Marathon Oil (MRO) 10-K 23 Feb 21 2020 FY Annual report Financial data

Cover Page

Cover Page - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Feb. 12, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-1513
Entity Registrant Name	Marathon Oil Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	25-0996816
Entity Address, Address Line One	5555 San Felipe Street,
Entity Address, City or Town	Houston,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77056-2723
City Area Code	(713)
Local Phone Number	629-6600
Title of 12(b) Security	Common Stock, par value $1.00
Trading Symbol	MRO
Security Exchange Name	NYSE
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 4,814
Entity Common Stock, Shares Outstanding		789,075,988
Entity Central Index Key	0000101778
Amendment Flag	false
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues and other income:
Revenues from contracts with customers	$ 3,097	$ 5,063	$ 5,902
Net gain (loss) on commodity derivatives	116	(72)	(14)
Income (loss) from equity method investments	(161)	87	225
Net gain on disposal of assets	9	50	319
Other income	25	62	150
Total revenues and other income	3,086	5,190	6,582
Costs and expenses:
Production	555	712	842
Shipping, handling and other operating	596	605	575
Exploration	181	149	289
Depreciation, depletion and amortization	2,316	2,397	2,441
Impairments	144	24	75
Taxes other than income	200	311	299
General and administrative	274	356	394
Total costs and expenses	4,266	4,554	4,915
Income (loss) from operations	(1,180)	636	1,667
Net interest and other	(256)	(244)	(226)
Other net periodic benefit (costs) credits	(1)	3	(14)
Loss on early extinguishment of debt	(28)	(3)	0
Income (loss) before income taxes	(1,465)	392	1,427
Provision (benefit) for income taxes	(14)	(88)	331
Net income (loss)	$ (1,451)	$ 480	$ 1,096
Net income (loss) per share:
Basic net income (loss) per share (in dollars per basic share)	$ (1.83)	$ 0.59	$ 1.30
Diluted net income (loss) per share (in dollars per diluted share)	$ (1.83)	$ 0.59	$ 1.29
Weighted average common shares outstanding:
Weighted average common shares outstanding - Basic (shares)	792	810	846
Weighted average common shares outstanding - Diluted (shares)	792	810	847

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (1,451)	$ 480	$ 1,096
Other comprehensive income (loss), net of tax
Change in actuarial gain (loss) and other for postretirement and postemployment plans	(30)	16	121
Change in derivative hedges unrecognized gain (loss)	(2)	2	0
Foreign currency translation adjustment related to sale of U.K. business	0	23	0
Other	0	1	4
Other comprehensive income (loss)	(32)	42	125
Comprehensive income (loss)	$ (1,483)	$ 522	$ 1,221

Consolidated Balance Sheet

Consolidated Balance Sheet - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 742	$ 858
Receivables, less reserve of $22 and $11	747	1,122
Inventories	76	72
Other current assets	47	83
Total current assets	1,612	2,135
Equity method investments	447	663
Property, plant and equipment, less accumulated depreciation, depletion and amortization of $20,358 and $18,003	15,638	17,000
Goodwill	0	95
Other noncurrent assets	259	352
Total assets	17,956	20,245
Current liabilities:
Accounts payable	837	1,307
Payroll and benefits payable	57	112
Accrued taxes	72	118
Other current liabilities	247	208
Total current liabilities	1,213	1,745
Long-term debt	5,404	5,501
Deferred tax liabilities	163	186
Defined benefit postretirement plan obligations	180	183
Asset retirement obligations	241	243
Deferred credits and other liabilities	194	234
Total liabilities	7,395	8,092
Commitments and contingencies
Stockholders’ Equity
Preferred stock – no shares issued or outstanding (no par value, 26 million shares authorized)	0	0
Issued – 937 million shares (par value $1 per share, 1.925 billion shares authorized at December 31, 2020 and December 31, 2019)	937	937
Held in treasury, at cost – 148 million shares and 141 million shares	(4,089)	(4,089)
Additional paid-in capital	7,174	7,207
Retained earnings	6,466	7,993
Accumulated other comprehensive income	73	105
Total stockholders’ equity	10,561	12,153
Total liabilities and stockholders’ equity	$ 17,956	$ 20,245

Consolidated Balance Sheet (Par

Consolidated Balance Sheet (Parentheticals) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Receivable reserves	$ 22	$ 11
Accumulated depreciation, depletion and amortization	$ 20,358	$ 18,003
Preferred stock issued (shares)	0	0
Preferred stock outstanding (shares)	0	0
Preferred stock par value (in usd per share)	$ 0	$ 0
Preferred stock authorized (shares)	26,000,000	26,000,000
Common stock issued (shares)	937,000,000	937,000,000
Common stock par value (in usd per share)	$ 1	$ 1
Common stock authorized (shares)	1,925,000,000	1,925,000,000
Held in treasury (shares)	148,000,000	141,000,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Operating activities:
Net income (loss)	$ (1,451)	$ 480	$ 1,096
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	2,316	2,397	2,441
Impairments	144	24	75
Exploratory dry well costs and unproved property impairments	159	114	255
Net gain on disposal of assets	(9)	(50)	(319)
Loss on early extinguishment of debt	28	3	0
Deferred income taxes	(22)	(34)	52
Net (gain) loss on derivative instruments	(116)	72	14
Net settlements of derivative instruments	143	52	(281)
Pension and other post retirement benefits, net	(43)	(52)	(65)
Stock-based compensation	57	60	53
Equity method investments, net	210	18	45
Changes in:
Current receivables	367	52	(133)
Inventories	(4)	3	(1)
Current accounts payable and accrued liabilities	(381)	(187)	179
Other current assets and liabilities	75	(4)	(22)
All other operating, net	0	(199)	(155)
Net cash provided by operating activities	1,473	2,749	3,234
Investing activities:
Additions to property, plant and equipment	(1,343)	(2,550)	(2,753)
Additions to other assets	15	36	(26)
Acquisitions, net of cash acquired	(1)	(293)	(25)
Disposal of assets, net of cash transferred to the buyer	18	(76)	1,264
Equity method investments - return of capital	7	64	57
All other investing, net	1	1	13
Net cash used in investing activities	(1,303)	(2,818)	(1,470)
Financing activities:
Borrowings	400	600	0
Debt repayments	(500)	(600)	0
Debt extinguishment costs	(27)	(2)	0
Purchases of common stock	(92)	(362)	(713)
Dividends paid	(64)	(162)	(169)
All other financing, net	(3)	(9)	23
Net cash used in financing activities	(286)	(535)	(859)
Effect of exchange rate on cash and cash equivalents	0	0	(2)
Net increase (decrease) in cash and cash equivalents	(116)	(604)	903
Cash and cash equivalents at beginning of period	858	1,462	563
Cash and cash equivalents included in current assets held for sale	0	0	(4)
Cash and cash equivalents at end of period	$ 742	$ 858	$ 1,462

Consolidated Statements of Stoc

Consolidated Statements of Stockholders Equity - USD ($) shares in Millions, $ in Millions	Total	Cumulative-effect adjustment	Preferred Stock	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Retained EarningsCumulative-effect adjustment	Accumulated Other Comprehensive Income (Loss)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Beginning Balance at Dec. 31, 2017	$ 11,708		$ 0	$ 937	$ (3,325)	$ 7,379	$ 6,779		$ (62)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued - stock-based compensation	112				221	(109)
Shares repurchased	(712)				(712)
Stock-based compensation	(32)					(32)
Net income (loss)	1,096						1,096
Other comprehensive income (loss)	125								125
Dividends paid	(169)						(169)
Ending Balance at Dec. 31, 2018	$ 12,128	$ (31)	$ 0	$ 937	$ (3,816)	7,238	7,706	$ (31)	63
Beginning Balance - Outstanding Stock (shares) at Dec. 31, 2017			0	937
Beginning Balance - Treasury Stock (shares) at Dec. 31, 2017					87
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued - stock based compensation (shares)					(6)
Shares repurchased (shares)					37
Ending Balance - Treasury Stock (shares) at Dec. 31, 2018					118
Ending Balance - Outstanding Stock (shares) at Dec. 31, 2018			0	937
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued - stock-based compensation	$ 63				$ 89	(26)
Shares repurchased	(362)				(362)
Stock-based compensation	(5)					(5)
Net income (loss)	480						480
Other comprehensive income (loss)	42								42
Dividends paid	(162)						(162)
Ending Balance at Dec. 31, 2019	$ 12,153	$ (12)	$ 0	$ 937	$ (4,089)	7,207	7,993		105
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued - stock based compensation (shares)					(2)
Shares repurchased (shares)					25
Ending Balance - Treasury Stock (shares) at Dec. 31, 2019	141				141
Ending Balance - Outstanding Stock (shares) at Dec. 31, 2019			0	937
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued - stock-based compensation	$ 31				$ 91	(60)
Shares repurchased	(91)				(91)
Stock-based compensation	27					27
Net income (loss)	(1,451)
Other comprehensive income (loss)	(32)								(32)
Dividends paid	(64)						(64)
Ending Balance at Dec. 31, 2020	$ 10,561		$ 0	$ 937	$ (4,089)	$ 7,174	$ 6,466		$ 73
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued - stock based compensation (shares)					(3)
Shares repurchased (shares)	0				10
Ending Balance - Treasury Stock (shares) at Dec. 31, 2020	148				148
Ending Balance - Outstanding Stock (shares) at Dec. 31, 2020			0	937

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parentheticals) - $ / shares	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends paid (in dollars per share)	$ 0.03	$ 0	$ 0	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.08	$ 0.20	$ 0.20

Summary of Principal Accounting

Summary of Principal Accounting Policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Principal Accounting Policies	Summary of Principal Accounting Policies We are an independent exploration and production company engaged in exploration, production and marketing of crude oil and condensate, NGLs and natural gas; as well as production and marketing of products manufactured from natural gas, such as LNG and methanol, in E.G. Basis of presentation and principles applied in consolidation – These consolidated financial statements, including notes, have been prepared in accordance with U.S. GAAP. These consolidated financial statements include the accounts of our controlled subsidiaries. Investments in unincorporated joint ventures and undivided interests in certain operating assets are consolidated on a pro rata basis. Equity method investments – Investments in entities over which we have significant influence, but not control, are accounted for using the equity method of accounting. This includes entities in which we hold majority ownership but the minority stockholders have substantive participating rights in the investee. Income from equity method investments represents our proportionate share of net income generated by the equity method investees and is reflected in revenues and other income in our consolidated statements of income. Equity method investments are included as noncurrent assets on the consolidated balance sheet. Equity method investments are assessed for impairment whenever changes in the facts and circumstances indicate a loss in value may have occurred. When a loss is deemed to have occurred and is other than temporary, the carrying value of the equity method investment is written down to fair value, and the amount of the write-down is included in income. Use of estimates – The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the respective reporting periods. Estimated quantities of crude oil and condensate, NGLs and natural gas reserves is a significant estimate that requires judgment. All of the reserve data included in this Form 10-K are estimates. Reservoir engineering is a subjective process of estimating underground accumulations of crude oil and condensate, NGLs and natural gas. There are numerous uncertainties inherent in estimating quantities of proved crude oil and condensate, NGLs and natural gas reserves. The accuracy of any reserves estimate is a function of the quality of available data and of engineering and geological interpretation and judgment. As a result, reserve estimates may be different from the quantities of crude oil and condensate, NGLs and natural gas that are ultimately recovered. See unaudited Supplementary Data – Supplementary Information on Oil and Gas Producing Activities for further detail. Other items subject to estimates and assumptions include the carrying amounts of property, plant and equipment, asset retirement obligations, goodwill, valuation of derivative instruments and valuation allowances for deferred income tax assets, among others. Although we believe these estimates are reasonable, actual results could differ from these estimates. Foreign currency transactions – The U.S. dollar is the functional currency of our foreign operating subsidiaries. Foreign currency transaction gains and losses are included in net income. Revenue recognition – Revenues associated with the sales of crude oil and condensate, NGLs and natural gas are recognized when our performance obligation is satisfied, which typically occurs at the point where control transfers to the customer based on contract terms. Revenue is measured as the amount the company expects to receive in exchange for transferring commodities to the customer. Our hydrocarbon sales are typically based on prevailing market-based prices and may include quality or location differential adjustments. Payment is generally due within 30 days of delivery. We typically incur shipping and handling costs prior to control transferring to the customer and account for these activities as fulfillment costs. These costs are reflected in shipping, handling and other operating expense in our consolidated statement of income. Our U.S. production of crude oil and condensate, NGLs and natural gas is generally sold immediately and transported to market. In our international segment, liquid hydrocarbon production may be stored as inventory and sold at a later time. Cash and cash equivalents – Cash and cash equivalents include cash on hand and on deposit and investments in highly liquid debt instruments with original maturities of three months or less. Accounts receivable – The majority of our receivables are from purchasers of commodities or joint interest owners in properties we operate, both of which are recorded at estimated or invoiced amounts and do not bear interest. We often have the ability to withhold future revenue disbursements to recover any non-payment of joint interest billings. We conduct credit reviews of commodity purchasers prior to making commodity sales to new customers or increasing credit for existing customers. Based on these reviews, we may require a standby letter of credit or a financial guarantee. We routinely assess the collectability of receivable balances to determine if the amount of the reserve in allowance for doubtful accounts is sufficient. Inventories – Crude oil and natural gas are recorded at weighted average cost and carried at the lower of cost or net realizable value. Supplies and other items consist principally of tubular goods and equipment, which are valued at weighted average cost and reviewed periodically for obsol escence or impairment when market conditions indicate . We may enter into a contract to sell a particular quantity and quality of crude oil at a specified location and date to a particular counterparty, and simultaneously agree to buy a particular quantity and quality of the same commodity at a specified location on the same or another specified date from the same counterparty. We account for such matching buy/sell arrangements as exchanges of inventory. Derivative instruments – We may use derivatives to manage a portion of our exposure to commodity price risk, commodity locational risk and interest rate risk. All derivative instruments are recorded at fair value. Commodity derivatives and interest rate swaps are reflected on our consolidated balance sheet on a net basis by counterparty, as they are governed by master netting agreements. Cash flows related to derivatives used to manage commodity price risk, and interest rate risk are classified in operating activities. Our derivative instruments contain no significant contingent credit features. Fair value hedges – We may use interest rate swaps to manage our exposure to interest rate risk associated with fixed interest rate debt in our portfolio. Changes in the fair values of both the hedged item and the related derivative are recognized immediately in net income with an offsetting effect included in the basis of the hedged item. The net effect is to report in net income the extent to which the hedge is not effective in achieving offsetting changes in fair value. Cash flow hedges – We may use interest rate derivative instruments to manage the risk of interest rate changes during the period prior to anticipated borrowings as well as to stabilize future lease payments on our future Houston office, and designate them as cash flow hedges. Derivative instruments designated as cash flow hedges are linked to specific assets and liabilities or to specific firm commitments or forecasted transactions. The changes in the fair value of a qualifying cash flow hedge are recorded in other comprehensive income until the hedged transaction affects earnings and are then reclassified into net income. Beginning in 2019, ineffective portions of a cash flow hedge are no longer measured or disclosed separately. However, if it is determined that the likelihood of the original forecasted transaction occurring is no longer probable or the cash flow hedge is no longer expected to be highly effective, subsequent changes in fair value of the derivatives instrument are recorded in net income. Derivatives not designated as hedges – Derivatives that are not designated as hedges may include commodity derivatives used primarily to manage price and locational risks on the forecasted sale of crude oil, NGLs and natural gas that we produce. Changes in the fair value of derivatives not designated as hedges are recognized immediately in net income. Concentrations of credit risk – All of our financial instruments, including derivatives, involve elements of credit and market risk. The most significant portion of our credit risk relates to nonperformance by counterparties. The counterparties to our financial instruments consist primarily of major financial institutions and companies within the energy industry. To manage counterparty risk associated with financial instruments, we select and monitor counterparties based on our assessment of their financial strength and on credit ratings, if available. Additionally, we limit the level of exposure with any single counterparty. Fair value transfer – We recognize transfers between levels of the fair value hierarchy as of the end of the reporting period. Property, plant and equipment – We use the successful efforts method of accounting for oil and gas producing activities. Property acquisition costs – Costs to acquire mineral interests in oil and natural gas properties, to drill exploratory wells in progress and those that find proved reserves and to drill development wells are capitalized. Costs to drill exploratory wells that do not find proved reserves, geological and geophysical costs and costs of carrying and retaining unproved properties are expensed. Costs incurred for exploratory wells that find reserves but cannot yet be classified as proved are capitalized if (1) the well has found a sufficient quantity of reserves to justify its completion as a producing well and (2) we are making sufficient progress assessing the reserves and the economic and operating viability of the project. The status of suspended exploratory well costs is monitored continuously and reviewed at least quarterly. Depreciation, depletion and amortization – Capitalized costs to acquire oil and natural gas properties are depreciated and depleted on a units-of-production basis based on estimated proved reserves. Capitalized costs of exploratory wells and development costs are depreciated and depleted on a units-of-production basis based on estimated proved developed reserves. Support equipment and other property, plant and equipment related to oil and gas producing activities, as well as property, plant and equipment unrelated to oil and gas producing activities, are recorded at cost and depreciated on a straight-line basis over the estimated useful lives of the assets. The table below summarizes these assets by type, useful life and the gross asset balance as of the periods presented. December 31, Type of Asset Range of Useful Lives 2020 2019 (in millions) Office furniture, equipment and computer hardware 4 to 15 years $ 682 $ 670 Pipelines 5 to 40 years $ 12 $ 12 Plants, facilities and infrastructure 3 to 40 years $ 1,646 $ 1,624 Impairments – We evaluate our oil and gas producing properties, including capitalized costs of exploratory wells and development costs, for impairment of value whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If the sum of the expected undiscounted future cash flows from the use of the asset and its eventual disposition is less than the carrying amount of the asset, an impairment loss is recognized based on the fair value of the asset. Oil and gas producing properties are reviewed for impairment on a field-by-field basis or, in certain instances, by logical grouping of assets if there is significant shared infrastructure or contractual terms that cause economic interdependency amongst separate, discrete fields. Oil and gas producing properties deemed to be impaired are written down to their fair value, as determined by discounted future net cash flows or, if available, comparable market value. We evaluate our unproved property investment and record impairment based on time or geologic factors. Information such as drilling results, reservoir performance, seismic interpretation or future plans to develop acreage is also considered. When unproved property investments are deemed to be impaired, this amount is reported in exploration expenses in our consolidated statements of income. Dispositions – When property, plant and equipment depreciated on an individual basis is sold or otherwise disposed of, any gains or losses are reflected in net gain (loss) on disposal of assets in our consolidated statements of income. Gains on the disposal of property, plant and equipment are recognized when earned, which is generally at the time of closing. If a loss on disposal is expected, such losses are recognized either when the assets are classified as held for sale, or are measured using a probability weighted income approach based on both the anticipated sales price and a held-for-use model depending on timing of the sale. Proceeds from the disposal of a portion of property, plant and equipment depreciated on a group basis are credited to accumulated depreciation, depletion and amortization with no immediate effect on net income until net book value is reduced to zero. Goodwill – Goodwill represents the excess of the purchase price over the estimated fair value of the net assets acquired in the acquisition of a business. Such goodwill is not amortized, but rather is tested for impairment annually and when events or changes in circumstances indicate that the fair value of a reporting unit with goodwill has been reduced below carrying value. The impairment test requires allocating goodwill and other assets and liabilities to a reporting unit. The fair value of a reporting unit is determined and compared to the book value of the reporting unit. If the fair value of the reporting unit is less than the book value, including goodwill, then the recorded goodwill is impaired to its implied fair value with a charge to impairments. Environmental costs – We provide for remediation costs and penalties when the responsibility to remediate is probable and the amount of associated costs can be reasonably estimated. The timing of remediation accruals coincides with completion of a feasibility study or the commitment to a formal plan of action. Remediation liabilities are accrued based on estimates of known environmental exposure and are discounted when the estimated amounts are reasonably fixed or reliably determinable. Environmental expenditures are capitalized only if the costs mitigate or prevent future contamination or if the costs improve the environmental safety or efficiency of the existing assets. Asset retirement obligations – The fair value of asset retirement obligations is recognized in the period in which the obligations are incurred if a reasonable estimate of fair value can be made. Our asset retirement obligations primarily relate to the abandonment of oil and gas producing facilities. Asset retirement obligations for such facilities include costs to dismantle and relocate or dispose of production platforms, gathering systems, wells and related structures and restoration costs of land, including those leased. Estimates of these costs are developed for each property based on the type of production facilities and equipment, reservoir characteristics, depth of the reservoir, market demand for equipment, currently available procedures and consultations with construction and engineering professionals. Inflation rates and credit-adjusted-risk-free interest rates are used to estimate the fair value of asset retirement obligations. Depreciation of capitalized asset retirement costs and accretion of asset retirement obligations are recorded over time. Depreciation is generally determined on a units-of-production basis based on estimated proved developed reserves for oil and gas production facilities, while accretion of the liability occurs over the useful lives of the assets. Deferred income taxes – Deferred tax assets and liabilities, measured at enacted tax rates, are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their tax bases as reported in our filings with the respective taxing authorities. We routinely assess the realizability of our deferred tax assets based on several interrelated factors and reduce such assets by a valuation allowance if it is more likely than not that some portion or all of the deferred tax assets will not be realized. These factors include whether we are in a cumulative loss position in recent years, our reversal of temporary differences, and our expectation to generate sufficient future taxable income. We use the liability method in determining our provision and liabilities for our income taxes, under which current and deferred tax liabilities and assets are recorded in accordance with enacted tax laws and rates. Stock-based compensation arrangements – The fair value of stock options is estimated on the date of grant using the Black-Scholes option pricing model. The model employs various assumptions, based on management’s best estimates at the time of grant, which impact the calculation of fair value and ultimately, the amount of expense that is recognized over the life of the stock option award. Of the required assumptions, the expected volatility of our stock price and the stock price in relation to the strike price have the most significant impact on the fair value calculation. We have utilized historical data and analyzed current information which reasonably support these assumptions. The fair value of our restricted stock awards, restricted stock units and Director restricted stock units is determined based on the market value of our common stock on the date of grant. Restricted stock awards, restricted stock units and Director restricted stock units are removed from Treasury Stock at grant, vesting and distribution, respectively. The fair value of our cash-settled stock-based performance units is estimated using the Monte Carlo simulation method. Since these awards are settled in cash at the end of a defined performance period, they are classified as a liability and are re-measured quarterly until settlement. The fair value of our stock-settled stock-based performance units is estimated using the Monte Carlo simulation method at grant date only. Since these awards are settled in stock, they are classified as equity.

Accounting Standards

Accounting Standards	12 Months Ended
	Dec. 31, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
Accounting Standards	Accounting Standards Recently Adopted Financial instruments – credit losses In June 2016, the FASB issued a new accounting standards update that changes the impairment model for trade receivables, net investments in leases, debt securities, loans and certain other instruments. On January 1, 2020 we adopted this standard using the modified retrospective transition method through a cumulative-effect adjustment of $12 million to retained earnings as of the beginning of the adoption period. The standard requires the use of a forward-looking “expected loss” model as opposed to the “incurred loss” model used previously. See Note 9 for more information on credit losses.

Income (loss) and Derivatives p

Income (loss) and Derivatives per Common Share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Income (loss) and Dividends per Common Share	Income (loss) and Dividends per Common Share Basic income (loss) per share is based on the weighted average number of common shares outstanding. Diluted income (loss) per share assumes exercise of stock options in all periods, provided the effect is not antidilutive. The per share calculations below exclude 7 million, 6 million and 6 million stock options in 2020, 2019 and 2018 that were antidilutive. Year Ended December 31, (In millions, except per share data) 2020 2019 2018 Net income (loss) $ (1,451) $ 480 $ 1,096 Weighted average common shares outstanding 792 810 846 Effect of dilutive securities — — 1 Weighted average common shares, diluted 792 810 847 Net income (loss) per share: Basic $ (1.83) $ 0.59 $ 1.30 Diluted $ (1.83) $ 0.59 $ 1.29 Dividends per share $ 0.08 $ 0.20 $ 0.20

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Acquisitions	Acquisitions United States Segment In the fourth quarter of 2019, we acquired approximately 40,000 net acres in a Texas Delaware oil play in West Texas from multiple sellers for $106 million. We accounted for these transactions as an asset acquisition, allocating the purchase price to unproved property within property, plant and equipment. During the fourth quarter of 2019, we acquired a 100% working interest in approximately 18,000 net acres in the Eagle Ford from Rocky Creek Resources, LLC and RCR Midstream, LLC for $191 million in cash, subject to post-closing adjustments. We accounted for this transaction as a business combination, with the entire purchase price allocated between proved property, unproved property and other assets, all within property, plant and equipment.

Dispositions

Dispositions	12 Months Ended
	Dec. 31, 2020
Discontinued Operations and Disposal Groups [Abstract]
Dispositions	Dispositions United States Segment In the third quarter of 2018, we closed on the sale of non-core, non-operated conventional properties, primarily in the Gulf of Mexico, for combined net proceeds of $16 million, before closing adjustments. A pre-tax gain of $32 million was recognized in the third quarter of 2018. International Segment On July 1, 2019, we closed on the sale of our U.K. business (Marathon Oil U.K. LLC and Marathon Oil West of Shetlands Limited) for proceeds of $95 million which reflects the assumption by RockRose Energy PLC (“RockRose”) of the U.K. business’ cash equivalent balance and working capital balance as of year-end 2018. During the third quarter of 2019, we recorded a $6 million liability and corresponding expense related to the estimated fair value of our exposure to surety bonds we continued to hold that guaranteed decommissioning liabilities of Marathon Oil U.K. LLC. In November 2019, RockRose posted replacement security and accordingly, we reversed the aforementioned $6 million (see Note 26 for further detail). Income before taxes relating to our U.K. business for the year ended December 31, 2019 and 2018, was $33 million and $261 million, respectively. See Note 13 and Note 20 for additional details on U.K. ARO and the defined benefit pension plan as it relates to this disposition. In the second quarter of 2019, we closed on the sale of our 15% non-operated interest in the Atrush block in Kurdistan for proceeds of $63 million, before closing adjustments.

Revenues

Revenues	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Revenues	Revenues The majority of our revenues are derived from the sale of crude oil and condensate, NGLs and natural gas under spot and term agreements with our customers in the United States and various international locations. As of December 31, 2020 and December 31, 2019, receivables from contracts with customers, included in receivables, less reserves were $572 million and $837 million, respectively. The following tables present our revenues from contracts with customers disaggregated by product type and geographic areas. United States Year Ended December 31, 2020 (In millions) Eagle Ford Bakken Oklahoma Northern Delaware Other U.S. Total Crude oil and condensate $ 830 $ 984 $ 235 $ 204 $ 69 $ 2,322 Natural gas liquids 74 54 89 20 6 243 Natural gas 86 34 127 18 10 275 Other 6 — — — 78 84 Revenues from contracts with customers $ 996 $ 1,072 $ 451 $ 242 $ 163 $ 2,924 Year Ended December 31, 2019 (In millions) Eagle Ford Bakken Oklahoma Northern Delaware Other U.S. Total Crude oil and condensate $ 1,358 $ 1,686 $ 425 $ 316 $ 102 $ 3,887 Natural gas liquids 114 46 116 26 5 307 Natural gas 121 39 156 16 17 349 Other 7 — — — 52 59 Revenues from contracts with customers $ 1,600 $ 1,771 $ 697 $ 358 $ 176 $ 4,602 Year Ended December 31, 2018 (In millions) Eagle Ford Bakken Oklahoma Northern Delaware Other U.S. Total Crude oil and condensate $ 1,554 $ 1,568 $ 426 $ 235 $ 164 $ 3,947 Natural gas liquids 205 62 181 38 9 495 Natural gas 145 38 184 20 26 413 Other 8 — — — 23 31 Revenues from contracts with customers $ 1,912 $ 1,668 $ 791 $ 293 $ 222 $ 4,886 International Year Ended December 31, 2020 (In millions) E.G. Crude oil and condensate $ 140 Natural gas liquids 4 Natural gas 29 Other — Revenues from contracts with customers $ 173 Year Ended December 31, 2019 (In millions) E.G. U.K. Other International Total Crude oil and condensate $ 271 $ 107 $ 20 $ 398 Natural gas liquids 4 1 — 5 Natural gas 32 12 — 44 Other — 14 — 14 Revenues from contracts with customers $ 307 $ 134 $ 20 $ 461 Year Ended December 31, 2018 (In millions) E.G. U.K. Libya Other International Total Crude oil and condensate $ 342 $ 282 $ 187 $ 77 $ 888 Natural gas liquids 4 5 — — 9 Natural gas 37 40 9 — 86 Other 1 32 — — 33 Revenues from contracts with customers $ 384 $ 359 $ 196 $ 77 $ 1,016 In 2020, sales to Marathon Petroleum Corporation and Koch Resources LLC and each of their respective affiliates, accounted for approximately 13% and 12%, respectively, of our total revenues. In 2019, sales to Marathon Petroleum Corporation, Koch Resources LLC, Valero Marketing and Supply and Shell Trading and their respective affiliates, accounted for approximately 13%, 13%, 11% and 10%, respectively, of our total revenues. In 2018, sales to Valero Marketing and Supply and Koch Resources LLC and their respective affiliates, each accounted for approximately 11% of our total revenues. The pricing in our hydrocarbon sales agreements are variable, determined using various published benchmarks which are adjusted for negotiated quality and location differentials. As a result, revenue collected under our agreements with customers is highly dependent on the market conditions and may fluctuate considerably as the hydrocarbon market prices rise or fall. Typically, our customers pay us monthly, within a short period of time after we deliver the hydrocarbon products. As such, we do not have any financing element associated with our contracts. We do not have any issues related to returns or refunds, as product specifications are standardized for the industry and are typically measured when transferred to a common carrier or midstream entity, and other contractual mechanisms (e.g., price adjustments) are used when products do not meet those specifications. In limited cases, we may also collect advance payments from customers as stipulated in our agreements; payments in excess of recognized revenue are recorded as contract liabilities on our consolidated balance sheet. Under our hydrocarbon sales agreements, the entire consideration amount is variable either due to pricing and/or volumes. We recognize revenue in the amount of variable consideration allocated to distinct units of hydrocarbons transferred to a customer. Such allocation reflects the amount of total consideration we expect to collect for completed deliveries of hydrocarbons and the terms of variable payment relate specifically to our efforts to satisfy the performance obligations under these contracts. Our performance obligations under our hydrocarbon sales agreements are to deliver either the entire production from the dedicated wells or specified contractual volumes of hydrocarbons. We often serve as the operator for jointly owned oil and gas properties. As part of this role, we perform activities to explore, develop and produce oil and gas properties in accordance with the joint operating arrangements. Other working interest owners reimburse us for costs incurred based on our agreements. We determined that these activities are not performed as part of customer relationships and such reimbursements will continue to not be recorded as revenues within the scope of the revenue accounting standard. In addition, we commonly market the share of production belonging to other working interest owners as the operator of jointly owned oil and gas properties. We concluded that those marketing activities are carried out as part of the collaborative arrangement. Therefore, we act as a principal only in regards to the sale of our share of production and recognize revenue for the volumes associated with our net production. Crude oil and condensate For the crude sales agreements, we satisfy our performance obligations and recognize revenue once customers take control of the crude at the designated delivery points, which include pipelines, trucks or vessels. Natural gas and NGLs When selling natural gas and NGLs, we engage midstream entities to process our production stream by separating natural gas from the NGLs. Frequently, these midstream entities also purchase our natural gas and NGLs under the same agreements. In these situations, we determined the performance obligation is complete and satisfied at the tailgate of the processing plant when the natural gas and NGLs become identifiable and measurable products. We determined the plant tailgate is the point in time where control is transferred to midstream entities and they are entitled to significant risks and rewards of ownership of the natural gas and NGLs. The amounts due to midstream entities for gathering and processing services are recognized as shipping and handling cost, since we make those payments in exchange for distinct services. Under some of our natural gas processing agreements, we have an option to take the processed natural gas and NGLs in-kind and sell to customers other than the processing company. In those circumstances, our performance obligations are complete after delivering the processed hydrocarbons to the customer at the designated delivery points, which may be the tailgate of the processing plant or an alternative delivery point requested by the customer. We have “percentage-of-proceeds” arrangements with some midstream entities where they retain a percentage of the proceeds collected for selling our processed natural gas and NGLs as compensation for their processing and marketing services. We recognize revenue for the gross sales volumes and recognize the proceeds retained by midstream companies as shipping and handling cost.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Segment Information	Segment Information We have two reportable operating segments. Both of these segments are organized and managed based upon geographic location and the nature of the products and services offered. • United States (“U.S.”) – explores for, produces and markets crude oil and condensate, NGLs and natural gas in the United States • International (“Int’l”) – explores for, produces and markets crude oil and condensate, NGLs and natural gas outside of the United States as well as produces and markets products manufactured from natural gas, such as LNG and methanol, in E.G. Segment income represents income which excludes certain items not allocated to our operating segments, net of income taxes. A portion of our corporate and operations general and administrative support costs are not allocated to the operating segments. These unallocated costs primarily consist of employment costs (including pension effects), professional services, facilities and other costs associated with corporate and operations support activities. Additionally, items which affect comparability such as: gains or losses on dispositions, impairments of proved and certain unproved properties, goodwill and equity method investments, certain exploration expenses relating to a strategic decision to exit conventional exploration, unrealized gains or losses on commodity and interest rate derivative instruments, effects of pension settlements and curtailments, or other items (as determined by the CODM) are not allocated to operating segments. Year Ended December 31, 2020 (In millions) U.S. Int’l Not Allocated to Segments Total Revenues from contracts with customers $ 2,924 $ 173 $ — $ 3,097 Net gain (loss) on commodity derivatives 143 — (27) (b) 116 Income (loss) from equity method investments — 10 (171) (c) (161) Net gain on disposal of assets — — 9 9 Other income 15 7 3 25 Less costs and expenses: Production 494 59 2 555 Shipping, handling and other operating 534 8 54 596 Exploration 97 — 84 (d) 181 Depreciation, depletion and amortization 2,211 82 23 2,316 Impairments — — 144 (e) 144 Taxes other than income 193 — 7 200 General and administrative 115 14 145 (f) 274 Net interest and other — — 256 256 Other net periodic benefit costs — — 1 (g) 1 Loss on early extinguishment of debt — — 28 28 Income tax benefit (9) (3) (2) (14) Segment income (loss) $ (553) $ 30 $ (928) $ (1,451) Total assets $ 16,063 $ 1,081 $ 812 $ 17,956 Capital expenditures (a) $ 1,137 $ 1 $ 13 $ 1,151 (a) Includes accruals and excludes acquisitions. (b) Unrealized loss on commodity derivative instruments (See Note 16 ). (c) Partial impairment of investment in equity method investee (See Note 24 ). (d) Primarily related to unproved property impairments of non-core acreage in our United States segment. (e) Includes the full impairment of the International reporting unit goodwill of $95 million (See Note 15 ) and proved property impairments of $49 million related to a damaged well in our United States segment. (f) Includes severance expenses associated with workforce reductions of $17 million. (g) Includes pension settlement loss of $30 million and pension curtailment gain of $17 million (See Note 20 ). Year Ended December 31, 2019 (In millions) U.S. Int’l Not Allocated to Segments Total Revenues from contracts with customers $ 4,602 $ 461 $ — $ 5,063 Net gain (loss) on commodity derivatives 52 — (124) (b) (72) Income from equity method investments — 87 — 87 Net gain on disposal of assets — — 50 (c) 50 Other income 13 9 40 62 Less costs and expenses: Production 588 126 (2) 712 Shipping, handling and other operating 561 26 18 605 Exploration 149 — — 149 Depreciation, depletion and amortization 2,250 121 26 2,397 Impairments — — 24 (d) 24 Taxes other than income 311 — — 311 General and administrative 127 25 204 356 Net interest and other — — 244 244 Other net periodic benefit credit — (3) — (e) (3) Loss on early extinguishment of debt — — 3 3 Income tax provision (benefit) 6 29 (123) (88) Segment income (loss) $ 675 $ 233 $ (428) $ 480 Total assets $ 17,781 $ 1,530 $ 934 $ 20,245 Capital expenditures (a) $ 2,550 $ 16 $ 25 $ 2,591 (a) Includes accruals and excludes acquisitions. (b) Unrealized loss on commodity derivative instruments (See Note 16 ). (c) Primarily related to the sale of our working interest in the Droshky field (Gulf of Mexico) and the sale of our U.K. business (See Note 5 ). (d) Primarily a result of anticipated sales of non-core proved properties in our International and United States segments (See Note 12 ). (e) Includes pension settlement loss of $12 million (See Note 20 ). Year Ended December 31, 2018 (In millions) U.S. Int’l Not Allocated to Segments Total Revenues from contracts with customers $ 4,886 $ 1,016 $ — $ 5,902 Net gain (loss) on commodity derivatives (281) — 267 (b) (14) Income from equity method investments — 225 — 225 Net gain on disposal of assets — — 319 (c) 319 Other income 16 12 122 (d) 150 Less costs and expenses: Production 625 215 2 842 Shipping, handling and other operating 499 70 6 575 Exploration 246 3 40 (e) 289 Depreciation, depletion and amortization 2,217 197 27 2,441 Impairments — — 75 (f) 75 Taxes other than income 301 — (2) 299 General and administrative 146 32 216 394 Net interest and other — — 226 226 Other net periodic benefit (costs) credits — (9) 23 (g) 14 Income tax provision (benefit) (21) 272 80 331 Segment income $ 608 $ 473 $ 15 $ 1,096 Total assets $ 17,321 $ 2,083 $ 1,917 $ 21,321 Capital expenditures (a) $ 2,620 $ 39 $ 26 $ 2,685 (a) Includes accruals and excludes acquisitions. (b) Unrealized gain on commodity derivative instruments (See Note 16 ). (c) Primarily related to the gain on sale of our Libya subsidiary (See Note 5 ). (d) Primarily a reduction of asset retirement obligations in our International segment (See Note 13 ). (e) Primarily related to dry well expense and unproved property impairments associated with the Rodo well in Alba Block Sub Area B, offshore E.G. (See Note 12 ). (f) Due to the anticipated sales of certain non-core proved properties in our International and United States segments (See Note 12 ). (g) Includes pension settlement loss of $21 million (See Note 20 ). The following summarizes property, plant and equipment and equity method investments. December 31, (In millions) 2020 2019 United States $ 15,224 $ 16,507 Equatorial Guinea 861 1,156 Total long-lived assets $ 16,085 $ 17,663

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income (loss) before income taxes were: Year Ended December 31, (In millions) 2020 2019 2018 United States $ (1,319) $ 43 $ 642 Foreign (146) 349 785 Total $ (1,465) $ 392 $ 1,427 Income tax provisions (benefits) were: Year Ended December 31, 2020 2019 2018 (In millions) Current Deferred Total Current Deferred Total Current Deferred Total Federal $ (5) $ — $ (5) $ (116) $ (3) $ (119) $ 6 $ — $ 6 State and local (2) (8) (10) 4 3 7 (1) (23) (24) Foreign 15 (14) 1 58 (34) 24 274 75 349 Total $ 8 $ (22) $ (14) $ (54) $ (34) $ (88) $ 279 $ 52 $ 331 A reconciliation of the federal statutory income tax rate applied to income (loss) before income taxes to the provision (benefit) for income taxes follows: Year Ended December 31, (In millions) 2020 2019 2018 Total pre-tax income (loss) $ (1,465) $ 392 $ 1,427 Total income tax expense (benefit) $ (14) $ (88) $ 331 Effective income tax rate 1 % (22) % 23 % Income taxes at the statutory tax rate (a) $ (308) $ 83 $ 300 Effects of foreign operations 23 (29) 214 Adjustments to valuation allowances 239 (28) (177) State income taxes, net of federal benefit 6 11 (17) Other federal tax effects 26 (125) 11 Income tax expense (benefit) $ (14) $ (88) $ 331 (a) Includes income tax benefits primarily related to our U.S. federal income taxes where we have maintained a full valuation allowance since December 2016. The effective income tax rate is influenced by a variety of factors including the geographic and functional sources of income and the relative magnitude of these sources of income. The difference between the total provision and the sum of the amounts allocated to segments is reported in the “Not Allocated to Segments” column of the tables in Note 7 . Effects of foreign operations – The effects of foreign operations increased our tax expense in 2020 largely due to book losses in foreign jurisdictions with no corresponding tax benefits. The effects of foreign operations decreased our tax expense in 2019 due to tax benefits related to our U.K. operations and pre-tax income in jurisdictions with effective tax rates lower than the U.S. The effects of foreign operations increased our tax expense in 2018 due to the mix of pre-tax income between high and low tax jurisdictions, including Libya where the tax rate was 93.5%. Excluding Libya, the effective tax rate would have been an expense of 14% in 2018. As a result of the sale of our Libya subsidiary in the first quarter of 2018, we do not expect to incur further tax expense related to Libya. Adjustments to valuation allowances – Since December 31, 2016, we have maintained a full valuation allowance on our net federal deferred tax assets. In all years, the most significant driver for the change in valuation allowance was due to current year activity in the U.S. Other federal tax effects – In 2020, the increase to other federal tax effects is largely related to non-deductible goodwill impairment. The 2019 decrease in other federal tax effects is primarily related to the settlement of the 2010-2011 U.S. Federal Tax Audit (“IRS Audit”) in the first quarter of 2019. The release of the accrued tax positions resulted in a $126 million tax benefit, primarily related to AMT credits. Deferred tax assets and liabilities resulted from the following: Year Ended December 31, (In millions) 2020 2019 Deferred tax assets: Employee benefits $ 77 $ 90 Operating loss carryforwards 1,966 1,685 Capital loss carryforwards — 1 Foreign tax credits 611 611 Other 43 27 Subtotal 2,697 2,414 Valuation allowance (948) (699) Total deferred tax assets 1,749 1,715 Deferred tax liabilities: Property, plant and equipment 1,892 1,861 Accrued revenue 20 40 Total deferred tax liabilities 1,912 1,901 Net deferred tax liabilities $ 163 $ 186 Net deferred tax assets $ — $ — Operating loss carryforwards – At December 31, 2020, we have a gross deferred tax asset related to our operating loss carryforwards of $2.0 billion, before valuation allowance. Deferred tax assets on U.S. operating loss carryforwards relating to tax years beginning prior to January 1, 2018, include $655 million that expire in 2035 - 2037. Deferred tax assets on U.S. operating loss carryforwards for tax years beginning after December 31, 2017, include $1.1 billion which can be carried forward indefinitely. Deferred tax assets on foreign operating loss carryforwards include $14 million that begin to expire in 2021. Deferred tax assets on state operating loss carryforwards of $184 million expire in 2021 through 2039. Foreign tax credits – At December 31, 2020, we reflect foreign tax credits of $611 million, which will expire in years 2022 through 2026. Valuation allowances – At December 31, 2020, we reflect a valuation allowance in our consolidated balance sheet of $948 million against our net deferred tax assets in various jurisdictions in which we operate. The increase in valuation allowance primarily relates to current year activity in the U.S. Property, plant and equipment – At December 31, 2020, we reflected a deferred tax liability of $1.9 billion. The increase primarily relates to current year activity in the U.S. Net deferred tax assets and liabilities were classified in the consolidated balance sheets as follows: December 31, (In millions) 2020 2019 Assets: Other noncurrent assets $ — $ — Liabilities: Noncurrent deferred tax liabilities 163 186 Net deferred tax liabilities $ 163 $ 186 Net deferred tax assets $ — $ — We are routinely undergoing examinations in the jurisdictions in which we operate. As of December 31, 2020, our income tax returns remain subject to examination in the following major tax jurisdictions for the tax years indicated: United States (a) 2008 - 2019 Equatorial Guinea 2007 - 2019 (a) Includes federal and state jurisdictions. The following table summarizes the activity in unrecognized tax benefits: (In millions) 2020 2019 2018 Beginning balance $ 13 $ 263 $ 126 Additions for tax positions of prior years — 13 152 Reductions for tax positions of prior years (5) (152) (15) Settlements — (111) — Ending balance $ 8 $ 13 $ 263 If the unrecognized tax benefits as of December 31, 2020 were recognized, $8 million would affect our effective income tax rate. As of December 31, 2020, we do not expect uncertain tax positions to significantly change within the next twelve months. During the first quarter of 2019, we withdrew our appeal related to the Brae area decommissioning costs in the U.K., thus the uncertain tax positions previously established are now considered effectively settled with no tax expense or benefit impact. Also, in the first quarter of 2019, we settled the 2010-2011 IRS Audit, resulting in a tax benefit of $126 million. Interest and penalties are recorded as part of the tax provision and were a $2 million tax benefit in 2020 and a $6 million and $2 million tax expense in 2019 and 2018 related to unrecognized tax benefits. As of December 31, 2020, we had no significant accrued interest or penalties related to income taxes. For December 31, 2019, $3 million of interest and penalties were accrued related to income taxes. In the third quarter of 2020, we received an $89 million cash refund related to alternative minimum tax credits and interest. This refund was accelerated as a result of the enactment of the Coronavirus Aid, Relief, and Economic Security Act, commonly referred to as the CARES Act, in the first quarter of 2020.

Credit Losses

Credit Losses	12 Months Ended
	Dec. 31, 2020
Credit Loss [Abstract]
Credit Losses	Credit Losses The majority of our receivables are from purchasers of commodities or joint interest owners in properties we operate, both of which are recorded at estimated or invoiced amounts and do not bear interest. The majority of these receivables have payment terms of 30 days or less. At the end of each reporting period, we assess the collectability of our receivables and estimate the expected credit losses using historical data, current market conditions and reasonable and supportable forecasts of future economic conditions. We are exposed to credit losses through the receivables generated from sales of crude oil, NGLs and natural gas to our customers. When dealing with the commodity purchasers, we conduct a credit review to assess each counterparty’s ability to pay. The credit review considers our expected billing exposure, timing for payment and the counterparty’s established credit rating with the rating agencies or our internal assessment of the counterparty’s creditworthiness based on our analysis of their financial statements. Our evaluation also considers contract terms and other factors, such as country and/or political risk. A credit limit is established for each counterparty based on the outcome of this review. We may require a bank letter of credit or a prepayment to mitigate credit risk. We monitor our ongoing credit exposure through active review of counterparty balances against contract terms and due dates. The expected credit losses related to receivables with the commodity purchasers were determined using the weighted average probability of default method. We also collect revenues from our non-operated joint properties where other oil and gas exploration and production companies operate the properties and market our share of production and remit payments to us. The current expected credit losses related to these receivables were determined using the loss rate method applied to aging pools. We are exposed to credit losses from joint interest billings to other joint interest owners for properties we operate. For this group of receivables, the expected credit losses are determined using the loss rate method applied to aging pools. Our counterparties in this group include numerous large, mid-size and small oil and gas exploration and production companies. Although we may have the ability to withhold future revenue disbursements to recover any non-payment of joint interest billings or require a prepayment of future costs through cash calls, our credit loss exposure with this group is more significant due to inherent ownership or billing adjustments. Also, some of our counterparties may experience liquidity problems and may not be able to meet their financial obligations to us. Liquidity problems may increase in the future if hydrocarbon demand and/ or prices don’t materially increase from 2020 levels. Our current-period provision reflects the anticipated effects caused by the market deterioration in 2020. Changes in the allowance for doubtful accounts balance for the year were as follows: (In millions) December 31, 2020 Beginning balance as of January 1 $ 11 Cumulative-effect adjustment 12 Current period provision (a) 22 Current period write offs (13) Recoveries of amounts previously reserved (10) Ending balance as of December 31 $ 22

Inventories

Inventories	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Inventories	Inventories Crude oil and natural gas are recorded at weighted average cost and carried at the lower of cost or net realizable value. Supplies and other items consist principally of tubular goods and equipment which are valued at weighted average cost and reviewed periodically for obsol escence or impairment when market conditions indicate. The continued volatility and future decline in crude oil and natural gas prices could affect the value of our inventories and result in future impairments. December 31, (In millions) 2020 2019 Crude oil and natural gas $ 10 $ 10 Supplies and other items 66 62 Inventories $ 76 $ 72

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment December 31, (In millions) 2020 2019 United States $ 15,156 $ 16,427 International 414 493 Not allocated to segments 68 80 Net property, plant and equipment $ 15,638 $ 17,000 Changes in our capitalized exploratory well costs were as follows: December 31, (In millions) 2020 2019 2018 Beginning balance as of January 1 $ 278 $ 297 $ 295 Additions 97 218 262 Charges to expense (a) (1) (5) (35) Transfers to development (164) (230) (197) Dispositions (b) — (2) (28) Ending balance as of December 31 $ 210 $ 278 $ 297 (a) 2018 includes $32 million related to the Rodo well in Alba Block Sub Area B (See Note 12 ). (b) 2018 includes the sale of our Libya subsidiary.

Impairment

Impairment	12 Months Ended
	Dec. 31, 2020
Impairments and Exploration Expenses [Abstract]
Impairments	Impairments During the first quarter of 2020, a global pandemic caused a substantial deterioration in the worldwide demand of hydrocarbons. The decreased demand, when coupled with an oversupplied market, caused a corresponding deterioration in hydrocarbon prices. We reviewed our long-lived assets for indicators of impairment during the first quarter by conducting a sensitivity analysis of the most impactful inputs to their undiscounted cash flows, including commodity prices, capital spend and reductions in production volumes to correspond with lower capital spending. Our review concluded that the carrying amounts of our long-lived assets are recoverable; however, further deterioration or a more sustained decline of commodity prices may result in impairment charges in future periods. We also reviewed our equity method investments for indicators of impairment. Equity method investments are assessed for impairment whenever changes in the facts and circumstances indicate a loss in value may have occurred. When a loss in value occurs that is deemed other than temporary, the carrying value of the equity method investment is written down to fair value. During the second and third quarters of 2020, we recognized impairments related to one of our EG Holdings equity method investments, as noted in the tables and further described below. The following table summarizes impairment charges of proved properties, goodwill and equity method investments and their corresponding fair values. 2020 2019 2018 (In millions) Fair Value Impairment Fair Value Impairment Fair Value Impairment Long-lived assets held for use $ — $ 49 $ 56 $ 24 $ 113 $ 75 Goodwill $ — $ 95 N/A $ — N/A $ — Equity method investment $ 119 $ 171 N/A $ — N/A $ — • 2020 – Impairments totaling $49 million of long-lived assets held for use resulted from a damaged, unsalvageable well and related equipment in the Louisiana Austin Chalk. The related fair value was measured based on the salvage value which resulted in a Level 3 classification. We impaired the entire balance of our goodwill in the International reporting unit totaling $95 million of goodwill. See Note 15 for further information. Impairments also include charges recognized for our equity method investments of $171 million. During the second and third quarters of 2020, the continuation of the depressed commodity prices, along with a reduction of our long-term price forecasts of a gas index in which one of our equity method investees transacts, caused us to perform a review of one of our equity method investments. Our review concluded that a loss of our investment value in one was other than temporary and we recorded an impairment. Our remaining investments in equity method investees did not experience losses in value that caused the fair values to be below their carrying values. We estimated the fair value of our equity method investment using an income approach, specifically utilizing a discounted cash flow analysis. The estimated fair value was based on significant inputs not observable in the market, such as the amount of gas processed by the plant, future commodity prices, forecasted operating expenses, discount rate and estimated cash returned to shareholders. Collectively, these inputs represent Level 3 measurements. The impairments of our equity method investments were recognized in income (loss) from equity method investments in our consolidated statements of income. The impairments caused us to incur a basis differential between the net book value of our investment and the amount of our underlying share of equity in the investee’s net assets. The amount of this basis differential was $140 million and is being accreted into income over the remaining useful life of the investee’s primary assets. Finally, we impaired $78 million of unproved property leases in Louisiana Austin Chalk in our United States segment which was recognized in exploration expense in our consolidated statements of income. The impairment resulted from a combination of factors including our geological assessment, seismic information, timing of lease expiration dates and decisions not to develop acreage deemed non-core. Collectively, these inputs represent Level 3 measurements. • 2019 – Impairments of $24 million, to an aggregate fair value of $56 million, were primarily a result of anticipated sales for certain non-core proved properties in our United States segment and the sale of our non-operated interest in the Atrush block (Kurdistan) in our International segment. The related fair value was measured using the market approach, based upon anticipated sales proceeds less costs to sell which resulted in a Level 2 classification. • 2018 – Impairments in our International and United States segments of $75 million, to a fair value of $113 million, were largely the result of anticipated sales for certain non-core proved properties. The related fair value measurement utilized the market approach, based upon anticipated sales proceeds less costs to sell which resulted in a Level 2 classification. See Note 5 for discussion of the divestitures in further detail and Note 7 for relevant detail regarding segment presentation.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations Asset retirement obligations primarily consist of estimated costs to remove, dismantle and restore land at the end of oil and gas production operations. Changes in asset retirement obligations for the periods ended December 31 were as follows: (In millions) 2020 2019 Beginning balance as of January 1 $ 254 $ 1,145 Incurred liabilities, including acquisitions 6 34 Settled liabilities, including dispositions (12) (1,110) Accretion expense (included in depreciation, depletion and amortization) 12 31 Revisions of estimates (6) 46 Held for sale (a) — 108 Ending balance as of December 31 $ 254 $ 254 (a) In the first quarter of 2019, we closed on the sale of our working interest in the Droshky field (Gulf of Mexico), including our $98 million asset retirement obligation. 2020 • Ending balance includes $13 million classified as short-term at December 31, 2020. 2019 • Settled liabilities primarily relates to the sale of our U.K. business, which closed during the third quarter of 2019, and the sale of the Droshky field (Gulf of Mexico). • Held for sale

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	Leases Supplemental balance sheet information related to leases was as follows: December 31, (In millions) 2020 2019 Leases: Balance Sheet Location: Right-of-use (“ROU”) asset Other noncurrent assets $ 133 $ 199 Current portion of long-term lease liability Other current liabilities $ 70 $ 101 Long-term lease liability Deferred credits and other liabilities $ 67 $ 107 In determining our ROU assets and long-term lease liabilities, the lease standard requires certain accounting policy decisions, while also providing a number of optional practical expedients for transition accounting. Our accounting policies and the practical expedients utilized are summarized below: • Implemented an accounting policy to not recognize any right-of-use assets and lease liabilities related to short-term leases on the balance sheet. • Implemented an accounting policy to not separate the lease and nonlease components for all asset classes, except for vessels. • Elected the package of practical expedients which allows us to not reassess our prior conclusions regarding the lease identification and lease classification for contracts that commenced or expired prior to the effective date. • Elected the practical expedient pertaining to land easements which allows us to continue accounting for existing agreements under the previous accounting policies as nonlease transactions. Any modifications of existing contracts or new agreements will be assessed under the new lease accounting guidance and may become leases in the future. We enter into various lease agreements to support our operations including drilling rigs, well fracturing equipment, compressors, buildings, aircraft, vessels, vehicles and miscellaneous field equipment. We primarily act as a lessee in these transactions and the majority of our existing leases are classified as either short-term or long-term operating leases. The majority of the drilling rig agreements and all of fracturing equipment agreements are classified as short-term leases based on the noncancellable period for which we have the right to use the equipment and assessment of options present in each agreement. We also incur variable lease costs under these agreements primarily related to chemicals and sand used in fracturing operations or various additional on-demand equipment and labor. The lease costs associated with the drilling rigs and fracturing equipment are primarily capitalized as part of the well costs. Our long-term leases are comprised of compressors, buildings, drilling rigs, aircraft, vessels, vehicles and miscellaneous field equipment. Our lease agreements may require both fixed and variable payments; none of the variable payments are rate or index-based, therefore only fixed payments were considered for recognizing lease liabilities and ROU assets related to long-term leases. Also, based on our election not to separate the lease and nonlease components, fixed payments related to equipment, crew and other nonlease components are included in the initial measurement of lease liabilities and ROU assets for all asset classes, except for vessels. For vessels, the contractual consideration was allocated between lease and nonlease components based on estimates provided by service providers. Our leased assets may be used in joint oil and gas operations with other working interest owners. We recognize lease liabilities and ROU assets only when we are the signatory to a contract as an operator of joint properties. Such lease liabilities and ROU assets are determined based on gross contractual obligations. As we use the leased assets for joint operations, we have the contractual right to recover the other working interest owners’ share of lease costs. As a result, our lease costs are presented on a net basis, reduced for any costs recoverable from other working interest owners. The table below presents our net lease costs for the years ended December 31, 2020 and 2019 with the majority of operating lease costs expensed as incurred, while the majority of the short-term and variable lease costs are capitalized into property, plant and equipment. (In millions) Year Ended December 31, 2020 Year Ended December 31, 2019 Lease costs: Operating lease costs (a) $ 75 $ 84 Short-term lease costs (b) 170 321 Variable lease costs (c) 23 107 Total lease costs $ 268 $ 512 Other information: Cash paid for amounts included in the measurement of operating lease liabilities $ 100 $ 100 ROU assets obtained in exchange for new operating lease liabilities (d) $ 46 $ 293 Reductions to ROU assets resulting from modifications or cancellations of operating leases $ (68) $ — (a) Represents our net share of the ROU asset amortization and the interest expense. (b) Represents our net share of lease costs arising from leases of less than one year but longer than one month that were not included in the lease liability. (c) Represents our net share of variable lease payments that were not included in the lease liability. (d) Represents the cumulative value of ROU assets recognized at lease inception during the year of 2020. This amount is then amortized as we utilize the ROU asset, the net effect of which is the ending ROU asset of $133 million (first table above). We use our periodic incremental borrowing rate to discount future contractual payments to their present values. The weighted average lease term and the discount rate relevant to long-term leases were two years and 3% as of December 31, 2020. The remaining annual undiscounted cash flows associated with long-term leases and the reconciliation of these cash flows to the lease liabilities recognized on the consolidated balance sheet is summarized below. (In millions) Operating Lease Obligations 2021 $ 77 2022 44 2023 11 2024 5 2025 4 Thereafter 2 Total undiscounted lease payments $ 143 Less: amount representing interest 6 Total operating lease liabilities $ 137 Less: current portion of long-term lease liability as of December 31, 2020 70 Long-term lease liability as of December 31, 2020 $ 67 Our wholly-owned subsidiary, Marathon E.G. Production Limited, is a lessor for residential housing in Equatorial Guinea, which is occupied by EGHoldings, a related party equity method investee – see Note 24 . The lease was classified as an operating lease and expires in 2024, with a lessee option to extend through 2034. Lease payments are fixed for the entire duration of the agreement at approximately $6 million per year. Our lease income is reported in other income in our consolidated statements of income for all periods presented. The undiscounted cash flows to be received under this lease agreement are summarized below. (In millions) Operating Lease Future Cash Receipts 2021 $ 6 2022 6 2023 6 2024 6 2025 6 Thereafter 53 Total undiscounted cash flows $ 83 In 2018, we signed an agreement with an owner/lessor to construct and lease a new build-to-suit office building in Houston, Texas. The lessor and other participants are providing financing for up to $340 million, to fund the estimated project costs, which was reduced effective August 2020, from $380 million to align with our revised estimate of the project costs.
Leases	Leases Supplemental balance sheet information related to leases was as follows: December 31, (In millions) 2020 2019 Leases: Balance Sheet Location: Right-of-use (“ROU”) asset Other noncurrent assets $ 133 $ 199 Current portion of long-term lease liability Other current liabilities $ 70 $ 101 Long-term lease liability Deferred credits and other liabilities $ 67 $ 107 In determining our ROU assets and long-term lease liabilities, the lease standard requires certain accounting policy decisions, while also providing a number of optional practical expedients for transition accounting. Our accounting policies and the practical expedients utilized are summarized below: • Implemented an accounting policy to not recognize any right-of-use assets and lease liabilities related to short-term leases on the balance sheet. • Implemented an accounting policy to not separate the lease and nonlease components for all asset classes, except for vessels. • Elected the package of practical expedients which allows us to not reassess our prior conclusions regarding the lease identification and lease classification for contracts that commenced or expired prior to the effective date. • Elected the practical expedient pertaining to land easements which allows us to continue accounting for existing agreements under the previous accounting policies as nonlease transactions. Any modifications of existing contracts or new agreements will be assessed under the new lease accounting guidance and may become leases in the future. We enter into various lease agreements to support our operations including drilling rigs, well fracturing equipment, compressors, buildings, aircraft, vessels, vehicles and miscellaneous field equipment. We primarily act as a lessee in these transactions and the majority of our existing leases are classified as either short-term or long-term operating leases. The majority of the drilling rig agreements and all of fracturing equipment agreements are classified as short-term leases based on the noncancellable period for which we have the right to use the equipment and assessment of options present in each agreement. We also incur variable lease costs under these agreements primarily related to chemicals and sand used in fracturing operations or various additional on-demand equipment and labor. The lease costs associated with the drilling rigs and fracturing equipment are primarily capitalized as part of the well costs. Our long-term leases are comprised of compressors, buildings, drilling rigs, aircraft, vessels, vehicles and miscellaneous field equipment. Our lease agreements may require both fixed and variable payments; none of the variable payments are rate or index-based, therefore only fixed payments were considered for recognizing lease liabilities and ROU assets related to long-term leases. Also, based on our election not to separate the lease and nonlease components, fixed payments related to equipment, crew and other nonlease components are included in the initial measurement of lease liabilities and ROU assets for all asset classes, except for vessels. For vessels, the contractual consideration was allocated between lease and nonlease components based on estimates provided by service providers. Our leased assets may be used in joint oil and gas operations with other working interest owners. We recognize lease liabilities and ROU assets only when we are the signatory to a contract as an operator of joint properties. Such lease liabilities and ROU assets are determined based on gross contractual obligations. As we use the leased assets for joint operations, we have the contractual right to recover the other working interest owners’ share of lease costs. As a result, our lease costs are presented on a net basis, reduced for any costs recoverable from other working interest owners. The table below presents our net lease costs for the years ended December 31, 2020 and 2019 with the majority of operating lease costs expensed as incurred, while the majority of the short-term and variable lease costs are capitalized into property, plant and equipment. (In millions) Year Ended December 31, 2020 Year Ended December 31, 2019 Lease costs: Operating lease costs (a) $ 75 $ 84 Short-term lease costs (b) 170 321 Variable lease costs (c) 23 107 Total lease costs $ 268 $ 512 Other information: Cash paid for amounts included in the measurement of operating lease liabilities $ 100 $ 100 ROU assets obtained in exchange for new operating lease liabilities (d) $ 46 $ 293 Reductions to ROU assets resulting from modifications or cancellations of operating leases $ (68) $ — (a) Represents our net share of the ROU asset amortization and the interest expense. (b) Represents our net share of lease costs arising from leases of less than one year but longer than one month that were not included in the lease liability. (c) Represents our net share of variable lease payments that were not included in the lease liability. (d) Represents the cumulative value of ROU assets recognized at lease inception during the year of 2020. This amount is then amortized as we utilize the ROU asset, the net effect of which is the ending ROU asset of $133 million (first table above). We use our periodic incremental borrowing rate to discount future contractual payments to their present values. The weighted average lease term and the discount rate relevant to long-term leases were two years and 3% as of December 31, 2020. The remaining annual undiscounted cash flows associated with long-term leases and the reconciliation of these cash flows to the lease liabilities recognized on the consolidated balance sheet is summarized below. (In millions) Operating Lease Obligations 2021 $ 77 2022 44 2023 11 2024 5 2025 4 Thereafter 2 Total undiscounted lease payments $ 143 Less: amount representing interest 6 Total operating lease liabilities $ 137 Less: current portion of long-term lease liability as of December 31, 2020 70 Long-term lease liability as of December 31, 2020 $ 67 Our wholly-owned subsidiary, Marathon E.G. Production Limited, is a lessor for residential housing in Equatorial Guinea, which is occupied by EGHoldings, a related party equity method investee – see Note 24 . The lease was classified as an operating lease and expires in 2024, with a lessee option to extend through 2034. Lease payments are fixed for the entire duration of the agreement at approximately $6 million per year. Our lease income is reported in other income in our consolidated statements of income for all periods presented. The undiscounted cash flows to be received under this lease agreement are summarized below. (In millions) Operating Lease Future Cash Receipts 2021 $ 6 2022 6 2023 6 2024 6 2025 6 Thereafter 53 Total undiscounted cash flows $ 83 In 2018, we signed an agreement with an owner/lessor to construct and lease a new build-to-suit office building in Houston, Texas. The lessor and other participants are providing financing for up to $340 million, to fund the estimated project costs, which was reduced effective August 2020, from $380 million to align with our revised estimate of the project costs.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2020
Goodwill Disclosure [Abstract]
Goodwill	Goodwill Goodwill is tested for impairment on an annual basis, or between annual tests when events or changes in circumstances indicate the fair value may have been reduced below its carrying value. During the first quarter of 2020, a global pandemic caused a substantial deterioration in the worldwide demand of hydrocarbons. This demand loss resulted in a significant decline in hydrocarbon prices. The commensurate decline in our market capitalization during the first quarter indicated that it was more likely than not that the fair value of the International reporting unit was less than its carrying value. We estimated the fair value of our International reporting unit using a combination of market and income approaches. The market approach referenced observable inputs specific to us and our industry, such as the price of our common equity, our enterprise value and valuation multiples of us and peers from the investor analyst community. The income approach utilized discounted cash flows, which were based on forecasted assumptions. Key assumptions to the income approach include future liquid hydrocarbon and natural gas pricing, estimated quantities of liquid hydrocarbons and natural gas proved and probable reserves, estimated timing of production, discount rates, future capital requirements, operating expenses and tax rates. The assumptions used in the income approach are consistent with those that management uses to make business decisions. These valuation methodologies represent Level 3 fair value measurements. Based on the results, we concluded our goodwill was fully impaired, and recorded an impairment of $95 million in the consolidated statements of income for the first quarter of 2020. The table below displays the allocated beginning goodwill balance of our International segment along with changes in the carrying amount of goodwill for 2020 and 2019: December 31, (In millions) 2020 2019 Beginning balance as of January 1, gross $ 95 $ 97 Less: accumulated impairments — — Beginning balance, net 95 97 Dispositions — (2) Impairment (95) — Ending balance as of December 30, net $ — $ 95

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives See Note 17 for further information regarding the fair value measurement of derivative instruments. See Note 1 for discussion of the types of derivatives we may use and the reasons for them. All of our commodity derivatives and interest rate derivatives are/were subject to enforceable master netting arrangements or similar agreements under which we report net amounts. The following tables present the gross fair values of derivative instruments and the reported net amounts along with where they appear on the consolidated balance sheets. December 31, 2020 (In millions) Asset Liability Net Asset (Liability) Balance Sheet Location Not Designated as Hedges Commodity $ 3 $ 1 $ 2 Other current assets Commodity 7 32 (25) Other current liabilities Interest Rate 10 — 10 Other noncurrent assets Total Not Designated as Hedges $ 20 $ 33 $ (13) Cash Flow Hedges Interest Rate $ 19 $ — $ 19 Other noncurrent assets Interest Rate — 16 (16) Deferred credits and other liabilities Total Designated Hedges $ 19 $ 16 $ 3 Total $ 39 $ 49 $ (10) December 31, 2019 (In millions) Asset Liability Net Asset (Liability) Balance Sheet Location Not Designated as Hedges Commodity $ 9 $ 1 $ 8 Other current assets Commodity 1 — 1 Other noncurrent assets Commodity — 5 (5) Other current liabilities Total Not Designated as Hedges $ 10 $ 6 $ 4 Cash Flow Hedges Interest Rate $ 2 $ — $ 2 Other noncurrent assets Total Designated Hedges $ 2 $ — $ 2 Total $ 12 $ 6 $ 6 Derivatives Not Designated as Hedges Commodity Derivatives We have entered into multiple crude oil, natural gas and NGL derivatives indexed to the respective indices as noted in the table below, related to a portion of our forecasted United States sales through 2021. These derivatives consist of three-way collars, two-way collars, fixed price swaps, basis swaps and NYMEX roll basis swaps. Three-way collars consist of a sold call (ceiling), a purchased put (floor) and a sold put. The ceiling price is the maximum we will receive for the contract volumes; the floor is the minimum price we will receive, unless the market price falls below the sold put strike price. In this case, we receive the NYMEX WTI price plus the difference between the floor and the sold put price. Two-way collars only consist of a sold call (ceiling) and a purchased put (floor). These crude oil, natural gas and NGL derivatives were not designated as hedges. The following table sets forth outstanding derivative contracts as of December 31, 2020 and the weighted average prices for those contracts: 2021 First Quarter Second Quarter Third Quarter Fourth Quarter Crude Oil NYMEX WTI Three-Way Collars Volume (Bbls/day) — 10,000 — — Weighted average price per Bbl: Ceiling $ — $ 58.72 $ — $ — Floor $ — $ 37.00 $ — $ — Sold put $ — $ 27.00 $ — $ — NYMEX WTI Two-Way Collars Volume (Bbls/day) 90,000 50,000 30,000 30,000 Weighted average price per Bbl: Ceiling $ 51.86 $ 52.98 $ 51.54 $ 51.54 Floor $ 35.44 $ 35.80 $ 35.67 $ 35.67 Basis Swaps - NYMEX WTI / ICE Brent (a) Volume (Bbls/day) 3,278 — — — Weighted average price per Bbl $ (7.24) $ — $ — $ — Basis Swaps - NYMEX WTI / UHC (b) Volume (Bbls/day) 14,000 14,000 — — Weighted average price per Bbl $ (1.80) $ (1.80) $ — $ — NYMEX Roll Basis Swaps Volume (Bbls/day) 50,000 50,000 $ — $ — Weighted average price per Bbl $ (0.13) $ (0.13) $ — $ — Natural Gas Henry Hub (“HH”) Two-Way Collars Volume (MMBtu/day) 250,000 200,000 200,000 200,000 Weighted average price per MMBtu: Ceiling $ 3.14 $ 3.05 $ 3.05 $ 3.05 Floor $ 2.52 $ 2.50 $ 2.50 $ 2.50 HH Fixed Price Swaps Volume (MMBtu/day) 50,000 50,000 50,000 50,000 Weighted average price per MMBtu $ 2.88 $ 2.88 $ 2.88 $ 2.88 NGL Fixed Price Propane Swaps (c) Volume (Bbls/day) 5,000 5,000 5,000 5,000 Weighted average price per Bbl $ 23.19 $ 23.19 $ 23.19 $ 23.19 (a) The basis differential price is indexed against Intercontinental Exchange (“ICE”) Brent and NYMEX WTI. (b) The basis differential price is indexed against U.S. Sweet Clearbrook (“UHC”) and NYMEX WTI. (c) The fixed price propane swap is priced at Mont Belvieu Spot Gas Liquids Prices: Non-TET Propane. The following table sets forth outstanding derivative contracts entered into between January 1, 2021 and February 15, 2021, and the weighted average prices for those contracts. 2021 First Quarter Second Quarter Third Quarter Fourth Quarter Crude Oil Basis Swaps - NYMEX WTI / UHC (a) Volume (Bbls/day) 344 1,000 — — Weighted average price per Bbl $ (1.80) $ (1.80) $ — $ — NYMEX WTI Three-Way Collars Volume (Bbls/day) — 30,000 10,000 — Weighted average price per Bbl: Ceiling $ — $ 62.36 $ 65.18 $ — Floor $ — $ 40.67 $ 45.00 $ — Sold put $ — $ 30.67 $ 35.00 $ — WTI Fixed Price Swaps Volume (Bbls/day) 20,000 — — — Weighted average price per Bbl $ 50.35 $ — $ — $ — (a) The basis differential price is indexed against U.S. Sweet Clearbrook (“UHC”) and NYMEX WTI. The mark-to-market impact and settlement of these commodity derivative instruments appears in the table below and is reflected in net gain (loss) on commodity derivatives in the consolidated statements of income. Year Ended December 31, (In millions) 2020 2019 2018 Unrealized mark-to-market gain (loss) $ (27) $ (124) $ 267 Net settlements of commodity derivative instruments $ 143 $ 52 $ (281) Interest Rate Swaps During 2020, we entered into forward starting interest rate swaps to hedge the variations in cash flows as a result of fluctuations in the London Interbank Offered Rate (“LIBOR”) benchmark interest rate related to forecasted interest payments of a future d ebt issuance in 2022. Each respective derivative contract can be tied to an anticipated underlying dollar notional amount. During the third quarter of 2020, we de-designated these forward starting interest rate swaps previously designated as cash flow hedges. At December 31, 2020, accumulated other comprehensive income included a net deferred loss of $2 million related to the de-designated forward starting interest rate swaps previously designated as cash flow hedges. No portion of this amount has been reclassified from accumulated other comprehensive income as of December 31, 2020. We expect to reclassify this amount into earnings as an adjustment to net interest and other upon the occurrence of the forecasted transactions. The following table presents, by maturity date, information about our de-designated forward starting interest rate swap agreements, including the rate. December 31, 2020 December 31, 2019 Maturity Date Aggregate Notional Amount (in millions) Weighted Average, LIBOR Aggregate Notional Amount (in millions) Weighted Average, LIBOR November 1, 2022 $ 500 0.99 % $ — — % The following table sets forth the net impact of the forward starting interest rate swap derivatives de-designated as cash flow hedges on other comprehensive income (loss). (In millions) Year Ended December 31, 2020 Interest Rate Swaps Beginning balance $ — Change in fair value recognized in other comprehensive income (loss) (2) Ending balance $ (2) Derivatives Designated as Cash Flow Hedges During 2020, we entered into forward starting interest rate swaps with a notional amount of $350 million to hedge variations in cash flows arising from fluctuations in the LIBOR benchmark interest rate related to forecasted interest payments of a future debt issuance in 2025. We expect to refinance these debt maturities in 2025. The swaps will terminate on or prior to the refinancing of the debt and the final value will be reclassified from accumulated other comprehensive income into earnings with each future interest payment. During 2019, we entered into forward starting interest rate swaps with a total notional amount of $320 million to hedge variations in cash flows related to the 1-month London Interbank Offered Rate (“LIBOR”) component of future lease payments of our future Houston office. These swaps will settle monthly on the same day the lease payment is made with the first swap settlement occurring in January 2022. We expect the first lease payment to commence sometime in the period from December 2021 to May 2022. The last swap will mature in September 2026. See Note 14 for further details regarding the lease of the new Houston office. The following table presents information about our interest rate swap agreements, including the weighted average LIBOR-based, fixed rate. December 31, 2020 December 31, 2019 Maturity Date Aggregate Notional Amount (in millions) Weighted Average, LIBOR Aggregate Notional Amount (in millions) Weighted Average, LIBOR June 1, 2025 $ 350 0.95 % $ — — % September 9, 2026 $ 320 1.51 % $ 320 1.51 % At December 31, 2020, accumulated other comprehensive income included deferred gains of $2 million related to forward starting interest rate swaps designated as cash flow hedges. No amounts related to these swaps are expected to impact the consolidated statements of income in the next 12 months.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Fair Values – Recurring The following tables present assets and liabilities accounted for at fair value on a recurring basis as of December 31, 2020 and 2019 by hierarchy level. December 31, 2020 (In millions) Level 1 Level 2 Level 3 Total Derivative instruments, assets Interest rate - not designated as cash flow hedges $ — $ 10 $ — $ 10 Interest rate - designated as cash flow hedges — 19 — 19 Derivative instruments, assets $ — $ 29 $ — $ 29 Derivative instruments, liabilities Commodity (a) $ — $ (23) $ — $ (23) Interest rate - designated as cash flow hedges — (16) — (16) Derivative instruments, liabilities $ — $ (39) $ — $ (39) Total $ — $ (10) $ — $ (10) December 31, 2019 (In millions) Level 1 Level 2 Level 3 Total Derivative instruments, assets Commodity (a) $ — $ 7 $ — $ 7 Interest rate - designated as cash flow hedges — 2 — 2 Derivative instruments, assets $ — $ 9 $ — $ 9 Derivative instruments, liabilities Commodity (a) $ (3) $ — $ — $ (3) Derivative instruments, liabilities $ (3) $ — $ — $ (3) Total $ (3) $ 9 $ — $ 6 (a) Derivative instruments are recorded on a net basis in our consolidated balance sheet (See Note 16 ). Commodity derivatives include three-way collars, two-way collars, fixed price swaps, basis swaps and NYMEX roll basis swaps. These instruments are measured at fair value using either a Black-Scholes or a modified Black-Scholes Model. For swaps, inputs to the models include only commodity prices and interest rates and are categorized as Level 1 because all assumptions and inputs are observable in active markets throughout the term of the instruments. For three-way collars and two-way collars, inputs to the models include commodity prices, and implied volatility and are categorized as Level 2 because predominantly all assumptions and inputs are observable in active markets throughout the term of the instruments. The forward starting interest rate swaps are measured at fair value with a market approach using actionable broker quotes, which are Level 2 inputs. See Note 16 for details on the forward starting interest swaps. Fair Values – Goodwill See Note 15 for detail information relating to goodwill. Fair Values – Nonrecurring See Note 5 and Note 12 for detail on our fair values for nonrecurring items, such as impairments. Fair Values – Financial Instruments Our current assets and liabilities include financial instruments, the most significant of which are receivables, the current portion of our long-term debt and payables. We believe the carrying values of our receivables 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 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, payables and derivative financial instruments, and their reported fair values by individual balance sheet line item at December 31, 2020 and 2019. December 31, 2020 2019 (In millions) Fair Carrying Fair Carrying Financial assets Current assets $ 4 $ 4 $ 4 $ 4 Other noncurrent assets 24 37 26 38 Total financial assets $ 28 $ 41 $ 30 $ 42 Financial liabilities Other current liabilities $ 72 $ 103 $ 62 $ 90 Long-term debt, including current portion (a) 6,077 5,431 6,174 5,529 Deferred credits and other liabilities 103 76 99 86 Total financial liabilities $ 6,252 $ 5,610 $ 6,335 $ 5,705 (a) Excludes debt issuance costs. Fair values of our notes receivable and 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.

Debt

Debt	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt	Debt Revolving Credit Facility As of December 31, 2020, we had no borrowings on our $3.0 billion unsecured revolving credit facility (“Credit Facility”). The Credit Facility matures on May 28, 2023 and we retain the ability to request two one-year extensions of the maturity date. The Credit Facility includes a single financial covenant requiring that our ratio of total debt to total capitalization not exceed 65% as of the last day of each fiscal quarter. This covenant calculation was modified in December 2020, when we executed the fifth amendment to our credit facility. The primary changes resulting from this amendment are (i) a modification to the debt to total capitalization covenant calculation that permits an add-back to shareholders’ equity for certain non-cash write-downs, (ii) the addition of certain customary events of default, including a cross payment event of default and (iii) certain restrictions on the incurrence of subsidiary indebtedness. Under the amended definition, our total debt to total capitalization ratio was 26% at December 31, 2020. If an event of default occurs, the lenders holding more than half of the commitments may terminate the commitments under the Credit Facility and require the immediate repayment of all outstanding borrowings and the cash collateralization of all outstanding letters of credit under the Credit Facility. Long-term debt The following table details our long-term debt: December 31, (In millions) 2020 2019 Senior unsecured notes: 2.800% notes due 2022 (a) $ 500 $ 1,000 9.375% notes due 2022 (b) 32 32 Series A notes due 2022 (b) 3 3 8.500% notes due 2023 (b) 70 70 8.125% notes due 2023 (b) 131 131 3.850% notes due 2025 (a) 900 900 4.400% notes due 2027 (a) 1,000 1,000 6.800% notes due 2032 (a) 550 550 6.600% notes due 2037 (a) 750 750 5.200% notes due 2045 (a) 500 500 Bonds: (c) 2.00% bonds due 2037 200 200 2.10% bonds due 2037 200 200 2.20% bonds due 2037 200 200 2.125% bonds due 2037 200 — 2.375% bonds due 2037 200 — Total (b) 5,436 5,536 Unamortized discount (5) (7) Unamortized debt issuance cost (27) (28) Total long-term debt $ 5,404 $ 5,501 (a) These notes contain a make-whole provision allowing us to repay the debt at a premium to market price. (b) In the event of a change in control, as defined in the related agreements, debt obligations totaling $236 million at December 31, 2020 may be declared immediately due and payable. (c) Mandatory purchase dates for these bonds: April 1, 2023 for the 2.00% bonds; July 1, 2024 for the 2.10% bonds; July 1, 2026 for the 2.20% bonds; July 1, 2024 for the 2.125% bonds; and July 1, 2026 for the 2.375% bonds. Subsequent to the various mandatory purchase dates, we will also have the right to convert and remarket these any time up to the 2037 maturity date. The following table shows future debt payments: (In millions) 2021 $ — 2022 535 2023 401 2024 400 2025 900 Thereafter 3,200 Total long-term debt, including current portion $ 5,436 Debt Remarketing On August 18, 2020, we closed a $400 million remarketing to investors of sub-series B bonds which are part of the $1 billion St. John the Baptist, State of Louisiana revenue refunding bonds originally issued and purchased in December 2017 . Debt Repurchases In October 2020, we repurchased $500 million of our 2.8% Senior Notes du e 2022 (“2022 Notes”).

Incentive Based Compensation

Incentive Based Compensation	12 Months Ended
	Dec. 31, 2020
Incentive Based Compensation Plans [Abstract]
Incentive Based Compensation	Incentive Based Compensation Description of stock-based compensation plans – The Marathon Oil Corporation 2019 Incentive Compensation Plan (the “2019 Plan”) was approved by our stockholders in May 2019 and authorizes the Compensation Committee of the Board of Directors to grant stock options, stock appreciation rights (“SARs”), stock awards (including restricted stock and restricted stock unit awards), performance unit awards and cash awards to employees. The 2019 Plan also allows us to provide equity compensation to our non-employee directors. No more than 27.9 million shares of our common stock may be issued under the 2019 Plan. In connection with the granting of an award under the 2019 Plan, the number of shares available for issuance under the 2019 Plan will be reduced by one share for each share of our common stock in respect of which the award is granted, except the awards that by their terms do not permit settlement in shares of our common stock will not reduce the number of shares of common stock available for issuance under the 2019 Plan. Shares subject to awards under the 2019 Plan that are forfeited, terminated or expire unexercised become available for future grants. In addition, the number of shares of our common stock reserved for issuance under the 2019 Plan will not be increased by shares tendered to satisfy the purchase price of an award, exchanged for other awards or withheld to satisfy tax withholding obligations. Shares issued as a result of awards granted under the 2019 Plan are generally funded out of common stock held in treasury, except to the extent there are insufficient treasury shares, in which case new common shares are issued. After approval of the 2019 Plan, no new grants were or will be made from any prior plans. Any awards previously granted under any prior plans shall continue to be exercisable in accordance with their original terms and conditions. Stock-based awards under the plans Stock options – We grant stock options under the 2019 Plan. Our stock options represent the right to purchase shares of our common stock at its fair market value on the date of grant. In general, our stock options vest ratably over a three-year period and have a maximum term of ten years from the date they are granted. SARs – At December 31, 2020, there are no SARs outstanding. Restricted stock – We grant restricted stock under the 2019 Plan. The restricted stock awards granted to officers generally vest three years from the date of grant, contingent on the recipient’s continued employment. We also grant restricted stock to certain non-officer employees based on their performance within certain guidelines and for retention purposes. The restricted stock awards to non-officers generally vest ratably over a three-year period, contingent on the recipient’s continued employment. Prior to vesting, all restricted stock recipients have the right to vote such stock and receive dividends thereon. The non-vested shares of restricted stock are not transferable and are held by our transfer agent. Stock-based performance units – We grant stock-based performance units to officers under the 2019 Plan. At the grant date, each unit represents the value of one share of our common stock. These units are settled in shares, and the number of shares of our common stock to be paid is based on the vesting percentage, which can be from zero to 200% based on performance achieved over a three-year performance period, and as determined by the Compensation Committee of the Board of Directors. 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 our Board of Directors. Dividend equivalents may accrue during the performance period and would be paid in cash at the end of the performance period based on the amount of dividends credited generally over the performance period on shares of our common stock that represent the value of the units granted multiplied by the vesting percentage. Restricted stock units – We maintain an equity compensation program for our non-employee directors. All non-employee directors receive annual grants of common stock units. Any units granted prior to 2012 must be held until completion of board service, at which time the non-employee director will receive common shares. For units granted between 2012 and 2016, common shares will generally vest following completion of board service or three years from the date of grant, whichever is earlier. For awards issued in 2017 and later, directors may elect to defer settlement of their common stock units until after they cease serving on the Board. Absent such an election to defer, common shares will vest upon the earlier of three years from the date of grant or completion of board service. Under the 2019 Plan, we also grant restricted stock units to officers, which generally vest three years from the date of the grant and restricted stock units to certain non-officer employees, which generally vest ratably over a three-year period. Both awards are contingent on the recipient’s continued employment. Grants of restricted stock units to these non-officer employees are generally based on their performance and for retention purposes. Common shares will be issued for these restricted stock units after vesting. Prior to vesting, recipients of restricted stock units typically receive dividend equivalent payments, but they may not vote. Total stock-based compensation expense – Total employee stock-based compensation expense was $55 million, $60 million and $53 million in 2020, 2019 and 2018. Due to the full valuation allowance on our net federal deferred tax assets, we recognized no tax benefit during these years. Cash received upon exercise of stock option awards was less than $1 million in 2020 and $1 million and $26 million in 2019 and 2018, respectively. There were no tax benefits recognized for deductions for stock awards settled during 2020, 2019 and 2018. Stock option awards – During 2020, 2019 and 2018 we granted stock option awards to officer employees. The weighted average grant date fair value of these awards was based on the following weighted average Black-Scholes assumptions: 2020 2019 2018 Exercise price per share $ 10.47 $ 16.79 $ 14.52 Expected annual dividend yield 1.9 % 1.2 % 1.4 % Expected life in years 6.14 5.82 6.45 Expected volatility 44 % 43 % 43 % Risk-free interest rate 1.5 % 2.5 % 2.8 % Weighted average grant date fair value of stock option awards granted $ 3.82 $ 6.62 $ 5.83 The following is a summary of stock option award activity in 2020. Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in millions) Outstanding at beginning of year 5,659,731 $ 23.55 Granted 1,132,808 $ 10.47 Exercised (52,333) $ 7.22 Canceled (725,951) $ 25.44 Outstanding at end of year 6,014,255 $ 21.00 5 years Exercisable at end of year 4,219,975 $ 24.63 4 years $ — Expected to vest 1,766,804 $ 12.50 9 years $ — The intrinsic value of stock option awards exercised during 2018 was $13 million while it was immaterial during 2020 and 2019. As of December 31, 2020, unrecognized compensation cost related to stock option awards was $4 million, which is expected to be recognized over a weighted average period of 1 year. Restricted stock awards and restricted stock units – The following is a summary of restricted stock and restricted stock unit award activity in 2020. Awards Weighted Average Grant Date Fair Value Unvested at beginning of year 7,174,386 $ 15.88 Granted 5,390,960 $ 8.50 Vested (3,127,762) $ 15.76 Canceled (1,585,830) $ 11.65 Unvested at end of year 7,851,754 $ 11.72 The vesting date fair value of restricted stock awards which vested during 2020, 2019 and 2018 was $49 million, $48 million and $48 million. The weighted average grant date fair value of restricted stock awards was $11.72, $15.88 and $14.04 for awards unvested at December 31, 2020, 2019 and 2018. As of December 31, 2020 there was $48 million of unrecognized compensation cost related to restricted stock awards which is expected to be recognized over a weighted average period of 1 year. Stock-based performance unit awards – During 2020, 2019 and 2018 we granted 1,038,676, 656,636 and 754,140 stock-based performance unit awards to officers. At December 31, 2020, there were 1,658,088 units outstanding. Total stock-based performance unit awards expense was $5 million, $7 million and $13 million in 2020, 2019 and 2018. The key assumptions used in the Monte Carlo simulation to determine the fair value of stock-based performance units granted in 2020, 2019 and 2018 were: 2020 (a) 2019 (a) 2018 Valuation date stock price $ 10.47 $ 16.79 $ 13.69 Expected annual dividend yield 1.9 % 1.2 % 1.5 % Expected volatility 39 % 43 % 41 % Risk-free interest rate 1.4 % 2.5 % 1.5 % Fair value of stock-based performance units outstanding $ 10.55 $ 20.66 $ 17.29

Defined Benefit Postretirement

Defined Benefit Postretirement Plans and Defined Contribution Plan	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Defined Benefit Postretirement Plans and Defined Contribution Plan	Defined Benefit Postretirement Plans and Defined Contribution Plan We have noncontributory defined benefit pension plans covering substantially all domestic employees. Benefits under these plans are based on plan provisions specific to each plan. We also had a noncontributory defined benefit pension plan covering eligible U.K. employees that was transferred to the buyer in connection with the sale of our U.K. business during 2019. See Note 5 for further information on this disposition. During the year ended December 31, 2019, we reclassified $20 million from accumulated other comprehensive income to pension assets upon remeasurement of the plan. We also have plans for other postretirement benefits covering our U.S. employees. Health care benefits are provided up to age 65 through comprehensive hospital, surgical and major medical benefit provisions subject to various cost-sharing features. Post-65 retiree health care benefits have been provided to certain U.S. employees on a defined contribution basis; this program terminated effective as of December 31, 2020. Life insurance benefits are provided to certain retiree beneficiaries. These other postretirement benefits are not funded in advance. Employees hired after 2016 are not eligible for any postretirement health care or life insurance benefits. Obligations and funded status – The following summarizes the obligations and funded status for our defined benefit pension and other postretirement plans. Pension Benefits Other Benefits 2020 2019 2020 2019 (In millions) U.S. Int’l U.S. Int’l U.S. U.S. Accumulated benefit obligation $ 298 $ — $ 343 $ — $ 80 $ 89 Change in pension benefit obligations: Beginning balance $ 354 $ — $ 326 $ 511 $ 89 $ 96 Service cost 19 — 19 — 1 1 Interest cost 9 — 12 8 2 3 Plan amendment — — — — — — Divestiture (a) — — — (549) — — Actuarial loss 36 — 48 36 4 9 Foreign currency exchange rate changes — — — 6 — — Gain due to curtailment (a) (1) — — — — — Settlements paid (104) — (45) — — — Benefits paid (5) — (6) (12) (16) (20) Ending balance $ 308 $ — $ 354 $ — $ 80 $ 89 Change in fair value of plan assets: Beginning balance $ 236 $ — $ 203 $ 594 $ — $ — Actual return on plan assets 18 — 44 68 — — Employer contributions 49 — 40 8 16 20 Foreign currency exchange rate changes — — — 8 — — Divestiture (b) — — — (666) — — Settlements paid (104) — (45) — — — Benefits paid (5) — (6) (12) (16) (20) Ending balance $ 194 $ — $ 236 $ — $ — $ — Funded status of plans at December 31 $ (114) $ — $ (118) $ — $ (80) $ (89) Amounts recognized in the consolidated balance sheets: Noncurrent assets $ — $ — $ — $ — $ — $ — Current liabilities (4) — (6) — (10) (18) Noncurrent liabilities (110) — (112) — (70) (71) Accrued benefit cost $ (114) $ — $ (118) $ — $ (80) $ (89) Pretax amounts in accumulated other comprehensive loss: Net loss $ 72 $ — $ 85 $ — $ 24 $ 23 Prior service credit (19) — (29) — (97) (129) (a) Related to workforce reductions, which reduced the future expected years of service for employees participating in the plans. (b) Refer to Note 5 for further information on the sale of our U.K. business. The pension and postretirement plans each experienced net actuarial losses in 2020. A decrease in discount rate used to measure the plans, which increased their respective benefit obligations, was the primary source of the actuarial losses. Components of net periodic benefit costs and other comprehensive (income) loss – The following summarizes the net periodic benefit costs and the amounts recognized as other comprehensive (income) loss for our defined benefit pension and other postretirement plans. Pension Benefits Other Benefits Year Ended December 31, Year Ended December 31, 2020 2019 2018 2020 2019 2018 (In millions) U.S. U.S. Int’l U.S. Int’l U.S. U.S. U.S. Components of net periodic benefit costs: Service cost $ 19 $ 19 $ — $ 18 $ — $ 1 $ 1 $ 2 Interest cost 9 12 8 12 14 2 3 7 Expected return on plan assets (11) (10) (11) (11) (24) — — — Amortization: - prior service credit (6) (7) — (10) — (18) (19) (8) - actuarial loss 9 7 — 11 — 2 1 1 Net settlement loss (a) 30 12 — 18 3 — — — Net curtailment gain (b) (3) — — — — (14) — — Net periodic benefit cost (credit) (c) $ 47 $ 33 $ (3) $ 38 $ (7) $ (27) $ (14) $ 2 Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax): Actuarial loss (gain) $ 27 $ 14 $ (21) $ (4) $ 8 $ 4 $ 9 $ (15) Settlement loss and amortization of actuarial gain (loss) (40) (19) (41) (29) (3) (2) (1) (1) Prior service cost (credit) — — — — 3 — — (99) Curtailment gain and amortization of prior service credit (cost) 10 7 (6) 10 — 32 19 8 Total recognized in other comprehensive (income) loss $ (3) $ 2 $ (68) $ (23) $ 8 $ 34 $ 27 $ (107) Total recognized in net periodic benefit cost and other comprehensive (income) loss $ 44 $ 35 $ (71) $ 15 $ 1 $ 7 $ 13 $ (105) (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 costs for that year. (b) Related to workforce reductions, which reduced the future expected years of service for employees participating in the plans. (c) Net periodic benefit costs (credits) reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years. Plan assumptions – The following summarizes the assumptions used to determine the benefit obligations at December 31, and net periodic benefit cost for the defined benefit pension and other postretirement plans for 2020, 2019 and 2018. Pension Benefits Other Benefits 2020 2019 2018 2020 2019 2018 (In millions) U.S. U.S. U.S. Int’l U.S. U.S. U.S. Weighted average assumptions used to determine benefit obligation: Discount rate 2.52 % 3.13 % 4.26 % 2.90 % 2.02 % 2.91 % 4.09 % Rate of compensation increase (a) 0.50 % 4.50 % 4.00 % — % 0.50 % 4.50 % 4.00 % Cash balance interest crediting 3.00 % 3.00 % 3.26 % — % — % — % — % Weighted average assumptions used to determine net periodic benefit cost: Discount rate 2.90 % 3.70 % 3.88 % 2.50 % 2.63 % 4.09 % 3.54 % Expected long-term return on plan assets 6.00 % 6.25 % 6.50 % 3.70 % — % — % — % Rate of compensation increase 4.50 % 4.00 % 4.00 % — % 4.50 % 4.00 % 4.00 % Cash balance interest crediting 3.00 % 3.00 % 3.00 % — % — % — % — % (a) The assumed rate of compensation increase is 0.50% for the year 2021 and 4.50% for future years. Expected long-term return on plan assets – The expected long-term return on plan assets assumption for our U.S. pension plan is determined based on an internally developed asset rate-of-return modeling tool which utilizes underlying assumptions based on actual returns by asset category and inflation and takes into account our U.S. pension plan’s asset allocation. The expected return for each asset category is then weighted based on the actual asset allocation to develop the overall expected long-term return on plan assets assumption. Assumed weighted average health care cost trend rates Employer provided subsidies for post-65 retiree health care coverage were frozen effective January 1, 2017 at January 1, 2016 established amount levels. Company contributions are funded to a Health Reimbursement Account on the retiree’s behalf to subsidize the retiree’s cost of obtaining health care benefits through a private exchange (the “post-65 retiree health benefits”). In the fourth quarter of 2018, we terminated the post-65 retiree health benefits effective as of December 31, 2020. The post-65 retiree health benefits will no longer be provided after that date. In addition, the pre-65 retiree medical coverage subsidy was frozen as of January 1, 2019, and the ability for retirees to opt in and out of this coverage, as well as pre-65 retiree dental and vision coverage, was also eliminated. Retirees must enroll in connection with retirement for such coverage, or they lose eligibility. These plan changes reduced our retiree medical benefit obligation by approximately $99 million at December 31, 2018. Plan investment policies and strategies – The investment policies for our U.S. pension plan assets reflect the funded status of the plan and expectations regarding our future ability to make further contributions. Long-term investment goals are to: (1) manage the assets in accordance with applicable legal requirements; (2) produce investment returns which meet or exceed the rates of return achievable in the capital markets while maintaining the risk parameters set by the plan’s investment committees and protecting the assets from any erosion of purchasing power; and (3) position the portfolios with a long-term risk/return orientation. Investment performance and risk is measured and monitored on an ongoing basis through quarterly investment meetings and periodic asset and liability studies. U.S. plan – The plan’s current targeted asset allocation is comprised of 55% equity securities and 45% other fixed income securities. Over time, as the plan’s funded ratio (as defined by the investment policy) improves, in order to reduce volatility in returns and to better match the plan’s liabilities, the allocation to equity securities will decrease while the amount allocated to fixed income securities will increase. The plan’s assets are managed by a third-party investment manager. International plan – As mentioned above, the plan covering eligible U.K. employees that was transferred to the buyer in connection with the sale of our U.K. business during 2019. Fair value measurements – Plan assets are measured at fair value. The following provides a description of the valuation techniques employed for each major plan asset class at December 31, 2020 and 2019. Cash and cash equivalents – Cash and cash equivalents are valued using a market approach and are considered Level 1. Equity securities – Investments in common stock are valued using a market approach at the closing price reported in an active market and are therefore considered Level 1. Private equity investments include interests in limited partnerships which are valued based on the sum of the estimated fair values of the investments held by each partnership, determined using a combination of market, income and cost approaches, plus working capital, adjusted for liabilities, currency translation and estimated performance incentives. These private equity investments are considered Level 3. Fixed income securities – Fixed income securities are valued using a market approach. U.S. treasury notes and exchange traded funds (“ETFs”) are valued at the closing price reported in an active market and are considered Level 1. Corporate bonds, private placements and GNMA/FNMA/FHLMC pools are valued using calculated yield curves created by models that incorporate various market factors. Primarily investments are held in U.S. and non-U.S. corporate bonds in diverse industries and are considered Level 2. Forward contracts included under government securities are traded in the over-the-counter market and occur between two parties only with no intermediary. The details of each contract such as trade size, price and maturity are tailored to each security and negotiated between the two parties, as such, these investments are considered Level 3. Other fixed income investments include zero coupon and interest rate swaps. Other – Other investments are comprised of an unallocated annuity contract, two limited liability companies and real estate. All are considered Level 3, as significant inputs to determine fair value are unobservable. Commingled funds – The investment in the commingled funds are valued using the net asset value of units held as a practical expedient. The commingled funds consist of equity and fixed income portfolios with underlying investments held in U.S. and non-U.S. securities. The following tables present the fair values of our defined benefit pension plan’s assets, by level within the fair value hierarchy, as of December 31, 2020 and 2019. December 31, 2020 (In millions) Level 1 Level 2 Level 3 Total Equity securities: Common stock $ 61 $ — $ — $ 61 Private equity — — 8 8 Other — — 18 18 Total investments, at fair value 61 — 26 87 Commingled funds (a) — — — 107 Total investments $ 61 $ — $ 26 $ 194 December 31, 2019 (In millions) Level 1 Level 2 Level 3 Total U.S. U.S. U.S. U.S. Cash and cash equivalents (b) $ (7) $ — $ — $ (7) Equity securities: Common stock 75 — — 75 Private equity — — 10 10 Fixed income securities: Corporate — 2 — 2 Exchange traded funds 3 — — 3 Government 31 11 5 47 Other — — 18 18 Total investments, at fair value 102 13 33 148 Commingled funds (a) — — — 88 Total investments $ 102 $ 13 $ 33 $ 236 (a) After the adoption of the FASB update for the fair value hierarchy, we separately report the investments for which fair value was measured using the net asset value per share as a practical expedient. Amounts presented in this table are intended to reconcile the fair value hierarchy to the pension plan assets. (b) The negative cash balance was due to the timing of when investment trades occur and when they settle. The activity during the year ended December 31, 2020 and 2019, for the assets using Level 3 fair value measurements was immaterial. Cash flows Estimated future benefit payments – The following gross benefit payments, which were estimated based on actuarial assumptions applied at December 31, 2020 and reflect expected future services, as appropriate, are to be paid in the years indicated. (In millions) Pension Benefits Other Benefits 2021 $ 31 $ 10 2022 28 9 2023 27 8 2024 25 7 2025 23 6 2026 through 2030 $ 104 $ 23 Contributions to defined benefit plans – We expect to make contributions to the funded pension plan of up to $40 million in 2021. Cash contributions to be paid from our general assets for the unfunded portion of our pension and postretirement plans are expected to be approximately $3 million and $10 million in 2021. Contributions to defined contribution plans – We contribute to several defined contribution plans for eligible employees. Contributions to these plans totaled $13 million, $18 million and $22 million in 2020, 2019 and 2018.

Reclassifications Out of Accumu

Reclassifications Out of Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Reclassifications Out of Accumulated Other Comprehensive Income (Loss)	Reclassifications Out of Accumulated Other Comprehensive Income (Loss) The following table presents a summary of amounts reclassified from accumulated other comprehensive income (loss): Year Ended December 31, (In millions) 2020 2019 Income Statement Line Postretirement and postemployment plans Amortization of prior service credit $ 24 $ 26 Amortization of actuarial loss (11) (8) Net settlement loss (30) (12) Net curtailment gain 17 — — 6 Other net periodic benefit credits Other U.K pension plan transferred to buyer (a)(b) — 83 Foreign currency translation adjustment related to sale of U.K. business (b) — 30 Income taxes related to sale of U.K. business (b) — (45) — 68 Net gain on disposal of assets Other insignificant items — 1 Net interest and other Total reclassifications to expense, net of tax (c) $ — $ 75 Net income (a) See Note 20 for detail on the U.K. pension plan. (b) See Note 5 for detail on the U.K. disposition. (c) During 2020 and 2019 we had a full valuation allowance on net federal deferred tax assets in the U.S. and as such, there is no tax impact to our postretirement and postemployment plans other than on the sale of the U.K. business.

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Year Ended December 31, (In millions) 2020 2019 2018 Included in operating activities: Interest paid, net of amounts capitalized $ 251 $ 253 $ 255 Income taxes paid to (received from) taxing authorities, net of refunds (a) (51) 73 287 Noncash investing activities: Increase (decrease) in asset retirement costs $ — $ 80 $ (183) Asset retirement obligations assumed by buyer (b) — 1,082 82 (a) 2020, 2019 and 2018 includes $94 million, $90 million and $37 million, related to tax refunds. (b) In 2019, our dispositions include the sale of the Droshky field (Gulf of Mexico), the sale of our non-operated interest in the Atrush block in Kurdistan and the sale of our U.K. business. See Note 5 for further detail on dispositions. Other noncash investing activities include accrued capital expenditures as of December 31, 2020, 2019 and 2018 of $95 million, $288 million and $250 million.

Other Items

Other Items	12 Months Ended
	Dec. 31, 2020
Interest and Other Income [Abstract]
Other Items	Other Items Net interest and other Year Ended December 31, (In millions) 2020 2019 2018 Interest: Interest income $ 5 $ 25 $ 32 Interest expense (279) (280) (280) Income on interest rate swaps 12 — — Total interest (262) (255) (248) Other: Net foreign currency gain — 4 9 Other 6 7 13 Total other 6 11 22 Net interest and other $ (256) $ (244) $ (226) Foreign currency – Aggregate foreign currency gains were included in the consolidated statements of income as follows: Year Ended December 31, (In millions) 2020 2019 2018 Net interest and other $ — $ 4 $ 9 Provision for income taxes — 2 10 Aggregate foreign currency gains $ — $ 6 $ 19

Equity Method Investments

Equity Method Investments	12 Months Ended
	Dec. 31, 2020
Equity Method Investments Disclosure [Abstract]
Equity Method Investments	Equity Method Investments During 2020, 2019 and 2018 our equity method investees were considered related parties and included: • EGHoldings, in which we have a 60% noncontrolling interest. EGHoldings is engaged in LNG production activity. • Alba Plant LLC, in which we have a 52% noncontrolling interest. Alba Plant LLC processes LPG. • AMPCO, in which we have a 45% noncontrolling interest. AMPCO is engaged in methanol production activity. Our equity method investments are summarized in the following table: Ownership as of December 31, (In millions) December 31, 2020 2020 2019 EGHoldings 60% $ 113 $ 310 Alba Plant LLC 52% 168 163 AMPCO 45% 166 190 Total $ 447 $ 663 Dividends and partnership distributions received from equity method investees (excluding distributions that represented a return of capital previously contributed) were $49 million in 2020, $105 million in 2019 and $270 million in 2018. During the year ended December 31, 2020, we recorded impairments of $171 million to an investment in an equity method investee, which was reflected in income (loss) from equity method investments in our consolidated statements of income. See Note 1 2 to the consolidated financial statements for further information on the equity method investee impairment. Summarized financial information for equity method investees is as follows: (In millions) 2020 2019 2018 Income data – year: Revenues and other income $ 586 $ 832 $ 1,269 Income (loss) from operations 16 250 588 Net income (loss) (3) 187 459 Balance sheet data – December 31: Current assets $ 389 $ 455 Noncurrent assets 941 1,049 Current liabilities 235 284 Noncurrent liabilities 170 183 Revenues from related parties were $38 million, $42 million and $48 million in 2020, 2019 and 2018, respectively, with the majority related to EGHoldings in all years. Current receivables from related parties at December 31, 2020 and 2019 were $24 million and $28 million, with the majority related to EGHoldings in 2020 and EGHoldings and Alba Plant LLC for 2019. Payables to related parties were $13 million and $11 million at December 31, 2020 and 2019, respectively, with the majority related to Alba Plant LLC in both periods.

Stockholders Equity

Stockholders Equity	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity Attributable to Parent [Abstract]
Stockholders’ Equity	Stockholders’ EquityDuring 2020, we acquired approximately 9 million of common shares at a cost of $85 million, which are held as treasury stock. During 2019, we acquired 24 million of common shares at a cost of $345 million under the same program. As of December 31, 2020 the total remaining share repurchase authorization was $1.3 billion. Purchases under the program are made at our discretion and may be in either open market transactions, including block purchases, or in privately negotiated transactions using cash on hand, cash generated from operations or proceeds from potential asset sales. This program may be changed based upon our financial condition or changes in market conditions and is subject to termination prior to completion. The repurchase program does not include specific price targets or timetables.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies In the second quarter of 2019, Marathon E.G. Production Limited (“MEGPL”), a consolidated and wholly-owned subsidiary, signed a series of agreements to process third-party Alen Unit gas through existing infrastructure located in Punta Europa, E.G. Our equity method investee, Alba Plant LLC, is also a party to some of the agreements. These agreements contain clauses that require MEGPL to indemnify the owners of the Alen Unit against injury to Alba Plant LLC’s personnel and damage to or loss of Alba Plant LLC’s automobiles, as well as third party claims caused by Alba Plant and certain environmental liabilities arising from certain hydrocarbons in the custody of Alba Plant LLC. Pursuant to these agreements, MEGPL agreed to indemnify third party property or events, including environmental liabilities, injury to Alba Plant LLC’s personnel and damage to or loss of Alba Plant LLC’s automobiles. At this time, we cannot reasonably estimate this obligation as we do not have any history of prior indemnification claims or environmental discharge or contamination. Therefore, we have not recorded a liability with respect to these indemnities since the amount of potential future payments under these indemnification clauses is not determinable. The agreements to process the third-party Alen Unit gas required the execution of third-party guarantees by Marathon Oil Corporation in favor of the Alen Unit’s owners. Two separate guarantees were executed during the second quarter of 2020; one for a maximum of $91 million pertaining to the payment obligations of Equatorial Guinea LNG Operations, S.A. and another for a maximum of $25 million pertaining to the payment obligations of Alba Plant LLC. Payment by us would be required if either of those entities fails to honor its payment obligations pursuant to the relevant agreements with the owners of the Alen Unit. Certain owners of the Alen Unit, or their affiliates, are also direct or indirect shareholders in Equatorial Guinea LNG Operations, S.A. and Alba Plant LLC. Each guarantee expires no later than December 31, 2027. We measured these guarantees at fair value using the net present value of premium payments we expect to receive from our investees. Our liability for these guarantees was $4 million as of December 31, 2020, with a corresponding receivable from our investees. Each of Equatorial Guinea LNG Operations, S.A. and Equatorial Guinea LNG Train 1, S.A. provided us with a pledge of its receivables as recourse against any payments we may make under the guaranty of Equatorial Guinea LNG Operations, S.A.’s performance. Various groups, including the State of North Dakota and three Indian tribes represented by the Bureau of Indian Affairs, have been involved in a dispute regarding the ownership of certain lands underlying the Missouri River and Little Missouri River. As a result, as of December 31, 2020, we have a $107 million current liability in suspended royalty and working interest revenue, including interest, and have a long-term receivable of $23 million for capital and expenses. In December 2019, we received a Notice of Violation from the North Dakota Department of Environmental Quality related to a release of produced water in North Dakota and a verbal notice of enforcement in January 2020 from the North Dakota Industrial Commission, related to a release of produced water in North Dakota. In January 2020, we received a Notice of Violation from the EPA related to the Clean Air Act. The enforcement actions will likely result in monetary sanctions and corrective actions yet-to-be specified; however, we do not believe this enforcement actions would have a material adverse effect on our consolidated financial position, results of operations or cash flow. We are a defendant in a number of legal and administrative proceedings arising in the ordinary course of business including, but not limited to, royalty claims, contract claims, tax disputes 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. Environmental matters – We have incurred and will continue to incur capital, operating and maintenance and remediation expenditures as a result of environmental laws and regulations. If these expenditures, as with all costs, are not ultimately offset by the prices we receive for our products and services, our operating results will be adversely affected. We believe that substantially all of our competitors must comply with similar environmental laws and regulations. However, the specific impact on each competitor may vary depending on a number of factors, including the age and location of its operating facilities, marketing areas and production processes. These laws generally provide for control of pollutants released into the environment and require responsible parties to undertake remediation of hazardous waste disposal sites. Penalties may be imposed for noncompliance. At December 31, 2020 and 2019, accrued liabilities for remediation were not material. It is not presently possible to estimate the ultimate amount of all remediation costs that might be incurred or the penalties that may be imposed. Guarantees – Over the years, we have sold various assets in the normal course of our business. Certain of the related agreements contain performance and general guarantees, including guarantees regarding inaccuracies in representations, warranties, covenants and agreements and environmental and general indemnifications that require us to perform upon the occurrence of a triggering event or condition. These guarantees and indemnifications are part of the normal course of selling assets. We are typically not able to calculate the maximum potential amount of future payments that could be made under such contractual provisions because of the variability inherent in the guarantees and indemnities. Most often, the nature of the guarantees and indemnities is such that there is no appropriate method for quantifying the exposure because the underlying triggering event has little or no past experience upon which a reasonable prediction of the outcome can be based. Contract commitments – At December 31, 2020 and 2019, contractual commitments to acquire property, plant and equipment totaled $15 million and $41 million. In connection with the sale of our operated producing properties in the greater Ewing Bank area and non-operated producing interests in the Petronius and Neptune fields in the Gulf of Mexico, we retained an overriding royalty interest in the properties. As part of the sale agreement, cumulative proceeds associated with the production of our override were $57 million as of December 31, 2020, and are dedicated solely to the satisfaction of the corresponding future abandonment obligations of the properties. The term of our override ends once sales proceeds equal $70 million.

Select Quarterly Financial Data

Select Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Select Quarterly Financial Data (Unaudited)	2020 2019 (In millions, 1st Qtr. 2nd Qtr. 3rd Qtr. 4th Qtr. 1st Qtr. 2nd Qtr. 3rd Qtr. 4th Qtr. Revenues from contracts with customers $ 1,024 $ 490 $ 761 $ 822 $ 1,200 $ 1,381 $ 1,249 $ 1,233 Income (loss) before income taxes (a)(b) (49) (765) (310) (341) 27 193 175 (3) Net income (loss) $ (46) $ (750) $ (317) $ (338) $ 174 $ 161 $ 165 $ (20) Income (loss) per basic and diluted share: Net income (loss) $ (0.06) $ (0.95) $ (0.40) $ (0.43) $ 0.21 $ 0.20 $ 0.21 $ (0.03) Dividends paid per share $ 0.05 $ — $ — $ 0.03 $ 0.05 $ 0.05 $ 0.05 $ 0.05 (a) The first quarter of 2020, includes mark-to-market gain on commodity derivatives of $171 million and a full impairment of goodwill in our International reporting unit of $95 million. (See Item 8. Financial Statements and Supplementary Data – Note 15 to the consolidated financial statements). Additionally, the second and third quarters of 2020 include impairments on an equity method investment of $152 million and $18 million, respectively. The fourth quarter of 2020 also includes $46 million of proved property impairments and $78 million of unproved property impairments. (For more information on impairments, see Item 8. Financial Statements and Supplementary Data – Note 12 to the consolidated financial statements). (b) The first and fourth quarter of 2019 includes a mark-to-market loss on commodity derivatives of $113 million and $55 million.

Summary of Principal Accounti_2

Summary of Principal Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of presentation and principles applied in consolidation	Basis of presentation and principles applied in consolidation – These consolidated financial statements, including notes, have been prepared in accordance with U.S. GAAP. These consolidated financial statements include the accounts of our controlled subsidiaries. Investments in unincorporated joint ventures and undivided interests in certain operating assets are consolidated on a pro rata basis.
Equity method investments	Equity method investments – Investments in entities over which we have significant influence, but not control, are accounted for using the equity method of accounting. This includes entities in which we hold majority ownership but the minority stockholders have substantive participating rights in the investee. Income from equity method investments represents our proportionate share of net income generated by the equity method investees and is reflected in revenues and other income in our consolidated statements of income. Equity method investments are included as noncurrent assets on the consolidated balance sheet.
Use of estimates	Use of estimates – The preparation of financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the respective reporting periods. Estimated quantities of crude oil and condensate, NGLs and natural gas reserves is a significant estimate that requires judgment. All of the reserve data included in this Form 10-K are estimates. Reservoir engineering is a subjective process of estimating underground accumulations of crude oil and condensate, NGLs and natural gas. There are numerous uncertainties inherent in estimating quantities of proved crude oil and condensate, NGLs and natural gas reserves. The accuracy of any reserves estimate is a function of the quality of available data and of engineering and geological interpretation and judgment. As a result, reserve estimates may be different from the quantities of crude oil and condensate, NGLs and natural gas that are ultimately recovered. See unaudited Supplementary Data – Supplementary Information on Oil and Gas Producing Activities for further detail. Other items subject to estimates and assumptions include the carrying amounts of property, plant and equipment, asset retirement obligations, goodwill, valuation of derivative instruments and valuation allowances for deferred income tax assets, among others. Although we believe these estimates are reasonable, actual results could differ from these estimates.
Foreign currency transactions	Foreign currency transactions – The U.S. dollar is the functional currency of our foreign operating subsidiaries. Foreign currency transaction gains and losses are included in net income.
Revenue recognition	Revenue recognition – Revenues associated with the sales of crude oil and condensate, NGLs and natural gas are recognized when our performance obligation is satisfied, which typically occurs at the point where control transfers to the customer based on contract terms. Revenue is measured as the amount the company expects to receive in exchange for transferring commodities to the customer. Our hydrocarbon sales are typically based on prevailing market-based prices and may include quality or location differential adjustments. Payment is generally due within 30 days of delivery. We typically incur shipping and handling costs prior to control transferring to the customer and account for these activities as fulfillment costs. These costs are reflected in shipping, handling and other operating expense in our consolidated statement of income. Our U.S. production of crude oil and condensate, NGLs and natural gas is generally sold immediately and transported to market. In our international segment, liquid hydrocarbon production may be stored as inventory and sold at a later time.
Cash and cash equivalents	Cash and cash equivalents – Cash and cash equivalents include cash on hand and on deposit and investments in highly liquid debt instruments with original maturities of three months or less.
Accounts receivable	Accounts receivable – The majority of our receivables are from purchasers of commodities or joint interest owners in properties we operate, both of which are recorded at estimated or invoiced amounts and do not bear interest. We often have the
Inventories	Inventories – Crude oil and natural gas are recorded at weighted average cost and carried at the lower of cost or net realizable value. Supplies and other items consist principally of tubular goods and equipment, which are valued at weighted average cost and reviewed periodically for obsol escence or impairment when market conditions indicate . We may enter into a contract to sell a particular quantity and quality of crude oil at a specified location and date to a particular counterparty, and simultaneously agree to buy a particular quantity and quality of the same commodity at a specified location on the same or another specified date from the same counterparty. We account for such matching buy/sell arrangements as exchanges of inventory.
Derivative instruments	Derivative instruments – We may use derivatives to manage a portion of our exposure to commodity price risk, commodity locational risk and interest rate risk. All derivative instruments are recorded at fair value. Commodity derivatives and interest rate swaps are reflected on our consolidated balance sheet on a net basis by counterparty, as they are governed by master netting agreements. Cash flows related to derivatives used to manage commodity price risk, and interest rate risk are classified in operating activities. Our derivative instruments contain no significant contingent credit features.
Hedges	Fair value hedges – We may use interest rate swaps to manage our exposure to interest rate risk associated with fixed interest rate debt in our portfolio. Changes in the fair values of both the hedged item and the related derivative are recognized immediately in net income with an offsetting effect included in the basis of the hedged item. The net effect is to report in net income the extent to which the hedge is not effective in achieving offsetting changes in fair value. Cash flow hedges – We may use interest rate derivative instruments to manage the risk of interest rate changes during the period prior to anticipated borrowings as well as to stabilize future lease payments on our future Houston office, and designate them as cash flow hedges. Derivative instruments designated as cash flow hedges are linked to specific assets and liabilities or to specific firm commitments or forecasted transactions. The changes in the fair value of a qualifying cash flow hedge are recorded in other comprehensive income until the hedged transaction affects earnings and are then reclassified into net income. Beginning in 2019, ineffective portions of a cash flow hedge are no longer measured or disclosed separately. However, if it is determined that the likelihood of the original forecasted transaction occurring is no longer probable or the cash flow hedge is no longer expected to be highly effective, subsequent changes in fair value of the derivatives instrument are recorded in net income.
Derivatives not designated as hedges	Derivatives not designated as hedges – Derivatives that are not designated as hedges may include commodity derivatives used primarily to manage price and locational risks on the forecasted sale of crude oil, NGLs and natural gas that we produce. Changes in the fair value of derivatives not designated as hedges are recognized immediately in net income
Concentrations of credit risk	Concentrations of credit risk – All of our financial instruments, including derivatives, involve elements of credit and market risk. The most significant portion of our credit risk relates to nonperformance by counterparties. The counterparties to our financial instruments consist primarily of major financial institutions and companies within the energy industry. To manage counterparty risk associated with financial instruments, we select and monitor counterparties based on our assessment of their financial strength and on credit ratings, if available. Additionally, we limit the level of exposure with any single counterparty.
Fair value transfer	Fair value transfer – We recognize transfers between levels of the fair value hierarchy as of the end of the reporting period.
Property, plant and equipment	Property, plant and equipment – We use the successful efforts method of accounting for oil and gas producing activities.
Property acquisition costs	Property acquisition costs – Costs to acquire mineral interests in oil and natural gas properties, to drill exploratory wells in progress and those that find proved reserves and to drill development wells are capitalized. Costs to drill exploratory wells that do not find proved reserves, geological and geophysical costs and costs of carrying and retaining unproved properties are expensed. Costs incurred for exploratory wells that find reserves but cannot yet be classified as proved are capitalized if (1) the well has found a sufficient quantity of reserves to justify its completion as a producing well and (2) we are making sufficient progress assessing the reserves and the economic and operating viability of the project. The status of suspended exploratory well costs is monitored continuously and reviewed at least quarterly.
Depreciation, depletion and amortization	Depreciation, depletion and amortization – Capitalized costs to acquire oil and natural gas properties are depreciated and depleted on a units-of-production basis based on estimated proved reserves. Capitalized costs of exploratory wells and development costs are depreciated and depleted on a units-of-production basis based on estimated proved developed reserves. Support equipment and other property, plant and equipment related to oil and gas producing activities, as well as property, plant and equipment unrelated to oil and gas producing activities, are recorded at cost and depreciated on a straight-line basis over the estimated useful lives of the assets. The table below summarizes these assets by type, useful life and the gross asset balance as of the periods presented. December 31, Type of Asset Range of Useful Lives 2020 2019 (in millions) Office furniture, equipment and computer hardware 4 to 15 years $ 682 $ 670 Pipelines 5 to 40 years $ 12 $ 12 Plants, facilities and infrastructure 3 to 40 years $ 1,646 $ 1,624
Impairments	Impairments – We evaluate our oil and gas producing properties, including capitalized costs of exploratory wells and development costs, for impairment of value whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If the sum of the expected undiscounted future cash flows from the use of the asset and its eventual disposition is less than the carrying amount of the asset, an impairment loss is recognized based on the fair value of the asset. Oil and gas producing properties are reviewed for impairment on a field-by-field basis or, in certain instances, by logical grouping of assets if there is significant shared infrastructure or contractual terms that cause economic interdependency amongst separate, discrete fields. Oil and gas producing properties deemed to be impaired are written down to their fair value, as determined by discounted future net cash flows or, if available, comparable market value. We evaluate our unproved property investment and record impairment based on time or geologic factors. Information such as drilling results, reservoir performance, seismic interpretation or future plans to develop acreage is also considered. When unproved property investments are deemed to be impaired, this amount is reported in exploration expenses in our consolidated statements of income.
Dispositions	Dispositions – When property, plant and equipment depreciated on an individual basis is sold or otherwise disposed of, any gains or losses are reflected in net gain (loss) on disposal of assets in our consolidated statements of income. Gains on the disposal of property, plant and equipment are recognized when earned, which is generally at the time of closing. If a loss on disposal is expected, such losses are recognized either when the assets are classified as held for sale, or are measured using a probability weighted income approach based on both the anticipated sales price and a held-for-use model depending on timing of the sale. Proceeds from the disposal of a portion of property, plant and equipment depreciated on a group basis are credited to accumulated depreciation, depletion and amortization with no immediate effect on net income until net book value is reduced to zero.
Goodwill	Goodwill – Goodwill represents the excess of the purchase price over the estimated fair value of the net assets acquired in the acquisition of a business. Such goodwill is not amortized, but rather is tested for impairment annually and when events or changes in circumstances indicate that the fair value of a reporting unit with goodwill has been reduced below carrying value. The impairment test requires allocating goodwill and other assets and liabilities to a reporting unit. The fair value of a reporting unit is determined and compared to the book value of the reporting unit. If the fair value of the reporting unit is less than the book value, including goodwill, then the recorded goodwill is impaired to its implied fair value with a charge to impairments.
Environmental costs	Environmental costs – We provide for remediation costs and penalties when the responsibility to remediate is probable and the amount of associated costs can be reasonably estimated. The timing of remediation accruals coincides with completion of a feasibility study or the commitment to a formal plan of action. Remediation liabilities are accrued based on estimates of known environmental exposure and are discounted when the estimated amounts are reasonably fixed or reliably determinable. Environmental expenditures are capitalized only if the costs mitigate or prevent future contamination or if the costs improve the environmental safety or efficiency of the existing assets.
Asset retirement obligations	Asset retirement obligations – The fair value of asset retirement obligations is recognized in the period in which the obligations are incurred if a reasonable estimate of fair value can be made. Our asset retirement obligations primarily relate to the abandonment of oil and gas producing facilities. Asset retirement obligations for such facilities include costs to dismantle and relocate or dispose of production platforms, gathering systems, wells and related structures and restoration costs of land, including those leased. Estimates of these costs are developed for each property based on the type of production facilities and equipment, reservoir characteristics, depth of the reservoir, market demand for equipment, currently available procedures and consultations with construction and engineering professionals.
Deferred income taxes	Deferred income taxes – Deferred tax assets and liabilities, measured at enacted tax rates, are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of assets and liabilities and their tax bases as reported in our filings with the respective taxing authorities. We routinely assess the realizability of our deferred tax assets based on several interrelated factors and reduce such assets by a valuation allowance if it is more likely than not that some portion or all of the deferred tax assets will not be realized. These factors include whether we are in a cumulative loss position in recent years, our reversal of temporary differences, and our expectation to generate sufficient future taxable income. We use the liability method in determining our provision and liabilities for our income taxes, under which current and deferred tax liabilities and assets are recorded in accordance with enacted tax laws and rates.
Stock based compensation arrangements	Stock-based compensation arrangements – The fair value of stock options is estimated on the date of grant using the Black-Scholes option pricing model. The model employs various assumptions, based on management’s best estimates at the time of grant, which impact the calculation of fair value and ultimately, the amount of expense that is recognized over the life of the stock option award. Of the required assumptions, the expected volatility of our stock price and the stock price in relation to the strike price have the most significant impact on the fair value calculation. We have utilized historical data and analyzed current information which reasonably support these assumptions. The fair value of our restricted stock awards, restricted stock units and Director restricted stock units is determined based on the market value of our common stock on the date of grant. Restricted stock awards, restricted stock units and Director restricted stock units are removed from Treasury Stock at grant, vesting and distribution, respectively. The fair value of our cash-settled stock-based performance units is estimated using the Monte Carlo simulation method. Since these awards are settled in cash at the end of a defined performance period, they are classified as a liability and are re-measured quarterly until settlement. The fair value of our stock-settled stock-based performance units is estimated using the Monte Carlo simulation method at grant date only. Since these awards are settled in stock, they are classified as equity.

Summary of Principal Accounti_3

Summary of Principal Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Schedule of Property Plant and Equipment	The table below summarizes these assets by type, useful life and the gross asset balance as of the periods presented. December 31, Type of Asset Range of Useful Lives 2020 2019 (in millions) Office furniture, equipment and computer hardware 4 to 15 years $ 682 $ 670 Pipelines 5 to 40 years $ 12 $ 12 Plants, facilities and infrastructure 3 to 40 years $ 1,646 $ 1,624 December 31, (In millions) 2020 2019 United States $ 15,156 $ 16,427 International 414 493 Not allocated to segments 68 80 Net property, plant and equipment $ 15,638 $ 17,000

Income (loss) and Dividends per

Income (loss) and Dividends per Common Share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The per share calculations below exclude 7 million, 6 million and 6 million stock options in 2020, 2019 and 2018 that were antidilutive. Year Ended December 31, (In millions, except per share data) 2020 2019 2018 Net income (loss) $ (1,451) $ 480 $ 1,096 Weighted average common shares outstanding 792 810 846 Effect of dilutive securities — — 1 Weighted average common shares, diluted 792 810 847 Net income (loss) per share: Basic $ (1.83) $ 0.59 $ 1.30 Diluted $ (1.83) $ 0.59 $ 1.29 Dividends per share $ 0.08 $ 0.20 $ 0.20

Revenues (Tables)

Revenues (Tables)	12 Months Ended
	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following tables present our revenues from contracts with customers disaggregated by product type and geographic areas. United States Year Ended December 31, 2020 (In millions) Eagle Ford Bakken Oklahoma Northern Delaware Other U.S. Total Crude oil and condensate $ 830 $ 984 $ 235 $ 204 $ 69 $ 2,322 Natural gas liquids 74 54 89 20 6 243 Natural gas 86 34 127 18 10 275 Other 6 — — — 78 84 Revenues from contracts with customers $ 996 $ 1,072 $ 451 $ 242 $ 163 $ 2,924 Year Ended December 31, 2019 (In millions) Eagle Ford Bakken Oklahoma Northern Delaware Other U.S. Total Crude oil and condensate $ 1,358 $ 1,686 $ 425 $ 316 $ 102 $ 3,887 Natural gas liquids 114 46 116 26 5 307 Natural gas 121 39 156 16 17 349 Other 7 — — — 52 59 Revenues from contracts with customers $ 1,600 $ 1,771 $ 697 $ 358 $ 176 $ 4,602 Year Ended December 31, 2018 (In millions) Eagle Ford Bakken Oklahoma Northern Delaware Other U.S. Total Crude oil and condensate $ 1,554 $ 1,568 $ 426 $ 235 $ 164 $ 3,947 Natural gas liquids 205 62 181 38 9 495 Natural gas 145 38 184 20 26 413 Other 8 — — — 23 31 Revenues from contracts with customers $ 1,912 $ 1,668 $ 791 $ 293 $ 222 $ 4,886 International Year Ended December 31, 2020 (In millions) E.G. Crude oil and condensate $ 140 Natural gas liquids 4 Natural gas 29 Other — Revenues from contracts with customers $ 173 Year Ended December 31, 2019 (In millions) E.G. U.K. Other International Total Crude oil and condensate $ 271 $ 107 $ 20 $ 398 Natural gas liquids 4 1 — 5 Natural gas 32 12 — 44 Other — 14 — 14 Revenues from contracts with customers $ 307 $ 134 $ 20 $ 461 Year Ended December 31, 2018 (In millions) E.G. U.K. Libya Other International Total Crude oil and condensate $ 342 $ 282 $ 187 $ 77 $ 888 Natural gas liquids 4 5 — — 9 Natural gas 37 40 9 — 86 Other 1 32 — — 33 Revenues from contracts with customers $ 384 $ 359 $ 196 $ 77 $ 1,016

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2020
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Year Ended December 31, 2020 (In millions) U.S. Int’l Not Allocated to Segments Total Revenues from contracts with customers $ 2,924 $ 173 $ — $ 3,097 Net gain (loss) on commodity derivatives 143 — (27) (b) 116 Income (loss) from equity method investments — 10 (171) (c) (161) Net gain on disposal of assets — — 9 9 Other income 15 7 3 25 Less costs and expenses: Production 494 59 2 555 Shipping, handling and other operating 534 8 54 596 Exploration 97 — 84 (d) 181 Depreciation, depletion and amortization 2,211 82 23 2,316 Impairments — — 144 (e) 144 Taxes other than income 193 — 7 200 General and administrative 115 14 145 (f) 274 Net interest and other — — 256 256 Other net periodic benefit costs — — 1 (g) 1 Loss on early extinguishment of debt — — 28 28 Income tax benefit (9) (3) (2) (14) Segment income (loss) $ (553) $ 30 $ (928) $ (1,451) Total assets $ 16,063 $ 1,081 $ 812 $ 17,956 Capital expenditures (a) $ 1,137 $ 1 $ 13 $ 1,151 (a) Includes accruals and excludes acquisitions. (b) Unrealized loss on commodity derivative instruments (See Note 16 ). (c) Partial impairment of investment in equity method investee (See Note 24 ). (d) Primarily related to unproved property impairments of non-core acreage in our United States segment. (e) Includes the full impairment of the International reporting unit goodwill of $95 million (See Note 15 ) and proved property impairments of $49 million related to a damaged well in our United States segment. (f) Includes severance expenses associated with workforce reductions of $17 million. (g) Includes pension settlement loss of $30 million and pension curtailment gain of $17 million (See Note 20 ). Year Ended December 31, 2019 (In millions) U.S. Int’l Not Allocated to Segments Total Revenues from contracts with customers $ 4,602 $ 461 $ — $ 5,063 Net gain (loss) on commodity derivatives 52 — (124) (b) (72) Income from equity method investments — 87 — 87 Net gain on disposal of assets — — 50 (c) 50 Other income 13 9 40 62 Less costs and expenses: Production 588 126 (2) 712 Shipping, handling and other operating 561 26 18 605 Exploration 149 — — 149 Depreciation, depletion and amortization 2,250 121 26 2,397 Impairments — — 24 (d) 24 Taxes other than income 311 — — 311 General and administrative 127 25 204 356 Net interest and other — — 244 244 Other net periodic benefit credit — (3) — (e) (3) Loss on early extinguishment of debt — — 3 3 Income tax provision (benefit) 6 29 (123) (88) Segment income (loss) $ 675 $ 233 $ (428) $ 480 Total assets $ 17,781 $ 1,530 $ 934 $ 20,245 Capital expenditures (a) $ 2,550 $ 16 $ 25 $ 2,591 (a) Includes accruals and excludes acquisitions. (b) Unrealized loss on commodity derivative instruments (See Note 16 ). (c) Primarily related to the sale of our working interest in the Droshky field (Gulf of Mexico) and the sale of our U.K. business (See Note 5 ). (d) Primarily a result of anticipated sales of non-core proved properties in our International and United States segments (See Note 12 ). (e) Includes pension settlement loss of $12 million (See Note 20 ). Year Ended December 31, 2018 (In millions) U.S. Int’l Not Allocated to Segments Total Revenues from contracts with customers $ 4,886 $ 1,016 $ — $ 5,902 Net gain (loss) on commodity derivatives (281) — 267 (b) (14) Income from equity method investments — 225 — 225 Net gain on disposal of assets — — 319 (c) 319 Other income 16 12 122 (d) 150 Less costs and expenses: Production 625 215 2 842 Shipping, handling and other operating 499 70 6 575 Exploration 246 3 40 (e) 289 Depreciation, depletion and amortization 2,217 197 27 2,441 Impairments — — 75 (f) 75 Taxes other than income 301 — (2) 299 General and administrative 146 32 216 394 Net interest and other — — 226 226 Other net periodic benefit (costs) credits — (9) 23 (g) 14 Income tax provision (benefit) (21) 272 80 331 Segment income $ 608 $ 473 $ 15 $ 1,096 Total assets $ 17,321 $ 2,083 $ 1,917 $ 21,321 Capital expenditures (a) $ 2,620 $ 39 $ 26 $ 2,685 (a) Includes accruals and excludes acquisitions. (b) Unrealized gain on commodity derivative instruments (See Note 16 ). (c) Primarily related to the gain on sale of our Libya subsidiary (See Note 5 ). (d) Primarily a reduction of asset retirement obligations in our International segment (See Note 13 ). (e) Primarily related to dry well expense and unproved property impairments associated with the Rodo well in Alba Block Sub Area B, offshore E.G. (See Note 12 ). (f) Due to the anticipated sales of certain non-core proved properties in our International and United States segments (See Note 12 ). (g) Includes pension settlement loss of $21 million (See Note 20 ).
Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country	The following summarizes property, plant and equipment and equity method investments. December 31, (In millions) 2020 2019 United States $ 15,224 $ 16,507 Equatorial Guinea 861 1,156 Total long-lived assets $ 16,085 $ 17,663

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	Income (loss) before income taxes were: Year Ended December 31, (In millions) 2020 2019 2018 United States $ (1,319) $ 43 $ 642 Foreign (146) 349 785 Total $ (1,465) $ 392 $ 1,427
Schedule of Components of Income Tax Expense (Benefit)	Income tax provisions (benefits) were: Year Ended December 31, 2020 2019 2018 (In millions) Current Deferred Total Current Deferred Total Current Deferred Total Federal $ (5) $ — $ (5) $ (116) $ (3) $ (119) $ 6 $ — $ 6 State and local (2) (8) (10) 4 3 7 (1) (23) (24) Foreign 15 (14) 1 58 (34) 24 274 75 349 Total $ 8 $ (22) $ (14) $ (54) $ (34) $ (88) $ 279 $ 52 $ 331
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the federal statutory income tax rate applied to income (loss) before income taxes to the provision (benefit) for income taxes follows: Year Ended December 31, (In millions) 2020 2019 2018 Total pre-tax income (loss) $ (1,465) $ 392 $ 1,427 Total income tax expense (benefit) $ (14) $ (88) $ 331 Effective income tax rate 1 % (22) % 23 % Income taxes at the statutory tax rate (a) $ (308) $ 83 $ 300 Effects of foreign operations 23 (29) 214 Adjustments to valuation allowances 239 (28) (177) State income taxes, net of federal benefit 6 11 (17) Other federal tax effects 26 (125) 11 Income tax expense (benefit) $ (14) $ (88) $ 331 (a) Includes income tax benefits primarily related to our U.S. federal income taxes where we have maintained a full valuation allowance since December 2016.
Schedule of Deferred Tax Assets and Liabilities	Deferred tax assets and liabilities resulted from the following: Year Ended December 31, (In millions) 2020 2019 Deferred tax assets: Employee benefits $ 77 $ 90 Operating loss carryforwards 1,966 1,685 Capital loss carryforwards — 1 Foreign tax credits 611 611 Other 43 27 Subtotal 2,697 2,414 Valuation allowance (948) (699) Total deferred tax assets 1,749 1,715 Deferred tax liabilities: Property, plant and equipment 1,892 1,861 Accrued revenue 20 40 Total deferred tax liabilities 1,912 1,901 Net deferred tax liabilities $ 163 $ 186 Net deferred tax assets $ — $ —
Net Deferred Tax Assets Liabilities Table	Net deferred tax assets and liabilities were classified in the consolidated balance sheets as follows: December 31, (In millions) 2020 2019 Assets: Other noncurrent assets $ — $ — Liabilities: Noncurrent deferred tax liabilities 163 186 Net deferred tax liabilities $ 163 $ 186 Net deferred tax assets $ — $ —
Income Tax Returns Remaining Subject To Examination Table	As of December 31, 2020, our income tax returns remain subject to examination in the following major tax jurisdictions for the tax years indicated: United States (a) 2008 - 2019 Equatorial Guinea 2007 - 2019 (a) Includes federal and state jurisdictions.
Summary Of Activity In Unrecognized Tax Benefits Table	The following table summarizes the activity in unrecognized tax benefits: (In millions) 2020 2019 2018 Beginning balance $ 13 $ 263 $ 126 Additions for tax positions of prior years — 13 152 Reductions for tax positions of prior years (5) (152) (15) Settlements — (111) — Ending balance $ 8 $ 13 $ 263

Credit Losses (Tables)

Credit Losses (Tables)	12 Months Ended
	Dec. 31, 2020
Credit Loss [Abstract]
Accounts Receivable, Allowance for Credit Loss	Changes in the allowance for doubtful accounts balance for the year were as follows: (In millions) December 31, 2020 Beginning balance as of January 1 $ 11 Cumulative-effect adjustment 12 Current period provision (a) 22 Current period write offs (13) Recoveries of amounts previously reserved (10) Ending balance as of December 31 $ 22

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2020
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	December 31, (In millions) 2020 2019 Crude oil and natural gas $ 10 $ 10 Supplies and other items 66 62 Inventories $ 76 $ 72

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Schedule of Property Plant and Equipment	The table below summarizes these assets by type, useful life and the gross asset balance as of the periods presented. December 31, Type of Asset Range of Useful Lives 2020 2019 (in millions) Office furniture, equipment and computer hardware 4 to 15 years $ 682 $ 670 Pipelines 5 to 40 years $ 12 $ 12 Plants, facilities and infrastructure 3 to 40 years $ 1,646 $ 1,624 December 31, (In millions) 2020 2019 United States $ 15,156 $ 16,427 International 414 493 Not allocated to segments 68 80 Net property, plant and equipment $ 15,638 $ 17,000
Schedule of Projects with Exploratory Well Costs Capitalized for More than One Year	Changes in our capitalized exploratory well costs were as follows: December 31, (In millions) 2020 2019 2018 Beginning balance as of January 1 $ 278 $ 297 $ 295 Additions 97 218 262 Charges to expense (a) (1) (5) (35) Transfers to development (164) (230) (197) Dispositions (b) — (2) (28) Ending balance as of December 31 $ 210 $ 278 $ 297 (a) 2018 includes $32 million related to the Rodo well in Alba Block Sub Area B (See Note 12 ). (b) 2018 includes the sale of our Libya subsidiary.

Impairment (Tables)

Impairment (Tables)	12 Months Ended
	Dec. 31, 2020
Impairments and Exploration Expenses [Abstract]
Summary of impaired assets	2020 2019 2018 (In millions) Fair Value Impairment Fair Value Impairment Fair Value Impairment Long-lived assets held for use $ — $ 49 $ 56 $ 24 $ 113 $ 75 Goodwill $ — $ 95 N/A $ — N/A $ — Equity method investment $ 119 $ 171 N/A $ — N/A $ —

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2020
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Change in Asset Retirement Obligation	Asset retirement obligations primarily consist of estimated costs to remove, dismantle and restore land at the end of oil and gas production operations. Changes in asset retirement obligations for the periods ended December 31 were as follows: (In millions) 2020 2019 Beginning balance as of January 1 $ 254 $ 1,145 Incurred liabilities, including acquisitions 6 34 Settled liabilities, including dispositions (12) (1,110) Accretion expense (included in depreciation, depletion and amortization) 12 31 Revisions of estimates (6) 46 Held for sale (a) — 108 Ending balance as of December 31 $ 254 $ 254 (a) In the first quarter of 2019, we closed on the sale of our working interest in the Droshky field (Gulf of Mexico), including our $98 million asset retirement obligation.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Supplemental Balance Sheet Information	Supplemental balance sheet information related to leases was as follows: December 31, (In millions) 2020 2019 Leases: Balance Sheet Location: Right-of-use (“ROU”) asset Other noncurrent assets $ 133 $ 199 Current portion of long-term lease liability Other current liabilities $ 70 $ 101 Long-term lease liability Deferred credits and other liabilities $ 67 $ 107
Lease Costs	The table below presents our net lease costs for the years ended December 31, 2020 and 2019 with the majority of operating lease costs expensed as incurred, while the majority of the short-term and variable lease costs are capitalized into property, plant and equipment. (In millions) Year Ended December 31, 2020 Year Ended December 31, 2019 Lease costs: Operating lease costs (a) $ 75 $ 84 Short-term lease costs (b) 170 321 Variable lease costs (c) 23 107 Total lease costs $ 268 $ 512 Other information: Cash paid for amounts included in the measurement of operating lease liabilities $ 100 $ 100 ROU assets obtained in exchange for new operating lease liabilities (d) $ 46 $ 293 Reductions to ROU assets resulting from modifications or cancellations of operating leases $ (68) $ — (a) Represents our net share of the ROU asset amortization and the interest expense. (b) Represents our net share of lease costs arising from leases of less than one year but longer than one month that were not included in the lease liability. (c) Represents our net share of variable lease payments that were not included in the lease liability. (d) Represents the cumulative value of ROU assets recognized at lease inception during the year of 2020. This amount is then amortized as we utilize the ROU asset, the net effect of which is the ending ROU asset of $133 million (first table above).
Operating Lease, Maturity	The remaining annual undiscounted cash flows associated with long-term leases and the reconciliation of these cash flows to the lease liabilities recognized on the consolidated balance sheet is summarized below. (In millions) Operating Lease Obligations 2021 $ 77 2022 44 2023 11 2024 5 2025 4 Thereafter 2 Total undiscounted lease payments $ 143 Less: amount representing interest 6 Total operating lease liabilities $ 137 Less: current portion of long-term lease liability as of December 31, 2020 70 Long-term lease liability as of December 31, 2020 $ 67
Operating Lease, Undiscounted Cash Flows to be Received	The undiscounted cash flows to be received under this lease agreement are summarized below. (In millions) Operating Lease Future Cash Receipts 2021 $ 6 2022 6 2023 6 2024 6 2025 6 Thereafter 53 Total undiscounted cash flows $ 83

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2020
Goodwill Disclosure [Abstract]
Schedule of Goodwill	The table below displays the allocated beginning goodwill balance of our International segment along with changes in the carrying amount of goodwill for 2020 and 2019: December 31, (In millions) 2020 2019 Beginning balance as of January 1, gross $ 95 $ 97 Less: accumulated impairments — — Beginning balance, net 95 97 Dispositions — (2) Impairment (95) — Ending balance as of December 30, net $ — $ 95

Derivatives (Tables)

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2020
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives as they appear on the Balance Sheet	The following tables present the gross fair values of derivative instruments and the reported net amounts along with where they appear on the consolidated balance sheets. December 31, 2020 (In millions) Asset Liability Net Asset (Liability) Balance Sheet Location Not Designated as Hedges Commodity $ 3 $ 1 $ 2 Other current assets Commodity 7 32 (25) Other current liabilities Interest Rate 10 — 10 Other noncurrent assets Total Not Designated as Hedges $ 20 $ 33 $ (13) Cash Flow Hedges Interest Rate $ 19 $ — $ 19 Other noncurrent assets Interest Rate — 16 (16) Deferred credits and other liabilities Total Designated Hedges $ 19 $ 16 $ 3 Total $ 39 $ 49 $ (10) December 31, 2019 (In millions) Asset Liability Net Asset (Liability) Balance Sheet Location Not Designated as Hedges Commodity $ 9 $ 1 $ 8 Other current assets Commodity 1 — 1 Other noncurrent assets Commodity — 5 (5) Other current liabilities Total Not Designated as Hedges $ 10 $ 6 $ 4 Cash Flow Hedges Interest Rate $ 2 $ — $ 2 Other noncurrent assets Total Designated Hedges $ 2 $ — $ 2 Total $ 12 $ 6 $ 6 Year Ended December 31, (In millions) 2020 2019 2018 Unrealized mark-to-market gain (loss) $ (27) $ (124) $ 267 Net settlements of commodity derivative instruments $ 143 $ 52 $ (281)
Schedule of Notional Amounts of Outstanding Derivative Positions	The following table sets forth outstanding derivative contracts as of December 31, 2020 and the weighted average prices for those contracts: 2021 First Quarter Second Quarter Third Quarter Fourth Quarter Crude Oil NYMEX WTI Three-Way Collars Volume (Bbls/day) — 10,000 — — Weighted average price per Bbl: Ceiling $ — $ 58.72 $ — $ — Floor $ — $ 37.00 $ — $ — Sold put $ — $ 27.00 $ — $ — NYMEX WTI Two-Way Collars Volume (Bbls/day) 90,000 50,000 30,000 30,000 Weighted average price per Bbl: Ceiling $ 51.86 $ 52.98 $ 51.54 $ 51.54 Floor $ 35.44 $ 35.80 $ 35.67 $ 35.67 Basis Swaps - NYMEX WTI / ICE Brent (a) Volume (Bbls/day) 3,278 — — — Weighted average price per Bbl $ (7.24) $ — $ — $ — Basis Swaps - NYMEX WTI / UHC (b) Volume (Bbls/day) 14,000 14,000 — — Weighted average price per Bbl $ (1.80) $ (1.80) $ — $ — NYMEX Roll Basis Swaps Volume (Bbls/day) 50,000 50,000 $ — $ — Weighted average price per Bbl $ (0.13) $ (0.13) $ — $ — Natural Gas Henry Hub (“HH”) Two-Way Collars Volume (MMBtu/day) 250,000 200,000 200,000 200,000 Weighted average price per MMBtu: Ceiling $ 3.14 $ 3.05 $ 3.05 $ 3.05 Floor $ 2.52 $ 2.50 $ 2.50 $ 2.50 HH Fixed Price Swaps Volume (MMBtu/day) 50,000 50,000 50,000 50,000 Weighted average price per MMBtu $ 2.88 $ 2.88 $ 2.88 $ 2.88 NGL Fixed Price Propane Swaps (c) Volume (Bbls/day) 5,000 5,000 5,000 5,000 Weighted average price per Bbl $ 23.19 $ 23.19 $ 23.19 $ 23.19 (a) The basis differential price is indexed against Intercontinental Exchange (“ICE”) Brent and NYMEX WTI. (b) The basis differential price is indexed against U.S. Sweet Clearbrook (“UHC”) and NYMEX WTI. (c) The fixed price propane swap is priced at Mont Belvieu Spot Gas Liquids Prices: Non-TET Propane. The following table sets forth outstanding derivative contracts entered into between January 1, 2021 and February 15, 2021, and the weighted average prices for those contracts. 2021 First Quarter Second Quarter Third Quarter Fourth Quarter Crude Oil Basis Swaps - NYMEX WTI / UHC (a) Volume (Bbls/day) 344 1,000 — — Weighted average price per Bbl $ (1.80) $ (1.80) $ — $ — NYMEX WTI Three-Way Collars Volume (Bbls/day) — 30,000 10,000 — Weighted average price per Bbl: Ceiling $ — $ 62.36 $ 65.18 $ — Floor $ — $ 40.67 $ 45.00 $ — Sold put $ — $ 30.67 $ 35.00 $ — WTI Fixed Price Swaps Volume (Bbls/day) 20,000 — — — Weighted average price per Bbl $ 50.35 $ — $ — $ — (a) The basis differential price is indexed against U.S. Sweet Clearbrook (“UHC”) and NYMEX WTI.
Schedule of Interest Rate Derivatives	The following table presents, by maturity date, information about our de-designated forward starting interest rate swap agreements, including the rate. December 31, 2020 December 31, 2019 Maturity Date Aggregate Notional Amount (in millions) Weighted Average, LIBOR Aggregate Notional Amount (in millions) Weighted Average, LIBOR November 1, 2022 $ 500 0.99 % $ — — % The following table sets forth the net impact of the forward starting interest rate swap derivatives de-designated as cash flow hedges on other comprehensive income (loss). (In millions) Year Ended December 31, 2020 Interest Rate Swaps Beginning balance $ — Change in fair value recognized in other comprehensive income (loss) (2) Ending balance $ (2) The following table presents information about our interest rate swap agreements, including the weighted average LIBOR-based, fixed rate. December 31, 2020 December 31, 2019 Maturity Date Aggregate Notional Amount (in millions) Weighted Average, LIBOR Aggregate Notional Amount (in millions) Weighted Average, LIBOR June 1, 2025 $ 350 0.95 % $ — — % September 9, 2026 $ 320 1.51 % $ 320 1.51 %

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables present assets and liabilities accounted for at fair value on a recurring basis as of December 31, 2020 and 2019 by hierarchy level. December 31, 2020 (In millions) Level 1 Level 2 Level 3 Total Derivative instruments, assets Interest rate - not designated as cash flow hedges $ — $ 10 $ — $ 10 Interest rate - designated as cash flow hedges — 19 — 19 Derivative instruments, assets $ — $ 29 $ — $ 29 Derivative instruments, liabilities Commodity (a) $ — $ (23) $ — $ (23) Interest rate - designated as cash flow hedges — (16) — (16) Derivative instruments, liabilities $ — $ (39) $ — $ (39) Total $ — $ (10) $ — $ (10) December 31, 2019 (In millions) Level 1 Level 2 Level 3 Total Derivative instruments, assets Commodity (a) $ — $ 7 $ — $ 7 Interest rate - designated as cash flow hedges — 2 — 2 Derivative instruments, assets $ — $ 9 $ — $ 9 Derivative instruments, liabilities Commodity (a) $ (3) $ — $ — $ (3) Derivative instruments, liabilities $ (3) $ — $ — $ (3) Total $ (3) $ 9 $ — $ 6 (a) Derivative instruments are recorded on a net basis in our consolidated balance sheet (See Note 16
Fair Value, by Balance Sheet Grouping	The following table summarizes financial instruments, excluding receivables, payables and derivative financial instruments, and their reported fair values by individual balance sheet line item at December 31, 2020 and 2019. December 31, 2020 2019 (In millions) Fair Carrying Fair Carrying Financial assets Current assets $ 4 $ 4 $ 4 $ 4 Other noncurrent assets 24 37 26 38 Total financial assets $ 28 $ 41 $ 30 $ 42 Financial liabilities Other current liabilities $ 72 $ 103 $ 62 $ 90 Long-term debt, including current portion (a) 6,077 5,431 6,174 5,529 Deferred credits and other liabilities 103 76 99 86 Total financial liabilities $ 6,252 $ 5,610 $ 6,335 $ 5,705 (a) Excludes debt issuance costs.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Disclosure [Abstract]
Debt Instrument Table	The following table details our long-term debt: December 31, (In millions) 2020 2019 Senior unsecured notes: 2.800% notes due 2022 (a) $ 500 $ 1,000 9.375% notes due 2022 (b) 32 32 Series A notes due 2022 (b) 3 3 8.500% notes due 2023 (b) 70 70 8.125% notes due 2023 (b) 131 131 3.850% notes due 2025 (a) 900 900 4.400% notes due 2027 (a) 1,000 1,000 6.800% notes due 2032 (a) 550 550 6.600% notes due 2037 (a) 750 750 5.200% notes due 2045 (a) 500 500 Bonds: (c) 2.00% bonds due 2037 200 200 2.10% bonds due 2037 200 200 2.20% bonds due 2037 200 200 2.125% bonds due 2037 200 — 2.375% bonds due 2037 200 — Total (b) 5,436 5,536 Unamortized discount (5) (7) Unamortized debt issuance cost (27) (28) Total long-term debt $ 5,404 $ 5,501 (a) These notes contain a make-whole provision allowing us to repay the debt at a premium to market price. (b) In the event of a change in control, as defined in the related agreements, debt obligations totaling $236 million at December 31, 2020 may be declared immediately due and payable.
Five Year Schedule Of Debt Payments Table	The following table shows future debt payments: (In millions) 2021 $ — 2022 535 2023 401 2024 400 2025 900 Thereafter 3,200 Total long-term debt, including current portion $ 5,436

Incentive Based Compensation (T

Incentive Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Incentive Based Compensation Plans [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	The weighted average grant date fair value of these awards was based on the following weighted average Black-Scholes assumptions: 2020 2019 2018 Exercise price per share $ 10.47 $ 16.79 $ 14.52 Expected annual dividend yield 1.9 % 1.2 % 1.4 % Expected life in years 6.14 5.82 6.45 Expected volatility 44 % 43 % 43 % Risk-free interest rate 1.5 % 2.5 % 2.8 % Weighted average grant date fair value of stock option awards granted $ 3.82 $ 6.62 $ 5.83
Schedule of Share-based Compensation, Stock Options, Activity	The following is a summary of stock option award activity in 2020. Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (in millions) Outstanding at beginning of year 5,659,731 $ 23.55 Granted 1,132,808 $ 10.47 Exercised (52,333) $ 7.22 Canceled (725,951) $ 25.44 Outstanding at end of year 6,014,255 $ 21.00 5 years Exercisable at end of year 4,219,975 $ 24.63 4 years $ — Expected to vest 1,766,804 $ 12.50 9 years $ —
Schedule of Nonvested Restricted Stock Units Activity	The following is a summary of restricted stock and restricted stock unit award activity in 2020. Awards Weighted Average Grant Date Fair Value Unvested at beginning of year 7,174,386 $ 15.88 Granted 5,390,960 $ 8.50 Vested (3,127,762) $ 15.76 Canceled (1,585,830) $ 11.65 Unvested at end of year 7,851,754 $ 11.72
Schedule of Performance Units, Valuation	The key assumptions used in the Monte Carlo simulation to determine the fair value of stock-based performance units granted in 2020, 2019 and 2018 were: 2020 (a) 2019 (a) 2018 Valuation date stock price $ 10.47 $ 16.79 $ 13.69 Expected annual dividend yield 1.9 % 1.2 % 1.5 % Expected volatility 39 % 43 % 41 % Risk-free interest rate 1.4 % 2.5 % 1.5 % Fair value of stock-based performance units outstanding $ 10.55 $ 20.66 $ 17.29

Defined Benefit Postretiremen_2

Defined Benefit Postretirement Plans and Defined Contribution Plan (Tables)	12 Months Ended
	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan	Obligations and funded status – The following summarizes the obligations and funded status for our defined benefit pension and other postretirement plans. Pension Benefits Other Benefits 2020 2019 2020 2019 (In millions) U.S. Int’l U.S. Int’l U.S. U.S. Accumulated benefit obligation $ 298 $ — $ 343 $ — $ 80 $ 89 Change in pension benefit obligations: Beginning balance $ 354 $ — $ 326 $ 511 $ 89 $ 96 Service cost 19 — 19 — 1 1 Interest cost 9 — 12 8 2 3 Plan amendment — — — — — — Divestiture (a) — — — (549) — — Actuarial loss 36 — 48 36 4 9 Foreign currency exchange rate changes — — — 6 — — Gain due to curtailment (a) (1) — — — — — Settlements paid (104) — (45) — — — Benefits paid (5) — (6) (12) (16) (20) Ending balance $ 308 $ — $ 354 $ — $ 80 $ 89 Change in fair value of plan assets: Beginning balance $ 236 $ — $ 203 $ 594 $ — $ — Actual return on plan assets 18 — 44 68 — — Employer contributions 49 — 40 8 16 20 Foreign currency exchange rate changes — — — 8 — — Divestiture (b) — — — (666) — — Settlements paid (104) — (45) — — — Benefits paid (5) — (6) (12) (16) (20) Ending balance $ 194 $ — $ 236 $ — $ — $ — Funded status of plans at December 31 $ (114) $ — $ (118) $ — $ (80) $ (89) Amounts recognized in the consolidated balance sheets: Noncurrent assets $ — $ — $ — $ — $ — $ — Current liabilities (4) — (6) — (10) (18) Noncurrent liabilities (110) — (112) — (70) (71) Accrued benefit cost $ (114) $ — $ (118) $ — $ (80) $ (89) Pretax amounts in accumulated other comprehensive loss: Net loss $ 72 $ — $ 85 $ — $ 24 $ 23 Prior service credit (19) — (29) — (97) (129) (a) Related to workforce reductions, which reduced the future expected years of service for employees participating in the plans. (b) Refer to Note 5 for further information on the sale of our U.K. business.
Schedule of Net Benefit Costs	Components of net periodic benefit costs and other comprehensive (income) loss – The following summarizes the net periodic benefit costs and the amounts recognized as other comprehensive (income) loss for our defined benefit pension and other postretirement plans. Pension Benefits Other Benefits Year Ended December 31, Year Ended December 31, 2020 2019 2018 2020 2019 2018 (In millions) U.S. U.S. Int’l U.S. Int’l U.S. U.S. U.S. Components of net periodic benefit costs: Service cost $ 19 $ 19 $ — $ 18 $ — $ 1 $ 1 $ 2 Interest cost 9 12 8 12 14 2 3 7 Expected return on plan assets (11) (10) (11) (11) (24) — — — Amortization: - prior service credit (6) (7) — (10) — (18) (19) (8) - actuarial loss 9 7 — 11 — 2 1 1 Net settlement loss (a) 30 12 — 18 3 — — — Net curtailment gain (b) (3) — — — — (14) — — Net periodic benefit cost (credit) (c) $ 47 $ 33 $ (3) $ 38 $ (7) $ (27) $ (14) $ 2 Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax): Actuarial loss (gain) $ 27 $ 14 $ (21) $ (4) $ 8 $ 4 $ 9 $ (15) Settlement loss and amortization of actuarial gain (loss) (40) (19) (41) (29) (3) (2) (1) (1) Prior service cost (credit) — — — — 3 — — (99) Curtailment gain and amortization of prior service credit (cost) 10 7 (6) 10 — 32 19 8 Total recognized in other comprehensive (income) loss $ (3) $ 2 $ (68) $ (23) $ 8 $ 34 $ 27 $ (107) Total recognized in net periodic benefit cost and other comprehensive (income) loss $ 44 $ 35 $ (71) $ 15 $ 1 $ 7 $ 13 $ (105) (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 costs for that year. (b) Related to workforce reductions, which reduced the future expected years of service for employees participating in the plans. (c) Net periodic benefit costs (credits) reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years.
Schedule of Assumptions Used	Plan assumptions – The following summarizes the assumptions used to determine the benefit obligations at December 31, and net periodic benefit cost for the defined benefit pension and other postretirement plans for 2020, 2019 and 2018. Pension Benefits Other Benefits 2020 2019 2018 2020 2019 2018 (In millions) U.S. U.S. U.S. Int’l U.S. U.S. U.S. Weighted average assumptions used to determine benefit obligation: Discount rate 2.52 % 3.13 % 4.26 % 2.90 % 2.02 % 2.91 % 4.09 % Rate of compensation increase (a) 0.50 % 4.50 % 4.00 % — % 0.50 % 4.50 % 4.00 % Cash balance interest crediting 3.00 % 3.00 % 3.26 % — % — % — % — % Weighted average assumptions used to determine net periodic benefit cost: Discount rate 2.90 % 3.70 % 3.88 % 2.50 % 2.63 % 4.09 % 3.54 % Expected long-term return on plan assets 6.00 % 6.25 % 6.50 % 3.70 % — % — % — % Rate of compensation increase 4.50 % 4.00 % 4.00 % — % 4.50 % 4.00 % 4.00 % Cash balance interest crediting 3.00 % 3.00 % 3.00 % — % — % — % — %
Schedule of Allocation of Plan Assets	The following tables present the fair values of our defined benefit pension plan’s assets, by level within the fair value hierarchy, as of December 31, 2020 and 2019. December 31, 2020 (In millions) Level 1 Level 2 Level 3 Total Equity securities: Common stock $ 61 $ — $ — $ 61 Private equity — — 8 8 Other — — 18 18 Total investments, at fair value 61 — 26 87 Commingled funds (a) — — — 107 Total investments $ 61 $ — $ 26 $ 194 December 31, 2019 (In millions) Level 1 Level 2 Level 3 Total U.S. U.S. U.S. U.S. Cash and cash equivalents (b) $ (7) $ — $ — $ (7) Equity securities: Common stock 75 — — 75 Private equity — — 10 10 Fixed income securities: Corporate — 2 — 2 Exchange traded funds 3 — — 3 Government 31 11 5 47 Other — — 18 18 Total investments, at fair value 102 13 33 148 Commingled funds (a) — — — 88 Total investments $ 102 $ 13 $ 33 $ 236 (a) After the adoption of the FASB update for the fair value hierarchy, we separately report the investments for which fair value was measured using the net asset value per share as a practical expedient. Amounts presented in this table are intended to reconcile the fair value hierarchy to the pension plan assets.
Schedule of Expected Benefit Payments	Estimated future benefit payments – The following gross benefit payments, which were estimated based on actuarial assumptions applied at December 31, 2020 and reflect expected future services, as appropriate, are to be paid in the years indicated. (In millions) Pension Benefits Other Benefits 2021 $ 31 $ 10 2022 28 9 2023 27 8 2024 25 7 2025 23 6 2026 through 2030 $ 104 $ 23

Reclassifications Out of Accu_2

Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Reclassification out of AOCI	The following table presents a summary of amounts reclassified from accumulated other comprehensive income (loss): Year Ended December 31, (In millions) 2020 2019 Income Statement Line Postretirement and postemployment plans Amortization of prior service credit $ 24 $ 26 Amortization of actuarial loss (11) (8) Net settlement loss (30) (12) Net curtailment gain 17 — — 6 Other net periodic benefit credits Other U.K pension plan transferred to buyer (a)(b) — 83 Foreign currency translation adjustment related to sale of U.K. business (b) — 30 Income taxes related to sale of U.K. business (b) — (45) — 68 Net gain on disposal of assets Other insignificant items — 1 Net interest and other Total reclassifications to expense, net of tax (c) $ — $ 75 Net income (a) See Note 20 for detail on the U.K. pension plan. (b) See Note 5 for detail on the U.K. disposition. (c) During 2020 and 2019 we had a full valuation allowance on net federal deferred tax assets in the U.S. and as such, there is no tax impact to our postretirement and postemployment plans other than on the sale of the U.K. business.

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2020
Supplemental Cash Flow Information [Abstract]
Schedule of Supplemental Cash Flow Information	Year Ended December 31, (In millions) 2020 2019 2018 Included in operating activities: Interest paid, net of amounts capitalized $ 251 $ 253 $ 255 Income taxes paid to (received from) taxing authorities, net of refunds (a) (51) 73 287 Noncash investing activities: Increase (decrease) in asset retirement costs $ — $ 80 $ (183) Asset retirement obligations assumed by buyer (b) — 1,082 82 (a) 2020, 2019 and 2018 includes $94 million, $90 million and $37 million, related to tax refunds. (b) In 2019, our dispositions include the sale of the Droshky field (Gulf of Mexico), the sale of our non-operated interest in the Atrush block in Kurdistan and the sale of our U.K. business. See Note 5 for further detail on dispositions. Other noncash investing activities include accrued capital expenditures as of December 31, 2020, 2019 and 2018 of $95 million, $288 million and $250 million.

Other Items (Tables)

Other Items (Tables)	12 Months Ended
	Dec. 31, 2020
Interest and Other Income [Abstract]
Schedule of Net Interest And Other Financing Table	Net interest and other Year Ended December 31, (In millions) 2020 2019 2018 Interest: Interest income $ 5 $ 25 $ 32 Interest expense (279) (280) (280) Income on interest rate swaps 12 — — Total interest (262) (255) (248) Other: Net foreign currency gain — 4 9 Other 6 7 13 Total other 6 11 22 Net interest and other $ (256) $ (244) $ (226)
Schedule of Foreign Currency Transactions Table	Foreign currency – Aggregate foreign currency gains were included in the consolidated statements of income as follows: Year Ended December 31, (In millions) 2020 2019 2018 Net interest and other $ — $ 4 $ 9 Provision for income taxes — 2 10 Aggregate foreign currency gains $ — $ 6 $ 19

Equity Method Investments (Tabl

Equity Method Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Equity Method Investments Disclosure [Abstract]
Schedule of Equity Method Investments	Our equity method investments are summarized in the following table: Ownership as of December 31, (In millions) December 31, 2020 2020 2019 EGHoldings 60% $ 113 $ 310 Alba Plant LLC 52% 168 163 AMPCO 45% 166 190 Total $ 447 $ 663
Income And Balance Sheet Information of Equity Investees Table	Summarized financial information for equity method investees is as follows: (In millions) 2020 2019 2018 Income data – year: Revenues and other income $ 586 $ 832 $ 1,269 Income (loss) from operations 16 250 588 Net income (loss) (3) 187 459 Balance sheet data – December 31: Current assets $ 389 $ 455 Noncurrent assets 941 1,049 Current liabilities 235 284 Noncurrent liabilities 170 183

Select Quarterly Financial Da_2

Select Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2020
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	2020 2019 (In millions, 1st Qtr. 2nd Qtr. 3rd Qtr. 4th Qtr. 1st Qtr. 2nd Qtr. 3rd Qtr. 4th Qtr. Revenues from contracts with customers $ 1,024 $ 490 $ 761 $ 822 $ 1,200 $ 1,381 $ 1,249 $ 1,233 Income (loss) before income taxes (a)(b) (49) (765) (310) (341) 27 193 175 (3) Net income (loss) $ (46) $ (750) $ (317) $ (338) $ 174 $ 161 $ 165 $ (20) Income (loss) per basic and diluted share: Net income (loss) $ (0.06) $ (0.95) $ (0.40) $ (0.43) $ 0.21 $ 0.20 $ 0.21 $ (0.03) Dividends paid per share $ 0.05 $ — $ — $ 0.03 $ 0.05 $ 0.05 $ 0.05 $ 0.05 (a) The first quarter of 2020, includes mark-to-market gain on commodity derivatives of $171 million and a full impairment of goodwill in our International reporting unit of $95 million. (See Item 8. Financial Statements and Supplementary Data – Note 15 to the consolidated financial statements). Additionally, the second and third quarters of 2020 include impairments on an equity method investment of $152 million and $18 million, respectively. The fourth quarter of 2020 also includes $46 million of proved property impairments and $78 million of unproved property impairments. (For more information on impairments, see Item 8. Financial Statements and Supplementary Data – Note 12 to the consolidated financial statements). (b) The first and fourth quarter of 2019 includes a mark-to-market loss on commodity derivatives of $113 million and $55 million.

Summary of Principal Accounti_4

Summary of Principal Accounting Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Office furniture, equipment and computer hardware
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 682	$ 670
Office furniture, equipment and computer hardware | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	4 years
Office furniture, equipment and computer hardware | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	15 years
Pipelines
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 12	12
Pipelines | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Pipelines | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years
Plants, facilities and infrastructure
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,646	$ 1,624
Plants, facilities and infrastructure | Minimum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Plants, facilities and infrastructure | Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	40 years

Accounting Standards (Details)

Accounting Standards (Details) - USD ($) $ in Millions	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment	$ 10,561		$ 12,153	$ 12,128	$ 11,708
Cumulative-effect adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment			(12)	(31)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment	$ 6,466		$ 7,993	7,706	$ 6,779
Retained Earnings | Cumulative-effect adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative-effect adjustment		$ (12)		$ (31)

Income (loss) and Dividends p_2

Income (loss) and Dividends per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Antidilutive securities excluded from computation of earnings per share (in shares)									7	6	6
Net income (loss)	$ (338)	$ (317)	$ (750)	$ (46)	$ (20)	$ 165	$ 161	$ 174	$ (1,451)	$ 480	$ 1,096
Weighted average common shares outstanding (in shares)									792	810	846
Effect of dilutive securities (in shares)									0	0	1
Weighted average common shares, diluted (in shares)									792	810	847
Diluted net income (loss) per share (in dollars per diluted share)									$ (1.83)	$ 0.59	$ 1.29
Basic net income (loss) per share (in dollars per basic share)									(1.83)	0.59	1.30
Dividends paid (in dollars per share)	$ 0.03	$ 0	$ 0	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.08	$ 0.20	$ 0.20

Acquisitions (Details)

Acquisitions (Details) a in Thousands, $ in Millions	3 Months Ended
	Sep. 30, 2020USD ($)	Dec. 31, 2019USD ($)a
Business Acquisition [Line Items]
Working interest percentage acquired		100.00%
Texas Delaware
Business Acquisition [Line Items]
Oil and gas acres, undeveloped, net | a		40
Payments to acquire oil and gas property | $		$ 106
Eagle Ford
Business Acquisition [Line Items]
Oil and gas acres, undeveloped, net | a		18
Payments to acquire oil and gas property | $	$ 191

Dispositions - United States E&

Dispositions - United States E&P Segment (Details) - United States E&P - Gulf of Mexico Assets - Disposal Group, Disposed of by Sale, Not Discontinued Operations $ in Millions	3 Months Ended
	Sep. 30, 2018USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal of assets, net of cash transferred to the buyer	$ 16
Gain on disposal	$ 32

Dispositions - International E&

Dispositions - International E&P Segment (Details) - USD ($) $ in Millions

Jul. 01, 2019

Dec. 31, 2020

Sep. 30, 2020

Jun. 30, 2020

Mar. 31, 2020

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Mar. 31, 2018

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Income from continuing operations before income taxes

$ (341)

$ (310)

$ (765)

$ (49)

$ (3)

$ 175

$ 193

$ 27

$ (1,465)

$ 392

$ 1,427

International | U.K. Business

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Surety bond exposure, liability

$ 6

International | U.K. Business | Disposal Group, Disposed of by Sale, Not Discontinued Operations

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Disposal of assets, net of cash transferred to the buyer

$ 95

Income from continuing operations before income taxes

$ 33

$ 261

International | Atrush Block in Kurdistan | Disposal Group, Disposed of by Sale, Not Discontinued Operations

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Disposal of assets, net of cash transferred to the buyer

$ 63

Percentage interest in property

15.00%

International | Marathon Oil Libya Limited | Disposal Group, Disposed of by Sale, Not Discontinued Operations

Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]

Disposal of assets, net of cash transferred to the buyer

$ 450

Percentage interest in property

16.33%

Gain on disposal

$ 255

Revenues - Narrative (Details)

Revenues - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue, Major Customer [Line Items]
Contract with customer, receivable, net	$ 572	$ 837
Revenue Benchmark | Marathon Petroleum Corporation | Customer Concentration Risk
Revenue, Major Customer [Line Items]
Concentration risk, percentage	13.00%	13.00%
Revenue Benchmark | Koch Resources LLC | Customer Concentration Risk
Revenue, Major Customer [Line Items]
Concentration risk, percentage	12.00%	13.00%	11.00%
Revenue Benchmark | Valero Marketing and Supply | Customer Concentration Risk
Revenue, Major Customer [Line Items]
Concentration risk, percentage		11.00%	11.00%
Revenue Benchmark | Shell Trading | Customer Concentration Risk
Revenue, Major Customer [Line Items]
Concentration risk, percentage		10.00%

Revenues - Revenues from Contra

Revenues - Revenues from Contracts with Customers by Product Type and Geographic Areas (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 822	$ 761	$ 490	$ 1,024	$ 1,233	$ 1,249	$ 1,381	$ 1,200	$ 3,097	$ 5,063	$ 5,902
United States E&P
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									2,924	4,602	4,886
United States E&P | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									996	1,600	1,912
United States E&P | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									1,072	1,771	1,668
United States E&P | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									451	697	791
United States E&P | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									242	358	293
United States E&P | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									163	176	222
United States E&P | Crude oil and condensate
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									2,322	3,887	3,947
United States E&P | Crude oil and condensate | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									830	1,358	1,554
United States E&P | Crude oil and condensate | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									984	1,686	1,568
United States E&P | Crude oil and condensate | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									235	425	426
United States E&P | Crude oil and condensate | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									204	316	235
United States E&P | Crude oil and condensate | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									69	102	164
United States E&P | Natural gas liquids
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									243	307	495
United States E&P | Natural gas liquids | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									74	114	205
United States E&P | Natural gas liquids | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									54	46	62
United States E&P | Natural gas liquids | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									89	116	181
United States E&P | Natural gas liquids | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									20	26	38
United States E&P | Natural gas liquids | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									6	5	9
United States E&P | Natural gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									275	349	413
United States E&P | Natural gas | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									86	121	145
United States E&P | Natural gas | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									34	39	38
United States E&P | Natural gas | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									127	156	184
United States E&P | Natural gas | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									18	16	20
United States E&P | Natural gas | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									10	17	26
United States E&P | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									84	59	31
United States E&P | Other | Eagle Ford
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									6	7	8
United States E&P | Other | Bakken
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0	0
United States E&P | Other | Oklahoma
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0	0
United States E&P | Other | Northern Delaware
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0	0
United States E&P | Other | Other U.S.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									78	52	23
International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										461	1,016
International | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									173	307	384
International | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										134	359
International | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers											196
International | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										20	77
International | Crude oil and condensate
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										398	888
International | Crude oil and condensate | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									140	271	342
International | Crude oil and condensate | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										107	282
International | Crude oil and condensate | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers											187
International | Crude oil and condensate | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										20	77
International | Natural gas liquids
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										5	9
International | Natural gas liquids | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									4	4	4
International | Natural gas liquids | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										1	5
International | Natural gas liquids | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers											0
International | Natural gas liquids | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										0	0
International | Natural gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										44	86
International | Natural gas | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									29	32	37
International | Natural gas | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										12	40
International | Natural gas | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers											9
International | Natural gas | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										0	0
International | Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										14	33
International | Other | E.G.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									$ 0	0	1
International | Other | U.K.
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										14	32
International | Other | Libya
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers											0
International | Other | Other International
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers										$ 0	$ 0

Segment Information (Details)

Segment Information (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020USD ($)	Sep. 30, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2020USD ($)segment	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment									2
Revenues from contracts with customers	$ 822	$ 761	$ 490	$ 1,024	$ 1,233	$ 1,249	$ 1,381	$ 1,200	$ 3,097	$ 5,063	$ 5,902
Net gain (loss) on commodity derivatives									116	(72)	(14)
Income (loss) from equity method investments									(161)	87	225
Net gain on disposal of assets									9	50	319
Other income									25	62	150
Production									555	712	842
Shipping, handling and other operating									596	605	575
Exploration									181	149	289
Depreciation, depletion and amortization									2,316	2,397	2,441
Impairments									144	24	75
Taxes other than income									200	311	299
General and administrative									274	356	394
Net interest and other									256	244	226
Other net periodic benefit (costs) credits									(1)	3	(14)
Loss on early extinguishment of debt									28	3	0
Provision (benefit) for income taxes									(14)	(88)	331
Net income (loss)	(338)	$ (317)	$ (750)	$ (46)	(20)	$ 165	$ 161	$ 174	(1,451)	480	1,096
Total assets	17,956				20,245				17,956	20,245	21,321
Capital expenditures									1,151	2,591	2,685
Goodwill, impairment loss									(95)	0	0
Severance costs									17
Impairment of assets held for use									49	24	75
Pension Benefits
Segment Reporting Information [Line Items]
Pension settlement loss									(30)		(21)
Int’l | Pension Benefits
Segment Reporting Information [Line Items]
Other net periodic benefit (costs) credits										0	(3)
Pension settlement loss									0	(12)
Net curtailment gain										0	0
United States E&P
Segment Reporting Information [Line Items]
Revenues from contracts with customers									2,924	4,602	4,886
International Exploration and Production
Segment Reporting Information [Line Items]
Revenues from contracts with customers										461	1,016
Goodwill, impairment loss									(95)	0
Operating Segments | United States E&P
Segment Reporting Information [Line Items]
Revenues from contracts with customers									2,924	4,602	4,886
Net gain (loss) on commodity derivatives									143	52	(281)
Income (loss) from equity method investments									0	0	0
Net gain on disposal of assets									0	0	0
Other income									15	13	16
Production									494	588	625
Shipping, handling and other operating									534	561	499
Exploration									97	149	246
Depreciation, depletion and amortization									2,211	2,250	2,217
Impairments									0	0	0
Taxes other than income									193	311	301
General and administrative									115	127	146
Net interest and other									0	0	0
Other net periodic benefit (costs) credits									0	0	0
Loss on early extinguishment of debt									0	0
Provision (benefit) for income taxes									(9)	6	(21)
Net income (loss)									(553)	675	608
Total assets	16,063				17,781				16,063	17,781	17,321
Capital expenditures									1,137	2,550	2,620
Operating Segments | International Exploration and Production
Segment Reporting Information [Line Items]
Revenues from contracts with customers									173	461	1,016
Net gain (loss) on commodity derivatives									0	0	0
Income (loss) from equity method investments									10	87	225
Net gain on disposal of assets									0	0	0
Other income									7	9	12
Production									59	126	215
Shipping, handling and other operating									8	26	70
Exploration									0	0	3
Depreciation, depletion and amortization									82	121	197
Impairments									0	0	0
Taxes other than income									0	0	0
General and administrative									14	25	32
Net interest and other									0	0	0
Other net periodic benefit (costs) credits									0	3	9
Loss on early extinguishment of debt									0	0
Provision (benefit) for income taxes									(3)	29	272
Net income (loss)									30	233	473
Total assets	1,081				1,530				1,081	1,530	2,083
Capital expenditures									1	16	39
Not Allocated to Segments
Segment Reporting Information [Line Items]
Revenues from contracts with customers									0	0	0
Net gain (loss) on commodity derivatives									(27)	(124)	267
Income (loss) from equity method investments									(171)	0	0
Net gain on disposal of assets									9	50	319
Other income									3	40	122
Production									2	(2)	2
Shipping, handling and other operating									54	18	6
Exploration									84	0	40
Depreciation, depletion and amortization									23	26	27
Impairments									144	24	75
Taxes other than income									7	0	(2)
General and administrative									145	204	216
Net interest and other									256	244	226
Other net periodic benefit (costs) credits									(1)	0	(23)
Loss on early extinguishment of debt									28	3
Provision (benefit) for income taxes									(2)	(123)	80
Net income (loss)									(928)	(428)	15
Total assets	$ 812				$ 934				812	934	1,917
Capital expenditures									13	$ 25	$ 26
Not Allocated to Segments | Pension Benefits
Segment Reporting Information [Line Items]
Net curtailment gain									$ (17)

Segment Information - Geographi

Segment Information - Geographical (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 16,085	$ 17,663
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	15,224	16,507
EQUATORIAL GUINEA
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-Lived Assets	$ 861	$ 1,156

Income Taxes - Schedule of Inco

Income Taxes - Schedule of Income (Loss) Before Tax Expense (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
United States									$ (1,319)	$ 43	$ 642
Foreign									(146)	349	785
Income (loss) before income taxes	$ (341)	$ (310)	$ (765)	$ (49)	$ (3)	$ 175	$ 193	$ 27	$ (1,465)	$ 392	$ 1,427

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Federal
Current	$ (5)	$ (116)	$ 6
Deferred	0	(3)	0
Total	(5)	(119)	6
State and local
Current	(2)	4	(1)
Deferred	(8)	3	(23)
Total	(10)	7	(24)
Foreign
Current	15	58	274
Deferred	(14)	(34)	75
Total	1	24	349
Total
Current	8	(54)	279
Deferred	(22)	(34)	52
Total income tax expense (benefit)	$ (14)	$ (88)	$ 331

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Tax Rate Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ (341)	$ (310)	$ (765)	$ (49)	$ (3)	$ 175	$ 193	$ 27	$ (1,465)	$ 392	$ 1,427
Total income tax expense (benefit)									$ (14)	$ (88)	$ 331
Effective income tax rate									1.00%	(22.00%)	23.00%
Income taxes at the statutory tax rate									$ (308)	$ 83	$ 300
Effects of foreign operations									23	(29)	214
Adjustments to valuation allowances									239	(28)	(177)
State income taxes, net of federal benefit									6	11	(17)
Other federal tax effects									$ 26	$ (125)	$ 11

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2020	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Effective income tax rate excluding Libya					14.00%
Tax benefit from release of foreign tax accruals		$ 126
Operating loss carryforwards			$ 1,966	$ 1,685
Foreign tax credits			611	611
Valuation allowance			(948)	(699)
Deferred tax liabilities			1,912	1,901
Unrecognized tax benefits that would impact effective tax rate			8	13	$ 263	$ 126
Interest and penalties recorded			(2)	(6)	(2)
Interest and penalties accrued				3
Proceeds from tax refunds	$ 89		94	$ 90	$ 37
United States
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expiration			655
Operating loss carryforwards, not subject to expiration			1,100
State
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expiration			184
Foreign
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, subject to expiration			$ 14

Income Taxes - Schedule of Net

Income Taxes - Schedule of Net Deferred Tax Asset/Liability (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Employee benefits	$ 77	$ 90
Operating loss carryforwards	1,966	1,685
Capital loss carryforwards	0	1
Foreign tax credits	611	611
Other	43	27
Subtotal	2,697	2,414
Valuation allowance	(948)	(699)
Total deferred tax assets	1,749	1,715
Deferred tax liabilities:
Property, plant and equipment	1,892	1,861
Accrued revenue	20	40
Total deferred tax liabilities	1,912	1,901
Net deferred tax liabilities	163	186
Net deferred tax assets	$ 0	$ 0

Income Taxes - Balance Sheet Cl

Income Taxes - Balance Sheet Classification (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets
Other noncurrent assets	$ 0	$ 0
Liabilities
Noncurrent deferred tax liabilities	163	186
Net deferred tax liabilities	163	186
Net deferred tax assets	$ 0	$ 0

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrecognized Tax Benefit Rollforward [Abstract]
Beginning balance	$ 13	$ 263	$ 126
Additions for tax positions of prior years	0	13	152
Reductions for tax positions of prior years	(5)	(152)	(15)
Settlements	0	(111)	0
Ending balance	$ 8	$ 13	$ 263

Credit Losses (Details)

Credit Losses (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance as of January 1	$ 11
Current period provision	22
Current period write offs	(13)
Recoveries of amounts previously reserved	(10)
Ending balance as of December 31	22
JIB Receivables
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Current period provision	12
Trade Receivables
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Current period provision	10
Cumulative-effect adjustment
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance as of January 1	$ 12

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Inventory Disclosure [Abstract]
Crude oil and natural gas	$ 10	$ 10
Supplies and sundry items	66	62
Inventories at cost	$ 76	$ 72

Property, Plant and Equipment -

Property, Plant and Equipment - Schedule of Property Plant and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 15,638	$ 17,000
Not Allocated to Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	68	80
United States E&P | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	15,156	16,427
International Exploration and Production | Operating Segments
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 414	$ 493

Property, Plant and Equipment_2

Property, Plant and Equipment - Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Increase (Decrease) in Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]
Beginning balance as of January 1	$ 278	$ 297	$ 295
Additions	97	218	262
Charges to expense	(1)	(5)	(35)
Transfers to development	(164)	(230)	(197)
Dispositions	0	(2)	(28)
Ending balance as of December 31	$ 210	$ 278	297
Rodo
Increase (Decrease) in Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]
Charges to expense			$ (32)

Property, Plant and Equipment_3

Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Amounts capitalized greater than one year after completion of drilling	$ 98	$ 30	$ 6

Impairments (Details)

Impairments (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Impaired Long-Lived Assets Held and Used [Line Items]
Long-Lived Assets			$ 16,085	$ 17,663
Impairment of assets held for use			49	24	$ 75
Goodwill			0	95
Impairment			95	0	0
Impairment	$ 18	$ 152	171	0	0
Fair Value
Impaired Long-Lived Assets Held and Used [Line Items]
Long-Lived Assets			0	$ 56	$ 113
Goodwill			0
Equity method investment			$ 119

Impairment - Narrative (Details

Impairment - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments				$ 144	$ 24	$ 75
Goodwill impairment				95	0	0
Equity method investment, impairment		$ 18	$ 152	171	0	0
Equity method investment, difference between carrying amount and underlying equity	$ 140			140
Long-Lived Assets	16,085			16,085	17,663
Fair Value
Impaired Long-Lived Assets Held and Used [Line Items]
Long-Lived Assets	0			0	$ 56	$ 113
Unproved Property
Impaired Long-Lived Assets Held and Used [Line Items]
Impairments	$ 78			$ 78

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance as of January 1	$ 1,145	$ 254	$ 1,145
Incurred liabilities, including acquisitions		6	34
Settled liabilities, including dispositions		(12)	(1,110)
Accretion expense (included in depreciation, depletion and amortization)		12	31
Revisions of estimates		(6)	46
Held for sale		0	108
Ending balance as of December 31		254	$ 254
Asset retirement obligation, current		$ 13
Droshky Field
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligation, sold during period	$ 98

Leases - Supplemental Balance S

Leases - Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	mro:Deferredcreditandotherliabilities	mro:Deferredcreditandotherliabilities
Right-of-use (“ROU”) asset	$ 133	$ 199
Current portion of long-term lease liability	70	101
Long-term lease liability	$ 67	$ 107

Leases - Lease Costs (Details)

Leases - Lease Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease costs	$ 75	$ 84
Short-term lease costs	170	321
Variable lease costs	23	107
Total lease costs	268	512
Cash paid for amounts included in the measurement of operating lease liabilities	100	100
ROU assets obtained in exchange for new operating lease liabilities	46	293
Reductions to ROU assets resulting from modifications or cancellations of operating leases	(68)	0
Right-of-use (“ROU”) asset	$ 133	$ 199

Leases - Narrative (Details)

Leases - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Jul. 31, 2020
Leases [Abstract]
Weighted average lease term	2 years
Discount rate	3.00%
Annual payments to be received	$ 6
Maximum financing available	340	$ 380
Total costs incurred under lease	$ 144
Term of contract	5 years
Finance lease extension term	5 years
Residual value guarantee	89.00%

Leases - Lease Maturity (Detail

Leases - Lease Maturity (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2021	$ 77
2022	44
2023	11
2024	5
2025	4
Thereafter	2
Total undiscounted lease payments	143
Less: amount representing interest	6
Total operating lease liabilities	137
Less: current portion of long-term lease liability as of December 31, 2020	70	$ 101
Long-term lease liability as of December 31, 2020	$ 67	$ 107

Leases - Lease Payments to be R

Leases - Lease Payments to be Received (Details) $ in Millions	Dec. 31, 2020USD ($)
Leases [Abstract]
2021	$ 6
2022	6
2023	6
2024	6
2025	6
Thereafter	53
Total undiscounted cash flows	$ 83

Goodwill - Narrative (Details)

Goodwill - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill Disclosure [Abstract]
Impairment	$ 95	$ 0	$ 0

Goodwill - Rollforward (Details

Goodwill - Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Beginning balance, net	$ 95
Goodwill, impairment loss	(95)	$ 0	$ 0
Ending balance, net	0	95
International Exploration and Production
Goodwill [Roll Forward]
Goodwill, gross		95	97
Less: accumulated impairment		0	0
Beginning balance, net	95	97
Dispositions	0	(2)
Goodwill, impairment loss	(95)	0
Ending balance, net	$ 0	$ 95	$ 97

Derivatives - Balance Sheet Com

Derivatives - Balance Sheet Components (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Asset	$ 39	$ 12
Liability	49	6
Net Asset (Liability)	(10)	6
Interest Rate | Not Designated as Hedges
Derivatives, Fair Value [Line Items]
Net Asset (Liability)	(2)	0
Not Designated as Hedges
Derivatives, Fair Value [Line Items]
Asset	20	10
Liability	33	6
Net Asset (Liability)	(13)	4
Not Designated as Hedges | Other current assets | Commodity
Derivatives, Fair Value [Line Items]
Asset	3	9
Liability	1	1
Net Asset (Liability)	2	8
Not Designated as Hedges | Other current liabilities | Commodity
Derivatives, Fair Value [Line Items]
Asset	7	0
Liability	32	5
Net Asset (Liability)	(25)	(5)
Not Designated as Hedges | Other noncurrent assets | Commodity
Derivatives, Fair Value [Line Items]
Asset		1
Liability		0
Net Asset (Liability)		1
Not Designated as Hedges | Other noncurrent assets | Interest Rate
Derivatives, Fair Value [Line Items]
Asset	10
Liability	0
Net Asset (Liability)	10
Cash Flow Hedges
Derivatives, Fair Value [Line Items]
Asset	19	2
Liability	16	0
Net Asset (Liability)	3	2
Cash Flow Hedges | Other noncurrent assets | Interest Rate
Derivatives, Fair Value [Line Items]
Asset	19	2
Liability	0	0
Net Asset (Liability)	19	$ 2
Cash Flow Hedges | Deferred credits and other liabilities | Interest Rate
Derivatives, Fair Value [Line Items]
Asset	0
Liability	16
Net Asset (Liability)	$ (16)

Derivatives - Outstanding Deriv

Derivatives - Outstanding Derivative Contracts (Details) - Not Designated as Hedges	Dec. 31, 2020Bbls_per_dayMMBTU_per_day$ / MMBTU$ / bbl
Three-Way Collars - Crude Oil 2021 Q1
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
Derivative, ceiling	0
Derivative, floor	0
Derivative, sold put	0
Three-Way Collars - Crude Oil 2021 Q2
Derivative [Line Items]
Derivative, volume | Bbls_per_day	10,000
Derivative, ceiling	58.72
Derivative, floor	37
Derivative, sold put	27
Three-Way Collars - Crude Oil 2021 Q3
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
Derivative, ceiling	0
Derivative, floor	0
Derivative, sold put	0
Three-Way Collars - Crude Oil 2021 Q4
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
Derivative, ceiling	0
Derivative, floor	0
Derivative, sold put	0
Two-Way Collars - Crude Oil 2021 Q1
Derivative [Line Items]
Derivative, volume | Bbls_per_day	90,000
Derivative, ceiling	51.86
Derivative, floor	35.44
Two-Way Collars - Crude Oil 2021 Q2
Derivative [Line Items]
Derivative, volume | Bbls_per_day	50,000
Derivative, ceiling	52.98
Derivative, floor	35.80
Two-Way Collars - Crude Oil 2021 Q3
Derivative [Line Items]
Derivative, volume | Bbls_per_day	30,000
Derivative, ceiling	51.54
Derivative, floor	35.67
Two-Way Collars - Crude Oil 2021 Q4
Derivative [Line Items]
Derivative, volume | Bbls_per_day	30,000
Derivative, ceiling	51.54
Derivative, floor	35.67
Brent Basis Swaps - Crude Oil 2021 Q1
Derivative [Line Items]
Derivative, volume | Bbls_per_day	3,278
Brent Basis Swaps - Crude Oil 2021 Q1 | Long
Derivative [Line Items]
Derivative, weighted average price	(7.24)
Brent Basis Swaps - Crude Oil 2021 Q2
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
Brent Basis Swaps - Crude Oil 2021 Q2 | Long
Derivative [Line Items]
Derivative, weighted average price	0
Brent Basis Swaps - Crude Oil 2021 Q3
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
Brent Basis Swaps - Crude Oil 2021 Q3 | Long
Derivative [Line Items]
Derivative, weighted average price	0
Brent Basis Swaps - Crude Oil 2021 Q4
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
Brent Basis Swaps - Crude Oil 2021 Q4 | Long
Derivative [Line Items]
Derivative, weighted average price	0
UHC Basis Swaps - Crude Oil 2021 Q1
Derivative [Line Items]
Derivative, volume | Bbls_per_day	14,000
UHC Basis Swaps - Crude Oil 2021 Q1 | Long
Derivative [Line Items]
Derivative, weighted average price	(1.80)
UHC Basis Swaps - Crude Oil 2021 Q2
Derivative [Line Items]
Derivative, volume | Bbls_per_day	14,000
UHC Basis Swaps - Crude Oil 2021 Q2 | Long
Derivative [Line Items]
Derivative, weighted average price	(1.80)
UHC Basis Swaps - Crude Oil 2021 Q3
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
UHC Basis Swaps - Crude Oil 2021 Q3 | Long
Derivative [Line Items]
Derivative, weighted average price	0
UHC Basis Swaps - Crude Oil 2021 Q4
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
UHC Basis Swaps - Crude Oil 2021 Q4 | Long
Derivative [Line Items]
Derivative, weighted average price	0
NYMEX Roll Basis Swaps - Crude Oil 2021 Q1
Derivative [Line Items]
Derivative, volume | Bbls_per_day	50,000
NYMEX Roll Basis Swaps - Crude Oil 2021 Q1 | Long
Derivative [Line Items]
Derivative, weighted average price	(0.13)
NYMEX Roll Basis Swaps - Crude Oil 2021 Q2
Derivative [Line Items]
Derivative, volume | Bbls_per_day	50,000
NYMEX Roll Basis Swaps - Crude Oil 2021 Q2 | Long
Derivative [Line Items]
Derivative, weighted average price	(0.13)
NYMEX Roll Basis Swaps - Crude Oil 2021 Q3
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
NYMEX Roll Basis Swaps - Crude Oil 2021 Q3 | Long
Derivative [Line Items]
Derivative, weighted average price	0
NYMEX Roll Basis Swaps - Crude Oil 2021 Q4
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
NYMEX Roll Basis Swaps - Crude Oil 2021 Q4 | Long
Derivative [Line Items]
Derivative, weighted average price	0
Two-Way Collars - Natural Gas 2021 Q1
Derivative [Line Items]
Derivative, volume | MMBTU_per_day	250,000
Derivative, ceiling | $ / MMBTU	3.14
Derivative, floor | $ / MMBTU	2.52
Two-Way Collars - Natural Gas 2021 Q2
Derivative [Line Items]
Derivative, volume | MMBTU_per_day	200,000
Derivative, ceiling | $ / MMBTU	3.05
Derivative, floor | $ / MMBTU	2.50
Two-Way Collars - Natural Gas 2021 Q3
Derivative [Line Items]
Derivative, volume | MMBTU_per_day	200,000
Derivative, ceiling | $ / MMBTU	3.05
Derivative, floor | $ / MMBTU	2.50
Two-Way Collars - Natural Gas 2021 Q4
Derivative [Line Items]
Derivative, volume | MMBTU_per_day	200,000
Derivative, ceiling | $ / MMBTU	3.05
Derivative, floor | $ / MMBTU	2.50
HH Basis Swaps - Natural Gas 2021 Q1
Derivative [Line Items]
Derivative, volume | MMBTU_per_day	50,000
HH Basis Swaps - Natural Gas 2021 Q1 | Short
Derivative [Line Items]
Derivative, weighted average price | $ / MMBTU	2.88
HH Basis Swaps - Natural Gas 2021 Q2
Derivative [Line Items]
Derivative, volume | MMBTU_per_day	50,000
HH Basis Swaps - Natural Gas 2021 Q2 | Short
Derivative [Line Items]
Derivative, weighted average price | $ / MMBTU	2.88
HH Basis Swaps - Natural Gas 2021 Q3
Derivative [Line Items]
Derivative, volume | MMBTU_per_day	50,000
HH Basis Swaps - Natural Gas 2021 Q3 | Short
Derivative [Line Items]
Derivative, weighted average price | $ / MMBTU	2.88
HH Basis Swaps - Natural Gas 2021 Q4
Derivative [Line Items]
Derivative, volume | MMBTU_per_day	50,000
HH Basis Swaps - Natural Gas 2021 Q4 | Short
Derivative [Line Items]
Derivative, weighted average price | $ / MMBTU	2.88
Fixed Price Propane Swaps - NGL 2021 Q1
Derivative [Line Items]
Derivative, volume | Bbls_per_day	5,000
Fixed Price Propane Swaps - NGL 2021 Q1 | Short
Derivative [Line Items]
Derivative, weighted average price	23.19
Fixed Price Propane Swaps - NGL 2021 Q2
Derivative [Line Items]
Derivative, volume | Bbls_per_day	5,000
Fixed Price Propane Swaps - NGL 2021 Q2 | Short
Derivative [Line Items]
Derivative, weighted average price	23.19
Fixed Price Propane Swaps - NGL 2021 Q3
Derivative [Line Items]
Derivative, volume | Bbls_per_day	5,000
Fixed Price Propane Swaps - NGL 2021 Q3 | Short
Derivative [Line Items]
Derivative, weighted average price	23.19
Fixed Price Propane Swaps - NGL 2021 Q4
Derivative [Line Items]
Derivative, volume | Bbls_per_day	5,000
Fixed Price Propane Swaps - NGL 2021 Q4 | Short
Derivative [Line Items]
Derivative, weighted average price	23.19

Derivatives - Subsequent Event

Derivatives - Subsequent Event Derivative Contracts (Details) - Not Designated as Hedges	Feb. 15, 2021Bbls_per_day$ / bbl	Dec. 31, 2020Bbls_per_day$ / bbl
UHC Basis Swaps - Crude Oil 2021 Q1
Derivative [Line Items]
Derivative, volume | Bbls_per_day		14,000
UHC Basis Swaps - Crude Oil 2021 Q1 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	344
UHC Basis Swaps - Crude Oil 2021 Q1 | Long
Derivative [Line Items]
Derivative, weighted average price		(1.80)
UHC Basis Swaps - Crude Oil 2021 Q1 | Long | Subsequent Event
Derivative [Line Items]
Derivative, weighted average price	(1.80)
UHC Basis Swaps - Crude Oil 2021 Q2
Derivative [Line Items]
Derivative, volume | Bbls_per_day		14,000
UHC Basis Swaps - Crude Oil 2021 Q2 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	1,000
UHC Basis Swaps - Crude Oil 2021 Q2 | Long
Derivative [Line Items]
Derivative, weighted average price		(1.80)
UHC Basis Swaps - Crude Oil 2021 Q2 | Long | Subsequent Event
Derivative [Line Items]
Derivative, weighted average price	(1.80)
UHC Basis Swaps - Crude Oil 2021 Q3
Derivative [Line Items]
Derivative, volume | Bbls_per_day		0
UHC Basis Swaps - Crude Oil 2021 Q3 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
UHC Basis Swaps - Crude Oil 2021 Q3 | Long
Derivative [Line Items]
Derivative, weighted average price		0
UHC Basis Swaps - Crude Oil 2021 Q3 | Long | Subsequent Event
Derivative [Line Items]
Derivative, weighted average price	0
UHC Basis Swaps - Crude Oil 2021 Q4
Derivative [Line Items]
Derivative, volume | Bbls_per_day		0
UHC Basis Swaps - Crude Oil 2021 Q4 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
UHC Basis Swaps - Crude Oil 2021 Q4 | Long
Derivative [Line Items]
Derivative, weighted average price		0
UHC Basis Swaps - Crude Oil 2021 Q4 | Long | Subsequent Event
Derivative [Line Items]
Derivative, weighted average price	0
Three-Way Collars - Crude Oil 2021 Q1
Derivative [Line Items]
Derivative, volume | Bbls_per_day		0
Derivative, ceiling		0
Derivative, floor		0
Derivative, sold put		0
Three-Way Collars - Crude Oil 2021 Q1 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
Derivative, ceiling	0
Derivative, floor	0
Derivative, sold put	0
Three-Way Collars - Crude Oil 2021 Q2
Derivative [Line Items]
Derivative, volume | Bbls_per_day		10,000
Derivative, ceiling		58.72
Derivative, floor		37
Derivative, sold put		27
Three-Way Collars - Crude Oil 2021 Q2 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	30,000
Derivative, ceiling	62.36
Derivative, floor	40.67
Derivative, sold put	30.67
Three-Way Collars - Crude Oil 2021 Q3
Derivative [Line Items]
Derivative, volume | Bbls_per_day		0
Derivative, ceiling		0
Derivative, floor		0
Derivative, sold put		0
Three-Way Collars - Crude Oil 2021 Q3 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	10,000
Derivative, ceiling	65.18
Derivative, floor	45
Derivative, sold put	35
Three-Way Collars - Crude Oil 2021 Q4
Derivative [Line Items]
Derivative, volume | Bbls_per_day		0
Derivative, ceiling		0
Derivative, floor		0
Derivative, sold put		0
Three-Way Collars - Crude Oil 2021 Q4 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
Derivative, ceiling	0
Derivative, floor	0
Derivative, sold put	0
WTI Fixed Rate Swaps - Crude Oil 2021 Q1 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	20,000
WTI Fixed Rate Swaps - Crude Oil 2021 Q1 | Short | Subsequent Event
Derivative [Line Items]
Derivative, weighted average price	50.35
WTI Fixed Rate Swaps - Crude Oil 2021 Q2 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
WTI Fixed Rate Swaps - Crude Oil 2021 Q2 | Short | Subsequent Event
Derivative [Line Items]
Derivative, weighted average price	0
WTI Fixed Rate Swaps - Crude Oil 2021 Q3 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
WTI Fixed Rate Swaps - Crude Oil 2021 Q3 | Short | Subsequent Event
Derivative [Line Items]
Derivative, weighted average price	0
WTI Fixed Rate Swaps - Crude Oil 2021 Q4 | Subsequent Event
Derivative [Line Items]
Derivative, volume | Bbls_per_day	0
WTI Fixed Rate Swaps - Crude Oil 2021 Q4 | Short | Subsequent Event
Derivative [Line Items]
Derivative, weighted average price	0

Derivatives - Schedule of mark-

Derivatives - Schedule of mark-to-market impact and commodity derivative settlements (Details) - Commodity - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized mark-to-market gain (loss)	$ (27)	$ (124)	$ 267
Net settlements of commodity derivative instruments	$ 143	$ 52	$ (281)

Derivatives - Narrative (Detail

Derivatives - Narrative (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Net Asset (Liability)	$ (10,000,000)	$ 6,000,000
Interest rate swap gain (loss) to be reclassified during next twelve months	0
Interest Rate
Derivative Instruments, Gain (Loss) [Line Items]
Deferred gain related to interest rate swaps	2,000,000
Not Designated as Hedges | Interest Rate
Derivative Instruments, Gain (Loss) [Line Items]
Net Asset (Liability)	$ (2,000,000)	$ 0

Derivatives - Schedule of Termi

Derivatives - Schedule of Terminated Interest Rate Swap Agreement (Details) - Interest Rate Contract, Maturing November 1, 2022 - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative, notional amount	$ 500	$ 0
Weighted average interest rate, LIBOR	0.99%	0.00%

Derivatives - Rollforward of In

Derivatives - Rollforward of Interest Rate Swap Agreements (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020USD ($)
Net Impact Of Derivatives De-Designated As Cash Flow Hedges [Roll Forward]
Beginning balance	$ 6
Ending balance	(10)
Interest Rate | Not Designated as Hedges
Net Impact Of Derivatives De-Designated As Cash Flow Hedges [Roll Forward]
Beginning balance	0
Change in fair value recognized in other comprehensive income (loss)	(2)
Ending balance	$ (2)

Derivatives - Schedule of Inter

Derivatives - Schedule of Interest Rate Swap Agreements (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Interest Rate Contract, Maturing June 1, 2025
Derivative [Line Items]
Derivative, notional amount	$ 350	$ 0
Weighted average interest rate, LIBOR	0.95%	0.00%
Interest Rate Contract, Maturing September 9, 2026
Derivative [Line Items]
Derivative, notional amount	$ 320	$ 320
Weighted average interest rate, LIBOR	1.51%	1.51%

Fair Value Measurements - Recur

Fair Value Measurements - Recurring (Details) - Recurring - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	$ 29	$ 9
Derivative instruments, liabilities	(39)	(3)
Total	(10)	6
Commodity
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets		7
Derivative instruments, liabilities	(23)	(3)
Interest Rate | Not Designated as Hedges
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	10
Interest Rate | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	19	2
Derivative instruments, liabilities	(16)
Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	0	0
Derivative instruments, liabilities	0	(3)
Total	0	(3)
Level 1 | Commodity
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets		0
Derivative instruments, liabilities	0	(3)
Level 1 | Interest Rate | Not Designated as Hedges
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	0
Level 1 | Interest Rate | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	0	0
Derivative instruments, liabilities	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	29	9
Derivative instruments, liabilities	(39)	0
Total	(10)	9
Level 2 | Commodity
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets		7
Derivative instruments, liabilities	(23)	0
Level 2 | Interest Rate | Not Designated as Hedges
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	10
Level 2 | Interest Rate | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	19	2
Derivative instruments, liabilities	(16)
Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	0	0
Derivative instruments, liabilities	0	0
Total	0	0
Level 3 | Commodity
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets		0
Derivative instruments, liabilities	0	0
Level 3 | Interest Rate | Not Designated as Hedges
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	0
Level 3 | Interest Rate | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative instruments, assets	0	$ 0
Derivative instruments, liabilities	$ 0

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values, Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value
Financial assets
Current assets	$ 4	$ 4
Other noncurrent assets	24	26
Total financial assets	28	30
Financial liabilities
Other current liabilities	72	62
Long-term debt, including current portion	6,077	6,174
Deferred credits and other liabilities	103	99
Total financial liabilities	6,252	6,335
Carrying Amount
Financial assets
Current assets	4	4
Other noncurrent assets	37	38
Total financial assets	41	42
Financial liabilities
Other current liabilities	103	90
Long-term debt, including current portion	5,431	5,529
Deferred credits and other liabilities	76	86
Total financial liabilities	$ 5,610	$ 5,705

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($)	Aug. 18, 2020	Oct. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt			$ 5,404,000,000	$ 5,501,000,000
St. John the Baptist Parish, State of Louisiana Revenue Bonds Due 2037
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 400,000,000
Revenue refunding bond					$ 1,000,000,000
Aggregate Maximum Tender
Debt Instrument [Line Items]
Repayments of debt		$ 500,000,000
Senior Unsecured Note Due 2022
Debt Instrument [Line Items]
Debt instrument, interest rate		2.80%
Long-term debt			500,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit, outstanding balance			0
Line of credit Facility, maximum borrowing capacity			$ 3,000,000,000
Covenant, ratio of indebtedness to net capital, maximum			65.00%
Ratio of indebtedness to net capital			0.26

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt, gross	$ 5,436	$ 5,536
Unamortized discount	(5)	(7)
Unamortized debt issuance cost	(27)	(28)
Total long-term debt	5,404	5,501
Debt immediately due if change in control	$ 236
Senior Unsecured Notes, 2.800%, Due 2022 | Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	2.80%
Long-term debt, gross	$ 500	1,000
Senior Unsecured Notes, 9.375%, Due 2022 | Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	9.375%
Long-term debt, gross	$ 32	32
Senior Unsecured Notes, Series A, Due 2022 | Senior Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 3	3
Senior Unsecured Notes, 8.500%, Due 2023 | Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	8.50%
Long-term debt, gross	$ 70	70
Senior Unsecured Notes, 8.125%, Due 2023 | Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	8.125%
Long-term debt, gross	$ 131	131
Senior Unsecured Notes, 3.850%, Due 2025 | Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	3.85%
Long-term debt, gross	$ 900	900
Senior Unsecured Notes, 4.400%, Due 2027 | Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	4.40%
Long-term debt, gross	$ 1,000	1,000
Senior Unsecured Notes, 6.800%, Due 2032 | Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	6.80%
Long-term debt, gross	$ 550	550
Senior Unsecured Notes, 6.600%, Due 2037 | Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	6.60%
Long-term debt, gross	$ 750	750
Senior Unsecured Notes, 5.200%, Due 2045 | Senior Unsecured Notes
Debt Instrument [Line Items]
Debt instrument, interest rate	5.20%
Long-term debt, gross	$ 500	500
Bonds, 2.00%, Due 2037 | Bonds
Debt Instrument [Line Items]
Debt instrument, interest rate	2.00%
Long-term debt, gross	$ 200	200
Bonds, 2.10%, Due 2037 | Bonds
Debt Instrument [Line Items]
Debt instrument, interest rate	2.10%
Long-term debt, gross	$ 200	200
Bonds, 2.20%, Due 2037 | Bonds
Debt Instrument [Line Items]
Debt instrument, interest rate	2.20%
Long-term debt, gross	$ 200	200
Bonds, 2.125%, Due 2037 | Bonds
Debt Instrument [Line Items]
Debt instrument, interest rate	2.125%
Long-term debt, gross	$ 200	0
Bonds, 2.375%, Due 2037 | Bonds
Debt Instrument [Line Items]
Debt instrument, interest rate	2.375%
Long-term debt, gross	$ 200	$ 0

Debt - Maturity (Details)

Debt - Maturity (Details) $ in Millions	Dec. 31, 2020USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
2021	$ 0
2022	535
2023	401
2024	400
2025	900
Thereafter	3,200
Total long-term debt, including current portion	$ 5,436

Incentive Based Compensation -

Incentive Based Compensation - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	27,900,000
Allocated stock-based compensation expense	$ 55,000,000	$ 60,000,000	$ 53,000,000
Proceeds from stock options exercised	1,000,000	1,000,000	26,000,000
Tax benefit realized from exercise of stock options	0	$ 0	0
Stock option awards, intrinsic value			$ 13,000,000
Unrecognized compensation costs	$ 4,000,000
Unrecognized compensation costs, period for recognition	1 year
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Maximum term	10 years
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards other than options, outstanding (in shares)	0
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)	$ 10.55	$ 20.66	$ 17.29
Performance Shares | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	0.00%
Performance Shares | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	200.00%
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs	$ 48,000,000
Unrecognized compensation costs, period for recognition	1 year
Vested in period, total fair value	$ 49,000,000	$ 48,000,000	$ 48,000,000
Weighted average grant date fair value (in dollars per share)	$ 11.72	$ 15.88	$ 14.04
Grants in period (in shares)	5,390,960
Restricted Stock | Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Restricted Stock | Non Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Restricted Stock Units (RSUs) | Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Restricted Stock Units (RSUs) | Non Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Performance Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards other than options, outstanding (in shares)	1,658,088
Allocated stock-based compensation expense	$ 5,000,000	$ 7,000,000	$ 13,000,000
Performance Unit | Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	1,038,676	656,636	754,140

Incentive Based Compensation _2

Incentive Based Compensation - Stock Option Award Assumptions (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price per share (in dollars per share)	$ 10.47	$ 16.79	$ 14.52
Expected annual dividend yield	1.90%	1.20%	1.40%
Expected life in years	6 years 1 month 20 days	5 years 9 months 25 days	6 years 5 months 12 days
Expected volatility	44.00%	43.00%	43.00%
Risk-free interest rate	1.50%	2.50%	2.80%
Weighted average grant date fair value of stock option awards granted (in dollars per share)	$ 3.82	$ 6.62	$ 5.83

Incentive Based Compensation _3

Incentive Based Compensation - Stock Option Award Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement [Abstract]
Stock option awards, intrinsic value			$ 13
Unrecognized compensation costs	$ 4
Unrecognized compensation costs, period for recognition	1 year
Stock Options
Number of Shares
Beginning of year, stock option awards (in shares)	5,659,731
Granted, stock option awards (in shares)	1,132,808
Exercised, stock option awards (in shares)	(52,333)
Canceled, stock option awards (in shares)	(725,951)
End of year, stock option awards (in shares)	6,014,255	5,659,731
Exercisable at end of year, stock option awards (in shares)	4,219,975
Expected to vest, stock option awards (in shares)	1,766,804
Weighted Average Exercise Price
Beginning of year, weighted average exercise price (in dollars per share)	$ 23.55
Granted, weighted average exercise price (in dollars per share)	10.47	$ 16.79	$ 14.52
Exercises, weighted average exercise price (in dollars per share)	7.22
Canceled, weighted average exercise price (in dollars per share)	25.44
End of year, weighted average exercise price (in dollars per share)	21	$ 23.55
Exercisable at end of year, weighted average exercise price (in dollars per share)	24.63
Expected to vest, weighted average exercise price (in dollars per share)	$ 12.50
Share-based Payment Arrangement [Abstract]
Outstanding at end of year, Weighted Average Remaining Contractual Term	5 years
Exercisable at end of year, Weighted Average Remaining Contractual Term	4 years
Expected to vest, Weighted Average Remaining Contractual Term	9 years
Outstanding at end of year, Average Intrinsic Value
Exercisable at end of year, Average Intrinsic Value	0
Expected to vest, Average Intrinsic Value	$ 0

Incentive Based Compensation _4

Incentive Based Compensation - Restricted Stock Awards and RSUs (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Awards
Unvested at beginning of year (in shares)	7,174,386
Granted (in shares)	5,390,960
Vested & Exercised (in shares)	(3,127,762)
Canceled (in shares)	(1,585,830)
Unvested at end of year (in shares)	7,851,754	7,174,386
Weighted Average Grant Date Fair Value
Unvested at beginning of year (in dollars per share)	$ 15.88	$ 14.04
Granted (in dollars per share)	8.50
Vested & Exercised (in dollars per share)	15.76
Canceled (in dollars per share)	11.65
Unvested at end of year (in dollars per share)	$ 11.72	$ 15.88

Incentive Based Compensation _5

Incentive Based Compensation - Performance Unit Awards (Details) - Performance Shares - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Valuation date stock price (in dollars per share)	$ 10.47	$ 16.79	$ 13.69
Expected annual dividend yield	1.90%	1.20%	1.50%
Expected volatility	39.00%	43.00%	41.00%
Risk-free interest rate	1.40%	2.50%	1.50%
Weighted average grant date fair value (in dollars per share)	$ 10.55	$ 20.66	$ 17.29

Defined Benefit Postretiremen_3

Defined Benefit Postretirement Plans and Defined Contribution Plan - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Decrease in other benefit obligations			$ (99)
Estimated future employer contributions in next year	$ 40
Employer discretionary contribution amount	$ 13	$ 18	$ 22
Equity Securities
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Target allocation percentage	55.00%
Fixed Income Securities
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Target allocation percentage	45.00%
Pension Benefits
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Reclassification from AOCI		$ 20
Unfunded Plans
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Estimated future employer contributions in next year	$ 3
Other Benefits
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Estimated future employer contributions in next year	$ 10

Defined Benefit Postretiremen_4

Defined Benefit Postretirement Plans and Defined Contribution Plan - Obligations and Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits
Change in benefit obligations:
Benefits paid	$ (30)		$ (21)
Pension Benefits | U.S.
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Accumulated benefit obligation	298	$ 343
Change in benefit obligations:
Beginning balance	354	326
Service cost	19	19	18
Interest cost	9	12	12
Plan amendment	0	0
Divestiture	0	0
Actuarial loss	36	48
Foreign currency exchange rate changes	0	0
Gain due to curtailment	(1)	0
Settlements paid	(104)	(45)
Benefits paid	(5)	(6)
Ending balance	308	354	326
Change in fair value of plan assets:
Beginning balance	236	203
Actual return on plan assets	18	44
Employer contributions	49	40
Foreign currency exchange rate changes	0	0
Divestiture	0	0
Settlements paid	(104)	(45)
Benefits paid	(5)	(6)
Ending balance	194	236	203
Funded status of plans at December 31
Funded status of plans at December 31	(114)	(118)
Amounts recognized in the consolidated balance sheets:
Noncurrent assets	0	0
Current liabilities	(4)	(6)
Noncurrent liabilities	(110)	(112)
Accrued benefit cost	(114)	(118)
Pretax amounts in accumulated other comprehensive loss:
Net loss	72	85
Prior service credit	(19)	(29)
Pension Benefits | Int’l
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Accumulated benefit obligation	0	0
Change in benefit obligations:
Beginning balance	0	511
Service cost	0	0	0
Interest cost	0	8	14
Plan amendment	0	0
Divestiture	0	(549)
Actuarial loss	0	36
Foreign currency exchange rate changes	0	6
Gain due to curtailment	0	0
Settlements paid	0	0
Benefits paid	0	(12)
Ending balance	0	0	511
Change in fair value of plan assets:
Beginning balance	0	594
Actual return on plan assets	0	68
Employer contributions	0	8
Foreign currency exchange rate changes	0	8
Divestiture	0	(666)
Settlements paid	0	0
Benefits paid	0	(12)
Ending balance	0	0	594
Funded status of plans at December 31
Funded status of plans at December 31	0	0
Amounts recognized in the consolidated balance sheets:
Noncurrent assets	0	0
Current liabilities	0	0
Noncurrent liabilities	0	0
Accrued benefit cost	0	0
Pretax amounts in accumulated other comprehensive loss:
Net loss	0	0
Prior service credit	0	0
Other Benefits | U.S.
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Accumulated benefit obligation	80	89
Change in benefit obligations:
Beginning balance	89	96
Service cost	1	1
Interest cost	2	3
Plan amendment	0	0
Divestiture	0	0
Actuarial loss	4	9
Foreign currency exchange rate changes	0	0
Gain due to curtailment	0	0
Settlements paid	0	0
Benefits paid	(16)	(20)
Ending balance	80	89	96
Change in fair value of plan assets:
Beginning balance	0	0
Actual return on plan assets	0	0
Employer contributions	16	20
Foreign currency exchange rate changes	0	0
Divestiture	0	0
Settlements paid	0	0
Benefits paid	(16)	(20)
Ending balance	0	0	0
Funded status of plans at December 31
Funded status of plans at December 31	(80)	(89)
Amounts recognized in the consolidated balance sheets:
Noncurrent assets	0	0
Current liabilities	(10)	(18)
Noncurrent liabilities	(70)	(71)
Accrued benefit cost	(80)	(89)
Pretax amounts in accumulated other comprehensive loss:
Net loss	24	23
Prior service credit	$ (97)	$ (129)
Other Benefits | Int’l
Change in benefit obligations:
Service cost			2
Interest cost			$ 7

Defined Benefit Postretiremen_5

Defined Benefit Postretirement Plans and Defined Contribution Plan - Schedule of Net Periodic Benefit Cost and OCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Depreciation, Depletion and Amortization [Abstract]
Net settlement loss	$ (1)	$ 3	$ (14)
Pension Benefits | U.S.
Components of net periodic benefit costs:
Service cost	19	19	18
Interest cost	9	12	12
Expected return on plan assets	(11)	(10)	(11)
Depreciation, Depletion and Amortization [Abstract]
- prior service cost (credit)	(6)	(7)	(10)
- actuarial loss	9	7	11
Net settlement loss	(30)	(12)	(18)
Net curtailment gain	(3)	0	0
Net periodic benefit cost	47	33	38
Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax):
Actuarial loss (gain)	27	14	(4)
Settlement loss and amortization of actuarial gain (loss)	(40)	(19)	(29)
Prior service cost (credit)	0	0	0
Curtailment gain and amortization of prior service credit (cost)	10	7	10
Total recognized in other comprehensive (income) loss	(3)	2	(23)
Total recognized in net periodic benefit cost and other comprehensive (income) loss	44	35	15
Pension Benefits | Int’l
Components of net periodic benefit costs:
Service cost	0	0	0
Interest cost	0	8	14
Expected return on plan assets		(11)	(24)
Depreciation, Depletion and Amortization [Abstract]
- prior service cost (credit)		0	0
- actuarial loss		0	0
Net settlement loss		0	(3)
Net curtailment gain		0	0
Net periodic benefit cost		(3)	(7)
Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax):
Actuarial loss (gain)		(21)	8
Settlement loss and amortization of actuarial gain (loss)		(41)	(3)
Prior service cost (credit)		0	3
Curtailment gain and amortization of prior service credit (cost)		(6)	0
Total recognized in other comprehensive (income) loss		(68)	8
Total recognized in net periodic benefit cost and other comprehensive (income) loss		(71)	1
Other Benefits | U.S.
Components of net periodic benefit costs:
Service cost	1	1
Interest cost	2	3
Expected return on plan assets	0	0
Depreciation, Depletion and Amortization [Abstract]
- prior service cost (credit)	(18)	(19)
- actuarial loss	2	1
Net settlement loss	0	0
Net curtailment gain	(14)	0
Net periodic benefit cost	(27)	(14)
Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax):
Actuarial loss (gain)	4	9
Settlement loss and amortization of actuarial gain (loss)	(2)	(1)
Prior service cost (credit)	0	0
Curtailment gain and amortization of prior service credit (cost)	32	19
Total recognized in other comprehensive (income) loss	34	27
Total recognized in net periodic benefit cost and other comprehensive (income) loss	$ 7	$ 13
Other Benefits | Int’l
Components of net periodic benefit costs:
Service cost			2
Interest cost			7
Expected return on plan assets			0
Depreciation, Depletion and Amortization [Abstract]
- prior service cost (credit)			(8)
- actuarial loss			1
Net settlement loss			0
Net curtailment gain			0
Net periodic benefit cost			2
Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax):
Actuarial loss (gain)			(15)
Settlement loss and amortization of actuarial gain (loss)			(1)
Prior service cost (credit)			(99)
Curtailment gain and amortization of prior service credit (cost)			8
Total recognized in other comprehensive (income) loss			(107)
Total recognized in net periodic benefit cost and other comprehensive (income) loss			$ (105)

Defined Benefit Postretiremen_6

Defined Benefit Postretirement Plans and Defined Contribution Plan - Plan Assumptions (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2021
Pension Benefits | U.S.
Weighted average assumptions used to determine benefit obligation:
Discount rate	2.52%	3.13%	4.26%
Rate of compensation increase	0.50%	4.50%	4.00%
Cash balance interest crediting	3.00%	3.00%	3.26%
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate	2.90%	3.70%	3.88%
Expected long-term return on plan assets	6.00%	6.25%	6.50%
Rate of compensation increase	4.50%	4.00%	4.00%
Cash balance interest crediting	3.00%	3.00%	3.00%
Pension Benefits | U.S. | Forecast
Weighted average assumptions used to determine benefit obligation:
Rate of compensation increase				4.50%
Pension Benefits | Int’l
Weighted average assumptions used to determine benefit obligation:
Discount rate			2.90%
Rate of compensation increase			0.00%
Cash balance interest crediting			0.00%
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate			2.50%
Expected long-term return on plan assets			3.70%
Rate of compensation increase			0.00%
Cash balance interest crediting			0.00%
Other Benefits | U.S.
Weighted average assumptions used to determine benefit obligation:
Discount rate	2.02%	2.91%	4.09%
Rate of compensation increase	0.50%	4.50%	4.00%
Cash balance interest crediting	0.00%	0.00%	0.00%
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate	2.63%	4.09%	3.54%
Expected long-term return on plan assets	0.00%	0.00%	0.00%
Rate of compensation increase	4.50%	4.00%	4.00%
Cash balance interest crediting	0.00%	0.00%	0.00%

Defined Benefit Postretiremen_7

Defined Benefit Postretirement Plans and Defined Contribution Plan - Fair Value of Defined Benefit Pension Plan Assets (Details) - Recurring - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Plan assets before comingled funds	$ 87	$ 148
Plan assets	194	236
Cash and cash equivalents(b)
Defined Benefit Plan Disclosure [Line Items]
Plan assets		(7)
Common stock
Defined Benefit Plan Disclosure [Line Items]
Plan assets	61	75
Private equity
Defined Benefit Plan Disclosure [Line Items]
Plan assets	8	10
Corporate
Defined Benefit Plan Disclosure [Line Items]
Plan assets		2
Exchange traded funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets		3
Government
Defined Benefit Plan Disclosure [Line Items]
Plan assets		47
Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	18	18
Commingled funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	107	88
Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets before comingled funds	61	102
Plan assets	61	102
Level 1 | Cash and cash equivalents(b)
Defined Benefit Plan Disclosure [Line Items]
Plan assets		(7)
Level 1 | Common stock
Defined Benefit Plan Disclosure [Line Items]
Plan assets	61	75
Level 1 | Private equity
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Level 1 | Corporate
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0
Level 1 | Exchange traded funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets		3
Level 1 | Government
Defined Benefit Plan Disclosure [Line Items]
Plan assets		31
Level 1 | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets before comingled funds	0	13
Plan assets	0	13
Level 2 | Cash and cash equivalents(b)
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0
Level 2 | Common stock
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Level 2 | Private equity
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Level 2 | Corporate
Defined Benefit Plan Disclosure [Line Items]
Plan assets		2
Level 2 | Exchange traded funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0
Level 2 | Government
Defined Benefit Plan Disclosure [Line Items]
Plan assets		11
Level 2 | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets before comingled funds	26	33
Plan assets	26	33
Level 3 | Cash and cash equivalents(b)
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0
Level 3 | Common stock
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Level 3 | Private equity
Defined Benefit Plan Disclosure [Line Items]
Plan assets	8	10
Level 3 | Corporate
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0
Level 3 | Exchange traded funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets		0
Level 3 | Government
Defined Benefit Plan Disclosure [Line Items]
Plan assets		5
Level 3 | Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 18	$ 18

Defined Benefit Postretiremen_8

Defined Benefit Postretirement Plans and Defined Contribution Plan - Cash Flows (Details) $ in Millions	Dec. 31, 2020USD ($)
Pension Benefits
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
2021	$ 31
2022	28
2023	27
2024	25
2025	23
2026 through 2030	104
Other Benefits
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
2021	10
2022	9
2023	8
2024	7
2025	6
2026 through 2030	$ 23

Reclassifications Out of Accu_3

Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other net periodic benefit (costs) credits									$ (1)	$ 3	$ (14)
Net gain on disposal of assets									9	50	319
Net interest and other									(256)	(244)	(226)
Net income (loss)	$ (338)	$ (317)	$ (750)	$ (46)	$ (20)	$ 165	$ 161	$ 174	(1,451)	480	$ 1,096
Amortization of prior service credit | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other net periodic benefit (costs) credits									24	26
Amortization of actuarial loss | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other net periodic benefit (costs) credits									(11)	(8)
Net settlement loss | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other net periodic benefit (costs) credits									(30)	(12)
Net curtailment gain | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other net periodic benefit (costs) credits									17	0
Postretirement and postemployment plans | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other net periodic benefit (costs) credits									0	6
Net income (loss)									0	75
U.K. pension plan transferred to buyer | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net gain on disposal of assets									0	83
Foreign currency translation adjustment related to sale of U.K. business | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net gain on disposal of assets									0	30
Income taxes related to sale of U.K. business | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net gain on disposal of assets									0	(45)
Other | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net gain on disposal of assets									0	68
Other insignificant items | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net interest and other									$ 0	$ 1

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating activities:
Interest paid, net of amounts capitalized		$ 251	$ 253	$ 255
Income taxes paid to (received from) taxing authorities, net of refunds		(51)	73	287
Noncash investing activities:
Increase (decrease) in asset retirement costs		0	80	(183)
Asset retirement obligations assumed by buyer		0	1,082	82
Proceeds from tax refunds	$ 89	94	90	37
Increase in capital expenditure accrual		$ 95	$ 288	$ 250

Other Items (Details)

Other Items (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net Interest and Other Financing [Abstract]
Interest income	$ 5	$ 25	$ 32
Interest expense	(279)	(280)	(280)
Income on interest rate swaps	12	0	0
Total interest	(262)	(255)	(248)
Net foreign currency gain	0	4	9
Other	6	7	13
Total other	6	11	22
Net interest and other	(256)	(244)	(226)
Aggregate foreign currency gains losses [Abstract]
Net interest and other	0	4	9
Provision for income taxes	0	2	10
Aggregate foreign currency gains	$ 0	$ 6	$ 19

Equity Method Investments - Nar

Equity Method Investments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investment, distribution			$ 49	$ 105	$ 270
Impairment	$ 18	$ 152	171	0	0
Revenue from related parties			38	42	$ 48
Accounts receivable, related parties			24	28
Accounts payable, related parties			$ 13	$ 11
EGHoldings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			60.00%
Alba Plant LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			52.00%
AMPCO
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage			45.00%

Equity Method Investments - Sum

Equity Method Investments - Summary of Equity Method Investments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 447	$ 663
EGHoldings
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	60.00%
Equity method investments	$ 113	310
Alba Plant LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	52.00%
Equity method investments	$ 168	163
AMPCO
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	45.00%
Equity method investments	$ 166	$ 190

Equity Method Investments - S_2

Equity Method Investments - Summary of Financial Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Revenues and other income									$ 3,086	$ 5,190	$ 6,582
Income (loss) from operations									(1,180)	636	1,667
Net income (loss)	$ (338)	$ (317)	$ (750)	$ (46)	$ (20)	$ 165	$ 161	$ 174	(1,451)	480	1,096
Current assets	1,612				2,135				1,612	2,135
Current liabilities	1,213				1,745				1,213	1,745
Consolidated Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Revenues and other income									586	832	1,269
Income (loss) from operations									16	250	588
Net income (loss)									(3)	187	$ 459
Current assets	389				455				389	455
Noncurrent assets	941				1,049				941	1,049
Current liabilities	235				284				235	284
Noncurrent liabilities	$ 170				$ 183				$ 170	$ 183

Stockholders Equity (Details)

Stockholders Equity (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Equity, Class of Treasury Stock [Line Items]
Shares repurchased (shares)	0
Shares repurchased, value	$ 91	$ 362	$ 712
Share Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Shares repurchased (shares)	9	24
Shares repurchased, value	$ 85	$ 345
Remaining share repurchase program authorized amount	$ 1,300

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	$ 4
Contingent royalty liability	107
Contingent capital and expense receivable, noncurrent	23
Commitments to acquire property, plant and equipment	15	$ 41
Override royalty, amount earned directed to corresponding asset retirement obligations	57
Override royalty - GOM future abandonment	70
Performance of Equatorial Guinea LNG Operations, S.A.
Guarantor Obligations [Line Items]
Guarantor obligations, maximum amount	91
Performance of Alba Plant LLC.
Guarantor Obligations [Line Items]
Guarantor obligations, maximum amount	$ 25

Select Quarterly Financial Da_3

Select Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenues from contracts with customers	$ 822	$ 761	$ 490	$ 1,024	$ 1,233	$ 1,249	$ 1,381	$ 1,200	$ 3,097	$ 5,063	$ 5,902
Income (loss) before income taxes	(341)	(310)	(765)	(49)	(3)	175	193	27	(1,465)	392	1,427
Net income (loss)	$ (338)	$ (317)	$ (750)	$ (46)	$ (20)	$ 165	$ 161	$ 174	$ (1,451)	$ 480	$ 1,096
Net income (loss) per basic and diluted share (in dollars per share)	$ (0.43)	$ (0.40)	$ (0.95)	$ (0.06)	$ (0.03)	$ 0.21	$ 0.20	$ 0.21
Dividends paid (in dollars per share)	$ 0.03	$ 0	$ 0	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.08	$ 0.20	$ 0.20
Impaired Long-Lived Assets Held and Used [Line Items]
Goodwill impairment									$ 95	$ 0	$ 0
Equity method investment, impairment		$ 18	$ 152						171	0	0
Impairment of oil and gas properties									144	$ 24	$ 75
Proved Property
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of oil and gas properties	$ 46
Unproved Property
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of oil and gas properties	$ 78								$ 78

Uncategorized Items - mro-20201

Label	Element	Value
Gain (Loss) on Sale of Derivatives	us-gaap_GainLossOnSaleOfDerivatives	$ 171,000,000
Gain (Loss) on Sale of Derivatives	us-gaap_GainLossOnSaleOfDerivatives	(113,000,000)
Gain (Loss) on Sale of Derivatives	us-gaap_GainLossOnSaleOfDerivatives	$ (55,000,000)