended September 30,
		Pension Benefits						Other Benefits
	(In millions)	2013			2012			2013			2012
	Service cost	$	14		$	12		$	1		$	1
	Interest cost	16			16			3			4
	Expected return on plan assets	(17		)	(14		)	—			—
	Amortization:
	– prior service cost (credit)	2			2			(2		)	(2		)
	– actuarial loss	9			12			—			—
	Net settlement loss(a)	15			34			—			—
	Net periodic benefit cost	$	39		$	62		$	2		$	3
		Nine months Ended September 30,
		Pension Benefits						Other Benefits
	(In millions)	2013			2012			2013			2012
	Service cost	$	42		$	37		$	3		$	3
	Interest cost	47			48			9			11
	Expected return on plan assets	(50		)	(46		)	—			—
	Amortization:
	– prior service cost (credit)	5			6			(5		)	(5		)
	– actuarial loss	38			37			—			—
	Net settlement loss(a)	32			34			—			—
	Net periodic benefit cost	$	114		$	116		$	7		$	9
	(a) Settlements are recognized as they occur, once it is probable that lump sum payments from a plan for a given year will exceed the plan's total service and interest cost for that year. Such settlements were recorded for our U.S. plans in the second and third quarters of 2013 and the third quarter of 2012.
	During the second and third quarters of 2013 and the third quarter of 2012, we recorded the effects of partial settlements of our U.S. pension plans and we remeasured the plans' assets and liabilities as of the applicable balance sheet dates. As a result, we recognized decreases of $24 million and $163 million in actuarial losses in other comprehensive income for the three months and nine months ended September 30, 2013, and an increase of $103 million in actuarial losses, net of settlement loss, for the three months and nine months ended September 30, 2012.
	During the first nine months of 2013, we made contributions of $50 million to our funded pension plans.  We expect to make additional contributions up to an estimated $17 million to our funded pension plans over the remainder of 2013.  Current benefit payments related to unfunded pension and other postretirement benefit plans were $19 million and $12 million during the first nine months of 2013.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Taxes Disclosure [Abstract]	'
Income Taxes [Text Block]	'
	Income Taxes
	The effective income tax rate is influenced by a variety of factors including the geographic sources of income and the relative magnitude of these sources of income. The provision for income taxes is allocated on a discrete, stand-alone basis to pretax segment income and to individual items not allocated to segments. The difference between the total provision and the sum of the amounts allocated to segments and to individual items not allocated to segments is reported in “Corporate and other unallocated items” in Note 7.
	Our effective income tax rates in the first nine months of 2013 and 2012 were 68 percent and 72 percent.   These rates are higher than the U.S. statutory rate of 35 percent due to earnings from foreign jurisdictions, primarily Norway and Libya, where the tax rates are in excess of the U.S. statutory rate.  In Libya, where the statutory tax rate is in excess of 90 percent, sales decreased in the third quarter of 2013 due to labor strikes at the Es Sider oil terminal and there remains uncertainty around future production and sales levels. Reliable estimates of 2013 and 2012 annual ordinary income from our Libyan operations could not be made and the range of possible scenarios when including ordinary income from our Libyan operations in the worldwide annual effective tax rate calculation demonstrates significant variability.  As such, for the first nine months of 2013 and 2012, estimated annual effective tax rates were calculated excluding Libya and applied to consolidated ordinary income excluding Libya and the tax provision applicable to Libyan ordinary income was recorded as a discrete item in the periods.  Excluding Libya, the effective tax rates would be 60 percent and 64 percent for the first nine months of 2013 and 2012. In the third quarter of 2013, we recorded a net favorable tax adjustment of $42 million, largely related to greater expected utilization of foreign tax credits in future periods than previously estimated.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Inventories [Text Block]	'
	Inventories
	Inventories are carried at the lower of cost or market value.
		September 30,		December 31,
	(In millions)	2013		2012
	Liquid hydrocarbons, natural gas and bitumen	$	46	$	73
	Supplies and other items	314		288
	Inventories, at cost	$	360	$	361

Property_Plant_and_Equipment

Property, Plant and Equipment	9 Months Ended
	Sep. 30, 2013
Property Plant And Equipment Disclosure [Abstract]	'
Property, Plant and Equipment [Text Block]	'
	Property, Plant and Equipment
		September 30,			December 31,
	(In millions)	2013			2012
	North America E&P	$	25,858		$	23,748
	International E&P	12,342			13,214
	Oil Sands Mining	10,337			10,127
	Corporate	456			449
	Total property, plant and equipment	48,993			47,538
	Less accumulated depreciation, depletion and amortization	(21,171		)	(19,266		)
	Net property, plant and equipment	$	27,822		$	28,272
	During the third quarter of 2013, our Libya production operations were impacted due to labor strikes at the Es Sider oil terminal. We had three oil liftings from Libya in July 2013, but no oil liftings in August or September. Uncertainty around sustained production and sales levels from Libya have existed since the first quarter of 2011 when production operations were suspended until limited production resumed in the fourth quarter of the same year.  We and our partners in the Waha concessions continue to assess the situation and the condition of our assets in Libya. As of September 30, 2013, our net property, plant and equipment investment in Libya was approximately $743 million.
	Exploratory well costs capitalized greater than one year after completion of drilling were $220 million as of September 30, 2013.  The net decrease of $9 million from December 31, 2012 primarily related to the conveyance of our interests in the Marcellus natural gas shale play to the operator in February 2013.
	Included in the total costs suspended for greater than one year are $127 million related to Angola Block 31 and $22 million related to Equatorial Guinea. The Angola Block 31 costs are included in the other noncurrent assets held for sale reported in Note 5. We intend to develop Block D offshore Equatorial Guinea through a unitization with the Alba field, which is now expected be completed late in 2014.

Asset_Retirement_Obligations_A

Asset Retirement Obligations Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]	'
Asset Retirement Obligation Disclosure [Text Block]	'
	Asset Retirement Obligations
	The following summarizes the changes in asset retirement obligations during the first nine months of 2013:
	(In millions)
	Beginning balance(a)	$	1,783
	Incurred, including acquisitions	10
	Settled, including dispositions	(41		)
	Accretion expense (included in depreciation, depletion and amortization)	103
	Revisions to previous estimates	306
	Held for sale	(41		)
	Ending balance(a)	$	2,120
	(a) Beginning and ending balances include asset retirement obligations of $34 million and $93 million classified as short-term at December 31, 2012 and September 30, 2013.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Fair Value Measurements [Text Block]	'
	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, 2013 and December 31, 2012 by fair value hierarchy level.
		September 30, 2013
	(In millions)	Level 1		Level 2		Level 3		Collateral		Total
	Derivative instruments, assets
	Commodity	$	—	$	5	$	—	$	—	$	5
	Interest rate	—		11		—		—		11
	Foreign currency	—		1		—		—		1
	Derivative instruments, assets	$	—	$	17	$	—	$	—	$	17
	Derivative instruments, liabilities
	Commodity	$	—	$	14	$	—	$	—	$	14
	Foreign currency	—		14		—		—		14
	Derivative instruments, liabilities	$	—	$	28	$	—	$	—	$	28
		December 31, 2012
	(In millions)	Level 1		Level 2		Level 3		Collateral		Total
	Derivative instruments, assets
	Commodity	$	—	$	52	$	—	$	1	$	53
	Interest rate	—		21		—		—		21
	Foreign currency	—		18		—		—		18
	Derivative instruments, assets	$	—	$	91	$	—	$	1	$	92
	Commodity swaps in Level 2 are measured at fair value with a market approach using prices obtained from exchanges or pricing services, which have been corroborated with data from active markets for similar assets or liabilities.  Commodity options in Level 2 are valued using the Black-Scholes Model.  Inputs to this model include prices as noted above, discount factors, and implied market volatility.  The inputs to this fair value measurement are categorized as Level 2 because predominantly all assumptions and inputs are observable in active markets throughout the term of the instruments.  Collateral deposits related to commodity derivatives are in broker accounts covered by master netting agreements.
	Interest rate swaps are measured at fair value with a market approach using actionable broker quotes which are Level 2 inputs.  Foreign currency forwards are measured at fair value with a market approach using third-party pricing services, such as Bloomberg L.P., which have been corroborated with data from active markets for similar assets or liabilities, and are Level 2 inputs.
	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.
		Three Months Ended September 30,
		2013				2012
	(In millions)	Fair Value		Impairment		Fair Value		Impairment
	Long-lived assets held for use	$	5	$	11	$	2	$	8
		Nine Months Ended September 30,
		2013				2012
	(In millions)	Fair Value		Impairment		Fair Value		Impairment
	Long-lived assets held for use	$	5	$	49	$	77	$	271
	All long-lived assets held for use that were impaired in the first nine months of 2013 and 2012 were held by our North America E&P segment. The fair values of each discussed below were measured using an income approach based upon internal estimates of future production levels, prices and discount rate, all of which are Level 3 inputs.  Inputs to the fair value measurement included reserve and production estimates made by our reservoir engineers, estimated commodity prices adjusted for quality and location differentials, and forecasted operating expenses for the remaining estimated life of the reservoir.
	In the first quarter of 2013, as a result of our decision to wind down operations in the Powder River Basin due to poor economics, an impairment of $15 million was recorded.
	In early 2012, production rates from the Ozona development in the Gulf of Mexico declined significantly. Accordingly, our reserve engineers prepared evaluations of our future production as well as our reserves and an impairment of $261 million was recorded in the first quarter of 2012.  As the development produced towards abandonment pressures, further downward revisions of reserves were taken, resulting in an additional impairment recorded in the fourth quarter of 2012. Ozona production ceased in the first quarter of 2013 and an additional $21 million impairment was recorded.
	Other impairments of long-lived assets held for use by our North America E&P segment in the first nine months of 2013 and 2012 were a result of reduced drilling expectations, reductions of estimated reserves or declining natural gas prices.
	Fair Values – Financial Instruments
	Our current assets and liabilities include financial instruments, the most significant of which are receivables, commercial paper and payables. We believe the carrying values of our receivables, commercial paper and payables 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.
	The following table summarizes financial instruments, excluding receivables, commercial paper, payables and derivative financial instruments, and their reported fair value by individual balance sheet line item at September 30, 2013 and December 31, 2012.
		September 30, 2013				December 31, 2012
		Fair		Carrying		Fair		Carrying
	(In millions)	Value		Amount		Value		Amount
	Financial assets
	Other noncurrent assets	$	168	$	165	$	189	$	186
	Total financial assets	168		165		189		186
	Financial liabilities
	Other current liabilities	13		13		13		13
	Long-term debt, including current portion(a)	6,941		6,461		7,610		6,642
	Deferred credits and other liabilities	164		161		94		94
	Total financial liabilities	$	7,118	$	6,635	$	7,717	$	6,749
	(a)      Excludes capital leases.
	Fair values of our financial assets included in other noncurrent assets, and of our financial liabilities included in other current liabilities and deferred credits and other liabilities are measured 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.
	Most of our long-term debt instruments are publicly-traded. A market approach, based upon quotes from major financial institutions, is used to measure the fair value of such debt. Because these quotes cannot be independently verified to an active market they are considered Level 3 inputs. The fair value of our debt that is not publicly-traded is measured using an income approach. The future debt service payments are discounted using the rate at which we currently expect to borrow. All inputs to this calculation are Level 3.

Derivatives

Derivatives	9 Months Ended
	Sep. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivatives [Text Block]	'
	Derivatives
	For information regarding the fair value measurement of derivative instruments, see Note 13. All of our interest rate and commodity derivatives are subject to enforceable master netting arrangements or similar agreements under which we may report net amounts. Netting is assessed by counterparty, and as of September 30, 2013 and December 31, 2012, there were no offsetting amounts. Positions by contract were all either assets or liabilities. The following tables present the gross fair values of derivative instruments, excluding cash collateral, and the reported net amounts along with where they appear on the consolidated balance sheets as of September 30, 2013 and December 31, 2012.
		30-Sep-13
	(In millions)	Asset				Liability				Net Asset				Balance Sheet Location
	Fair Value Hedges
	Foreign currency	$	1			$	—			$	1			Other current assets
	Interest rate	11				—				11				Other noncurrent assets
	Total Designated Hedges	12				—				12
	Not Designated as Hedges
	Commodity	5				—				5				Other current assets
	Total Not Designated as Hedges	5				—				5
	Total	$	17			$	—			$	17
		30-Sep-13
	(In millions)	Asset				Liability				Net Liability				Balance Sheet Location
	Fair Value Hedges
	Foreign currency	$	—			$	14			$	14			Other current liabilities
	Total Designated Hedges	—				14				14
	Not Designated as Hedges
	Commodity	—				14				14				Other current liabilities
	Total Not Designated as Hedges	—				14				14
	Total	$	—			$	28			$	28
		31-Dec-12
	(In millions)	Asset				Liability				Net Asset				Balance Sheet Location
	Fair Value Hedges
	Foreign currency	$	18			$	—			$	18			Other current assets
	Interest rate	21				—				21				Other noncurrent assets
	Total Designated Hedges	39				—				39
	Not Designated as Hedges
	Commodity	52				—				52				Other current assets
	Total Not Designated as Hedges	52				—				52
	Total	$	91			$	—			$	91
	Derivatives Designated as Fair Value Hedges
	The following table presents by maturity date, information about our interest rate swap agreements as of September 30, 2013, including the weighted average, London Interbank Offer Rate (“LIBOR”)-based, floating rate.
	Maturity Dates	Aggregate Notional Amount (in millions)			Weighted Average, LIBOR-Based, Floating Rate
	1-Oct-17	$	600		4.67	%
	15-Mar-18	$	300		4.51	%
	As of December 31, 2012, we had multiple interest rate swap agreements with a total notional amount of $600 million, a weighted average, LIBOR-based, floating rate of 4.70 percent and a maturity date of October 1, 2017.
	As of September 30, 2013 and December 31, 2012, our foreign currency forwards had an aggregate notional amount of 3,115 million and 3,043 million Norwegian Kroner at a weighted average forward rate of 5.874 and 5.780. These forwards hedge our current Norwegian tax liability and have settlement dates through February 2014.
	The pretax effect of derivative instruments designated as hedges of fair value in our consolidated statements of income are summarized in the table below. There is no ineffectiveness related to the fair value hedges.
			Gain (Loss)
			Three Months Ended September 30,								Nine Months Ended September 30,
	(In millions)	Income Statement Location	2013				2012				2013				2012
	Derivative
	Interest rate	Net interest and other	$	5			$	6			$	(9	)		$	17
	Foreign currency	Provision for income taxes	$	5			$	22			$	(41	)		$	(18	)
	Hedged Item
	Long-term debt	Net interest and other	$	(5	)		$	(6	)		$	9			$	(17	)
	Accrued taxes	Provision for income taxes	$	(5	)		$	(22	)		$	41			$	18
	Derivatives not Designated as Hedges
	In August 2012, we entered into crude oil derivatives related to a portion of our forecast North America E&P crude oil sales through December 31, 2013. These commodity derivatives were not designated as hedges and are shown in the table below.
	Remaining Term	Bbls per Day	Weighted Average Price per Bbl	Benchmark
	Swaps
	October 2013 - December 2013	20,000	$96.29	West Texas Intermediate
	October 2013 - December 2013	25,000	$109.19	Brent
	Option Collars
	October 2013 - December 2013	15,000	$90.00 floor / $101.17 ceiling	West Texas Intermediate
	October 2013 - December 2013	15,000	$100.00 floor / $116.30 ceiling	Brent
	The following table summarizes the effect of all derivative instruments not designated as hedges in our consolidated statements of income.
			Gain (Loss)
			Three Months Ended September 30,								Nine Months Ended September 30,
	(In millions)	Income Statement Location	2013				2012				2013				2012
	Commodity	Sales and other operating revenues, including related party	$	(86	)		$	45			$	(73	)		$	46

Incentive_Based_Compensation_P

Incentive Based Compensation Plans	9 Months Ended
	Sep. 30, 2013
Incentive Based Compensation Plans [Abstract]	'
Incentive Based Compensation [Text Block]	'
	Incentive Based Compensation
	Stock option and restricted stock awards
	The following table presents a summary of stock option and restricted stock award activity for the first nine months of 2013:
		Stock Options					Restricted Stock
		Number of			Weighted		Awards		Weighted
		Shares			Average				Average Grant
					Exercise Price				Date Fair Value
	Outstanding at December 31, 2012	19,536,965				$26.19	4,177,884			$29.02
	Granted	1,704,734		(a)		$33.30	1,254,935			$32.96
	Options Exercised/Stock Vested	(2,098,887	)			$22.31	(1,609,730	)		$28.09
	Canceled	(708,701	)			$34.01	(384,719	)		$29.91
	Outstanding at September 30, 2013	18,434,111				$26.99	3,438,370			$30.80
	(a)    The weighted average grant date fair value of stock option awards granted was $10.51 per share.
	Performance unit awards
	In the first quarter of 2013, we granted 353,600 performance units to certain officers that provide a cash payout upon the achievement of certain performance goals at the end of a 36-month performance period.  The performance goals are tied to our total shareholder return (“TSR”) as compared to TSR for a group of peer companies determined by the Compensation Committee of the Board of Directors.   At the grant date, each unit represents the value of one share of our common stock, while payout after completion of the performance period will be based on the value of anywhere from zero to two times the number of units granted.  Dividend equivalents accrue during the performance period and are paid in cash at the end of the performance period based on the number of shares that would represent the value of the units.  The fair value of these performance units is re-measured on a quarterly basis using the Monte Carlo simulation method.  These performance units are accounted for as liability awards because they are to be settled in cash at the end of the performance period and their fair value is expensed over the performance period.

Reclassifications_out_of_Accum

Reclassifications out of Accumulated Other Comprehensive Income Reclassifications out of Accumulated Other Comprehensive Income	9 Months Ended
	Sep. 30, 2013
Reclassifications out of AccumulatedOtherComprehensiveIncome [Abstract]	'
Reclassifications Out of Accumulated Other Comprehensive Loss	'
	Reclassifications Out of Accumulated Other Comprehensive Loss
	The following table presents a summary of amounts reclassified from accumulated other comprehensive loss to net income in their entirety:
		Three Months Ended September 30, 2013			Nine Months Ended September 30, 2013
	(In millions)							Income Statement Line
	Accumulated Other Comprehensive Loss Components
		Income (Expense)
	Postretirement and postemployment plans
	Amortization of actuarial loss	$	(9	)	$	(38	)	General and administrative
	Net settlement loss	(15		)	(32		)	General and administrative
		9			26			Provision for income taxes
		(15		)	(44		)	Net of tax
	Other insignificant items, net of tax	—			(1		)
	Total reclassifications for the period	$	(15	)	$	(45	)	Net income

Stockholders_Equity_Stockholde

Stockholders' Equity Stockholders' Equity	9 Months Ended
	Sep. 30, 2013
Stockholders' Equity Attributable to Parent [Abstract]	'
Stockholders' Equity Note Disclosure [Text Block]	'
	Stockholders' Equity
	In the third quarter of 2013, we acquired 14 million common shares at a cost of $500 million under our $5 billion authorized share repurchase program.

Supplemental_Cash_Flow_Informa

Supplemental Cash Flow Information	9 Months Ended
	Sep. 30, 2013
Supplemental Cash Flow Information [Abstract]	'
Supplemental Cash Flow Information [Text Block]	'
	Supplemental Cash Flow Information
		Nine Months Ended September 30,
	(In millions)	2013			2012
	Net cash provided from operating activities:
	Interest paid (net of amounts capitalized)	$	216		$	164
	Income taxes paid to taxing authorities	3,218			3,457
	Commercial paper, net:
	Commercial paper - issuances	$	4,975		$	10,420
	- repayments	(4,975		)	(8,581		)
	Noncash investing activities:
	Asset retirement costs capitalized	$	316		$	47
	Debt payments made by United States Steel	—			19
	Liabilities assumed in acquisition	—			85
	Change in capital expenditure accrual	(129		)	170
	Asset retirement obligations assumed by buyer	92			7

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	We are a defendant in a number of lawsuits arising in the ordinary course of business, including, but not limited to, royalty claims, contract claims and environmental claims.  While the ultimate outcome and impact to us cannot be predicted with certainty, we believe the resolution of these proceedings will not have a material adverse effect on our consolidated financial position, results of operations or cash flows.  Certain of these matters are discussed below.
	Litigation – In March 2011, Noble Drilling (U.S.) LLC (“Noble”) filed a lawsuit against us in the District Court of Harris County, Texas, alleging, among other things, breach of contract, breach of the duty of good faith and fair dealing, and negligent misrepresentation, relating to a multi-year drilling contract for a newly constructed drilling rig to be deployed in the U.S. Gulf of Mexico.  We filed an answer in April 2011, contending, among other things, failure to perform, failure to comply with material obligations, failure to mitigate alleged damages and that Noble failed to provide the rig according to the operating, performance and safety requirements specified in the drilling contract. In April 2013, we filed a counterclaim against Noble alleging, among other things, breach of contract and breach of the duty of good faith relating to the multi-year drilling contract. The counterclaim also included a breach of contract claim for reimbursement for the value of fuel used by Noble under an offshore daywork drilling contract. The parties have reached a tentative settlement of this litigation. We believe that the settlement of this litigation will not have a material adverse effect on our consolidated results of operations, financial position or cash flows.
	Contractual commitments – At September 30, 2013, Marathon’s contract commitments to acquire property, plant and equipment were $1,154 million.

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Basis of Accounting [Text Block]	'
	These consolidated financial statements are unaudited; however, in the opinion of 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 disclosed otherwise.  These consolidated financial statements, including notes, have been prepared in accordance with the applicable rules of the Securities and Exchange Commission ("SEC") and do not include all of the information and disclosures required by accounting principles generally accepted in the United States of America for complete financial statements.
Reclassification, Policy [Policy Text Block]	'
	Beginning in the first quarter of 2013, we changed the presentation of our consolidated statements of income, primarily to present additional details of revenues and expenses and to classify certain expenses more consistently with our peer group of independent exploration and production companies. To effect these changes, reclassifications of previously reported amounts were made and are reflected in these consolidated financial statements. As a result of the reclassifications, general and administrative expenses for the third quarter and first nine months of 2012 increased by $40 million and $110 million which primarily includes certain costs associated with operations support and operations management. Offsetting reductions are reflected in production, other operating and exploration expenses and taxes other than income.

Income_per_Common_Share_Tables

Income per Common Share (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	'
		Three Months Ended September 30,
		2013				2012
	(In millions, except per share data)	Basic		Diluted		Basic		Diluted
	Net income	$	569	$	569	$	450	$	450
	Weighted average common shares outstanding	707		707		706		706
	Effect of dilutive securities	—		4		—		3
	Weighted average common shares, including
	dilutive effect	707		711		706		709
	Per share:
	Net income		$0.80		$0.80		$0.64		$0.63
		Nine Months Ended September 30,
		2013				2012
	(In millions, except per share data)	Basic		Diluted		Basic		Diluted
	Net income	$	1,378	$	1,378	$	1,260	$	1,260
	Weighted average common shares outstanding	708		708		705		705
	Effect of dilutive securities	—		4		—		4
	Weighted average common shares, including
	dilutive effect	708		712		705		709
	Per share:
	Net income	$1.95		$1.94		$1.79		$1.78

Dispositions_Dispositions_Tabl

Dispositions Dispositions (Tables)	9 Months Ended
	Sep. 30, 2013
Dispositions Disclosure [Abstract]	'
Disclosure of Long Lived Assets Held-for-sale [Table Text Block]	'
	Angola Block 31 is reflected as held for sale in the September 30, 2013 consolidated balance sheet as follows:
	(In millions)
	Other current assets	$	15
	Other noncurrent assets	1,598
	Total assets	1,613
	Other current liabilities	42
	Deferred credits and other liabilities	41
	Total liabilities	$	83

Acquisitions_Tables

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	'
	The following table summarizes the amounts allocated to the assets acquired and liabilities assumed for Paloma Partners II, LLC based upon their fair values at the acquisition date:
	(In millions)
	Assets:
	Cash	$	8
	Receivables	22
	Inventories	1
	Total current assets acquired	31
	Property, plant and equipment	822
	Total assets acquired	$	853
	Liabilities:
	Accounts payable	78
	Asset retirement obligations	7
	Total liabilities assumed	85
	Net assets acquired	$	768

Segment_Information_Tables

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Information Disclosure [Abstract]	'
Schedule of Segment Reporting Information, by Segment [Table Text Block]	'
		Three Months Ended September 30, 2013
	(In millions)	N.A. E&P				Int'l E&P				OSM				Total
	Revenues:
	Sales and other operating revenues	$	1,321			$	1,396			$	463			$	3,180
	Marketing revenues	607				58				3				668
	Segment revenues	$	1,928			$	1,454			$	466			3,848
	Unrealized loss on crude oil derivative instruments													(61		)
	Total revenues													$	3,787
	Segment income	$	242			$	321			$	106			$	669
	Income from equity method investments	—				114				—				114
	Depreciation, depletion and amortization	490				179				54				723
	Income tax provision	143				714				35				892
	Capital expenditures	831				254				65				1,150
		Three Months Ended September 30, 2012
	(In millions)	N.A. E&P				Int'l E&P				OSM				Total
	Revenues:
	Sales and other operating revenues	$	993			$	1,907			$	460			$	3,360
	Marketing revenues	548				73				10				631
	Segment revenues	$	1,541			$	1,980			$	470			3,991
	Unrealized gain on crude oil derivative instruments													45
	Total revenues													$	4,036
	Segment income	$	107			$	405			$	66			$	578
	Income from equity method investments	1				121				—				122
	Depreciation, depletion and amortization	360				194				60				614
	Income tax provision	66				1,219				20				1,305
	Capital expenditures	1,045				229				41				1,315
		Nine Months Ended September 30, 2013
	(In millions)	N.A. E&P				Int'l E&P				OSM				Total
	Revenues:
	Sales and other operating revenues	$	3,820			$	5,015			$	1,204			$	10,039
	Marketing revenues	1,391				194				12				1,597
	Segment revenues	$	5,211			$	5,209			$	1,216			11,636
	Unrealized loss on crude oil derivative instruments													(61		)
	Total revenues													$	11,575
	Segment income	$	404			$	1,156			$	164			$	1,724
	Income from equity method investments	—				309				—				309
	Depreciation, depletion and amortization	1,458				575				154				2,187
	Income tax provision	242				2,860				55				3,157
	Capital expenditures	2,705				720				207				3,632
		Nine Months Ended September 30, 2012
	(In millions)	N.A. E&P				Int'l E&P				OSM				Total
	Revenues:
	Sales and other operating revenues	$	2,738			$	5,383			$	1,158			$	9,279
	Marketing revenues	2,019				193				25				2,237
	Segment revenues	$	4,757			$	5,576			$	1,183			11,516
	Unrealized gain on crude oil derivative instruments													45
	Total revenues													$	11,561
	Segment income	$	281			$	1,185			$	154			$	1,620
	Income from equity method investments	2				258				—				260
	Depreciation, depletion and amortization	964				622				159				1,745
	Income tax provision	166				3,260				50				3,476
	Capital expenditures	2,887				569				136				3,592
Reconciliation of Revenue from Segments to Consolidated [Table Text Block]	'
	The following reconciles total revenues to sales and other operating revenues as reported in the consolidated statements of income:
		Three Months Ended September 30,						Nine Months Ended September 30,
	(In millions)	2013			2012			2013			2012
	Total revenues	$	3,787		$	4,036		$	11,575		$	11,561
	Less:  Marketing revenues	668			631			1,597			2,237
	Sales and other operating revenues, including related party	$	3,119		$	3,405		$	9,978		$	9,324
Reconciliation of Segment Income to Net Income [Table Text Block]	'
	The following reconciles segment income to net income as reported in the consolidated statements of income:
		Three Months Ended September 30,						Nine Months Ended September 30,
	(In millions)	2013			2012			2013			2012
	Segment income	$	669		$	578		$	1,724		$	1,620
	Items not allocated to segments, net of income taxes:
	Corporate and other unallocated items	(61		)	(146		)	(288		)	(294		)
	Unrealized gain (loss) on crude oil derivative instruments	(39		)	29			(39		)	29
	Net gain (loss) on dispositions	—			(11		)	(9		)	72
	Impairments	—			—			(10		)	(167		)
	Net income	$	569		$	450		$	1,378		$	1,260

Defined_Benefit_Postretirement1

Defined Benefit Postretirement Plans (Tables)	9 Months Ended
	Sep. 30, 2013
Defined Benefit Postretirement Plans Disclosure [Abstract]	'
Schedule of Defined Benefit Plans Disclosures [Table Text Block]	'
	The following summarizes the components of net periodic benefit cost:
		Three Months Ended September 30,
		Pension Benefits						Other Benefits
	(In millions)	2013			2012			2013			2012
	Service cost	$	14		$	12		$	1		$	1
	Interest cost	16			16			3			4
	Expected return on plan assets	(17		)	(14		)	—			—
	Amortization:
	– prior service cost (credit)	2			2			(2		)	(2		)
	– actuarial loss	9			12			—			—
	Net settlement loss(a)	15			34			—			—
	Net periodic benefit cost	$	39		$	62		$	2		$	3
		Nine months Ended September 30,
		Pension Benefits						Other Benefits
	(In millions)	2013			2012			2013			2012
	Service cost	$	42		$	37		$	3		$	3
	Interest cost	47			48			9			11
	Expected return on plan assets	(50		)	(46		)	—			—
	Amortization:
	– prior service cost (credit)	5			6			(5		)	(5		)
	– actuarial loss	38			37			—			—
	Net settlement loss(a)	32			34			—			—
	Net periodic benefit cost	$	114		$	116		$	7		$	9
	(a) Settlements are recognized as they occur, once it is probable that lump sum payments from a plan for a given year will exceed the plan's total service and interest cost for that year. Such settlements were recorded for our U.S. plans in the second and third quarters of 2013 and the third quarter of 2012.

Inventories_Tables

Inventories (Tables)	9 Months Ended
	Sep. 30, 2013
Inventory Disclosure [Abstract]	'
Schedule of Inventory, Current [Table Text Block]	'
		September 30,		December 31,
	(In millions)	2013		2012
	Liquid hydrocarbons, natural gas and bitumen	$	46	$	73
	Supplies and other items	314		288
	Inventories, at cost	$	360	$	361

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	9 Months Ended
	Sep. 30, 2013
Property Plant And Equipment Disclosure [Abstract]	'
Schedule Of Property Plant And Equipment [Table Text Block]	'
		September 30,			December 31,
	(In millions)	2013			2012
	North America E&P	$	25,858		$	23,748
	International E&P	12,342			13,214
	Oil Sands Mining	10,337			10,127
	Corporate	456			449
	Total property, plant and equipment	48,993			47,538
	Less accumulated depreciation, depletion and amortization	(21,171		)	(19,266		)
	Net property, plant and equipment	$	27,822		$	28,272

Asset_Retirement_Obligations_A1

Asset Retirement Obligations Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]	'
Schedule of Change in Asset Retirement Obligation [Table Text Block]	'
	The following summarizes the changes in asset retirement obligations during the first nine months of 2013:
	(In millions)
	Beginning balance(a)	$	1,783
	Incurred, including acquisitions	10
	Settled, including dispositions	(41		)
	Accretion expense (included in depreciation, depletion and amortization)	103
	Revisions to previous estimates	306
	Held for sale	(41		)
	Ending balance(a)	$	2,120
	(a) Beginning and ending balances include asset retirement obligations of $34 million and $93 million classified as short-term at December 31, 2012 and September 30, 2013.

Fair_Value_Measurements_Fair_V

Fair Value Measurements Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]	'
	The following tables present assets and liabilities accounted for at fair value on a recurring basis as of September 30, 2013 and December 31, 2012 by fair value hierarchy level.
		September 30, 2013
	(In millions)	Level 1		Level 2		Level 3		Collateral		Total
	Derivative instruments, assets
	Commodity	$	—	$	5	$	—	$	—	$	5
	Interest rate	—		11		—		—		11
	Foreign currency	—		1		—		—		1
	Derivative instruments, assets	$	—	$	17	$	—	$	—	$	17
	Derivative instruments, liabilities
	Commodity	$	—	$	14	$	—	$	—	$	14
	Foreign currency	—		14		—		—		14
	Derivative instruments, liabilities	$	—	$	28	$	—	$	—	$	28
		December 31, 2012
	(In millions)	Level 1		Level 2		Level 3		Collateral		Total
	Derivative instruments, assets
	Commodity	$	—	$	52	$	—	$	1	$	53
	Interest rate	—		21		—		—		21
	Foreign currency	—		18		—		—		18
	Derivative instruments, assets	$	—	$	91	$	—	$	1	$	92
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Table Text Block]	'
	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.
		Three Months Ended September 30,
		2013				2012
	(In millions)	Fair Value		Impairment		Fair Value		Impairment
	Long-lived assets held for use	$	5	$	11	$	2	$	8
		Nine Months Ended September 30,
		2013				2012
	(In millions)	Fair Value		Impairment		Fair Value		Impairment
	Long-lived assets held for use	$	5	$	49	$	77	$	271
Fair Value, by Balance Sheet Grouping [Table Text Block]	'
	The following table summarizes financial instruments, excluding receivables, commercial paper, payables and derivative financial instruments, and their reported fair value by individual balance sheet line item at September 30, 2013 and December 31, 2012.
		September 30, 2013				December 31, 2012
		Fair		Carrying		Fair		Carrying
	(In millions)	Value		Amount		Value		Amount
	Financial assets
	Other noncurrent assets	$	168	$	165	$	189	$	186
	Total financial assets	168		165		189		186
	Financial liabilities
	Other current liabilities	13		13		13		13
	Long-term debt, including current portion(a)	6,941		6,461		7,610		6,642
	Deferred credits and other liabilities	164		161		94		94
	Total financial liabilities	$	7,118	$	6,635	$	7,717	$	6,749
	(a)      Excludes capital leases.

Derivatives_Tables

Derivatives (Tables)	9 Months Ended
	Sep. 30, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivatives as they appear on the balance sheet [Table Text Block]	'
	The following tables present the gross fair values of derivative instruments, excluding cash collateral, and the reported net amounts along with where they appear on the consolidated balance sheets as of September 30, 2013 and December 31, 2012.
		30-Sep-13
	(In millions)	Asset				Liability				Net Asset				Balance Sheet Location
	Fair Value Hedges
	Foreign currency	$	1			$	—			$	1			Other current assets
	Interest rate	11				—				11				Other noncurrent assets
	Total Designated Hedges	12				—				12
	Not Designated as Hedges
	Commodity	5				—				5				Other current assets
	Total Not Designated as Hedges	5				—				5
	Total	$	17			$	—			$	17
		30-Sep-13
	(In millions)	Asset				Liability				Net Liability				Balance Sheet Location
	Fair Value Hedges
	Foreign currency	$	—			$	14			$	14			Other current liabilities
	Total Designated Hedges	—				14				14
	Not Designated as Hedges
	Commodity	—				14				14				Other current liabilities
	Total Not Designated as Hedges	—				14				14
	Total	$	—			$	28			$	28
		31-Dec-12
	(In millions)	Asset				Liability				Net Asset				Balance Sheet Location
	Fair Value Hedges
	Foreign currency	$	18			$	—			$	18			Other current assets
	Interest rate	21				—				21				Other noncurrent assets
	Total Designated Hedges	39				—				39
	Not Designated as Hedges
	Commodity	52				—				52				Other current assets
	Total Not Designated as Hedges	52				—				52
	Total	$	91			$	—			$	91
Effects of derivatives designated as fair value hedges [Table Text Block]	'
	The pretax effect of derivative instruments designated as hedges of fair value in our consolidated statements of income are summarized in the table below. There is no ineffectiveness related to the fair value hedges.
			Gain (Loss)
			Three Months Ended September 30,								Nine Months Ended September 30,
	(In millions)	Income Statement Location	2013				2012				2013				2012
	Derivative
	Interest rate	Net interest and other	$	5			$	6			$	(9	)		$	17
	Foreign currency	Provision for income taxes	$	5			$	22			$	(41	)		$	(18	)
	Hedged Item
	Long-term debt	Net interest and other	$	(5	)		$	(6	)		$	9			$	(17	)
	Accrued taxes	Provision for income taxes	$	(5	)		$	(22	)		$	41			$	18
Schedule of Interest Rate Derivatives [Table Text Block]	'
	The following table presents by maturity date, information about our interest rate swap agreements as of September 30, 2013, including the weighted average, London Interbank Offer Rate (“LIBOR”)-based, floating rate.
	Maturity Dates	Aggregate Notional Amount (in millions)			Weighted Average, LIBOR-Based, Floating Rate
	1-Oct-17	$	600		4.67	%
	15-Mar-18	$	300		4.51	%
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]	'
	Remaining Term	Bbls per Day	Weighted Average Price per Bbl	Benchmark
	Swaps
	October 2013 - December 2013	20,000	$96.29	West Texas Intermediate
	October 2013 - December 2013	25,000	$109.19	Brent
	Option Collars
	October 2013 - December 2013	15,000	$90.00 floor / $101.17 ceiling	West Texas Intermediate
	October 2013 - December 2013	15,000	$100.00 floor / $116.30 ceiling	Brent
Effects of derivatives not designated as hedges	'
	The following table summarizes the effect of all derivative instruments not designated as hedges in our consolidated statements of income.
			Gain (Loss)
			Three Months Ended September 30,								Nine Months Ended September 30,
	(In millions)	Income Statement Location	2013				2012				2013				2012
	Commodity	Sales and other operating revenues, including related party	$	(86	)		$	45			$	(73	)		$	46

Incentive_Based_Compensation_P1

Incentive Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2013
Incentive Based Compensation Plans [Abstract]	'
Table of Incentive based compensation activity [Table Text Block]	'
	The following table presents a summary of stock option and restricted stock award activity for the first nine months of 2013:
		Stock Options					Restricted Stock
		Number of			Weighted		Awards		Weighted
		Shares			Average				Average Grant
					Exercise Price				Date Fair Value
	Outstanding at December 31, 2012	19,536,965				$26.19	4,177,884			$29.02
	Granted	1,704,734		(a)		$33.30	1,254,935			$32.96
	Options Exercised/Stock Vested	(2,098,887	)			$22.31	(1,609,730	)		$28.09
	Canceled	(708,701	)			$34.01	(384,719	)		$29.91
	Outstanding at September 30, 2013	18,434,111				$26.99	3,438,370			$30.80
	(a)    The weighted average grant date fair value of stock option awards granted was $10.51 per share.

Reclassifications_out_of_Accum1

Reclassifications out of Accumulated Other Comprehensive Income Reclassifications out of Accumulated Other Comprehensive Income (Tables)	9 Months Ended
	Sep. 30, 2013
Reclassifications out of AccumulatedOtherComprehensiveIncome [Abstract]	'
Schedule of Amounts Reclassified out of Accumulated Other Comprehensive Income [Table Text Block]	'
	The following table presents a summary of amounts reclassified from accumulated other comprehensive loss to net income in their entirety:
		Three Months Ended September 30, 2013			Nine Months Ended September 30, 2013
	(In millions)							Income Statement Line
	Accumulated Other Comprehensive Loss Components
		Income (Expense)
	Postretirement and postemployment plans
	Amortization of actuarial loss	$	(9	)	$	(38	)	General and administrative
	Net settlement loss	(15		)	(32		)	General and administrative
		9			26			Provision for income taxes
		(15		)	(44		)	Net of tax
	Other insignificant items, net of tax	—			(1		)
	Total reclassifications for the period	$	(15	)	$	(45	)	Net income

Supplemental_Cash_Flow_Informa1

Supplemental Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2013
Supplemental Cash Flow Information [Abstract]	'
Supplemental Cash Flow Information [Table Text Block]	'
		Nine Months Ended September 30,
	(In millions)	2013			2012
	Net cash provided from operating activities:
	Interest paid (net of amounts capitalized)	$	216		$	164
	Income taxes paid to taxing authorities	3,218			3,457
	Commercial paper, net:
	Commercial paper - issuances	$	4,975		$	10,420
	- repayments	(4,975		)	(8,581		)
	Noncash investing activities:
	Asset retirement costs capitalized	$	316		$	47
	Debt payments made by United States Steel	—			19
	Liabilities assumed in acquisition	—			85
	Change in capital expenditure accrual	(129		)	170
	Asset retirement obligations assumed by buyer	92			7

Basis_of_Presentation_Reclassi

Basis of Presentation Reclassifications (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
General and administrative	$152	$179	$490	$499
Reclassifications [Member]	'	'	'	'
General and administrative	'	$40	'	$110

Variable_Interest_Entity_Detai

Variable Interest Entity (Details) (Variable Interest Entity, Not Primary Beneficiary [Member], USD $)	Sep. 30, 2013
In Millions, unless otherwise specified
Variable Interest Entity, Not Primary Beneficiary [Member]	'
Variable Interest Entity [Line Items]	'
Recorded liability related to unconsolidated VIE	$3
Maximum exposure to loss related to unconsolidated VIE	$707

Income_per_Common_Share_Detail

Income per Common Share (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]	'	'	'	'
Net income	$569	$450	$1,378	$1,260
Weighted average common shares outstanding, basic	707	706	708	705
Effect of dilutive securities	4	3	4	4
Weighted average common shares outstanding, diluted	711	709	712	709
Basic:	'	'	'	'
Net income, per basic share	$0.80	$0.64	$1.95	$1.79
Diluted:	'	'	'	'
Net income, per diluted share	$0.80	$0.63	$1.94	$1.78
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	4	10	5	10

Dispositions_Details

Dispositions (Details) (USD $)	9 Months Ended		1 Months Ended		1 Months Ended			3 Months Ended	1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Feb. 28, 2013	Feb. 28, 2013	Jan. 31, 2013	Jun. 30, 2013	Sep. 30, 2012	Jan. 31, 2012	31-May-12
			DJ Basin [Member]	Marcellus Shale [Member]	Neptune Gas Plant [Member]	Alaska EP [Member]	Angola Blk 31 [Member]	Eagle Ford Shale Member [Member]	GOM Pipelines [Member]	Indonesia [Member]
								acre
Dispositions Detail [Line Items]	'	'	'	'	'	'	'	'	'	'
Gas and oil acreages undeveloped and developed net	'	'	'	'	'	'	'	5,800	'	'
Pretax gain/loss on sale	'	'	($114,000,000)	($43,000,000)	$98,000,000	$55,000,000	'	($18,000,000)	$166,000,000	($36,000,000)
Interest Percentage	'	'	'	'	'	'	10.00%	'	'	'
Proceeds from Sale of Oil and Gas Property and Equipment	402,000,000	193,000,000	19,000,000	'	166,000,000	195,000,000	'	9,000,000	206,000,000	-36,000,000
Proceeds from Sale of Oil and Gas Property and Equipment, Six Month Escrow	'	'	'	'	'	50,000,000	'	'	'	'
Transaction Value, Disposition	'	'	'	'	'	'	$1,500,000,000	'	'	'

Dispositions_Dispositions_2_De

Dispositions Dispositions 2 (Details) (Angola Blk 31 [Member], USD $)	Sep. 30, 2013
In Millions, unless otherwise specified
Angola Blk 31 [Member]	'
Long Lived Assets Held-for-sale [Line Items]	'
Disposal Group, Including Discontinued Operation, Other Current Assets	$15
Disposal Group, Including Discontinued Operation, Other Noncurrent Assets	1,598
Assets Held-for-sale, at Carrying Value	1,613
Liabilities of Disposal Group, Including Discontinued Operation, Current	42
Liabilities of Disposal Group, Including Discontinued Operation, Noncurrent	41
Liabilities of Disposal Group, Including Discontinued Operation	$83

Acquisitions_Details

Acquisitions (Details) (USD $)	1 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Jul. 31, 2013	Sep. 30, 2012	Jul. 31, 2013
	Eagle Ford [Member]	Eagle Ford Paloma [Member]	Eagle Ford Paloma [Member]
	acres	acres
Business Acquisition [Line Items]	'	'	'
Fair Value Inputs, Discount Rate	10.00%	10.00%	'
Gas and oil acreages undeveloped and developed net	4,800	20,000	'
Business Combination, Consideration Transferred, Including Equity Interest in Acquiree Held Prior to Combination [Abstract]	'	'	'
Payments to Acquire Businesses, Gross	$74	$768	'
Business Combination, Consideration Transferred, Other	23	'	'
Business Combination, Consideration Transferred	97	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]	'	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	'	'	8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables	'	'	22
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory	'	'	1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	'	'	31
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	'	'	822
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	'	'	853
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable	'	'	78
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities,Asset Retirement Obligations	'	'	7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	'	'	85
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	'	'	$768

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]	'	'	'	'
Sales and other operating revenues, including related party	$3,119	$3,405	$9,978	$9,324
Marketing revenues	668	631	1,597	2,237
Segment income	669	578	1,724	1,620
Income from equity method investments	114	122	309	260
Depreciation, depletion and amortization	720	625	2,205	1,779
Income tax provision (benefit)	787	1,279	2,890	3,231
North America Exploration and Production [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Sales and other operating revenues, including related party	1,321	993	3,820	2,738
Marketing revenues	607	548	1,391	2,019
Segment revenues	1,928	1,541	5,211	4,757
Segment income	242	107	404	281
Income from equity method investments	0	1	0	2
Depreciation, depletion and amortization	490	360	1,458	964
Income tax provision (benefit)	143	66	242	166
Capital expenditures	831	1,045	2,705	2,887
International Exploration and Production [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Sales and other operating revenues, including related party	1,396	1,907	5,015	5,383
Marketing revenues	58	73	194	193
Segment revenues	1,454	1,980	5,209	5,576
Segment income	321	405	1,156	1,185
Income from equity method investments	114	121	309	258
Depreciation, depletion and amortization	179	194	575	622
Income tax provision (benefit)	714	1,219	2,860	3,260
Capital expenditures	254	229	720	569
Oil Sands Mining Segment [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Sales and other operating revenues, including related party	463	460	1,204	1,158
Marketing revenues	3	10	12	25
Segment revenues	466	470	1,216	1,183
Segment income	106	66	164	154
Income from equity method investments	0	0	0	0
Depreciation, depletion and amortization	54	60	154	159
Income tax provision (benefit)	35	20	55	50
Capital expenditures	65	41	207	136
Total All Segments [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Sales and other operating revenues, including related party	3,180	3,360	10,039	9,279
Marketing revenues	668	631	1,597	2,237
Segment revenues	3,848	3,991	11,636	11,516
Unrealized loss on crude oil derivative instruments	-61	45	-61	45
Segment reporting revenue from external customers	3,787	4,036	11,575	11,561
Segment income	669	578	1,724	1,620
Income from equity method investments	114	122	309	260
Depreciation, depletion and amortization	723	614	2,187	1,745
Income tax provision (benefit)	892	1,305	3,157	3,476
Capital expenditures	$1,150	$1,315	$3,632	$3,592

Segment_Information_Details_2

Segment Information (Details 2) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reconciliation Of Segment Revenues To Revenues As Presented On Income Statement [Abstract]	'	'	'	'
Sales and other operating revenues, including related party	$3,119	$3,405	$9,978	$9,324
Marketing revenues	668	631	1,597	2,237
Reconciliation from Segment Totals to Consolidated [Abstract]	'	'	'	'
Segment income	669	578	1,724	1,620
Items not allocated to segments, net of income taxes:	'	'	'	'
Corporate and other unallocated items	-61	-146	-288	-294
Unrealized gain (loss) on crude oil derivative instruments, not allocated to segments	-39	29	-39	29
Gain (loss) on dispositions, not allocated to segments	0	-11	-9	72
Impairments, not allocated to segments	0	0	-10	-167
Net income	$569	$450	$1,378	$1,260

Defined_Benefit_Postretirement2

Defined Benefit Postretirement Plans (Details) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Pension and Other Postretirement Benefit Contributions [Abstract]	'		'		'		'
Pension Contributions	'		'		$50		'
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year	'		'		17		'
Defined Benefit Plan, Benefits Paid	'		'		19		'
Other Postretirement Benefits Payments	'		'		12		'
United States and Foreign Pension Plans Defined Benefit [Member]	'		'		'		'
Defined Benefit Plan Net Periodic Benefit Cost [Line Items]	'		'		'		'
Service cost	14		12		42		37
Interest cost	16		16		47		48
Expected return on plan assets	-17		-14		-50		-46
Amortization:	'		'		'		'
- prior service cost (credit)	2		2		5		6
-actuarial loss (gain)	9		12		38		37
Net settlement loss	15	[1]	34	[1]	32	[1]	34	[1]
Net periodic benefit cost	39		62		114		116
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	24		-103		163		-103
Other Postretirement Benefit Plans Defined Benefit [Member]	'		'		'		'
Defined Benefit Plan Net Periodic Benefit Cost [Line Items]	'		'		'		'
Service cost	1		1		3		3
Interest cost	3		4		9		11
Expected return on plan assets	0		0		0		0
Amortization:	'		'		'		'
- prior service cost (credit)	-2		-2		-5		-5
-actuarial loss (gain)	0		0		0		0
Net settlement loss	0		0		0		0
Net periodic benefit cost	$2		$3		$7		$9
[1]	(a) Settlements are recognized as they occur, once it is probable that lump sum payments from a plan for a given year will exceed the plan's total service and interest cost for that year. Such settlements were recorded for our U.S. plans in the second and third quarters of 2013 and the third quarter of 2012.

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012
Effective Tax Rate Reconciliation [Abstract]	'	'	'
Effective income tax rate excluding Libya	'	60.00%	64.00%
Statutory rate	'	35.00%	35.00%
Effective income tax rate	'	68.00%	72.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount	$42	'	'
Minimum [Member]	'	'	'
Income Taxes [Line Items]	'	'	'
Libya Statutory Income Tax Rate	'	90.00%	90.00%

Inventories_Details

Inventories (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Liquid hydrocarbons natural gas and bitumen	$46	$73
Supplies and other items	314	288
Total inventories, at cost	$360	$361

Property_Plant_and_Equipment_D

Property, Plant and Equipment (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Segment Reporting Information [Line Items]	'	'
Less accumulated depreciation, depletion and amortization	($21,171)	($19,266)
Property, plant and equipment, net	27,822	28,272
Libya 1 [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Property, plant and equipment, net	743	'
North America Exploration and Production [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Total property, plant and equipment	25,858	23,748
International Exploration and Production [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Total property, plant and equipment	12,342	13,214
Oil Sands Mining Segment [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Total property, plant and equipment	10,337	10,127
Corporate [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Total property, plant and equipment	456	449
Total All Segments [Member]	'	'
Segment Reporting Information [Line Items]	'	'
Total property, plant and equipment	$48,993	$47,538

Property_Plant_and_Equipment_P

Property, Plant and Equipment Property, Plant and Equipment (Details 3) (USD $)	Sep. 30, 2013
In Millions, unless otherwise specified
Total Deferred Exploratory Well Costs [Abstract]	'
Amounts capitalized greater than one year after completion of drilling	$220
Capitalized exploratory well cost period increase decrease for sold assets	9
Angola Blk 31 [Member]	'
Total Deferred Exploratory Well Costs [Abstract]	'
Amounts capitalized greater than one year after completion of drilling	127
EQUATORIAL GUINEA	'
Total Deferred Exploratory Well Costs [Abstract]	'
Amounts capitalized greater than one year after completion of drilling	$22

Asset_Retirement_Obligations_A2

Asset Retirement Obligations Asset Retirement Obligations (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]	'		'
Asset Retirement Obligation Begining Balance	$1,783		'
Asset Retirement Obligation, Liabilities Incurred	10		'
Asset Retirement Obligation, Liabilities Settled	-41		'
Asset Retirement Obligation, Accretion Expense	103		'
Asset Retirement Obligation, Revision of Estimate	306		'
Asset Retirement Obligation, Held for Sale	-41		'
Asset Retirement Obligation Ending Balance	2,120	[1]	'
Asset Retirement Obligation, Current	$93		$34
[1]	(a) Beginning and ending balances include asset retirement obligations of $34 million and $93 million classified as short-term at December 31, 2012 and September 30, 2013.

Fair_Value_Measurements_Detail

Fair Value Measurements (Details-Recurring) (Fair Value, Measurements, Recurring [Member], USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	$17	$92
Derivative Liabilities	28	'
Commodity Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	5	53
Derivative Liabilities	14	'
Interest rate [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	11	21
Foreign Exchange Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	1	18
Derivative Liabilities	14	'
Fair Value, Inputs, Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Derivative Liabilities	0	'
Fair Value, Inputs, Level 1 [Member] | Commodity Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Derivative Liabilities	0	'
Fair Value, Inputs, Level 1 [Member] | Interest rate [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Exchange Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Derivative Liabilities	0	'
Fair Value Inputs Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	17	91
Derivative Liabilities	28	'
Fair Value Inputs Level 2 [Member] | Commodity Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	5	52
Derivative Liabilities	14	'
Fair Value Inputs Level 2 [Member] | Interest rate [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	11	21
Fair Value Inputs Level 2 [Member] | Foreign Exchange Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	1	18
Derivative Liabilities	14	'
Fair Value, Inputs, Level 3 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Derivative Liabilities	0	'
Fair Value, Inputs, Level 3 [Member] | Commodity Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Derivative Liabilities	0	'
Fair Value, Inputs, Level 3 [Member] | Interest rate [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Exchange Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Derivative Liabilities	0	'
Fair Value (no inputs) Collateral [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	1
Derivative Liabilities	0	'
Fair Value (no inputs) Collateral [Member] | Commodity Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	1
Derivative Liabilities	0	'
Fair Value (no inputs) Collateral [Member] | Interest rate [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Fair Value (no inputs) Collateral [Member] | Foreign Exchange Contract [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]	'	'
Derivative Assets	0	0
Derivative Liabilities	$0	'

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 2-Nonrecurring) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2013	Mar. 31, 2013	Mar. 31, 2012	Sep. 30, 2013	Sep. 30, 2012
					Fair Value, Inputs, Level 3 [Member]	Fair Value, Inputs, Level 3 [Member]	Fair Value, Inputs, Level 3 [Member]	Fair Value, Measurements, Nonrecurring [Member]	Fair Value, Measurements, Nonrecurring [Member]
					Assets Held and Used Powder River Basin [Member]	Assets Held and Used Ozona [Member]	Assets Held and Used Ozona [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]	'	'	'	'	'	'	'	'	'
Property, Plant, and Equipment, Fair Value Disclosure	'	'	'	'	'	'	'	$5	$2
Fair value of long-lived assets held for use, year-to-date	'	'	'	'	'	'	'	5	77
Assets, Fair Value Adjustment	$11	$8	$49	$271	$15	$21	$261	'	'

Fair_Value_Measurements_Detail2

Fair Value Measurements (Details 3-Reported) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Fair Value [Member]	'	'
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]	'	'
Other noncurrent financial assets	$168	$189
Total financial assets	168	189
Financial liabilities	'	'
Other current financial liabilities	13	13
Long-term debt, including current portion	6,941	7,610
Deferred credits and other financial liabilities	164	94
Financial Liabilities Fair Value Disclosure	7,118	7,717
Carrying Amount [Member]	'	'
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]	'	'
Other noncurrent financial assets	165	186
Total financial assets	165	186
Financial liabilities	'	'
Other current financial liabilities	13	13
Long-term debt, including current portion	6,461	6,642
Deferred credits and other financial liabilities	161	94
Financial Liabilities Fair Value Disclosure	$6,635	$6,749

Derivatives_DetailsBS

Derivatives (Details-BS) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	$17	$91
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	17	91
Derivative Liability, Fair Value, Gross Asset	0	'
Derivative Liability, Fair Value, Gross Liability	28	'
Derivative Liability, Fair Value, Net	28	'
Not Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	5	52
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	5	52
Commodity Contract [Member] | Other Current Assets [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	5	52
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	5	52
Commodity Contract [Member] | Other Current Liabilities [Member] | Not Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Asset	0	'
Derivative Liability, Fair Value, Gross Liability	14	'
Derivative Liability, Fair Value, Net	14	'
Not Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Asset	0	'
Derivative Liability, Fair Value, Gross Liability	14	'
Derivative Liability, Fair Value, Net	14	'
Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	12	39
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	12	39
Derivative Liability, Fair Value, Gross Asset	0	'
Derivative Liability, Fair Value, Gross Liability	14	'
Derivative Liability, Fair Value, Net	14	'
Fair Value Hedging [Member] | Foreign Exchange Contract [Member] | Other Current Assets [Member] | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	1	18
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	1	18
Fair Value Hedging [Member] | Foreign Exchange Contract [Member] | Other Current Liabilities [Member] | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Liability, Fair Value, Gross Asset	0	'
Derivative Liability, Fair Value, Gross Liability	14	'
Derivative Liability, Fair Value, Net	14	'
Fair Value Hedging [Member] | Interest rate [Member] | Other Noncurrent Assets [Member] | Designated as Hedging Instrument [Member]	'	'
Derivatives Fair Value [Line Items]	'	'
Derivative Asset, Fair Value, Gross Asset	11	21
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Net	$11	$21

Derivatives_Details_2Fair_Valu

Derivatives (Details 2-Fair Value Hedges)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012
	USD ($)	USD ($)	USD ($)	USD ($)	Fair Value Hedging [Member]	Fair Value Hedging [Member]	Notes Due 2018 [Member]	Debentures Due 2017 [Member]	Debentures Due 2017 [Member]
					Foreign Exchange Contract [Member]	Foreign Exchange Contract [Member]	Fair Value Hedging [Member]	Fair Value Hedging [Member]	Fair Value Hedging [Member]
					NOK	NOK	Interest Rate Contract [Member]	Interest Rate Contract [Member]	Interest Rate Contract [Member]
							USD ($)	USD ($)	USD ($)
Derivative [Line Items]	'	'	'	'	'	'	'	'	'
Derivative, Notional Amount	'	'	'	'	3,115,000,000	3,043,000,000	$300,000,000	$600,000,000	$600,000,000
Weighted-average, LIBOR-based, floating rate	'	'	'	'	'	'	4.51%	4.67%	4.70%
Derivative, Average Forward Exchange Rate	'	'	'	'	5.874	5.78	'	'	'
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	$0	$0	$0	$0	'	'	'	'	'

Derivatives_Details_3Fair_Valu

Derivatives (Details 3-Fair Value Hedges IS & OCI) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net interest and other [Member]	'	'	'	'
Gain (Loss) on Derivative Instruments [Line Items]	'	'	'	'
Change in unrealized gain (loss) on hedged item in fair value hedge	($5)	($6)	$9	($17)
Provision For Income Taxes [Member]	'	'	'	'
Gain (Loss) on Derivative Instruments [Line Items]	'	'	'	'
Change in unrealized gain (loss) on hedged item in fair value hedge	-5	-22	41	18
Interest rate [Member] | Net interest and other [Member]	'	'	'	'
Gain (Loss) on Derivative Instruments [Line Items]	'	'	'	'
Gain (loss) on derivative instruments recognized in income	5	6	-9	17
Foreign Exchange Contract [Member] | Provision For Income Taxes [Member]	'	'	'	'
Gain (Loss) on Derivative Instruments [Line Items]	'	'	'	'
Gain (loss) on derivative instruments recognized in income	$5	$22	($41)	($18)

Derivatives_Derivatives_Detail

Derivatives Derivatives (Details 4-Non Hedges Commodity) (Details) (Not Designated as Hedging Instrument [Member], Commodity Contract [Member])	3 Months Ended
	Sep. 30, 2013
Swap [Member] | West Texas Intermediate [Member]	'
Exploration and Production Commodity Derivative [Line Items]	'
Commodity Derivative, Nonmonetary Notional Amount	20,000
Derivative, Swap Type, Average Fixed Price	96.29
Swap [Member] | Brent [Member]	'
Exploration and Production Commodity Derivative [Line Items]	'
Commodity Derivative, Nonmonetary Notional Amount	25,000
Derivative, Swap Type, Average Fixed Price	109.19
Option Collar [Member] | West Texas Intermediate [Member]	'
Exploration and Production Commodity Derivative [Line Items]	'
Commodity Derivative, Nonmonetary Notional Amount	15,000
Derivative, Average Floor Price	90
Derivative, Average Cap Price	101.17
Option Collar [Member] | Brent [Member]	'
Exploration and Production Commodity Derivative [Line Items]	'
Commodity Derivative, Nonmonetary Notional Amount	15,000
Derivative, Average Floor Price	100
Derivative, Average Cap Price	116.3

Derivatives_Derivatives_Detail1

Derivatives Derivatives (Details 5-Non Hedges) (Details) (Not Designated as Hedging Instrument [Member], Commodity [Member], Sales and other operating revenues [Member], USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Not Designated as Hedging Instrument [Member] | Commodity [Member] | Sales and other operating revenues [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Derivative Instruments, Gain (Loss) Recognized in Income, Net	($86)	$45	($73)	$46

Incentive_Based_Compensation_P2

Incentive Based Compensation Plans (Details 2) (USD $)	9 Months Ended
	Sep. 30, 2013
Stock Options	'
Beginning year stock option awards	19,536,965
Granted stock option awards	1,704,734	[1]
Exercised stock option awards	-2,098,887
Canceled stock option awards	-708,701
End of year stock option awards	18,434,111
Beginning year weighted average exercise price	$26.19
Granted weighted average exercise price	$33.30
Exercises weighted average exercise price	$22.31
Canceled weighted average exercise price	$34.01
End of year weighted average exercise price	$26.99
Stock options weighted average grant date fair value	$10.51
[1]	The weighted average grant date fair value of stock option awards granted was $10.51 per share.

Incentive_Based_Compensation_P3

Incentive Based Compensation Plans (Details 4-Restricted) (USD $)	9 Months Ended
	Sep. 30, 2013
Restricted Stock	'
Beginning year unvested restricted stock	4,177,884
Granted restricted stock	1,254,935
Vested restricted stock	-1,609,730
Forfeited restricted stock	-384,719
End of year unvested restricted stock	3,438,370
Beginning year weighted average grant date fair value unvested restricted stock	$29.02
Granted restricted stock weighted average grant date fair value restricted stock	$32.96
Vested restricted stock weighted average grant date fair value restricted stock	$28.09
Forfeited restricted stock weighted average grant date fair value restricted stock	$29.91
End of year weighted average grant date fair value unvested restricted stock	$30.80

Incentive_Based_Compensation_P4

Incentive Based Compensation Plans (Details 5-Performance)	3 Months Ended
	Mar. 31, 2013
Performance Unit Disclosures [Abstract]	'
Performance Unit Granted	353,600
Performance Unit Awards Vesting Period	'36 months

Reclassifications_out_of_Accum2

Reclassifications out of Accumulated Other Comprehensive Income Reclassifications out of Accumulated Other Comprehensive Income (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Provision for income taxes	($787)	($1,279)	($2,890)	($3,231)
Income before income taxes	1,356	1,729	4,268	4,491
Other Expenses	-126	-112	-323	-311
Total reclassification for the period	569	450	1,378	1,260
Reclassification out of Accumulated Other Comprehensive Income [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Actuarial loss	-9	'	-38	'
Net settlement loss	-15	'	-32	'
Provision for income taxes	9	'	26	'
Income before income taxes	-15	'	-44	'
Other Expenses	0	'	-1	'
Total reclassification for the period	($15)	'	($45)	'

Stockholders_Equity_Stockholde1

Stockholders' Equity Stockholders' Equity (Details) (USD $)	3 Months Ended	9 Months Ended
Share data in Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012
Stockholders' Equity Attributable to Parent [Abstract]	'	'	'
Stock Repurchased During Period, Shares	14	'	'
Payments for Repurchase of Common Stock	$500,000,000	$500,000,000	$0
Stock Repurchase Program, Authorized Amount	$5,000,000,000	'	'

Supplemental_Cash_Flow_Informa2

Supplemental Cash Flow Information (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Net cash provided by operating activities included:	'	'
Interest paid (net of amounts capitalized)	$216	$164
Income taxes paid to taxing authorities	3,218	3,457
Commercial paper, net:	'	'
Commercial paper - issuances	4,975	10,420
Commercial paper - repayments	-4,975	-8,581
Noncash investing activities:	'	'
Asset retirement costs capitalized	316	47
Debt payments made by United States Steel	0	19
Liabilities Assumed	0	85
Change in capital expenditure accrual	-129	170
Asset retirement obligations assumed by buyer	$92	$7

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	Sep. 30, 2013
In Millions, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]	'
Commitments to acquire property, plant and equipment	$1,154