Marathon Oil (MRO) 10-K 22 Feb 18 2017 Q4 Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Feb. 15, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Period Focus	Q4
Document Fiscal Year Focus	2,017
Amendment Flag	false
Entity Registrant Name	Marathon Oil Corp
Entity Central Index Key	101,778
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well Known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		849,755,866
Entity Public Float			$ 10,050

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues and other income:
Sales and other operating revenues, including related party	$ 4,211	$ 2,930	$ 4,136
Marketing revenues	162	240	499
Income from equity method investments	256	175	145
Net gain (loss) on disposal of assets	58	389	120
Other income	78	53	53
Total revenues and other income	4,765	3,787	4,953
Costs and expenses:
Production	706	712	979
Marketing, including purchases from related parties	168	245	500
Other operating	431	484	410
Exploration	409	323	971
Depreciation, depletion and amortization	2,372	2,156	2,721
Impairments	229	67	721
Taxes other than income	183	151	216
General and administrative	400	481	588
Total costs and expenses	4,898	4,619	7,106
Income from operations	(133)	(832)	(2,153)
Net interest and other	(270)	(332)	(286)
Gain (Loss) on Extinguishment of Debt	(51)	0	0
Income from continuing operations before income taxes	(454)	(1,164)	(2,439)
Provision for income taxes	376	923	(738)
Income from continuing operations	(830)	(2,087)	(1,701)
Discontinued operations	(4,893)	(53)	(503)
Net income (loss)	$ (5,723)	$ (2,140)	$ (2,204)
Basic:
Income from continuing operations (in dollars per basic share)	$ (0.97)	$ (2.55)	$ (2.51)
Discontinued operations (in dollars per basic share)	(5.76)	(0.06)	(0.75)
Net income (in dollars per basic share)	(6.73)	(2.61)	(3.26)
Diluted:
Income from continuing operations (in dollars per diluted share)	(0.97)	(2.55)	(2.51)
Discontinued operations (in dollars per diluted share)	(5.76)	(0.06)	(0.75)
Net income (in dollars per diluted share)	(6.73)	(2.61)	(3.26)
Dividends (in dollars per share)	$ 0.2	$ 0.20	$ 0.68
Weighted average shares:
Basic	850	819	677
Diluted	850	819	677

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (5,723)	$ (2,140)	$ (2,204)
Postretirement and postemployment plans
Change in actuarial loss and other	21	16	228
Income tax benefit (provision) on postretirement and postemployment plans	7	(4)	(86)
Postretirement and postemployment plans, net of tax	28	12	142
Derivative hedges
Net unrecognized gain (loss)	(13)	61	0
Reclassification of gains on terminated derivative hedges	(47)	0	0
Income tax provision on derivative hedges	21	(22)	0
Derivative hedges, net of tax	(39)	39	0
Net recognized loss reclassified to discontinued operations	34	0	0
Income tax provision (benefit)	(4)	0	0
Foreign currency hedges, net of tax	30	0	0
Other, net of tax	2	1	0
Other comprehensive income (loss)	21	52	142
Comprehensive income (loss)	$ (5,702)	$ (2,088)	$ (2,062)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 563	$ 2,488
Receivables, less reserve of $12 and $6	1,082	748
Notes, Loans and Financing Receivable, Net, Current	748	0
Inventories	126	136
Other current assets	36	66
Disposal Group, Including Discontinued Operation, Assets, Current	11	227
Total current assets	2,566	3,665
Equity method investments	847	931
Property, plant and equipment, less accumulated depreciation, depletion and amortization of $21,564 and $20,255	17,665	16,727
Goodwill	115	115
Other noncurrent assets	764	558
Noncurrent assets held for sale	55	9,098
Total assets	22,012	31,094
Current liabilities:
Accounts payable	1,395	967
Payroll and benefits payable	108	129
Accrued taxes	177	94
Other current liabilities	288	243
Long-term debt due within one year	0	686
Disposal Group, Including Discontinued Operation, Liabilities, Current	0	121
Total current liabilities	1,968	2,240
Long-term debt	5,494	6,581
Deferred tax liabilities	833	769
Defined benefit postretirement plan obligations	362	345
Asset retirement obligations	1,428	1,602
Deferred credit and other liabilities	217	225
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	2	1,791
Total liabilities	10,304	13,553
Commitments and contingencies
Stockholders’ Equity
Preferred stock no shares issued or outstanding (no par value, 26 million shares authorized)	0	0
Common stock issued - 937 million and 937 million shares (par value $1 per share, 1.1 billion shares authorized)	937	937
Common stock, held in treasury, at cost – 87 million and 90 million shares	(3,325)	(3,431)
Additional paid-in capital	7,379	7,446
Retained earnings	6,779	12,672
Accumulated other comprehensive loss	(62)	(83)
Total stockholders equity	11,708	17,541
Total liabilities and stockholders equity	$ 22,012	$ 31,094

Consolidated Balance Sheets Par

Consolidated Balance Sheets Parentheticals - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Consolidated Balance Sheets Parenthetical [Abstract]
Allowance for doubtful accounts	$ 12	$ 6
Less accumulated depreciation, depletion and amortization	$ (21,564)	$ (20,255)
Preferred stock, no par value	$ 0	$ 0
Preferred stock, shares authorized	26,000,000	26,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 1	$ 1
Common stock, shares authorized	1,100,000,000	1,100,000,000
Common stock, shares issued	937,000,000	937,000,000
Held in treasury, shares	87,000,000	90,000,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Cash Flows [Abstract]
Net income (loss)	$ (5,723)	$ (2,140)	$ (2,204)
Adjustments to reconcile net income to net cash provided by operating activities:
Discontinued operations	4,893	53	503
Depreciation, depletion and amortization	2,372	2,156	2,721
Impairments	229	67	721
Exploratory dry well costs and unproved property impairments	323	220	867
Net (gain) loss on disposal of assets	(58)	(389)	(120)
Deferred income taxes	(61)	828	(804)
Gain (Loss) on Sale of Derivatives	(11)	63	(126)
Net cash received (paid) in settlement of derivative instruments	98	61	55
Share-based Compensation	50	48	45
Equity method investments, net	20	17	33
Changes in:
Current receivables	(334)	67	790
Inventories	10	64	25
Current accounts payable and accrued liabilities	297	(137)	(906)
All other operating, net	(117)	(77)	(63)
Net cash provided by continuing operations	1,988	901	1,537
Investing activities:
Additions to property, plant and equipment	(1,974)	(1,204)	(3,485)
Acquisitions, net of cash acquired	(1,891)	(902)	0
Disposal of assets	1,787	1,219	225
Investments - return of capital	64	55	77
Payments to Acquire Investments	0	0	(925)
Proceeds from Sale, Maturity and Collection of Investments	0	0	925
All other investing, net	(30)	(1)	24
Net cash used in investing activities	(2,044)	(833)	(3,159)
Financing activities:
Borrowings	988	0	1,996
Debt repayments	(2,764)	(1)	(1,069)
Payment for Debt Extinguishment or Debt Prepayment Cost	(46)	0	0
Proceeds from Issuance of Common Stock	0	1,236	0
Purchases of common stock	(11)	(6)	(11)
Dividends paid	(170)	(162)	(460)
All other financing, net	0	1	(5)
Net cash provided by (used in) financing activities	(2,003)	1,068	451
Cash Provided by (Used in) Operating Activities, Discontinued Operations	141	177	39
Investing activities of discontinued operations	(13)	(41)	(43)
Change in cash included in current assets held for sale	2	100	90
Net cash provided by discontinued operations	130	236	86
Effect of Exchange Rate on Cash and Cash Equivalents, Continuing Operations	4	(3)	(3)
Net increase (decrease) in cash and cash equivalents	(1,925)	1,369	(1,088)
Cash and cash equivalents at beginning of period	2,488	1,119	2,207
Cash and cash equivalents at end of period	$ 563	$ 2,488	$ 1,119

Consolidated Statements of Stoc

Consolidated Statements of Stockholders Equity - USD ($) shares in Millions, $ in Millions	Total	Preferred Stock [Member]	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares				95
Beginning Balance at Dec. 31, 2014	$ 21,020	$ 0	$ 770	$ (3,642)	$ 6,531	$ 17,638	$ (277)
Shares Beginning Balance at Dec. 31, 2014			770
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued - stock based compensation	64			96	(32)
Shares repurchased	(8)			$ (8)
Stock-based compensation	(1)				(1)
Net loss	(2,204)					(2,204)
Other Comprehensive Income (Loss), Net of Tax, Incl Disc Ops	142						142
Dividends paid	(460)					(460)
Shares issued - stock based compensation				(2)
Shares repurchased				0
Ending Balance at Dec. 31, 2015	18,553	0	$ 770	$ (3,554)	6,498	14,974	(135)
Shares Ending Balance at Dec. 31, 2015			770
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares				93
Shares issued - stock based compensation	42			$ 128	(86)
Shares repurchased	(5)			$ (5)
Stock-based compensation	(35)				(35)
Net loss	(2,140)					(2,140)
Other Comprehensive Income (Loss), Net of Tax, Incl Disc Ops	52						52
Dividends paid	(162)					(162)
Common stock issuance	1,236		$ 167		1,069
Shares issued - stock based compensation				(3)
Shares repurchased				0
Stock Issued During Period, Shares, New Issues			167
Ending Balance at Dec. 31, 2016	$ 17,541	0	$ 937	$ (3,431)	7,446	12,672	(83)
Shares Ending Balance at Dec. 31, 2016			937
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares	90			90
Shares issued - stock based compensation	$ 67			$ 117	(50)
Shares repurchased	(11)			$ (11)
Stock-based compensation	(17)				(17)
Net loss	(5,723)					(5,723)
Other Comprehensive Income (Loss), Net of Tax, Incl Disc Ops	21						21
Dividends paid	(170)					(170)
Common stock issuance	0
Shares issued - stock based compensation				(3)
Shares repurchased				0
Ending Balance at Dec. 31, 2017	$ 11,708	$ 0	$ 937	$ (3,325)	$ 7,379	$ 6,779	$ (62)
Shares Ending Balance at Dec. 31, 2017			937
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury shares	87			87

Summary of Principal Accounting

Summary of Principal Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Principal Accounting Policies	Summary of Principal Accounting Policies We are a global energy 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 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 revenue 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. Differences in the basis of the investments and the separate net asset value of the investees, if any, are amortized into income over the remaining useful lives of the underlying assets, except for the excess related to goodwill. Reclassifications – We have reclassified certain prior year amounts between operating cash flow categories to present it on a basis comparable with the current year's presentation with no impact on net cash provided by operating activities. Discontinued operations – As a result of the sale of our Canadian business in 2017, we reflected this business as discontinued operations in all periods presented. Disclosures in this report related to results of operations and cash flows are presented on the basis of continuing operations unless otherwise stated. Assets and liabilities are presented as held for sale in the historical periods in the consolidated balance sheets. See Note 5 for discussion of the divestiture in further detail. As discussed above we closed on the sale of our Canadian business, which includes our Oil Sands Mining segment and exploration stage in-situ leases in the second quarter 2017. The characteristics and composition of our North America E&P reporting segment remained unchanged and there was no effect on previously reported segment information. As all our remaining properties within the segment are located within the United States, we concluded that our North America E&P segment would be renamed United States E&P segment, effective June 30, 2017. During the year, no changes occurred to our International E&P segment. See Note 6 for further information on our reportable segments. 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 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 are recognized when products are shipped or services are provided to customers, title is transferred, the sales price is fixed or determinable and collectability is reasonably assured. We follow the sales method of accounting for crude oil and natural gas production imbalances and would recognize a liability if our existing proved reserves were not adequate to cover an imbalance. Imbalances have not been significant in the periods presented. In the lower 48 states of the U.S., production volumes of crude oil and condensate, NGLs and natural gas are generally sold immediately and transported to market. In international locations, liquid hydrocarbon production volumes 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. Short-term Investments - Our short-term investments are comprised of bank time deposits with original maturities of greater than three months but less than twelve months. They are classified as held-to-maturity investments, which are recorded at amortized cost. Accounts receivable – The majority of our receivables are from joint interest owners in properties we operate or from purchasers of commodities, both of which are recorded at 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. Notes receivable - We hold two notes receivable from the sale of our Canadian business, which closed in the second quarter of 2017 . Both notes receivable were initially recorded at fair value and are reported at amortized cost. The notes receivable are evaluated for collectability on an individual basis each reporting period, based on the financial condition of the debtor. No allowances for credit losses were established for the notes receivable as of December 31, 2017 . See Note 5 for additional discussion. 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, foreign currency 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, foreign currency 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 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 effective portion of changes in the fair value of a qualifying cash flow hedge are recorded in other comprehensive income until the hedged item is reclassified to net income when the underlying forecasted transaction is recognized in net income. Ineffective portions of a cash flow hedge’s change in fair value are recognized currently within net interest and other on the consolidated statements of income. However, if it is determined that the likelihood of the original forecasted transaction occurring is no longer probable, the entire accumulated gain or loss recognized in other comprehensive income is immediately reclassified into 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 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. If significant transfers occur, they would be disclosed in Note 14 to the consolidated financial statements. 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 as summarized below. Type of Asset Range of Useful Lives Office furniture, equipment and computer hardware 4 to 15 years Pipelines 10 to 40 years Plants, facilities and infrastructure 3 to 40 years 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 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. Major maintenance activities – Costs for planned major maintenance are expensed in the period incurred and can include the costs of contractor repair services, materials and supplies, equipment rentals and our labor 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 – 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 and seabed, including those leased. Estimates of these costs are developed for each property based on the type of production facilities and equipment, depth of water, 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 and common stock units is determined based on the market value of our common stock on the date of grant. Unearned stock-based compensation is charged to stockholders’ equity when restricted stock awards are granted. The fair value of our 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. Our stock-based compensation expense is recognized based on management’s best estimate of the awards that are expected to vest, using the straight-line attribution method for all service-based awards with a graded vesting feature. If actual forfeiture results are different than expected, adjustments to recognized compensation expense may be required in future periods. During the first quarter of 2017, we adopted the accounting standards update issued by the FASB in March 2016 pertaining to share-based payment transactions. As a result of this adoption, all cash payments for withheld shares made to taxing authorities on the employees' behalf are presented within the financing activities section instead of the operating activities section of the statement of cash flows. We elected the retrospective method for adoption of this update and the change in the statement of cash flows is not material for the years ended December 31, 2016 or 2015. Excess tax benefits were classified as an operating activity within the statement of cash flows on a prospective basis beginning in 2017; as such, prior periods were not adjusted. See Note 2 for additional discussion.

Accounting Standards

Accounting Standards	12 Months Ended
	Dec. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Accounting Standards	Accounting Standards Not Yet Adopted In May 2014 and August 2015, the FASB issued an update that supersedes the existing revenue recognition requirements. This standard includes a five-step revenue recognition model to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. Among other things, the standard requires enhanced disclosures about revenue, provides guidance for transactions that were not previously addressed comprehensively and improves guidance for multiple-element arrangements. This standard is effective for us in the first quarter of 2018 and shall be applied retrospectively to each prior reporting period presented (“full retrospective method”) or with the cumulative effect of initially applying the update recognized at the date of initial application (“modified retrospective method”). We will adopt this new standard in the first quarter of 2018 using the modified retrospective method. The adoption of this ASU will not have a material impact on our consolidated results of operations, financial position or cash flows. However, as a result of this standard we will change our presentation of marketing revenues and marketing expenses from the current gross presentation to a net presentation for a portion of our international contracts. For the years ended December 31, 2017 and 2016 , we expect the impact of this change to be a reduction of approximately $130 million and $100 million , respectively, in marketing revenue and expenses in our consolidated results of operations. We will provide the disclosures required by this standard, such as key sources of revenues from transactions with customers, disaggregated revenue information, and significant accounting estimates and judgments, beginning in the first quarter of 2018. In March 2017, the FASB issued a new accounting standards update that will change how employers that sponsor defined pension and/or other postretirement benefit plans present the net periodic benefit cost in the income statement. Employers will present the service cost component of net periodic benefit cost in the same income statement line item(s) as other employee compensation costs arising from services rendered during the period. Only the service cost component will be eligible for capitalization in assets. We will adopt this standard in the first quarter of 2018 on a retrospective basis, and will reclassify certain amounts from general and administrative expense to the exploration, production and our new other net periodic benefit costs expense categories on our consolidated statements of income. In August 2016, the FASB issued a new accounting standards update which seeks to reduce the existing diversity in practice in how certain transactions are classified in the statement of cash flows. We will adopt this standard during the first quarter of 2018 on a retrospective basis with no significant impact on our consolidated results of operations, financial position or cash flows. In November 2016, the FASB issued a new accounting standards update that requires entities to show the changes in the total of cash, cash equivalents and restricted cash in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash in the statement of cash flows. When cash, cash equivalents, and restricted cash are presented in more than one line item on the balance sheet, the standard requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. This reconciliation can be presented either on the face of the statement of cash flows or in the notes to the financial statements. We will adopt this standard in the first quarter of 2018 on a retrospective basis and do not expect the adoption of this standard to have a significant impact on our consolidated results of operations, financial position or cash flows. In February 2017, the FASB issued a new accounting standards update that clarifies the accounting for the sale or transfer of nonfinancial assets and in substance nonfinancial assets to noncustomers, including partial sales. The standard also clarifies that the derecognition of all businesses (except those related to conveyances of oil and gas mineral rights or contracts with customers) should be accounted for in accordance with the derecognition and deconsolidation guidance in Subtopic 810-10. We will adopt this standard in the first quarter of 2018 using the modified retrospective approach with no material impact on our consolidated results of operations, financial position or cash flows. In January 2017, the FASB issued a new accounting standards update that changes the definition of a business to assist entities with evaluating when a set of transferred assets and activities constitutes a business. The guidance requires an entity to evaluate if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets; if so, the set of transferred assets and activities would not represent a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs by more closely aligning it with how outputs are described in the new revenue guidance. We will adopt this standard in the first quarter of 2018 on a prospective basis. Since we adopted the standard on a prospective basis, adoption of this standard will not have a significant impact on our consolidated results of operations, financial position or cash flows for prior periods. In January 2016, the FASB issued an accounting standards update that addresses certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. We plan to adopt this standard in the first quarter of 2018 and do not expect the adoption of this standard to have a significant impact on our consolidated results of operations, financial position or cash flows. In February 2016, the FASB issued a new lease accounting standard, which requires lessees to recognize most leases, including operating leases, on the balance sheet as a right of use asset and lease liability. Short-term leases can continue being accounted for off balance sheet based on a policy election. This standard does not apply to leases to explore for or use minerals, oil, natural gas and similar non-regenerative resources, including the intangible right to explore for those natural resources and rights to use the land in which those natural resources are contained. This standard is effective for us in the first quarter of 2019 and shall be applied using a modified retrospective approach at the beginning of the earliest period presented in the financial statements. Early adoption is permitted. While we will have to recognize a right of use asset and lease liability on the adoption date, we continue to evaluate the provisions of this accounting standards update and assessing the effects it will have on our consolidated results of operations, financial position or cash flows. In August 2017, the FASB issued a new accounting standards update that amends the hedge accounting model to enable entities to hedge certain financial and nonfinancial risk attributes previously not allowed. The amendment also reduces the overall complexity of documenting, assessing and measuring hedge effectiveness. This standard is effective for us in the first quarter of 2019. Early adoption is permitted in any interim or annual period. The amendment mandates modified retrospective adoption when accounting for hedge relationships in effect as of the adoption date. We are evaluating the provisions of this accounting standards update, including transition requirements, and are assessing the impact it may have on our results of operations, financial position, or cash flows. In January 2017, the FASB issued a new accounting standards update that eliminates the requirement to calculate the implied fair value of the goodwill (i.e., Step 2 of goodwill impairment test under the current guidance) to measure a goodwill impairment charge. The standard will require entities to record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value (i.e., measure the charge based on Step 1 under the current guidance). This standard is effective for us in the first quarter of 2020 and shall be applied on a prospective basis. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. Since we will adopt the standard on a prospective basis, we do not expect an impact on our consolidated results of operations, financial position or cash flows for prior periods. 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. The standard requires the use of a forward-looking “expected loss” model as opposed to the current “incurred loss” model. This standard is effective for us in the first quarter of 2020 and will be adopted on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the adoption period. Early adoption is permitted starting January 2019. We are evaluating the provisions of this accounting standards update and assessing the impact, if any, it may have on our consolidated results of operations, financial position or cash flows.
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Accounting Standards Not Yet Adopted In May 2014 and August 2015, the FASB issued an update that supersedes the existing revenue recognition requirements. This standard includes a five-step revenue recognition model to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. Among other things, the standard requires enhanced disclosures about revenue, provides guidance for transactions that were not previously addressed comprehensively and improves guidance for multiple-element arrangements. This standard is effective for us in the first quarter of 2018 and shall be applied retrospectively to each prior reporting period presented (“full retrospective method”) or with the cumulative effect of initially applying the update recognized at the date of initial application (“modified retrospective method”). We will adopt this new standard in the first quarter of 2018 using the modified retrospective method. The adoption of this ASU will not have a material impact on our consolidated results of operations, financial position or cash flows. However, as a result of this standard we will change our presentation of marketing revenues and marketing expenses from the current gross presentation to a net presentation for a portion of our international contracts. For the years ended December 31, 2017 and 2016 , we expect the impact of this change to be a reduction of approximately $130 million and $100 million , respectively, in marketing revenue and expenses in our consolidated results of operations. We will provide the disclosures required by this standard, such as key sources of revenues from transactions with customers, disaggregated revenue information, and significant accounting estimates and judgments, beginning in the first quarter of 2018. In March 2017, the FASB issued a new accounting standards update that will change how employers that sponsor defined pension and/or other postretirement benefit plans present the net periodic benefit cost in the income statement. Employers will present the service cost component of net periodic benefit cost in the same income statement line item(s) as other employee compensation costs arising from services rendered during the period. Only the service cost component will be eligible for capitalization in assets. We will adopt this standard in the first quarter of 2018 on a retrospective basis, and will reclassify certain amounts from general and administrative expense to the exploration, production and our new other net periodic benefit costs expense categories on our consolidated statements of income. In August 2016, the FASB issued a new accounting standards update which seeks to reduce the existing diversity in practice in how certain transactions are classified in the statement of cash flows. We will adopt this standard during the first quarter of 2018 on a retrospective basis with no significant impact on our consolidated results of operations, financial position or cash flows. In November 2016, the FASB issued a new accounting standards update that requires entities to show the changes in the total of cash, cash equivalents and restricted cash in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash in the statement of cash flows. When cash, cash equivalents, and restricted cash are presented in more than one line item on the balance sheet, the standard requires a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet. This reconciliation can be presented either on the face of the statement of cash flows or in the notes to the financial statements. We will adopt this standard in the first quarter of 2018 on a retrospective basis and do not expect the adoption of this standard to have a significant impact on our consolidated results of operations, financial position or cash flows. In February 2017, the FASB issued a new accounting standards update that clarifies the accounting for the sale or transfer of nonfinancial assets and in substance nonfinancial assets to noncustomers, including partial sales. The standard also clarifies that the derecognition of all businesses (except those related to conveyances of oil and gas mineral rights or contracts with customers) should be accounted for in accordance with the derecognition and deconsolidation guidance in Subtopic 810-10. We will adopt this standard in the first quarter of 2018 using the modified retrospective approach with no material impact on our consolidated results of operations, financial position or cash flows. In January 2017, the FASB issued a new accounting standards update that changes the definition of a business to assist entities with evaluating when a set of transferred assets and activities constitutes a business. The guidance requires an entity to evaluate if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets; if so, the set of transferred assets and activities would not represent a business. The guidance also requires a business to include at least one substantive process and narrows the definition of outputs by more closely aligning it with how outputs are described in the new revenue guidance. We will adopt this standard in the first quarter of 2018 on a prospective basis. Since we adopted the standard on a prospective basis, adoption of this standard will not have a significant impact on our consolidated results of operations, financial position or cash flows for prior periods. In January 2016, the FASB issued an accounting standards update that addresses certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. We plan to adopt this standard in the first quarter of 2018 and do not expect the adoption of this standard to have a significant impact on our consolidated results of operations, financial position or cash flows. In February 2016, the FASB issued a new lease accounting standard, which requires lessees to recognize most leases, including operating leases, on the balance sheet as a right of use asset and lease liability. Short-term leases can continue being accounted for off balance sheet based on a policy election. This standard does not apply to leases to explore for or use minerals, oil, natural gas and similar non-regenerative resources, including the intangible right to explore for those natural resources and rights to use the land in which those natural resources are contained. This standard is effective for us in the first quarter of 2019 and shall be applied using a modified retrospective approach at the beginning of the earliest period presented in the financial statements. Early adoption is permitted. While we will have to recognize a right of use asset and lease liability on the adoption date, we continue to evaluate the provisions of this accounting standards update and assessing the effects it will have on our consolidated results of operations, financial position or cash flows. In August 2017, the FASB issued a new accounting standards update that amends the hedge accounting model to enable entities to hedge certain financial and nonfinancial risk attributes previously not allowed. The amendment also reduces the overall complexity of documenting, assessing and measuring hedge effectiveness. This standard is effective for us in the first quarter of 2019. Early adoption is permitted in any interim or annual period. The amendment mandates modified retrospective adoption when accounting for hedge relationships in effect as of the adoption date. We are evaluating the provisions of this accounting standards update, including transition requirements, and are assessing the impact it may have on our results of operations, financial position, or cash flows. In January 2017, the FASB issued a new accounting standards update that eliminates the requirement to calculate the implied fair value of the goodwill (i.e., Step 2 of goodwill impairment test under the current guidance) to measure a goodwill impairment charge. The standard will require entities to record an impairment charge based on the excess of a reporting unit’s carrying amount over its fair value (i.e., measure the charge based on Step 1 under the current guidance). This standard is effective for us in the first quarter of 2020 and shall be applied on a prospective basis. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. Since we will adopt the standard on a prospective basis, we do not expect an impact on our consolidated results of operations, financial position or cash flows for prior periods. 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. The standard requires the use of a forward-looking “expected loss” model as opposed to the current “incurred loss” model. This standard is effective for us in the first quarter of 2020 and will be adopted on a modified retrospective basis through a cumulative-effect adjustment to retained earnings as of the beginning of the adoption period. Early adoption is permitted starting January 2019. We are evaluating the provisions of this accounting standards update and assessing the impact, if any, it may have on our consolidated results of operations, financial position or cash flows. Recently Adopted In March 2016, the FASB issued a new accounting standards update that changes several aspects of accounting for share-based payment transactions, including a requirement to recognize all excess tax benefits and tax deficiencies as income tax expense or benefit in the income statement, classification of awards as either equity or liabilities, and classification on the statement of cash flows. This standard was effective for us in the first quarter of 2017. The new standard requires a company to make a policy election on how it accounts for forfeitures; we elected to continue estimating forfeitures using the same methodology practiced prior to adoption of this standard. See Note 1 for the impact this standard has on the presentation of our financial statements. In July 2015, the FASB issued an update that requires an entity to measure inventory at the lower of cost or net realizable value. This excludes inventory measured using LIFO or the retail inventory method. This standard was effective for us in the first quarter of 2017, and was applied prospectively. Adoption of this standard did not have a significant impact on our consolidated results of operations, financial position or cash flows.

Income per Common Share

Income per Common Share	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Income per Common Share	Income (Loss) per Common Share Basic income (loss) per share is based on the weighted average number of common shares outstanding. Diluted income per share assumes exercise of stock options in all years, provided the effect is not antidilutive. The per share calculations below exclude 11 million , 13 million and 13 million stock options in 2017 , 2016 and 2015 that were antidilutive. Year Ended December 31, (In millions, except per share data) 2017 2016 2015 Income (loss) from continuing operations $ (830 ) $ (2,087 ) $ (1,701 ) Income (loss) from discontinued operations (4,893 ) (53 ) (503 ) Net income (loss) $ (5,723 ) $ (2,140 ) $ (2,204 ) Weighted average common shares outstanding 850 819 677 Per basic share: Income (loss) from continuing operations $ (0.97 ) $ (2.55 ) $ (2.51 ) Income (loss) from discontinued operations $ (5.76 ) $ (0.06 ) $ (0.75 ) Net income (loss) $ (6.73 ) $ (2.61 ) $ (3.26 ) Per diluted share: Income (loss) from continuing operations $ (0.97 ) $ (2.55 ) $ (2.51 ) Income (loss) from discontinued operations $ (5.76 ) $ (0.06 ) $ (0.75 ) Net income (loss) $ (6.73 ) $ (2.61 ) $ (3.26 )

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2017
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	Acquisitions 2017 - United States E&P In the fourth quarter of 2017, we closed on our acquisition of additional acreage in the Northern Delaware basin of New Mexico from a private seller for $63 million in cash, subject to post-closing adjustments. We accounted for this transaction as an asset acquisition, allocating the purchase price to unproved property within property, plant and equipment. In the second quarter of 2017, we closed on our acquisitions of approximately 91,000 net acres in the Permian basin, including over 70,000 net acres in the Northern Delaware basin of New Mexico. On May 1, 2017, we closed on our acquisition with BC Operating, Inc. and other entities for $1.1 billion in cash, subject to post-closing adjustments, to acquire approximately 70,000 net surface acres and current production of approximately 5,000 net barrels of oil equivalent per day. On June 1, 2017, we closed on our acquisition with Black Mountain Oil & Gas and other private sellers for approximately $700 million in cash, subject to post-closing adjustments, to acquire approximately 21,000 net surface acres. The purchase price for these acquisitions was paid with cash on hand. We accounted for these transactions as asset acquisitions, with substantially all of the purchase price allocated to unproved property within property, plant and equipment. 2016 - United States E&P On August 1, 2016, we closed on our acquisition of PayRock Energy Holdings, LLC (“PayRock”), a portfolio company of EnCap Investments, including approximately 61,000 net surface acres in the oil window of the Anadarko Basin STACK play in Oklahoma. The purchase price of $904 million , subject to closing adjustments, was paid with cash on hand. We accounted for this transaction as an asset acquisition, with a majority of the purchase price allocated to unproved property within property, plant and equipment.

Dispositions

Dispositions	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Dispositions	Dispositions Oil Sands Mining Segment On May 31, 2017 we closed on the sale of our Canadian business, which included our 20 % non-operated interest in the AOSP to Shell and Canadian Natural Resources Limited (“CNRL”) for $2.5 billion , excluding closing adjustments. Under the terms of the agreement, $1.8 billion was paid to us upon closing and the remaining proceeds will be paid in the first quarter of 2018. At closing we received two notes receivable for the remaining proceeds, each with a face value of $375 million . We recorded these notes receivable at fair value, see Note 14 for fair value measurements. Our notes receivable are with 10084751 Canada Limited (“Canada Limited”), an affiliate of Shell Canada Limited, and CNRL. The Canada Limited note receivable is guaranteed by Shell Canada Limited and the CNRL note receivable is guaranteed by Toronto Dominion Bank. In the first quarter of 2017, we recorded an after-tax non-cash impairment charge of $4.96 billion primarily related to the property, plant and equipment of our Canadian business. As the effective date of the transaction was January 1, 2017, we recorded a loss on sale of $43 million during the second quarter of 2017 due to second quarter results of operations from our Canadian business that were recorded in our financial statements but transferred to the buyer upon closing. Our Canadian business is reflected as discontinued operations in the consolidated statements of income and the consolidated statements of cash flows for all periods presented. The following table contains select amounts reported in our consolidated statements of income as discontinued operations: Year Ended December 31, (In millions) 2017 2016 2015 Total sales and other revenues and other income $ 431 $ 863 $ 908 Net gain (loss) on disposal of assets (43 ) — — Total revenues and other income 388 863 908 Costs and expenses: Production expenses 254 601 715 Exploration expenses — 7 347 Depreciation, depletion and amortization 40 239 236 Impairments 6,636 — 31 Other 25 87 98 Total costs and expenses 6,955 934 1,427 Pretax income (loss) from discontinued operations (6,567 ) (71 ) (519 ) Provision (benefit) for income taxes (1,674 ) (18 ) (16 ) Income (loss) from discontinued operations $ (4,893 ) $ (53 ) $ (503 ) The following table presents the carrying value of the major categories of assets and liabilities of our Canadian business reported as discontinued operations and other non-core international assets and liabilities from continuing operations, that are reflected as held for sale on our consolidated balance sheets at December 31, 2017 and December 31, 2016: December 31, December 31, (In millions) 2017 2016 Assets held for sale Current assets: Cash and cash equivalents $ — $ 2 Accounts receivables — 129 Inventories — 91 Other — 4 Total current assets held for sale—discontinued operations — 226 Total current assets held for sale—continuing operations 11 1 Total current assets held for sale $ 11 $ 227 Noncurrent assets: Property, plant and equipment, net $ — $ 8,991 Other — 106 Total noncurrent assets held for sale—discontinued operations — 9,097 Total noncurrent assets held for sale—continuing operations 55 1 Total noncurrent assets held for sale $ 55 $ 9,098 Liabilities associated with assets held for sale Current liabilities: Accounts payable $ — $ 111 Other — 10 Total current liabilities held for sale—discontinued operations — 121 Total current liabilities held for sale—continuing operations — — Total current liabilities held for sale $ — $ 121 Noncurrent liabilities: Asset retirement obligations $ — $ 95 Deferred tax liabilities — 1,669 Other — 20 Total noncurrent liabilities held for sale—discontinued operations — 1,784 Total noncurrent liabilities held for sale—continuing operations 2 7 Total noncurrent liabilities held for sale $ 2 $ 1,791 United States E&P Segment As disclosed above, we closed on the sale of our Canadian business in May of 2017. This sale included interests in our exploration stage in-situ leases which were included within our historically named North America E&P Segment. See Note 6 for further detail on our segments. These interests have been reflected as discontinued operations and are included within the disclosure above. In July 2017, we entered into an agreement to sell certain conventional assets in Oklahoma. We closed on the sale in September 2017 for proceeds of $25 million , and recognized a pre-tax gain of $21 million . In September 2016, we entered into an agreement to sell certain non-operated CO2 and waterflood assets in West Texas and New Mexico. The sale closed in late October for proceeds of $235 million , and we recognized a total pre-tax gain of $63 million . During the third quarter 2016, we sold certain non-operated assets primarily in West Texas and New Mexico to multiple purchasers for combined proceeds of approximately $67 million , and recognized a total pre-tax gain of $55 million . In April 2016, we announced the sale of our Wyoming upstream and midstream assets. During the second quarter, we received proceeds of approximately $690 million and recorded a pre-tax gain of $266 million with the remaining asset sales closing in November 2016 for proceeds of $155 million , excluding closing adjustments. A pre-tax gain of $38 million was recognized in the fourth quarter 2016. In March and April 2016, we entered into separate agreements to sell our 10% working interest in the outside-operated Shenandoah discovery in the Gulf of Mexico, operated natural gas assets in the Piceance basin in Colorado and certain undeveloped acreage in West Texas for a combined total of approximately $80 million in proceeds. We closed on certain of the asset sales and recognized a net pre-tax loss on sale of $48 million in 2016, the remaining asset closed in 2017 with a net pre-tax gain on sale of $32 million . In November 2015, we entered into an agreement to sell 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. The transaction closed in December 2015, excluding the Neptune field, for proceeds of $111 million . A $228 million pretax gain was recorded in the fourth quarter of 2015. The Neptune field transaction closed during the first quarter of 2016 for cash proceeds of $4 million . In August 2015, we closed the sale of our East Texas, North Louisiana and Wilburton, Oklahoma natural gas assets for proceeds of $100 million and recorded a pretax loss of $1 million . During the second quarter of 2015, we recorded a non-cash impairment charge of $44 million related to these assets (see Note 14 ). International E&P Segment In the third quarter of 2017, we entered into separate agreements to sell certain non-core properties in our International E&P segment for combined proceeds of $53 million , before closing adjustments. We closed on one of the asset sales in the second half of 2017 and recognized no net pre-tax gain or loss on sale. The remaining asset sale is expected to close during 2018 and is classified as held for sale in the consolidated balance sheet as of December 31, 2017, with total assets of $66 million and total liabilities of $2 million . See Note 10 for further detail on impairment expenses recognized concurrently with these agreements. In the third quarter of 2015, we entered into agreements to sell our East Africa exploration acreage in Ethiopia and Kenya. A pretax loss of $109 million was recorded in the third quarter of 2015. This transaction closed during the first quarter of 2016.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Segment Information	Segment Information We have two reportable operating segments. Each of these segments is organized and managed based upon both geographic location and the nature of the products and services it offers. • United States E&P ("U.S. E&P") – explores for, produces and markets crude oil and condensate, NGLs and natural gas in the United States • International E&P ("Int'l E&P") – explores for, produces and markets crude oil and condensate, NGLs and natural gas outside of the United States and produces and markets products manufactured from natural gas, such as LNG and methanol, in E.G. Information regarding assets by segment is not presented because it is not reviewed by the chief operating decision maker (“CODM”). Segment income (loss) represents income (loss) which excludes certain items not allocated to segments, net of income taxes, attributable to the operating segments. A portion of our corporate and operations support general and administrative 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, certain impairments, change in tax expense associated with a tax rate change, changes in our valuation allowance, unrealized gains or losses on derivative instruments, pension settlement losses or other items (as determined by the CODM) are not allocated to operating segments. As discussed in Note 5 , we closed on the sale of our Canadian business, which includes our Oil Sands Mining segment and exploration stage in-situ leases, in the second quarter of 2017. The Canadian business is reflected as discontinued operations and is excluded from segment information in all periods presented. Additionally, we renamed our North America E&P segment to United States E&P segment effective June 30, 2017 in all periods presented. See Note 1 for further information. Year Ended December 31, 2017 Not Allocated (In millions) U.S. E&P Int'l E&P to Segments Total Sales and other operating revenues $ 3,138 $ 1,154 $ (81 ) (b) $ 4,211 Marketing revenues 29 133 — 162 Total revenues 3,167 1,287 (81 ) 4,373 Income from equity method investments — 256 — 256 Net gain on disposal of assets and other income 13 6 117 (c) 136 Less: Production expenses 476 229 1 706 Marketing costs 36 132 — 168 Other operating 354 77 — 431 Exploration 154 5 250 (d) 409 Depreciation, depletion and amortization 2,011 328 33 2,372 Impairments 4 — 225 (e) 229 Taxes other than income 173 — 10 183 General and administrative 119 32 249 (f) 400 Net interest and other — — 270 (g) 270 Loss on early extinguishment of debt — — 51 (h) 51 Income tax provision (benefit) 1 372 3 376 Segment income (loss) / Income (loss) from continuing operations $ (148 ) $ 374 $ (1,056 ) $ (830 ) Capital expenditures (a) $ 2,081 $ 42 $ 27 $ 2,150 (a) Includes accruals. (b) Unrealized loss on commodity derivative instruments. (c) Primarily related to sale of certain conventional assets in Oklahoma and Colorado. (See Note 5 ). (d) Primarily related to unproved property impairments associated with certain non-core properties within our International E&P segment. (See Note 10 ). (e) Primarily related to proved property impairments associated with certain non-core properties within our International E&P segment. (See Note 10 ). (f) Includes pension settlement loss of $32 million (see Note 17 ). (g) Includes a gain of $47 million resulting from the termination of our forward starting interest rate swaps. (See Note 13 .) (h) Primarily related to the make-whole call provisions paid upon redemption of our senior unsecured notes. (See Note 15 .) Year Ended December 31, 2016 Not Allocated (In millions) U.S. E&P Int'l E&P to Segments Total Sales and other operating revenues $ 2,375 $ 665 $ (110 ) (b) $ 2,930 Marketing revenues 135 105 — 240 Total revenues 2,510 770 (110 ) 3,170 Income (loss) from equity method investments — 175 — 175 Net gain on disposal of assets and other income 28 32 382 (c) 442 Less: Production expenses 486 226 — 712 Marketing costs 142 103 — 245 Other operating 328 43 113 (d) 484 Exploration 127 17 179 (e) 323 Depreciation, depletion and amortization 1,835 276 45 2,156 Impairments 20 — 47 (f) 67 Taxes other than income 149 — 2 151 General and administrative 94 35 352 (g) 481 Net interest and other — — 332 332 Income tax provision (benefit) (228 ) 49 1,102 (h) 923 Segment income (loss) / Income (loss) from continuing operations $ (415 ) $ 228 $ (1,900 ) $ (2,087 ) Capital expenditures (a) $ 936 $ 82 $ 18 $ 1,036 (a) Includes accruals. (b) Unrealized loss on commodity derivative instruments. (c) Primarily related to net gain on disposal of assets (see Note 5 ). (d) Includes termination payment on our Gulf of Mexico deepwater drilling rig commitment of $113 million . (e) Primarily related to impairments associated with decision to not drill remaining Gulf of Mexico undeveloped leases (See Note 10 ). (f) Proved property impairments (see Note 10 ). (g) Includes pension settlement loss of $103 million and severance related expenses associated with workforce reductions of $8 million (see Note 17 ). (h) Increased valuation allowance on certain of our deferred tax assets $1,346 million (see Note 7 ). Year Ended December 31, 2015 Not Allocated (In millions) U.S. E&P Int'l E&P to Segments Total Sales and other operating revenues $ 3,358 $ 728 $ 50 (b) $ 4,136 Marketing revenues 396 103 — 499 Total revenues 3,754 831 50 4,635 Income from equity method investments — 157 (12 ) (c) 145 Net gain on disposal of assets and other income 24 27 122 (d) 173 Less: Production expenses 724 255 — 979 Marketing costs 401 99 — 500 Other operating 335 48 27 410 Exploration 314 101 556 (e) 971 Depreciation, depletion and amortization 2,377 295 49 2,721 Impairments 2 — 719 (f) 721 Taxes other than income 215 — 1 216 General and administrative 127 44 417 (g) 588 Net interest and other — — 286 286 Income tax provision (benefit) (265 ) 61 (534 ) (738 ) Segment income (loss) / Income (loss) from continuing operations $ (452 ) $ 112 $ (1,361 ) $ (1,701 ) Capital expenditures (a) $ 2,553 $ 368 $ 25 $ 2,946 (a) Includes accruals. (b) Unrealized gain on commodity derivative instruments. (c) Partial impairment of investment in equity method investee (See Note 14 ). (d) Primarily related to gain on sale of our properties and interests in the Gulf of Mexico, partially offset by the loss on sale of East Africa exploration acreage (see Note 5 ). (e) Unproved property impairments associated with lower forecasted commodity prices and change in conventional exploration strategy (See Note 10 ). (f) Includes goodwill impairment (see Note 12 ) and proved property impairments (see Note 10 ). (g) Includes pension settlement loss of $119 million (see Note 17 ) and severance related expenses associated with workforce reductions of $55 million . Revenues from external customers are attributed to geographic areas based upon selling location. The following summarizes revenues from external customers by geographic area. Year Ended December 31, (In millions) 2017 2016 2015 United States $ 3,086 $ 2,400 $ 3,804 Equatorial Guinea 530 444 444 Libya 431 54 — U.K. 289 263 380 Other international 37 9 7 Total revenues $ 4,373 $ 3,170 $ 4,635 In 2017, sales to Vitol and each of their respective affiliates accounted for approximately 10% of our total revenues. In 2016 , sales to Valero Marketing and Supply, Tesoro Petroleum, and Flint Hills Resources and each of their respective affiliates accounted for approximately 13% , 11% and 10% of our total revenues. In 2015 , sales to Shell Oil and its affiliates accounted for approximately 10% of our total revenues. The following summarizes revenues by product line. Year Ended December 31, (In millions) 2017 2016 2015 Crude oil and condensate $ 3,477 $ 2,605 $ 3,963 Natural gas liquids 338 198 203 Natural gas 510 356 464 Other 48 11 5 Total revenues $ 4,373 $ 3,170 $ 4,635 The following summarizes property, plant and equipment and equity method investments. December 31, (In millions) 2017 2016 United States $ 15,971 $ 14,272 Equatorial Guinea 1,582 1,794 Other international 959 1,592 Total long-lived assets $ 18,512 $ 17,658

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Income (loss) before tax expense for continuing operations was: Year Ended December 31, (In millions) 2017 2016 2015 United States $ (783 ) $ (1,449 ) $ (2,384 ) Foreign 329 285 (55 ) Total $ (454 ) $ (1,164 ) $ (2,439 ) Income tax provisions (benefits) for continuing operations were: Year Ended December 31, 2017 2016 2015 (In millions) Current Deferred Total Current Deferred Total Current Deferred Total Federal $ (32 ) $ 41 $ 9 $ 2 $ 836 $ 838 $ (41 ) $ (684 ) $ (725 ) State and local (14 ) 2 (12 ) 2 8 10 (8 ) (18 ) (26 ) Foreign 483 (104 ) 379 91 (16 ) 75 115 (102 ) 13 Total $ 437 $ (61 ) $ 376 $ 95 $ 828 $ 923 $ 66 $ (804 ) $ (738 ) A reconciliation of the federal statutory income tax rate applied to income (loss) from continuing operations before income taxes to the provision (benefit) for income taxes follows: Year Ended December 31, (In millions) 2017 2016 2015 Total pre-tax income (loss) from continuing operations $ (454 ) $ (1,164 ) $ (2,439 ) Total income tax expense (benefit) $ 376 $ 923 $ (738 ) Effective income tax expense (benefit) rate on continuing operations 83 % 79 % (30 )% Income taxes at the statutory tax rate of 35% (a) $ (159 ) $ (407 ) $ (854 ) Effects of foreign operations 140 47 (55 ) Adjustments to valuation allowances 446 1,270 95 State income taxes (19 ) 9 (15 ) Tax law change (35 ) 6 (3 ) Goodwill impairment — — 94 Other federal tax effects 3 (2 ) — Income tax expense (benefit) on continuing operations $ 376 $ 923 $ (738 ) (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 appears in the "Not Allocated to Segments" column of the tables in Note 6 . Effects of foreign operations – The effects of foreign operations increased our tax expense in 2017, 2016, and 2015 due to the mix of pretax income between high and low tax jurisdictions. This increase primarily relates to increased sales volumes in Libya during 2017 where the tax rate is 93.5%. Excluding Libya, the effective tax rates on continuing operations would be an expense of 5% in 2017 , an expense of 79% in 2016 , and a benefit of 29% in 2015 . Adjustments to valuation allowances - Since December 31, 2016, we have maintained a full valuation allowance on our net federal deferred tax assets. In 2017, we recorded a $446 million valuation allowance primarily related to current year activity in the U.S. Included within the $446 million is a $41 million out-of-period adjustment as a result of identifying certain deferred tax assets for which the impact should have been recorded to other comprehensive income, but had been recorded to income from continuing operations in 2016. Change in tax law – On December 22, 2017, the U.S. enacted the Tax Cuts and Jobs Act (the “Tax Reform Legislation”). Tax Reform Legislation, which is also commonly referred to as “U.S. tax reform”, significantly changes U.S. corporate income tax laws by, among other things, reducing the U.S. corporate income tax rate to 21% starting in 2018, and repeal of the corporate alternative minimum tax (“AMT”), and a one-time deemed repatriation of accumulated foreign earnings. In the fourth quarter of 2017, we remeasured our deferred taxes at 21% , in accordance with U.S. GAAP standards. The impact of the remeasurement on our federal deferred tax assets and liabilities was equally offset by an adjustment to our valuation allowance with no material impact to current year earnings. We recorded a net benefit of $35 million , classified as a receivable within other noncurrent assets on the consolidated balance sheet, during the fourth quarter of 2017 related to the repeal of the corporate AMT. Although the $35 million net benefit represents what we believe is a reasonable estimate of the impact of the income tax effects of the Act on our consolidated financial statements as of December 31, 2017, it should be considered provisional. We do not expect to pay U.S. federal cash taxes on the deemed repatriation due to an accumulated deficit in foreign earnings for tax purposes. Once we finalize certain tax positions when we file our 2017 federal tax return, we will be able to conclude whether any further adjustments are required to our net tax position as of December 31, 2017. Any adjustments to these provisional amounts will be reported as a component of income tax expense (benefit) in the reporting period in which any such adjustments are determined, which will be no later than the fourth quarter of 2018. Deferred tax assets and liabilities resulted from the following: Year Ended December 31, (In millions) 2017 2016 Deferred tax assets: Employee benefits $ 111 $ 228 Operating loss carryforwards 1,030 1,065 Capital loss carryforwards 3 4 Foreign tax credits 611 4,430 Other credit carryforwards — 35 Investments in subsidiaries and affiliates 174 91 Other 69 86 Subtotal 1,998 5,939 Valuation Allowance (926 ) (4,301 ) Total deferred tax assets 1,072 1,638 Deferred tax liabilities: Property, plant and equipment 1,332 3,672 Accrued revenue 81 75 Other 3 (7 ) Total deferred tax liabilities 1,416 3,740 Net deferred tax liabilities $ 344 $ 2,102 Foreign Tax Credits - As a result of U.S. tax reform, we have reduced our foreign tax credits at December 31, 2017, which are offset by a corresponding reduction in valuation allowance, by $3,819 million due to the remote likelihood these credits will be utilized before expiration. We have not elected any of our foreign earnings to be permanently reinvested abroad. Additionally due to U.S. tax reform, we do not expect future foreign earnings from operations to be subject to tax in the U.S. The remaining foreign tax credits, which are offset by a valuation allowance, expire in 2022 through 2027. Operating loss carryforwards - At December 31, 2017, our operating loss carryforwards before valuation allowance includes $898 million from the U.S. that expire in 2035-2037. Foreign operating loss carryforwards include $13 million that begin to expire in 2018. State operating loss carryforwards of $119 million expire in 2018 through 2037. Valuation allowances – At December 31, 2017, we reflect a valuation allowance in our consolidated balance sheet of $926 million against our net deferred tax assets in various jurisdictions in which we operate. The reduction primarily related to the reduction of foreign tax credits in the U.S. In 2016 and 2015, we increased our valuation allowance by $1,268 million and $99 million respectively. Net deferred tax liabilities were classified in the consolidated balance sheets as follows: December 31, (In millions) 2017 2016 Assets: Other noncurrent assets $ 489 $ 336 Liabilities: Noncurrent deferred tax liabilities 833 769 Noncurrent liabilities held for sale — 1,669 Net deferred tax liabilities $ 344 $ 2,102 We are continuously undergoing examination of our U.S. federal income tax returns by the IRS. Such audits have been completed through the 2014 tax year, with the exception of 2010-11. During the third quarter of 2017, we received a partnership adjustment notification related to the 2010 and 2011 tax years, for which we have filed a Tax Court Petition in the fourth quarter of 2017. We believe adequate provision has been made for federal income taxes and interest which may become payable for years not yet settled. See Note 24 for further detail. Further, we are routinely involved in U.S. state income tax audits and foreign jurisdiction tax audits. We believe all other audits will be resolved within the amounts paid and/or provided for these liabilities. As of December 31, 2017 , our income tax returns remain subject to examination in the following major tax jurisdictions for the tax years indicated: United States (a) 2008-2016 Equatorial Guinea 2007-2016 Libya 2012-2016 United Kingdom 2008-2016 (a) Includes federal and state jurisdictions. The following table summarizes the activity in unrecognized tax benefits: (In millions) 2017 2016 2015 Beginning balance $ 66 $ 65 $ 80 Additions for tax positions of prior years 83 6 1 Reductions for tax positions of prior years (3 ) (5 ) — Settlements (20 ) — (7 ) Statute of limitations — — (9 ) Ending balance $ 126 $ 66 $ 65 If the unrecognized tax benefits as of December 31, 2017 were recognized, $10 million would affect our effective income tax rate. As of December 31, 2017 , there are $83 million uncertain tax positions for which it is reasonably possible that the amount could significantly change during the next twelve months. If this were to significantly change, we estimate that any revisions to current and deferred tax liabilities would have no cumulative adverse earnings impact on our consolidated results of operations. The U.K. tax authorities have challenged the timing of deductibility for certain Brae area decommissioning costs. In the fourth quarter of 2017, we received an adverse ruling from the U.K. first-tier tax tribunal. As a result of the adverse ruling, in the fourth quarter of 2017 we established an uncertain tax position. We have appealed the ruling, but were required to pay the disputed tax amount and associated interest in order to pursue the appeal. The payment of the disputed tax and interest, approximately $108 million , is not considered a settlement of the tax dispute with the U.K. tax authorities. If we prevail in appeals, we will be refunded the tax and interest paid, however, if we do not prevail no further material cash payments are expected due to the initial payment required to appeal the adverse ruling. See Note 24 for further detail. Interest and penalties are recorded as part of the tax provision and were $2 million , $1 million and $1 million related to unrecognized tax benefits in 2017 , 2016 and 2015 . As of December 31, 2017 and 2016 , $25 million and $15 million of interest and penalties were accrued related to income taxes.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
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. December 31, (In millions) 2017 2016 Crude oil and natural gas $ 9 $ 6 Supplies and other items 117 130 Inventories $ 126 $ 136

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment December 31, (In millions) 2017 2016 United States E&P $ 15,867 $ 14,158 International E&P 1,710 2,470 Corporate 88 99 Net property, plant and equipment $ 17,665 $ 16,727 At December 31, 2017, 2016 and 2015 we had total deferred exploratory well costs as follows: December 31, (In millions) 2017 2016 2015 Amounts capitalized less than one year after completion of drilling $ 263 $ 131 $ 352 Amounts capitalized greater than one year after completion of drilling 32 118 85 Total deferred exploratory well costs $ 295 $ 249 $ 437 Number of projects with costs capitalized greater than one year after completion of drilling 1 3 2 (In millions) 2017 2016 2015 Beginning balance $ 249 $ 437 $ 573 Additions 212 299 610 Charges to expense (a) (64 ) (23 ) (111 ) Transfers to development (102 ) (388 ) (635 ) Dispositions (b) — (76 ) — Ending balance $ 295 $ 249 $ 437 (a) Includes $64 million in exploratory well costs being expensed as a result of our agreement to sell Diaba License G4-223 in the Republic of Gabon in August of 2017. See Note 10 for further detail. (b) Includes sale of GOM assets in 2016. Exploratory well costs capitalized greater than one year after completion of drilling are associated with one project in E.G. with costs of $ 32 million as of December 31, 2017 . Management believes this project with suspended exploratory drilling costs exhibit sufficient quantities of hydrocarbons to justify potential development based on current plans. For this project in E.G., drilling was completed on the Rodo well in Alba Block Sub Area B, offshore E. G. in the first quarter of 2015, and we have since completed a seismic feasibility study. In 2017, we received approval for and proceeded to perform a seismic reprocessing program. After completion of this program we will evaluate drilling opportunities within Sub Area B.

Impairment and Exploration Expe

Impairment and Exploration Expenses (Notes)	12 Months Ended
	Dec. 31, 2017
Impairments and Exploration Expenses [Abstract]
Impairments and Exploration Expenses [Text Block]	Impairments and Exploration Expenses Impairments As a result of our announced disposition of our Canadian business in the first quarter of 2017, we recorded a pre-tax non-cash impairment charge of $6.6 billion primarily related to property, plant and equipment. This impairment in our Canadian business is reflected as discontinued operations in the consolidated statements of income and the consolidated statements of cash flows for all periods presented The following table summarizes impairment charges of proved properties: Year Ended December 31, (in millions) 2017 2016 2015 Total impairments $ 229 $ 67 $ 721 • 2017 - Impairments were primarily a result of lower forecasted long-term commodity prices and the anticipated sales of certain non-core proved properties in our International E&P segment of $136 million . Additionally, included in proved property impairments was $89 million relating to the Gulf of Mexico and certain conventional Oklahoma assets primarily as a result of lower forecasted long-term commodity prices. • 2016 - Impairments of $67 million consisted primarily of proved properties in Oklahoma and the Gulf of Mexico as a result of lower forecasted commodity prices and revisions to estimated abandonment costs. • 2015 - Impairments included $340 million for the goodwill impairment of the United States E&P reporting unit, and $335 million related to proved properties (primarily in Colorado and the Gulf of Mexico) as a result of lower forecasted commodity prices, and $44 million associated with our disposition of natural gas assets in East Texas, North Louisiana and Wilburton, Oklahoma. See Note 6 for relevant detail regarding segment presentation, Note 12 for further detail regarding the goodwill impairment and Note 14 for fair value measurements related to impairments of proved properties and long-lived assets. Exploration expense The following table summarizes the components of exploration expenses: Year Ended December 31, (In millions) 2017 2016 2015 Exploration Expenses Unproved property impairments $ 246 $ 195 $ 655 Dry well costs 77 25 212 Geological and geophysical 25 5 31 Other 61 98 73 Total exploration expenses $ 409 $ 323 $ 971 Unproved property impairments and dry well costs • 2017 - As a result of lower forecasted long-term commodity prices and the anticipated sales of certain non-core properties in our International E&P segment, we recorded a non-cash charge of $159 million comprised of $95 million in unproved property impairments; and $64 million in dry well costs related to our Diaba License G4-223 in the Republic of Gabon. Also, because of our decision not to develop the Tchicuate offshore Block in the Republic of Gabon, we recorded a non-cash impairment charge of $43 million to unproved property. • 2016 - Unproved property impairments recorded of $195 million were primarily a result of our decision to not drill any of our remaining Gulf of Mexico undeveloped leases and also includes certain other unproved properties in the United States. Lower dry well expense was a result of the strategic decision to transition out of our conventional exploration program during 2015. • 2015 - Primarily due to changes in our conventional exploration strategy (Gulf of Mexico, Canadian in-situ assets and Harir block in the Kurdistan Region of Iraq), relinquishment of certain properties in the Gulf of Mexico, the operated Solomon exploration well in the Gulf of Mexico and our unproved property in Colorado as a result of the proved property impairment mentioned above. Dry well costs include the operated Solomon exploration well in the Gulf of Mexico, and our operated Sodalita West #1 exploratory well in E.G. See Note 6 for relevant detail regarding segment presentation of unproved property impairments.

Asset Retirement Obligations (N

Asset Retirement Obligations (Notes)	12 Months Ended
	Dec. 31, 2017
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 or seabed at the end of oil and gas production operations. Changes in asset retirement obligations were as follows: For Year Ended December 31, (In millions) 2017 2016 Beginning balance $ 1,652 $ 1,544 Incurred liabilities, including acquisitions 25 14 Settled liabilities, including dispositions (50 ) (74 ) Accretion expense (included in depreciation, depletion and amortization) 85 79 Revisions of estimates (227 ) 96 Held for sale (2 ) (7 ) Ending balance $ 1,483 $ 1,652 2017 • Settled liabilities include dispositions, primarily related to the sale of certain conventional assets in Oklahoma as well as retirements in the U.K. and the Gulf of Mexico. • Revisions of estimates were primarily due to changes in U.K. estimated costs as well as timing of abandonment activities in the U.K. • Ending balance includes $55 million classified as short-term at December 31, 2017 . 2016 • Settled liabilities include dispositions, primarily related to the Gulf of Mexico and Wyoming as well as retirements in the Gulf of Mexico. • Revisions of estimates were primarily due to changes in timing of abandonment activities as well as changes in cost estimated in the U.K. • Ending balance includes $50 million classified as short-term at December 31, 2016 .

Goodwill (Notes)

Goodwill (Notes)	12 Months Ended
	Dec. 31, 2017
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 of a reporting unit with goodwill may have been reduced below its carrying value. Goodwill is tested for impairment at the reporting unit level. Our reporting units are the same as our reporting segments, of which only International E&P includes goodwill. We estimate the fair value of our International E&P 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 our 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. We performed our annual impairment test in the second quarter of 2017 and concluded no impairment was required. As of the date of our last impairment assessment, the fair value of our International E&P reporting unit exceeded its book value by over 40% . We believe the estimates and assumptions used in our impairment assessments are reasonable and based on available market information, but variations in such assumptions could result in materially different calculations of fair value and determinations of whether or not an impairment is indicated. The table below displays the allocated beginning goodwill balances by segment along with changes in the carrying amount of goodwill for 2017 and 2016 : (In millions) U.S. E&P Int'l E&P Total 2016 Beginning balance, gross $ — $ 115 $ 115 Less: accumulated impairments — — — Beginning balance, net — 115 115 Dispositions — — — Impairment — — — Ending balance, net $ — $ 115 $ 115 2017 Beginning balance, gross $ — $ 115 $ 115 Less: accumulated impairments — — — Beginning balance, net — 115 115 Dispositions — — — Impairment — — — Ending balance, net $ — $ 115 $ 115

Derivatives

Derivatives	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives For further information regarding the fair value measurement of derivative instruments see Note 14 . See Note 1 for discussion of the types of derivatives we use and the reasons for them. All of our commodity derivatives and historical interest rate derivatives are subject to enforceable master netting arrangements or similar agreements under which we may 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, 2017 (In millions) Asset Liability Net Asset Balance Sheet Location Not Designated as Hedges Commodity $ — $ 138 $ (138 ) Other current liabilities Commodity — 2 (2 ) Deferred credits and other liabilities Total Not Designated as Hedges $ — $ 140 $ (140 ) Total $ — $ 140 $ (140 ) December 31, 2016 (In millions) Asset Liability Net Asset Balance Sheet Location Fair Value Hedges Interest rate $ 3 $ — $ 3 Other current assets Interest rate 1 — 1 Other noncurrent assets Cash Flow Hedges Interest rate $ 64 $ — $ 64 Other noncurrent assets Total Designated Hedges $ 68 $ — $ 68 Not Designated as Hedges Commodity $ — $ 60 $ (60 ) Other current liabilities Total Not Designated as Hedges $ — $ 60 $ (60 ) Total $ 68 $ 60 $ 8 Derivatives Designated as Fair Value Hedges During the third quarter of 2017, we terminated all of our interest rate swaps designated as fair value hedges. The pretax effects of derivative instruments designated as hedges of fair value in our consolidated statements of income has a gross impact that is not material to net interest and other in all periods presented. Additionally, there is no ineffectiveness related to fair value hedges in all periods presented. The following table presents, by maturity date, information about our interest rate swap agreements, including the weighted average, London Interbank Offer Rate (“LIBOR”) based, floating rate. December 31, 2017 December 31, 2016 Aggregate Notional Amount Weighted Average, LIBOR-Based, Aggregate Notional Amount Weighted Average, LIBOR-Based, Maturity Dates (in millions) Floating Rate (in millions) Floating Rate October 1, 2017 $ — — % $ 600 5.10 % March 15, 2018 $ — — % $ 300 5.04 % The pretax effect of derivative instruments designated as hedges of fair value in our consolidated statements of income is summarized in the table below. There is no ineffectiveness related to the historical fair value hedges. Gain (Loss) Year Ended December 31, (In millions) Income Statement Location 2017 2016 2015 Derivative Interest rate Net interest and other $ — $ (4 ) $ — Hedged Item Debt Net interest and other $ — $ 4 $ — Derivatives Not Designated as Hedges Interest Rate Swaps During the third quarter of 2016, we entered into forward starting interest rate swaps to hedge the variations in cash flows related to fluctuations in long term interest rates from debt that were probable to be refinanced by us in 2018, specifically interest rate risk associated with future changes in the benchmark treasury rate. We designated these derivative instruments as cash flow hedges. During the second quarter of 2017, we de-designated the forward starting interest rate swaps previously designated as cash flow hedges. In the third quarter of 2017, the forecasted transaction consummated and we issued $1 billion in senior unsecured notes. See Note 15 for further detail. As a result, we terminated our forward starting interest rate swaps receiving proceeds of $54 million . We recognized a gain of $47 million , related to deferred gains reclassified from accumulated other comprehensive income, in net interest and other during 2017. The following table presents, by maturity date, information about our terminated forward starting interest rate swap agreements, including the rate. December 31, 2017 December 31, 2016 Aggregate Notional Amount Weighted Average, LIBOR Aggregate Notional Amount Weighted Average, LIBOR Maturity Dates (in millions) Fixed Rate (in millions) Fixed Rate March 15, 2018 $ — — % $ 750 1.57 % The following table sets forth the net impact of the terminated forward starting interest rate swap derivatives de-designated as cash flow hedges on other comprehensive income (loss). Year Ended December 31, (In millions) 2017 2016 2015 Interest Rate Swaps Beginning balance $ 60 $ — $ — Change in fair value recognized in other comprehensive income (13 ) 64 — Reclassification from other comprehensive income (47 ) (4 ) — Ending balance $ — $ 60 $ — Commodity Derivatives We have entered into multiple crude oil and natural gas derivatives indexed to NYMEX WTI and Henry Hub related to a portion of our forecasted United States E&P sales through 2019. These commodity derivatives consist of three-way collars, swaps, and 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/Henry Hub price plus the difference between the floor and the sold put price. These commodity derivatives were not designated as hedges. The following table sets forth outstanding derivative contracts as of December 31, 2017 and the weighted average prices for those contracts: Crude Oil 2018 2019 First Quarter Second Quarter Third Quarter Fourth Quarter First Quarter Second Quarter Three-Way Collars (a) Volume (Bbls/day) 85,000 85,000 85,000 85,000 10,000 10,000 Weighted average price per Bbl: Ceiling $56.38 $56.38 $56.96 $56.96 $60.00 $60.00 Floor $51.65 $51.65 $51.53 $51.53 $55.00 $55.00 Sold put $45.00 $45.00 $44.65 $44.65 $47.00 $47.00 Swaps Volume (Bbls/day) 20,000 20,000 — — — — Weighted average price per Bbl $55.12 $55.12 $— $— $— $— Basis Swaps (b) Volume (Bbls/day) 5,000 5,000 10,000 10,000 — — Weighted average price per Bbl $(0.60) $(0.60) $(0.67) $(0.67) $— $— (a) Between January 1, 2018 and February 12, 2018, we entered into 10,000 Bbls/day of three-way collars for July - December 2018 with an average ceiling price of $63.51 , a floor price of $57.00 , and a sold put price of $50.00 and 20,000 Bbls/day of three-way collars for January - June 2019 with an average ceiling price of $67.92 , a floor price of $53.50 , and a sold put price of $46.50 . (b) The basis differential price is between WTI Midland and WTI Cushing. Natural Gas 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Three-Way Collars Volume (MMBtu/day) 200,000 160,000 160,000 160,000 Weighted average price per MMBtu Ceiling $3.79 $3.61 $3.61 $3.61 Floor $3.08 $3.00 $3.00 $3.00 Sold put $2.55 $2.50 $2.50 $2.50 The mark-to-market impact and settlement of these commodity derivative instruments appears in sales and other operating revenues in our consolidated statements of income for the years ended December 31, 2017, 2016, and 2015. The December 31, 2017, 2016, and 2015 impact was a net loss of $36 million , a net loss of $66 million , and a net gain of $128 million , respectively. Net settlements of commodity derivative instruments for the years ended December 31, 2017, 2016, and 2015 were gains of $45 million , $44 million , and $78 million , respectively.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
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 by hierarchy level. December 31, 2017 (In millions) Level 1 Level 2 Level 3 Total Derivative instruments, assets Interest rate — — — — Derivative instruments, assets $ — $ — $ — $ — Derivative instruments, liabilities Commodity (a) $ (20 ) $ (120 ) $ — $ (140 ) Derivative instruments, liabilities $ (20 ) $ (120 ) $ — $ (140 ) December 31, 2016 (In millions) Level 1 Level 2 Level 3 Total Derivative instruments, assets Interest rate $ — $ 68 $ — $ 68 Derivative instruments, assets $ — $ 68 $ — $ 68 Derivative instruments, liabilities Commodity (a) $ — $ 60 $ — $ 60 Derivative instruments, liabilities $ — $ 60 $ — $ 60 (a) Derivative instruments are recorded on a net basis in our balance sheet (see Note 13 ). Commodity derivatives include three-way collars, swaps, and basis swaps. These instruments are measured at fair value using either a Black-Scholes or a modified Black-Scholes Model. For swaps and basis swaps, inputs to the models include 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, inputs to the models include commodity prices, interest rates, 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. Historically, both our interest rate swaps and 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 13 for additional discussion of the types of derivative instruments we use. Fair values – Nonrecurring The following table shows the values of assets, by major category, measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition. 2017 2016 2015 (In millions) Fair Value Impairment Fair Value Impairment Fair Value Impairment Long-lived assets held for use $ 179 $ 229 $ 15 $ 67 $ 56 $ 386 Long-lived assets held for use that were impaired are discussed below. The fair values, unless otherwise noted, were measured using an income approach based upon internal estimates of future production levels, prices and discount rate, all of which are Level 3 inputs. Inputs to the fair value measurement include reserve and production estimates made by our reservoir engineers, estimated future commodity prices adjusted for quality and location differentials and forecasted operating expenses for the remaining estimated life of the reservoir. United States E&P In the third quarter of 2017, impairments of $65 million were recorded consisting of certain proved properties in the Gulf of Mexico as a result of lower forecasted long-term commodity prices, to an aggregate fair value of $66 million . In the third quarter of 2016, impairments of $47 million were recorded consisting primarily of conventional non-core proved properties in Oklahoma as a result of lower forecasted long-term commodity prices, to an aggregate fair value of $15 million . During the fourth quarter of 2016, we recorded an impairment of $17 million as a result of abandonment cost revisions related to the Ozona development in the Gulf of Mexico which ceased productions in 2013. In the third quarter of 2015, impairments of $ 333 million were recorded primarily related to certain producing assets in Colorado and the Gulf of Mexico as a result of lower forecasted commodity prices, to an aggregate fair value of $ 41 million . During the second quarter of 2015, we recorded an impairment charge of $ 44 million related to East Texas, North Louisiana and Wilburton, Oklahoma natural gas assets as a result of the anticipated sale. The fair values were measured using a probability weighted income approach based on both the anticipated sale price and held-for-use model. International E&P In the third quarter of 2017, we recorded proved property impairments of $136 million , to an aggregate fair value of $103 million , on certain non-core properties in our International E&P segment primarily as a result of lower forecasted long-term commodity prices and as a result of the anticipated sales of certain non-core international assets. The fair values were measured using the market approach, based upon either anticipated sales proceeds less costs to sell or a market comparable sales price per boe. This resulted in a Level 2 classification. See Note 5 for further information about the divestment of certain non-core properties in our International E&P segment. In the third quarter of 2015, a partial impairment of $12 million was recorded to an investment in an equity method investee as a result of lower forecasted commodity prices, to a fair value of $604 million . The impairment was reflected in income from equity method investments in our consolidated statement of income. Canadian discontinued operations As a result of our announced disposition of our Canadian business in the first quarter of 2017, we recorded a pre-tax non-cash impairment charge of $6.6 billion primarily related to property, plant and equipment. This impairment was recorded for excess net book value over anticipated sales proceeds less costs to sell. Fair values of assets held for sale were determined based upon the anticipated sales proceeds less costs to sell, which resulted in a Level 2 classification. See Note 5 for relevant detail regarding dispositions Fair values – Financial instruments Our current assets and liabilities include financial instruments, the most significant of which are receivables, 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 value by individual balance sheet line item at December 31, 2017 and 2016 . December 31, 2017 2016 (In millions) Fair Value Carrying Amount Fair Value Carrying Amount Financial assets Other current assets (a) $ 762 $ 761 $ 7 $ 7 Other noncurrent assets 159 161 105 108 Total financial assets $ 921 $ 922 $ 112 $ 115 Financial liabilities Other current liabilities $ 32 $ 43 $ 68 $ 75 Long-term debt, including current portion (b) 5,976 5,526 7,449 7,292 Deferred credits and other liabilities 110 103 114 107 Total financial liabilities $ 6,118 $ 5,672 $ 7,631 $ 7,474 (a) Includes our two notes receivable relating to the sale of our Canadian business as of December 31, 2017, see note 5 for further information. (b) Excludes capital leases, debt issuance costs and historical interest rate swap adjustments. 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. Most of our long-term debt instruments are publicly-traded. A market approach, based upon quotes from major financial institutions, which are Level 2 inputs, is used to measure the fair value of such debt. The fair value of our debt that is not publicly-traded is measured using an income approach. The future debt service payments are discounted using the rate at which we currently expect to borrow. All inputs to this calculation are Level 3.

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt	Debt Short-term debt As of December 31, 2017 , we had no borrowings against our $3.4 billion unsecured revolving credit facility (as amended, the "Credit Facility"), as described below. Revolving Credit Facility In June 2017, we extended the maturity date of our Credit Facility from May 28, 2020 to May 28, 2021. In July 2017, we increased our $3.3 billion unsecured Credit Facility by $93 million to a total of $3.4 billion . Fees on the unused commitment of each lender, as well as the borrowing options under the Credit Facility, remain unaffected by the increase and term extension. We have the ability to request two additional one -year extensions and an option to increase the commitment amount by up to an additional $107 million , subject to the consent of any increasing lenders. The sub-facilities for swing-line loans and letters of credit remain unchanged allowing up to an aggregate amount of $100 million and $500 million , respectively. The Credit Facility includes a covenant requiring that our ratio of total debt to total capitalization not exceed 65% as of the last day of each fiscal quarter. 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. As of December 31, 2017 , we were in compliance with this covenant with a debt-to-capitalization ratio of 32% . Long-term debt The following table details our long-term debt: December 31, (In millions) 2017 2016 Senior unsecured notes: 6.000% notes due 2017 — 682 5.900% notes due 2018 — 854 7.500% notes due 2019 — 228 2.700% notes due 2020 (a) 600 600 2.800% notes due 2022 (a) 1,000 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 — 6.800% notes due 2032 (a) 550 550 6.600% notes due 2037 (a) 750 750 5.200% notes due 2045 (a) 500 500 Capital leases: Capital lease obligation expiring in 2018 — 1 Other obligations: 5.125% obligation relating to revenue bonds due 2037 — 1,000 Total (b) 5,536 7,301 Unamortized discount (10 ) (9 ) Fair value adjustments (c) — 7 Unamortized debt issuance cost (32 ) (35 ) Amounts due within one year — (683 ) Total long-term debt $ 5,494 $ 6,581 (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, 2017 may be declared immediately due and payable. (c) See Notes 13 and 14 for information on historical interest rate swaps. Debt Issuance On July 24, 2017, we issued $1 billion of 4.4% senior unsecured notes that will mature on July 15, 2027. Interest on the senior unsecured notes is payable semi-annually beginning January 15, 2018. We may redeem some or all of the senior unsecured notes at any time at the applicable redemption price, plus accrued interest, if any. During the third quarter of 2017, we used the net proceeds of $990 million plus existing cash on hand to redeem the following senior unsecured notes: • $682 million 6.0% Notes Due in 2017 • $854 million 5.9% Notes Due in 2018 • $228 million 7.5% Notes Due in 2019 During the year ended 2017, as a result of the above redemption of $1.76 billion in senior unsecured notes, we recognized a loss on early extinguishment of debt of $46 million , primarily due to make-whole call provisions. In connection with the redemption of the senior unsecured notes, we terminated our forward starting interest rate swaps, which resulted in proceeds of $54 million and a gain of approximately $47 million into earnings in 2017. See Note 13 for further detail on our historical forward starting interest rate swaps. Debt Redemption In December 2017, we entered into a transaction to purchase $1 billion of 3.75% municipal revenue bonds due in 2037, to be issued by the Parish of St. John the Baptist, State of Louisiana (the "Parish"). The Parish will use the proceeds to redeem $1 billion of 5.125% municipal revenue bonds due in 2037 with cash on hand in a refunding transaction. We purchased the $1 billion of 3.75% municipal revenue bonds due in 2037 on their date of issuance to hold for our own account and potential remarketing to the public at a future date. The following table shows future debt payments: (In millions) 2018 $ — 2019 — 2020 600 2021 — 2022 1,035 Thereafter 3,901 Total long-term debt, including current portion $ 5,536

Incentive Based Compensation Pl

Incentive Based Compensation Plans	12 Months Ended
	Dec. 31, 2017
Incentive Based Compensation Plans [Abstract]
Incentive Based Compensation	Incentive Based Compensation Description of stock-based compensation plans – The Marathon Oil Corporation 2016 Incentive Compensation Plan (the "2016 Plan") was approved by our stockholders in May 2016 and authorizes the Compensation Committee of the Board of Directors to grant stock options, SARs, stock awards (including restricted stock and restricted stock unit awards) and performance unit awards to employees. The 2016 Plan also allows us to provide equity compensation to our non-employee directors. No more than 55 million shares of our common stock may be issued under the 2016 Plan. For stock options and SARs, the number of shares available for issuance under the 2016 Plan will be reduced by one share for each share of our common stock in respect of which the award is granted. For stock awards (including restricted stock and restricted stock unit awards), the number of shares available for issuance under the 2016 Plan will be reduced by 2.41 shares for each share of our common stock in respect of which the award is granted. Shares subject to awards under the 2016 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 2016 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 2016 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 2016 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 2016 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, 2017, there are no SARs outstanding. Restricted stock – We grant restricted stock under the 2016 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 2016 Plan. At the grant date, each unit represents the value of one share of our common stock. These units are settled in cash, and the amount of the payment is based on (1) the vesting percentage, which can be from zero to 200% based on performance achieved and (2) the value of our common stock on the date vesting is 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 number of shares that would represent the value of the units. 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. We also grant restricted stock units to certain non-officer international employees which generally vest ratably over a three -year period, contingent on the recipient's continued employment. Grants of restricted stock units to these non-officer international employees are 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 $50 million , $51 million and $57 million in 2017 , 2016 and 2015 , while the total related income tax benefits were $19 million and $20 million in 2016 and 2015. Due to the full valuation allowance on our net federal deferred tax assets, we realized no tax benefit during 2017. During 2016 and 2015 , cash received upon exercise of stock option awards was $1 million and $9 million . There was no cash received upon exercise of stock option awards for 2017. There were no tax benefits realized for deductions for stock awards settled during 2017, 2016 and 2015. Stock option awards – During 2017 , 2016 and 2015 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: 2017 2016 2015 Exercise price per share $15.80 $7.22 $29.06 Expected annual dividend yield 1.3 % 2.8 % 2.9 % Expected life in years 6.4 6.3 6.2 Expected volatility 42 % 36 % 32 % Risk-free interest rate 2.1 % 1.4 % 1.7 % Weighted average grant date fair value of stock option awards granted $6.07 $1.97 $6.84 The following is a summary of stock option award activity in 2017 . Number Weighted Average Weighted Average Remaining Aggregate Intrinsic Value of Shares Exercise Price Contractual Term (in millions) Outstanding at beginning of year 11,915,533 $27.71 Granted 799,591 $15.80 Exercised (8,666) $7.22 Canceled (2,375,682) $33.31 Outstanding at end of year 10,330,776 $25.52 4 years $ 13 Exercisable at end of year 8,661,893 $27.91 3 years $ 5 Expected to vest 1,650,737 $13.08 9 years $ 8 The intrinsic value of stock option awards exercised during 2017 and 2016 were not material. The intrinsic value of stock awards exercised during 2015 was $6 million . As of December 31, 2017 , unrecognized compensation cost related to stock option awards was $4 million , which is expected to be recognized over a weighted average period of one year. Restricted stock awards and restricted stock units – The following is a summary of restricted stock and restricted stock unit award activity in 2017 . Awards Weighted Average Grant Date Fair Value Unvested at beginning of year 6,933,533 $14.44 Granted 4,198,624 $16.13 Vested & Exercised (2,472,367 ) $17.67 Canceled (1,086,945 ) $15.03 Unvested at end of year 7,572,845 $14.24 The vesting date fair value of restricted stock awards which vested during 2017 , 2016 and 2015 was $30 million , $16 million and $26 million . The weighted average grant date fair value of restricted stock awards was $14.24 , $14.44 and $30.76 for awards unvested at December 31, 2017 , 2016 and 2015 . As of December 31, 2017 there was $67 million of unrecognized compensation cost related to restricted stock awards which is expected to be recognized over a weighted average period of one year. Stock-based performance unit awards – During 2017 , 2016 and 2015 we granted 563,631 , 1,205,517 and 382,335 stock-based performance unit awards to officers. At December 31, 2017 , there were 1,510,823 units outstanding. Total stock-based performance unit awards expense was $8 million in 2017 and $6 million in 2016. We had no stock-based performance unit awards expense in 2015. The key assumptions used in the Monte Carlo simulation to determine the fair value of stock-based performance units granted in 2017, 2016 and 2015 were: 2017 2016 2015 (a) Valuation date stock price $16.93 $16.93 $16.93 Expected annual dividend yield 1.2 % 1.2 % 1.2 % Expected volatility 54 % 34 % 33 % Risk-free interest rate 1.9 % 1.7 % 1.4 % Fair value of stock-based performance units outstanding $21.63 $19.86 $0.00 (a) As of December 31, 2017, there were no 2015 performance unit awards outstanding.

Defined Benefit Postretirement

Defined Benefit Postretirement Plans and Defined Contribution Plan (Notes)	12 Months Ended
	Dec. 31, 2017
Defined Benefit Plan [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, as well as U.K. employees who were hired before April 2010. Certain employees located in E.G., who are U.S. or U.K. based, also participate in these plans. Benefits under these plans are based on plan provisions specific to each plan. For the U.K. pension plan, the principal employer and plan trustees reached a decision to close the plan to future benefit accruals effective December 31, 2015. We also have defined benefit 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-age 65 health care benefits are provided to certain U.S. employees on a defined contribution basis. 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 2017 2016 2017 2016 (In millions) U.S. Int’l U.S. Int’l U.S. U.S. Accumulated benefit obligation 378 599 386 583 221 227 Change in benefit obligations: Beginning balance $ 397 $ 583 $ 525 $ 579 $ 227 $ 260 Service cost 22 — 25 — 2 2 Interest cost 13 17 16 23 8 11 Plan amendment — — — 1 — (38 ) Actuarial loss (gain) 42 (7 ) 78 139 5 11 Foreign currency exchange rate changes — 52 — (108 ) — — Divestiture — — — — — — Settlements paid (84 ) (31 ) (240 ) (36 ) — — Benefits paid (6 ) (15 ) (7 ) (15 ) (21 ) (19 ) Ending balance $ 384 $ 599 $ 397 $ 583 $ 221 $ 227 Change in fair value of plan assets: Beginning balance $ 227 $ 595 $ 354 $ 608 $ — $ — Actual return on plan assets 27 47 25 129 — — Employer contributions 52 17 95 18 21 20 Foreign currency exchange rate changes — 57 — (109 ) — — Divestiture — — — — — — Settlements paid (84 ) (31 ) (240 ) (36 ) — — Benefits paid (6 ) (15 ) (7 ) (15 ) (21 ) (20 ) Ending balance $ 216 $ 670 $ 227 $ 595 $ — $ — Funded status of plans at December 31 $ (168 ) $ 71 $ (170 ) $ 12 $ (221 ) $ (227 ) Amounts recognized in the consolidated balance sheets: Noncurrent assets — 71 — 12 — — Current liabilities (6 ) — (4 ) — (21 ) (21 ) Noncurrent liabilities (162 ) — (166 ) — (200 ) (206 ) Accrued benefit cost $ (168 ) $ 71 $ (170 ) $ 12 $ (221 ) $ (227 ) Pretax amounts in accumulated other comprehensive loss: Net loss (gain) $ 122 $ 58 $ 130 $ 81 $ 30 $ 25 Prior service cost (credit) (45 ) 3 (55 ) 4 (56 ) (63 ) Components of net periodic benefit cost from continuing operations 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, 2017 2016 2015 2017 2016 2015 (In millions) U.S. Int’l U.S. Int’l U.S. Int’l U.S. U.S. U.S. Components of net periodic benefit cost: Service cost $ 22 $ — $ 25 $ — $ 29 $ 14 $ 2 $ 2 $ 3 Interest cost 13 17 16 23 25 25 8 11 11 Expected return on plan assets (13 ) (30 ) (18 ) (35 ) (30 ) (37 ) — — — Amortization: - prior service cost (credit) (10 ) — (10 ) 1 (7 ) 1 (7 ) (3 ) (4 ) - actuarial loss 8 1 14 — 22 2 — — 1 Net curtailment loss (gain) (a) — — — — (5 ) 4 — — (7 ) Net settlement loss (b) 28 4 97 6 119 — — — — Net periodic benefit cost (c) $ 48 $ (8 ) $ 124 $ (5 ) $ 153 $ 9 $ 3 $ 10 $ 4 Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax): Actuarial loss (gain) $ 28 $ (26 ) $ 70 $ 41 $ 30 $ (25 ) $ 5 $ 11 $ (21 ) Amortization of actuarial gain (loss) (36 ) (4 ) (111 ) (6 ) (134 ) (2 ) — — (1 ) Prior service cost (credit) — — — 1 (89 ) 1 — (38 ) — Amortization of prior service credit (cost) 10 — 10 (1 ) 7 (5 ) 7 3 13 Total recognized in other comprehensive (income) loss $ 2 $ (30 ) $ (31 ) $ 35 $ (186 ) $ (31 ) $ 12 $ (24 ) $ (9 ) Total recognized in net periodic benefit cost and other comprehensive (income) loss $ 50 $ (38 ) $ 93 $ 30 $ (33 ) $ (22 ) $ 15 $ (14 ) $ (5 ) (a) Related to workforce reductions, which reduced the future expected years of service for employees participating in the plans and the impact of discontinuing accruals for future benefits under the U.K. pension plan effective December 31, 2015. (b) Settlement losses are recorded when lump sum payments from a plan in a period exceed the plan’s total service and interest costs for the period. (c) Net periodic benefit cost reflects a calculated market-related value of plan assets which recognizes changes in fair value over three years. The estimated net loss and prior service credit for our defined benefit pension plans that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2018 are $13 million and $10 million . The estimated net loss and prior service credit for our other defined benefit postretirement plans that will be amortized from accumulated other comprehensive loss into net periodic benefit cost in 2018 are $1 million and $7 million . 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 2017 , 2016 and 2015 . Pension Benefits Other Benefits 2017 2016 2015 2017 2016 2015 (In millions) U.S. Int’l U.S. Int’l U.S. Int’l U.S. U.S. U.S. Weighted average assumptions used to determine benefit obligation: Discount rate 3.55 % 2.50 % 4.02 % 2.70 % 4.04 % 3.90 % 3.54 % 3.98 % 4.36 % Rate of compensation increase (a) 4.00 % — 4.00 % — 4.00 % — 4.00 % 4.00 % 4.00 % Weighted average assumptions used to determine net periodic benefit cost: Discount rate 3.86 % 2.70 % 3.66 % 3.90 % 3.79 % 3.70 % 3.98 % 4.36 % 3.93 % Expected long-term return on plan assets 6.50 % 4.50 % 6.75 % 5.50 % 6.75 % 5.70 % — — — Rate of compensation increase (a) 4.00 % — 4.00 % — % 4.00 % 3.60 % 4.00 % 4.00 % 4.00 % (a) No future benefits will be incurred for the U.K. plan after December 31, 2015. Therefore, rate of compensation increase is no longer applicable to this plan. Expected long-term return on plan assets – The expected long-term return on plan assets assumption for our U.S. funded plan is determined based on an asset rate-of-return modeling tool developed by a third-party investment group 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. To determine the expected long-term return on plan assets assumption for our international plans, we consider the current level of expected returns on risk-free investments (primarily government bonds), the historical levels of the risk premiums associated with the other applicable asset categories and the expectations for future returns of each asset class. 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 2017 2016 2015 Initial health care trend rate 8.00 % 8.25 % 8.00 % Ultimate trend rate 4.70 % 4.50 % 4.50 % Year ultimate trend rate is reached 2025 2025 2024 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. Therefore, a 1% change in health care cost trend rates would not have a material impact on either the service and interest cost components and the postretirement benefit obligations. Plan investment policies and strategies – The investment policies for our U.S. and international pension plan assets reflect the funded status of the plans 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 – Our international plan's target asset allocation is comprised of 55% equity securities and 45% fixed income securities. The plan assets are invested in ten separate portfolios, mainly pooled fund vehicles, managed by several professional investment managers whose performance is measured independently by a third-party asset servicing consulting firm. 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, 2017 and 2016 . Cash and cash equivalents – Cash and cash equivalents are valued using a market approach and are considered Level 1. This investment also includes a cash reserve account (a collective short-term investment fund) that is valued using an income approach and is considered Level 2. Equity securities - Investments in common stock and preferred 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. These private equity investments are considered Level 3. Investments in pooled funds are valued using a market approach at the net asset value ("NAV") of units held. The various funds consist of either an equity or fixed income investment portfolio with underlying investments held in U.S. and non-U.S. securities. Nearly all of the underlying investments are publicly-traded. The majority of the pooled funds are benchmarked against a relative public index. These are considered Level 2. 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, non-U.S. government bonds, private placements, taxable municipals, GNMA/FNMA pools, and Yankee bonds 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. Other fixed income investments include futures contracts, real estate investment trusts, credit default, zero coupon, and interest rate swaps. The investment in the commingled funds is valued using the NAV 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. Pooled funds primarily have investments held in U.S. and non-U.S. publicly traded investment grade government and corporate bonds and are considered Level 2. Other – Other investments are comprised of an unallocated annuity contract, two limited liability companies, real estate and U.S. treasury futures. All are considered Level 3, as significant inputs to determine fair value are unobservable. 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, 2017 and 2016 . December 31, 2017 (In millions) Level 1 Level 2 Level 3 Total U.S. Int’l U.S. Int’l U.S. Int’l U.S. Int’l Cash and cash equivalents $ 6 $ 1 $ — $ — $ — $ — $ 6 $ 1 Equity securities: Common stock 81 — — — — — 81 — Private equity — — — — 16 — 16 — Mutual and pooled funds — 151 — 115 — — — 266 Fixed income securities: Corporate — — 6 — — — 6 — Exchange traded funds 5 — — — — — 5 — Government 19 — 2 — 3 — 24 — Pooled funds — — — 403 — — — 403 Other — — — — 19 — 19 — Total investments, at fair value 111 152 8 518 38 — 157 670 Commingled funds (a) — — — — — — 59 — Total investments $ 111 $ 152 $ 8 $ 518 $ 38 $ — $ 216 $ 670 December 31, 2016 (In millions) Level 1 Level 2 Level 3 Total U.S. Int’l U.S. Int’l U.S. Int’l U.S. Int’l Cash and cash equivalents $ 8 $ 5 $ — $ — $ — $ — $ 8 $ 5 Equity securities: Common stock 82 — — — — — 82 — Private equity — — — — 20 — 20 — Mutual and pooled funds — 201 — 159 — — — 360 Fixed income securities: Corporate — — 52 — — — 52 — Exchange traded funds 5 — — — — — 5 — Government 6 — 19 — — — 25 — Pooled funds — — — 230 — — — 230 Other — — — — 21 — 21 — Total investments, at fair value 101 206 71 389 41 — 213 595 Commingled funds (a) — — — — — — 14 — Total investments $ 101 $ 206 $ 71 $ 389 $ 41 $ — $ 227 $ 595 (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. See Note 2 for further information on the FASB update. The activity during the year ended December 31, 2017 and 2016 , 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, 2017 and reflect expected future services, as appropriate, are to be paid in the years indicated. Pension Benefits Other Benefits (In millions) U.S. Int’l U.S. 2018 $ 43 $ 17 $ 21 2019 40 18 20 2020 37 17 20 2021 33 19 19 2022 30 21 18 2023 through 2027 123 118 74 Contributions to defined benefit plans – We expect to make contributions to the funded pension plans of up to $65 million in 2018 . Cash contributions to be paid from our general assets for the unfunded pension and postretirement plans are expected to be approximately $6 million and $21 million in 2018 . Contributions to defined contribution plans – We contribute to several defined contribution plans for eligible employees. Contributions to these plans totaled $20 million , $20 million and $20 million in 2017 , 2016 and 2015 .

Reclassifications Out of Accumu

Reclassifications Out of Accumulated Other Comprehensive Income (Notes)	12 Months Ended
	Dec. 31, 2017
Reclassifications out of AccumulatedOtherComprehensiveIncome [Abstract]
Reclassification out of AOCI [Text Block]	Reclassifications Out of Accumulated Other Comprehensive Loss The following table presents a summary of amounts reclassified from accumulated other comprehensive loss: Year Ended December 31, (In millions) 2017 2016 Income Statement Line Postretirement and postemployment plans Amortization of actuarial loss $ (9 ) $ (14 ) General and administrative Net settlement loss (32 ) (103 ) General and administrative Derivative hedges Recognized gain on terminated derivative hedge 46 — Net interest and other Ineffective portion of derivative hedge 1 4 Net interest and other 6 (113 ) Income (loss) from operations (40 ) 41 (Provision) benefit for income taxes Total reclassifications to expense, net of tax $ (34 ) $ (72 ) Income (loss) from continuing operations Foreign currency hedges Net recognized loss in discontinued operations, net of tax (30 ) — Income (loss) from discontinued operations Total reclassifications to expense $ (64 ) $ (72 )

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Information	Supplemental Cash Flow Information Year Ended December 31, (In millions) 2017 2016 2015 Net cash used in operating activities: Interest paid (net of amounts capitalized) $ (379 ) $ (375 ) $ (325 ) Income taxes paid to taxing authorities (a) (391 ) (84 ) (171 ) Noncash investing activities, related to continuing operations: Changes in asset retirement costs $ (202 ) $ 110 $ (95 ) Asset retirement obligations assumed by buyer 14 40 251 Increase in capital expenditure accrual 176 — — Notes receivable for disposition of assets 748 — — (a) Includes a payment of $108 million made to U.K. taxing authorities to preserve our appeal rights, see Note 7 - Income Taxes for additional discussion.

Other Items

Other Items	12 Months Ended
	Dec. 31, 2017
Interest and Other Income [Abstract]
Interest and Other Income [Text Block]	Other Items Net interest and other Year Ended December 31, (In millions) 2017 2016 2015 Interest: Interest income $ 34 $ 14 $ 9 Interest expense (380 ) (398 ) (350 ) Income on interest rate swaps 53 13 11 Interest capitalized 3 18 19 Total interest (290 ) (353 ) (311 ) Other: Net foreign currency gain (loss) 8 6 4 Other 12 15 21 Total other 20 21 25 Net interest and other $ (270 ) $ (332 ) $ (286 ) Foreign currency – Aggregate foreign currency gains (losses) were included in the consolidated statements of income as follows: Year Ended December 31, (In millions) 2017 2016 2015 Net interest and other $ 8 $ 6 $ 4 Provision for income taxes 57 (32 ) (11 ) Aggregate foreign currency gains (losses) $ 65 $ (26 ) $ (7 )

Equity Method Investments and R

Equity Method Investments and Related Party Transactions (Notes)	12 Months Ended
	Dec. 31, 2017
Equity Method Investments Disclosure [Abstract]
Equity Method Investments and Related Party Transactions	Equity Method Investments and Related Party Transactions During 2017 , 2016 and 2015 only our equity method investees were considered related parties and they 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% 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, 2017 2017 2016 EGHoldings 60% $ 456 $ 550 Alba Plant LLC 52% 214 215 AMPCO 45% 177 165 Other investments — 1 Total $ 847 $ 931 Dividends and partnership distributions received from equity method investees (excluding distributions that represented a return of capital previously contributed) were $276 million in 2017 , $192 million in 2016 and $178 million in 2015 . Summarized financial information for equity method investees is as follows: (In millions) 2017 2016 2015 Income data – year (a) : Revenues and other income $ 1,294 $ 770 $ 769 Income from operations 631 346 313 Net income 508 313 280 Balance sheet data – December 31: Current assets $ 586 $ 525 Noncurrent assets 1,044 1,173 Current liabilities 221 218 Noncurrent liabilities 94 47 (a) See Item 15 Exhibits, Financial Statement Schedules which contains the Alba Plant LLC audited financial statements, which have been included pursuant to Rule 3-09 of Regulation S-X. Revenues from related parties were $60 million , $54 million and $51 million in 2017 , 2016 and 2015 , with the majority related to EGHoldings in all years. Purchases from related parties were $132 million , $103 million and $207 million in 2017 , 2016 and 2015 with the majority related to Alba Plant LLC in all years. Current receivables from related parties at December 31, 2017 and 2016 , were $24 million , and $23 million . Payables to related parties were $14 million and $11 million at December 31, 2017 and 2016 , with the majority related to Alba Plant LLC.

Stockholders Equity (Notes)

Stockholders Equity (Notes)	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity Attributable to Parent [Abstract]
Stockholders’ Equity	Stockholders’ Equity In March 2016, we issued 166,750,000 shares of our common stock, par value $1 per share, at a price of $7.65 per share, excluding underwriting discounts and commissions, for net proceeds of $1,236 million . The proceeds were used to strengthen our balance sheet and for general corporate purposes, including funding a portion of our Capital Development Program. There were no share repurchases during 2017 or 2016 under our publicly announced plans or programs. As of December 31, 2017 the total remaining share repurchase authorization was $1.5 billion . Purchases under the program may be in either open market transactions, including block purchases, or in privately negotiated transactions using cash on hand, cash generated from operations, proceeds from potential asset sales or cash from available borrowings to acquire shares. 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.

Leases (Notes)

Leases (Notes)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Leases	Leases We lease a wide variety of facilities and equipment under operating leases, including land, building space, equipment and vehicles. Most long-term leases include renewal options and, in certain leases, purchase options. Future minimum commitments for operating lease obligations having noncancellable lease terms in excess of one year are as follows: (In millions) Operating Lease Obligations 2018 $ 29 2019 28 2020 27 2021 26 2022 5 Later years 4 Sublease rentals — Total minimum lease payments $ 119 * Future minimum commitments for capital lease obligations are nil as of December 31, 2017. Operating lease rental expense related to continuing operations was $87 million , $87 million and $99 million in 2017 , 2016 and 2015 .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The U.K. tax authorities have challenged the timing of deductibility for certain Brae area decommissioning costs, which we claimed for U.K. corporation tax purposes. The dispute relates to the timing of the deduction and does not dispute the general deductibility of decommissioning costs. In the third quarter of 2017, a hearing took place at the U.K.’s First-tier Tribunal with respect to this tax deduction. In the fourth quarter of 2017, we received notification from the U.K.’s First-tier Tribunal that the judge sided with the U.K. tax authorities with respect to the timing of the decommissioning cost deductions. We intend to appeal this decision and estimate that any revisions to current and deferred tax liabilities, if we do not prevail in the appeals process, would have no cumulative adverse earnings impact on our consolidated results of operations. In accordance with U.K. regulations, we have paid the amount of tax and interest in question, approximately $108 million , prior to our appeal. As a result of the negative ruling we no longer consider this position to be more-likely-than-not to be sustained and have created an uncertain tax position related to the Brae area decommissioning costs. The payment of the tax and interest to the U.K. tax authorities is not to settle the position, but a regulatory requirement to appeal in the U.K. If we ultimately prevail in appeals, the U.K. tax authorities will refund the tax and interest, however, if we ultimately lose in appeals no material future payments related to this issue will be required. See Note 7 for further detail. We are continuously undergoing examination of our U.S. federal income tax returns by the IRS. These audits have been completed through the 2014 tax year, except for tax years 2010 and 2011. During the third quarter of 2017, we received a partnership adjustment notification related to the 2010 and 2011 tax years, for which we have filed a Tax Court Petition in the fourth quarter of 2017. We believe that it is more likely than not that we will prevail. 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 federal, state, local and foreign laws and regulations relating to the environment. If these expenditures, as with all costs, are not ultimately reflected in the prices of 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, 2017 and 2016 , 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 – We have entered into a performance guarantee related to asset retirement obligations with aggregate maximum potential undiscounted payments totaling $35 million as of December 31, 2017 . Under the terms of this guarantee arrangement, we would be required to perform should the guaranteed party fail to fulfill its obligations under the specified arrangements. 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, 2017 and 2016 , contractual commitments to acquire property, plant and equipment totaled $102 million and $144 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, proceeds associated with the production of our override, up to $70 million , 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 .

Summary of Principal Accounti32

Summary of Principal Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Principles applied in consolidation	Basis of presentation and principles applied in consolidation – 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 revenue 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. Differences in the basis of the investments and the separate net asset value of the investees, if any, are amortized into income over the remaining useful lives of the underlying assets, except for the excess related to goodwill. Reclassifications – We have reclassified certain prior year amounts between operating cash flow categories to present it on a basis comparable with the current year's presentation with no impact on net cash provided by operating activities. Discontinued operations – As a result of the sale of our Canadian business in 2017, we reflected this business as discontinued operations in all periods presented. Disclosures in this report related to results of operations and cash flows are presented on the basis of continuing operations unless otherwise stated. Assets and liabilities are presented as held for sale in the historical periods in the consolidated balance sheets. See Note 5 for discussion of the divestiture in further detail. As discussed above we closed on the sale of our Canadian business, which includes our Oil Sands Mining segment and exploration stage in-situ leases in the second quarter 2017. The characteristics and composition of our North America E&P reporting segment remained unchanged and there was no effect on previously reported segment information. As all our remaining properties within the segment are located within the United States, we concluded that our North America E&P segment would be renamed United States E&P segment, effective June 30, 2017. During the year, no changes occurred to our International E&P segment. See Note 6 for further information on our reportable segments.
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.
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 are recognized when products are shipped or services are provided to customers, title is transferred, the sales price is fixed or determinable and collectability is reasonably assured. We follow the sales method of accounting for crude oil and natural gas production imbalances and would recognize a liability if our existing proved reserves were not adequate to cover an imbalance. Imbalances have not been significant in the periods presented. In the lower 48 states of the U.S., production volumes of crude oil and condensate, NGLs and natural gas are generally sold immediately and transported to market. In international locations, liquid hydrocarbon production volumes may be stored as inventory and sold at a later time.
Gas balancing policy	We follow the sales method of accounting for crude oil and natural gas production imbalances and would recognize a liability if our existing proved reserves were not adequate to cover an imbalance. Imbalances have not been significant in the periods presented.
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.
Investment, Policy [Policy Text Block]	Short-term Investments - Our short-term investments are comprised of bank time deposits with original maturities of greater than three months but less than twelve months. They are classified as held-to-maturity investments, which are recorded at amortized cost.
Accounts receivable	Accounts receivable – The majority of our receivables are from joint interest owners in properties we operate or from purchasers of commodities, both of which are recorded at 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. Notes receivable - We hold two notes receivable from the sale of our Canadian business, which closed in the second quarter of 2017 . Both notes receivable were initially recorded at fair value and are reported at amortized cost. The notes receivable are evaluated for collectability on an individual basis each reporting period, based on the financial condition of the debtor. No allowances for credit losses were established for the notes receivable as of December 31, 2017 . See Note 5 for additional discussion.
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, foreign currency 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, foreign currency 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 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 effective portion of changes in the fair value of a qualifying cash flow hedge are recorded in other comprehensive income until the hedged item is reclassified to net income when the underlying forecasted transaction is recognized in net income. Ineffective portions of a cash flow hedge’s change in fair value are recognized currently within net interest and other on the consolidated statements of income. However, if it is determined that the likelihood of the original forecasted transaction occurring is no longer probable, the entire accumulated gain or loss recognized in other comprehensive income is immediately reclassified into 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 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. If significant transfers occur, they would be disclosed in Note 14 to the consolidated financial statements.
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 as summarized below. Type of Asset Range of Useful Lives Office furniture, equipment and computer hardware 4 to 15 years Pipelines 10 to 40 years Plants, facilities and infrastructure 3 to 40 years
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 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.
Major maintenance activities	Major maintenance activities – Costs for planned major maintenance are expensed in the period incurred and can include the costs of contractor repair services, materials and supplies, equipment rentals and our labor costs.
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 and seabed, including those leased. Estimates of these costs are developed for each property based on the type of production facilities and equipment, depth of water, 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 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 and common stock units is determined based on the market value of our common stock on the date of grant. Unearned stock-based compensation is charged to stockholders’ equity when restricted stock awards are granted. The fair value of our 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. Our stock-based compensation expense is recognized based on management’s best estimate of the awards that are expected to vest, using the straight-line attribution method for all service-based awards with a graded vesting feature. If actual forfeiture results are different than expected, adjustments to recognized compensation expense may be required in future periods. During the first quarter of 2017, we adopted the accounting standards update issued by the FASB in March 2016 pertaining to share-based payment transactions. As a result of this adoption, all cash payments for withheld shares made to taxing authorities on the employees' behalf are presented within the financing activities section instead of the operating activities section of the statement of cash flows. We elected the retrospective method for adoption of this update and the change in the statement of cash flows is not material for the years ended December 31, 2016 or 2015. Excess tax benefits were classified as an operating activity within the statement of cash flows on a prospective basis beginning in 2017; as such, prior periods were not adjusted. See Note 2 for additional discussion.

Income per Common Share (Tables

Income per Common Share (Tables)	12 Months Ended
	Dec. 31, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The per share calculations below exclude 11 million , 13 million and 13 million stock options in 2017 , 2016 and 2015 that were antidilutive. Year Ended December 31, (In millions, except per share data) 2017 2016 2015 Income (loss) from continuing operations $ (830 ) $ (2,087 ) $ (1,701 ) Income (loss) from discontinued operations (4,893 ) (53 ) (503 ) Net income (loss) $ (5,723 ) $ (2,140 ) $ (2,204 ) Weighted average common shares outstanding 850 819 677 Per basic share: Income (loss) from continuing operations $ (0.97 ) $ (2.55 ) $ (2.51 ) Income (loss) from discontinued operations $ (5.76 ) $ (0.06 ) $ (0.75 ) Net income (loss) $ (6.73 ) $ (2.61 ) $ (3.26 ) Per diluted share: Income (loss) from continuing operations $ (0.97 ) $ (2.55 ) $ (2.51 ) Income (loss) from discontinued operations $ (5.76 ) $ (0.06 ) $ (0.75 ) Net income (loss) $ (6.73 ) $ (2.61 ) $ (3.26 )

Dispositions (Tables)

Dispositions (Tables)	12 Months Ended
	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures	The following table contains select amounts reported in our consolidated statements of income as discontinued operations: Year Ended December 31, (In millions) 2017 2016 2015 Total sales and other revenues and other income $ 431 $ 863 $ 908 Net gain (loss) on disposal of assets (43 ) — — Total revenues and other income 388 863 908 Costs and expenses: Production expenses 254 601 715 Exploration expenses — 7 347 Depreciation, depletion and amortization 40 239 236 Impairments 6,636 — 31 Other 25 87 98 Total costs and expenses 6,955 934 1,427 Pretax income (loss) from discontinued operations (6,567 ) (71 ) (519 ) Provision (benefit) for income taxes (1,674 ) (18 ) (16 ) Income (loss) from discontinued operations $ (4,893 ) $ (53 ) $ (503 ) The following table presents the carrying value of the major categories of assets and liabilities of our Canadian business reported as discontinued operations and other non-core international assets and liabilities from continuing operations, that are reflected as held for sale on our consolidated balance sheets at December 31, 2017 and December 31, 2016: December 31, December 31, (In millions) 2017 2016 Assets held for sale Current assets: Cash and cash equivalents $ — $ 2 Accounts receivables — 129 Inventories — 91 Other — 4 Total current assets held for sale—discontinued operations — 226 Total current assets held for sale—continuing operations 11 1 Total current assets held for sale $ 11 $ 227 Noncurrent assets: Property, plant and equipment, net $ — $ 8,991 Other — 106 Total noncurrent assets held for sale—discontinued operations — 9,097 Total noncurrent assets held for sale—continuing operations 55 1 Total noncurrent assets held for sale $ 55 $ 9,098 Liabilities associated with assets held for sale Current liabilities: Accounts payable $ — $ 111 Other — 10 Total current liabilities held for sale—discontinued operations — 121 Total current liabilities held for sale—continuing operations — — Total current liabilities held for sale $ — $ 121 Noncurrent liabilities: Asset retirement obligations $ — $ 95 Deferred tax liabilities — 1,669 Other — 20 Total noncurrent liabilities held for sale—discontinued operations — 1,784 Total noncurrent liabilities held for sale—continuing operations 2 7 Total noncurrent liabilities held for sale $ 2 $ 1,791

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Year Ended December 31, 2017 Not Allocated (In millions) U.S. E&P Int'l E&P to Segments Total Sales and other operating revenues $ 3,138 $ 1,154 $ (81 ) (b) $ 4,211 Marketing revenues 29 133 — 162 Total revenues 3,167 1,287 (81 ) 4,373 Income from equity method investments — 256 — 256 Net gain on disposal of assets and other income 13 6 117 (c) 136 Less: Production expenses 476 229 1 706 Marketing costs 36 132 — 168 Other operating 354 77 — 431 Exploration 154 5 250 (d) 409 Depreciation, depletion and amortization 2,011 328 33 2,372 Impairments 4 — 225 (e) 229 Taxes other than income 173 — 10 183 General and administrative 119 32 249 (f) 400 Net interest and other — — 270 (g) 270 Loss on early extinguishment of debt — — 51 (h) 51 Income tax provision (benefit) 1 372 3 376 Segment income (loss) / Income (loss) from continuing operations $ (148 ) $ 374 $ (1,056 ) $ (830 ) Capital expenditures (a) $ 2,081 $ 42 $ 27 $ 2,150 (a) Includes accruals. (b) Unrealized loss on commodity derivative instruments. (c) Primarily related to sale of certain conventional assets in Oklahoma and Colorado. (See Note 5 ). (d) Primarily related to unproved property impairments associated with certain non-core properties within our International E&P segment. (See Note 10 ). (e) Primarily related to proved property impairments associated with certain non-core properties within our International E&P segment. (See Note 10 ). (f) Includes pension settlement loss of $32 million (see Note 17 ). (g) Includes a gain of $47 million resulting from the termination of our forward starting interest rate swaps. (See Note 13 .) (h) Primarily related to the make-whole call provisions paid upon redemption of our senior unsecured notes. (See Note 15 .) Year Ended December 31, 2016 Not Allocated (In millions) U.S. E&P Int'l E&P to Segments Total Sales and other operating revenues $ 2,375 $ 665 $ (110 ) (b) $ 2,930 Marketing revenues 135 105 — 240 Total revenues 2,510 770 (110 ) 3,170 Income (loss) from equity method investments — 175 — 175 Net gain on disposal of assets and other income 28 32 382 (c) 442 Less: Production expenses 486 226 — 712 Marketing costs 142 103 — 245 Other operating 328 43 113 (d) 484 Exploration 127 17 179 (e) 323 Depreciation, depletion and amortization 1,835 276 45 2,156 Impairments 20 — 47 (f) 67 Taxes other than income 149 — 2 151 General and administrative 94 35 352 (g) 481 Net interest and other — — 332 332 Income tax provision (benefit) (228 ) 49 1,102 (h) 923 Segment income (loss) / Income (loss) from continuing operations $ (415 ) $ 228 $ (1,900 ) $ (2,087 ) Capital expenditures (a) $ 936 $ 82 $ 18 $ 1,036 (a) Includes accruals. (b) Unrealized loss on commodity derivative instruments. (c) Primarily related to net gain on disposal of assets (see Note 5 ). (d) Includes termination payment on our Gulf of Mexico deepwater drilling rig commitment of $113 million . (e) Primarily related to impairments associated with decision to not drill remaining Gulf of Mexico undeveloped leases (See Note 10 ). (f) Proved property impairments (see Note 10 ). (g) Includes pension settlement loss of $103 million and severance related expenses associated with workforce reductions of $8 million (see Note 17 ). (h) Increased valuation allowance on certain of our deferred tax assets $1,346 million (see Note 7 ). Year Ended December 31, 2015 Not Allocated (In millions) U.S. E&P Int'l E&P to Segments Total Sales and other operating revenues $ 3,358 $ 728 $ 50 (b) $ 4,136 Marketing revenues 396 103 — 499 Total revenues 3,754 831 50 4,635 Income from equity method investments — 157 (12 ) (c) 145 Net gain on disposal of assets and other income 24 27 122 (d) 173 Less: Production expenses 724 255 — 979 Marketing costs 401 99 — 500 Other operating 335 48 27 410 Exploration 314 101 556 (e) 971 Depreciation, depletion and amortization 2,377 295 49 2,721 Impairments 2 — 719 (f) 721 Taxes other than income 215 — 1 216 General and administrative 127 44 417 (g) 588 Net interest and other — — 286 286 Income tax provision (benefit) (265 ) 61 (534 ) (738 ) Segment income (loss) / Income (loss) from continuing operations $ (452 ) $ 112 $ (1,361 ) $ (1,701 ) Capital expenditures (a) $ 2,553 $ 368 $ 25 $ 2,946 (a) Includes accruals. (b) Unrealized gain on commodity derivative instruments. (c) Partial impairment of investment in equity method investee (See Note 14 ). (d) Primarily related to gain on sale of our properties and interests in the Gulf of Mexico, partially offset by the loss on sale of East Africa exploration acreage (see Note 5 ). (e) Unproved property impairments associated with lower forecasted commodity prices and change in conventional exploration strategy (See Note 10 ). (f) Includes goodwill impairment (see Note 12 ) and proved property impairments (see Note 10 ). (g) Includes pension settlement loss of $119 million (see Note 17 ) and severance related expenses associated with workforce reductions of $55 million .
Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area	The following summarizes revenues from external customers by geographic area. Year Ended December 31, (In millions) 2017 2016 2015 United States $ 3,086 $ 2,400 $ 3,804 Equatorial Guinea 530 444 444 Libya 431 54 — U.K. 289 263 380 Other international 37 9 7 Total revenues $ 4,373 $ 3,170 $ 4,635
Revenue from External Customers by Products and Services	The following summarizes revenues by product line. Year Ended December 31, (In millions) 2017 2016 2015 Crude oil and condensate $ 3,477 $ 2,605 $ 3,963 Natural gas liquids 338 198 203 Natural gas 510 356 464 Other 48 11 5 Total revenues $ 4,373 $ 3,170 $ 4,635
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) 2017 2016 United States $ 15,971 $ 14,272 Equatorial Guinea 1,582 1,794 Other international 959 1,592 Total long-lived assets $ 18,512 $ 17,658

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	Income (loss) before tax expense for continuing operations was: Year Ended December 31, (In millions) 2017 2016 2015 United States $ (783 ) $ (1,449 ) $ (2,384 ) Foreign 329 285 (55 ) Total $ (454 ) $ (1,164 ) $ (2,439 )
Schedule of Components of Income Tax Expense (Benefit)	Income tax provisions (benefits) for continuing operations were: Year Ended December 31, 2017 2016 2015 (In millions) Current Deferred Total Current Deferred Total Current Deferred Total Federal $ (32 ) $ 41 $ 9 $ 2 $ 836 $ 838 $ (41 ) $ (684 ) $ (725 ) State and local (14 ) 2 (12 ) 2 8 10 (8 ) (18 ) (26 ) Foreign 483 (104 ) 379 91 (16 ) 75 115 (102 ) 13 Total $ 437 $ (61 ) $ 376 $ 95 $ 828 $ 923 $ 66 $ (804 ) $ (738 )
Schedule of Effective Income Tax Rate Reconciliation	A reconciliation of the federal statutory income tax rate applied to income (loss) from continuing operations before income taxes to the provision (benefit) for income taxes follows: Year Ended December 31, (In millions) 2017 2016 2015 Total pre-tax income (loss) from continuing operations $ (454 ) $ (1,164 ) $ (2,439 ) Total income tax expense (benefit) $ 376 $ 923 $ (738 ) Effective income tax expense (benefit) rate on continuing operations 83 % 79 % (30 )% Income taxes at the statutory tax rate of 35% (a) $ (159 ) $ (407 ) $ (854 ) Effects of foreign operations 140 47 (55 ) Adjustments to valuation allowances 446 1,270 95 State income taxes (19 ) 9 (15 ) Tax law change (35 ) 6 (3 ) Goodwill impairment — — 94 Other federal tax effects 3 (2 ) — Income tax expense (benefit) on continuing operations $ 376 $ 923 $ (738 )
Schedule of Deferred Tax Assets and Liabilities	Deferred tax assets and liabilities resulted from the following: Year Ended December 31, (In millions) 2017 2016 Deferred tax assets: Employee benefits $ 111 $ 228 Operating loss carryforwards 1,030 1,065 Capital loss carryforwards 3 4 Foreign tax credits 611 4,430 Other credit carryforwards — 35 Investments in subsidiaries and affiliates 174 91 Other 69 86 Subtotal 1,998 5,939 Valuation Allowance (926 ) (4,301 ) Total deferred tax assets 1,072 1,638 Deferred tax liabilities: Property, plant and equipment 1,332 3,672 Accrued revenue 81 75 Other 3 (7 ) Total deferred tax liabilities 1,416 3,740 Net deferred tax liabilities $ 344 $ 2,102
Net Deferred Tax Assets Liabilities Table	Net deferred tax liabilities were classified in the consolidated balance sheets as follows: December 31, (In millions) 2017 2016 Assets: Other noncurrent assets $ 489 $ 336 Liabilities: Noncurrent deferred tax liabilities 833 769 Noncurrent liabilities held for sale — 1,669 Net deferred tax liabilities $ 344 $ 2,102
Income Tax Returns Remaining Subject To Examination Table	As of December 31, 2017 , our income tax returns remain subject to examination in the following major tax jurisdictions for the tax years indicated: United States (a) 2008-2016 Equatorial Guinea 2007-2016 Libya 2012-2016 United Kingdom 2008-2016 (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) 2017 2016 2015 Beginning balance $ 66 $ 65 $ 80 Additions for tax positions of prior years 83 6 1 Reductions for tax positions of prior years (3 ) (5 ) — Settlements (20 ) — (7 ) Statute of limitations — — (9 ) Ending balance $ 126 $ 66 $ 65

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	December 31, (In millions) 2017 2016 Crude oil and natural gas $ 9 $ 6 Supplies and other items 117 130 Inventories $ 126 $ 136

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Schedule Of Property Plant And Equipment	Property, Plant and Equipment December 31, (In millions) 2017 2016 United States E&P $ 15,867 $ 14,158 International E&P 1,710 2,470 Corporate 88 99 Net property, plant and equipment $ 17,665 $ 16,727
Schedule of Projects with Exploratory Well Costs Capitalized for More than One Year	At December 31, 2017, 2016 and 2015 we had total deferred exploratory well costs as follows: December 31, (In millions) 2017 2016 2015 Amounts capitalized less than one year after completion of drilling $ 263 $ 131 $ 352 Amounts capitalized greater than one year after completion of drilling 32 118 85 Total deferred exploratory well costs $ 295 $ 249 $ 437 Number of projects with costs capitalized greater than one year after completion of drilling 1 3 2 (In millions) 2017 2016 2015 Beginning balance $ 249 $ 437 $ 573 Additions 212 299 610 Charges to expense (a) (64 ) (23 ) (111 ) Transfers to development (102 ) (388 ) (635 ) Dispositions (b) — (76 ) — Ending balance $ 295 $ 249 $ 437 (a) Includes $64 million in exploratory well costs being expensed as a result of our agreement to sell Diaba License G4-223 in the Republic of Gabon in August of 2017. See Note 10 for further detail. (b) Includes sale of GOM assets in 2016.

Impairment and Exploration Ex39

Impairment and Exploration Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Impairments and Exploration Expenses [Abstract]
Details of Impairment of Long-Lived Assets Held and Used by Asset [Table Text Block]	The following table summarizes impairment charges of proved properties: Year Ended December 31, (in millions) 2017 2016 2015 Total impairments $ 229 $ 67 $ 721
Exploration Expenses [Table Text Block]	The following table summarizes the components of exploration expenses: Year Ended December 31, (In millions) 2017 2016 2015 Exploration Expenses Unproved property impairments $ 246 $ 195 $ 655 Dry well costs 77 25 212 Geological and geophysical 25 5 31 Other 61 98 73 Total exploration expenses $ 409 $ 323 $ 971

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2017
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Change in Asset Retirement Obligation	Changes in asset retirement obligations were as follows: For Year Ended December 31, (In millions) 2017 2016 Beginning balance $ 1,652 $ 1,544 Incurred liabilities, including acquisitions 25 14 Settled liabilities, including dispositions (50 ) (74 ) Accretion expense (included in depreciation, depletion and amortization) 85 79 Revisions of estimates (227 ) 96 Held for sale (2 ) (7 ) Ending balance $ 1,483 $ 1,652

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill Disclosure [Abstract]
Schedule of Goodwill [Table Text Block]	The table below displays the allocated beginning goodwill balances by segment along with changes in the carrying amount of goodwill for 2017 and 2016 : (In millions) U.S. E&P Int'l E&P Total 2016 Beginning balance, gross $ — $ 115 $ 115 Less: accumulated impairments — — — Beginning balance, net — 115 115 Dispositions — — — Impairment — — — Ending balance, net $ — $ 115 $ 115 2017 Beginning balance, gross $ — $ 115 $ 115 Less: accumulated impairments — — — Beginning balance, net — 115 115 Dispositions — — — Impairment — — — Ending balance, net $ — $ 115 $ 115

Derivatives (Tables)

Derivatives (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 (In millions) Asset Liability Net Asset Balance Sheet Location Not Designated as Hedges Commodity $ — $ 138 $ (138 ) Other current liabilities Commodity — 2 (2 ) Deferred credits and other liabilities Total Not Designated as Hedges $ — $ 140 $ (140 ) Total $ — $ 140 $ (140 ) December 31, 2016 (In millions) Asset Liability Net Asset Balance Sheet Location Fair Value Hedges Interest rate $ 3 $ — $ 3 Other current assets Interest rate 1 — 1 Other noncurrent assets Cash Flow Hedges Interest rate $ 64 $ — $ 64 Other noncurrent assets Total Designated Hedges $ 68 $ — $ 68 Not Designated as Hedges Commodity $ — $ 60 $ (60 ) Other current liabilities Total Not Designated as Hedges $ — $ 60 $ (60 ) Total $ 68 $ 60 $ 8
Schedule of Interest Rate Derivatives	The following table presents, by maturity date, information about our interest rate swap agreements, including the weighted average, London Interbank Offer Rate (“LIBOR”) based, floating rate. December 31, 2017 December 31, 2016 Aggregate Notional Amount Weighted Average, LIBOR-Based, Aggregate Notional Amount Weighted Average, LIBOR-Based, Maturity Dates (in millions) Floating Rate (in millions) Floating Rate October 1, 2017 $ — — % $ 600 5.10 % March 15, 2018 $ — — % $ 300 5.04 %
Effects of derivatives designated as fair value hedges	The pretax effect of derivative instruments designated as hedges of fair value in our consolidated statements of income is summarized in the table below. There is no ineffectiveness related to the historical fair value hedges. Gain (Loss) Year Ended December 31, (In millions) Income Statement Location 2017 2016 2015 Derivative Interest rate Net interest and other $ — $ (4 ) $ — Hedged Item Debt Net interest and other $ — $ 4 $ —
Schedule of Interest Rate Swaps	The following table presents, by maturity date, information about our terminated forward starting interest rate swap agreements, including the rate. December 31, 2017 December 31, 2016 Aggregate Notional Amount Weighted Average, LIBOR Aggregate Notional Amount Weighted Average, LIBOR Maturity Dates (in millions) Fixed Rate (in millions) Fixed Rate March 15, 2018 $ — — % $ 750 1.57 %
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table sets forth the net impact of the terminated forward starting interest rate swap derivatives de-designated as cash flow hedges on other comprehensive income (loss). Year Ended December 31, (In millions) 2017 2016 2015 Interest Rate Swaps Beginning balance $ 60 $ — $ — Change in fair value recognized in other comprehensive income (13 ) 64 — Reclassification from other comprehensive income (47 ) (4 ) — Ending balance $ — $ 60 $ —
Schedule of Notional Amounts of Outstanding Derivative Positions	The following table sets forth outstanding derivative contracts as of December 31, 2017 and the weighted average prices for those contracts: Crude Oil 2018 2019 First Quarter Second Quarter Third Quarter Fourth Quarter First Quarter Second Quarter Three-Way Collars (a) Volume (Bbls/day) 85,000 85,000 85,000 85,000 10,000 10,000 Weighted average price per Bbl: Ceiling $56.38 $56.38 $56.96 $56.96 $60.00 $60.00 Floor $51.65 $51.65 $51.53 $51.53 $55.00 $55.00 Sold put $45.00 $45.00 $44.65 $44.65 $47.00 $47.00 Swaps Volume (Bbls/day) 20,000 20,000 — — — — Weighted average price per Bbl $55.12 $55.12 $— $— $— $— Basis Swaps (b) Volume (Bbls/day) 5,000 5,000 10,000 10,000 — — Weighted average price per Bbl $(0.60) $(0.60) $(0.67) $(0.67) $— $— (a) Between January 1, 2018 and February 12, 2018, we entered into 10,000 Bbls/day of three-way collars for July - December 2018 with an average ceiling price of $63.51 , a floor price of $57.00 , and a sold put price of $50.00 and 20,000 Bbls/day of three-way collars for January - June 2019 with an average ceiling price of $67.92 , a floor price of $53.50 , and a sold put price of $46.50 . (b) The basis differential price is between WTI Midland and WTI Cushing. Natural Gas 2018 First Quarter Second Quarter Third Quarter Fourth Quarter Three-Way Collars Volume (MMBtu/day) 200,000 160,000 160,000 160,000 Weighted average price per MMBtu Ceiling $3.79 $3.61 $3.61 $3.61 Floor $3.08 $3.00 $3.00 $3.00 Sold put $2.55 $2.50 $2.50 $2.50

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
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 by hierarchy level. December 31, 2017 (In millions) Level 1 Level 2 Level 3 Total Derivative instruments, assets Interest rate — — — — Derivative instruments, assets $ — $ — $ — $ — Derivative instruments, liabilities Commodity (a) $ (20 ) $ (120 ) $ — $ (140 ) Derivative instruments, liabilities $ (20 ) $ (120 ) $ — $ (140 ) December 31, 2016 (In millions) Level 1 Level 2 Level 3 Total Derivative instruments, assets Interest rate $ — $ 68 $ — $ 68 Derivative instruments, assets $ — $ 68 $ — $ 68 Derivative instruments, liabilities Commodity (a) $ — $ 60 $ — $ 60 Derivative instruments, liabilities $ — $ 60 $ — $ 60 (a) Derivative instruments are recorded on a net basis in our balance sheet (see Note 13 )
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis	The following table shows the values of assets, by major category, measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition. 2017 2016 2015 (In millions) Fair Value Impairment Fair Value Impairment Fair Value Impairment Long-lived assets held for use $ 179 $ 229 $ 15 $ 67 $ 56 $ 386
Fair Value, by Balance Sheet Grouping	The following table summarizes financial instruments, excluding receivables, payables and derivative financial instruments, and their reported fair value by individual balance sheet line item at December 31, 2017 and 2016 . December 31, 2017 2016 (In millions) Fair Value Carrying Amount Fair Value Carrying Amount Financial assets Other current assets (a) $ 762 $ 761 $ 7 $ 7 Other noncurrent assets 159 161 105 108 Total financial assets $ 921 $ 922 $ 112 $ 115 Financial liabilities Other current liabilities $ 32 $ 43 $ 68 $ 75 Long-term debt, including current portion (b) 5,976 5,526 7,449 7,292 Deferred credits and other liabilities 110 103 114 107 Total financial liabilities $ 6,118 $ 5,672 $ 7,631 $ 7,474 (a) Includes our two notes receivable relating to the sale of our Canadian business as of December 31, 2017, see note 5 for further information. (b) Excludes capital leases, debt issuance costs and historical interest rate swap adjustments.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Debt Instrument Table	The following table details our long-term debt: December 31, (In millions) 2017 2016 Senior unsecured notes: 6.000% notes due 2017 — 682 5.900% notes due 2018 — 854 7.500% notes due 2019 — 228 2.700% notes due 2020 (a) 600 600 2.800% notes due 2022 (a) 1,000 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 — 6.800% notes due 2032 (a) 550 550 6.600% notes due 2037 (a) 750 750 5.200% notes due 2045 (a) 500 500 Capital leases: Capital lease obligation expiring in 2018 — 1 Other obligations: 5.125% obligation relating to revenue bonds due 2037 — 1,000 Total (b) 5,536 7,301 Unamortized discount (10 ) (9 ) Fair value adjustments (c) — 7 Unamortized debt issuance cost (32 ) (35 ) Amounts due within one year — (683 ) Total long-term debt $ 5,494 $ 6,581 (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, 2017 may be declared immediately due and payable. (c) See Notes 13 and 14 for information on historical interest rate swaps.
Five Year Schedule Of Debt Payments Table	The following table shows future debt payments: (In millions) 2018 $ — 2019 — 2020 600 2021 — 2022 1,035 Thereafter 3,901 Total long-term debt, including current portion $ 5,536

Incentive Based Compensation 45

Incentive Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2017
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: 2017 2016 2015 Exercise price per share $15.80 $7.22 $29.06 Expected annual dividend yield 1.3 % 2.8 % 2.9 % Expected life in years 6.4 6.3 6.2 Expected volatility 42 % 36 % 32 % Risk-free interest rate 2.1 % 1.4 % 1.7 % Weighted average grant date fair value of stock option awards granted $6.07 $1.97 $6.84
Schedule of Share-based Compensation, Stock Options, Activity	The following is a summary of stock option award activity in 2017 . Number Weighted Average Weighted Average Remaining Aggregate Intrinsic Value of Shares Exercise Price Contractual Term (in millions) Outstanding at beginning of year 11,915,533 $27.71 Granted 799,591 $15.80 Exercised (8,666) $7.22 Canceled (2,375,682) $33.31 Outstanding at end of year 10,330,776 $25.52 4 years $ 13 Exercisable at end of year 8,661,893 $27.91 3 years $ 5 Expected to vest 1,650,737 $13.08 9 years $ 8
Schedule of Nonvested Restricted Stock Units Activity	The following is a summary of restricted stock and restricted stock unit award activity in 2017 . Awards Weighted Average Grant Date Fair Value Unvested at beginning of year 6,933,533 $14.44 Granted 4,198,624 $16.13 Vested & Exercised (2,472,367 ) $17.67 Canceled (1,086,945 ) $15.03 Unvested at end of year 7,572,845 $14.24
Schedule of Performance Units, Valuation [Table Text Block]	The key assumptions used in the Monte Carlo simulation to determine the fair value of stock-based performance units granted in 2017, 2016 and 2015 were: 2017 2016 2015 (a) Valuation date stock price $16.93 $16.93 $16.93 Expected annual dividend yield 1.2 % 1.2 % 1.2 % Expected volatility 54 % 34 % 33 % Risk-free interest rate 1.9 % 1.7 % 1.4 % Fair value of stock-based performance units outstanding $21.63 $19.86 $0.00 (a) As of December 31, 2017, there were no 2015 performance unit awards outstanding.

Defined Benefit Postretiremen46

Defined Benefit Postretirement Plans and Defined Contribution Plan (Tables)	12 Months Ended
	Dec. 31, 2017
Defined Benefit Plan [Abstract]
Summary Of Defined Benefit Pension Plans With Accumulated Benefit Obligations	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 2017 2016 2017 2016 (In millions) U.S. Int’l U.S. Int’l U.S. U.S. Accumulated benefit obligation 378 599 386 583 221 227 Change in benefit obligations: Beginning balance $ 397 $ 583 $ 525 $ 579 $ 227 $ 260 Service cost 22 — 25 — 2 2 Interest cost 13 17 16 23 8 11 Plan amendment — — — 1 — (38 ) Actuarial loss (gain) 42 (7 ) 78 139 5 11 Foreign currency exchange rate changes — 52 — (108 ) — — Divestiture — — — — — — Settlements paid (84 ) (31 ) (240 ) (36 ) — — Benefits paid (6 ) (15 ) (7 ) (15 ) (21 ) (19 ) Ending balance $ 384 $ 599 $ 397 $ 583 $ 221 $ 227 Change in fair value of plan assets: Beginning balance $ 227 $ 595 $ 354 $ 608 $ — $ — Actual return on plan assets 27 47 25 129 — — Employer contributions 52 17 95 18 21 20 Foreign currency exchange rate changes — 57 — (109 ) — — Divestiture — — — — — — Settlements paid (84 ) (31 ) (240 ) (36 ) — — Benefits paid (6 ) (15 ) (7 ) (15 ) (21 ) (20 ) Ending balance $ 216 $ 670 $ 227 $ 595 $ — $ — Funded status of plans at December 31 $ (168 ) $ 71 $ (170 ) $ 12 $ (221 ) $ (227 ) Amounts recognized in the consolidated balance sheets: Noncurrent assets — 71 — 12 — — Current liabilities (6 ) — (4 ) — (21 ) (21 ) Noncurrent liabilities (162 ) — (166 ) — (200 ) (206 ) Accrued benefit cost $ (168 ) $ 71 $ (170 ) $ 12 $ (221 ) $ (227 ) Pretax amounts in accumulated other comprehensive loss: Net loss (gain) $ 122 $ 58 $ 130 $ 81 $ 30 $ 25 Prior service cost (credit) (45 ) 3 (55 ) 4 (56 ) (63 )
Schedule Of Net Periodic Benefit Cost And Other Comprehensive Income	Components of net periodic benefit cost from continuing operations 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, 2017 2016 2015 2017 2016 2015 (In millions) U.S. Int’l U.S. Int’l U.S. Int’l U.S. U.S. U.S. Components of net periodic benefit cost: Service cost $ 22 $ — $ 25 $ — $ 29 $ 14 $ 2 $ 2 $ 3 Interest cost 13 17 16 23 25 25 8 11 11 Expected return on plan assets (13 ) (30 ) (18 ) (35 ) (30 ) (37 ) — — — Amortization: - prior service cost (credit) (10 ) — (10 ) 1 (7 ) 1 (7 ) (3 ) (4 ) - actuarial loss 8 1 14 — 22 2 — — 1 Net curtailment loss (gain) (a) — — — — (5 ) 4 — — (7 ) Net settlement loss (b) 28 4 97 6 119 — — — — Net periodic benefit cost (c) $ 48 $ (8 ) $ 124 $ (5 ) $ 153 $ 9 $ 3 $ 10 $ 4 Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax): Actuarial loss (gain) $ 28 $ (26 ) $ 70 $ 41 $ 30 $ (25 ) $ 5 $ 11 $ (21 ) Amortization of actuarial gain (loss) (36 ) (4 ) (111 ) (6 ) (134 ) (2 ) — — (1 ) Prior service cost (credit) — — — 1 (89 ) 1 — (38 ) — Amortization of prior service credit (cost) 10 — 10 (1 ) 7 (5 ) 7 3 13 Total recognized in other comprehensive (income) loss $ 2 $ (30 ) $ (31 ) $ 35 $ (186 ) $ (31 ) $ 12 $ (24 ) $ (9 ) Total recognized in net periodic benefit cost and other comprehensive (income) loss $ 50 $ (38 ) $ 93 $ 30 $ (33 ) $ (22 ) $ 15 $ (14 ) $ (5 ) (a) Related to workforce reductions, which reduced the future expected years of service for employees participating in the plans and the impact of discontinuing accruals for future benefits under the U.K. pension plan effective December 31, 2015. (b) Settlement losses are recorded when lump sum payments from a plan in a period exceed the plan’s total service and interest costs for the period. (c) Net periodic benefit cost 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 2017 , 2016 and 2015 . Pension Benefits Other Benefits 2017 2016 2015 2017 2016 2015 (In millions) U.S. Int’l U.S. Int’l U.S. Int’l U.S. U.S. U.S. Weighted average assumptions used to determine benefit obligation: Discount rate 3.55 % 2.50 % 4.02 % 2.70 % 4.04 % 3.90 % 3.54 % 3.98 % 4.36 % Rate of compensation increase (a) 4.00 % — 4.00 % — 4.00 % — 4.00 % 4.00 % 4.00 % Weighted average assumptions used to determine net periodic benefit cost: Discount rate 3.86 % 2.70 % 3.66 % 3.90 % 3.79 % 3.70 % 3.98 % 4.36 % 3.93 % Expected long-term return on plan assets 6.50 % 4.50 % 6.75 % 5.50 % 6.75 % 5.70 % — — — Rate of compensation increase (a) 4.00 % — 4.00 % — % 4.00 % 3.60 % 4.00 % 4.00 % 4.00 % (a) No future benefits will be incurred for the U.K. plan after December 31, 2015. Therefore, rate of compensation increase is no longer applicable to this plan.
Schedule of Health Care Cost Trend Rates	Assumed weighted average health care cost trend rates 2017 2016 2015 Initial health care trend rate 8.00 % 8.25 % 8.00 % Ultimate trend rate 4.70 % 4.50 % 4.50 % Year ultimate trend rate is reached 2025 2025 2024
Fair Value of Defined Benefit Pension Plans 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, 2017 and 2016 . December 31, 2017 (In millions) Level 1 Level 2 Level 3 Total U.S. Int’l U.S. Int’l U.S. Int’l U.S. Int’l Cash and cash equivalents $ 6 $ 1 $ — $ — $ — $ — $ 6 $ 1 Equity securities: Common stock 81 — — — — — 81 — Private equity — — — — 16 — 16 — Mutual and pooled funds — 151 — 115 — — — 266 Fixed income securities: Corporate — — 6 — — — 6 — Exchange traded funds 5 — — — — — 5 — Government 19 — 2 — 3 — 24 — Pooled funds — — — 403 — — — 403 Other — — — — 19 — 19 — Total investments, at fair value 111 152 8 518 38 — 157 670 Commingled funds (a) — — — — — — 59 — Total investments $ 111 $ 152 $ 8 $ 518 $ 38 $ — $ 216 $ 670 December 31, 2016 (In millions) Level 1 Level 2 Level 3 Total U.S. Int’l U.S. Int’l U.S. Int’l U.S. Int’l Cash and cash equivalents $ 8 $ 5 $ — $ — $ — $ — $ 8 $ 5 Equity securities: Common stock 82 — — — — — 82 — Private equity — — — — 20 — 20 — Mutual and pooled funds — 201 — 159 — — — 360 Fixed income securities: Corporate — — 52 — — — 52 — Exchange traded funds 5 — — — — — 5 — Government 6 — 19 — — — 25 — Pooled funds — — — 230 — — — 230 Other — — — — 21 — 21 — Total investments, at fair value 101 206 71 389 41 — 213 595 Commingled funds (a) — — — — — — 14 — Total investments $ 101 $ 206 $ 71 $ 389 $ 41 $ — $ 227 $ 595 (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. See Note 2 for further information on the FASB update.
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, 2017 and reflect expected future services, as appropriate, are to be paid in the years indicated. Pension Benefits Other Benefits (In millions) U.S. Int’l U.S. 2018 $ 43 $ 17 $ 21 2019 40 18 20 2020 37 17 20 2021 33 19 19 2022 30 21 18 2023 through 2027 123 118 74

Reclassifications Out of Accu47

Reclassifications Out of Accumulated Other Comprehensive Income (Tables)	12 Months Ended
	Dec. 31, 2017
Reclassifications out of AccumulatedOtherComprehensiveIncome [Abstract]
Reclassification out of AOCI [Text Block]	Reclassifications Out of Accumulated Other Comprehensive Loss The following table presents a summary of amounts reclassified from accumulated other comprehensive loss: Year Ended December 31, (In millions) 2017 2016 Income Statement Line Postretirement and postemployment plans Amortization of actuarial loss $ (9 ) $ (14 ) General and administrative Net settlement loss (32 ) (103 ) General and administrative Derivative hedges Recognized gain on terminated derivative hedge 46 — Net interest and other Ineffective portion of derivative hedge 1 4 Net interest and other 6 (113 ) Income (loss) from operations (40 ) 41 (Provision) benefit for income taxes Total reclassifications to expense, net of tax $ (34 ) $ (72 ) Income (loss) from continuing operations Foreign currency hedges Net recognized loss in discontinued operations, net of tax (30 ) — Income (loss) from discontinued operations Total reclassifications to expense $ (64 ) $ (72 )

Supplemental Cash Flow Inform48

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]	Year Ended December 31, (In millions) 2017 2016 2015 Net cash used in operating activities: Interest paid (net of amounts capitalized) $ (379 ) $ (375 ) $ (325 ) Income taxes paid to taxing authorities (a) (391 ) (84 ) (171 ) Noncash investing activities, related to continuing operations: Changes in asset retirement costs $ (202 ) $ 110 $ (95 ) Asset retirement obligations assumed by buyer 14 40 251 Increase in capital expenditure accrual 176 — — Notes receivable for disposition of assets 748 — — (a) Includes a payment of $108 million made to U.K. taxing authorities to preserve our appeal rights, see Note 7 - Income Taxes for additional discussion.

Other Items (Tables)

Other Items (Tables)	12 Months Ended
	Dec. 31, 2017
Interest and Other Income [Abstract]
Schedule Of Net Interest And Other Financing Table	Net interest and other Year Ended December 31, (In millions) 2017 2016 2015 Interest: Interest income $ 34 $ 14 $ 9 Interest expense (380 ) (398 ) (350 ) Income on interest rate swaps 53 13 11 Interest capitalized 3 18 19 Total interest (290 ) (353 ) (311 ) Other: Net foreign currency gain (loss) 8 6 4 Other 12 15 21 Total other 20 21 25 Net interest and other $ (270 ) $ (332 ) $ (286 )
Schedule Of Foreign Currency Transactions Table	Foreign currency – Aggregate foreign currency gains (losses) were included in the consolidated statements of income as follows: Year Ended December 31, (In millions) 2017 2016 2015 Net interest and other $ 8 $ 6 $ 4 Provision for income taxes 57 (32 ) (11 ) Aggregate foreign currency gains (losses) $ 65 $ (26 ) $ (7 )

Equity Method Investments and50

Equity Method Investments and Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
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, 2017 2017 2016 EGHoldings 60% $ 456 $ 550 Alba Plant LLC 52% 214 215 AMPCO 45% 177 165 Other investments — 1 Total $ 847 $ 931
Income And Balance Sheet Information of Equity Investees Table	Summarized financial information for equity method investees is as follows: (In millions) 2017 2016 2015 Income data – year (a) : Revenues and other income $ 1,294 $ 770 $ 769 Income from operations 631 346 313 Net income 508 313 280 Balance sheet data – December 31: Current assets $ 586 $ 525 Noncurrent assets 1,044 1,173 Current liabilities 221 218 Noncurrent liabilities 94 47 (a) See Item 15 Exhibits, Financial Statement Schedules which contains the Alba Plant LLC audited financial statements, which have been included pursuant to Rule 3-09 of Regulation S-X.

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Future Minimum Commitments For Capital And Operating Leases Table	Future minimum commitments for operating lease obligations having noncancellable lease terms in excess of one year are as follows: (In millions) Operating Lease Obligations 2018 $ 29 2019 28 2020 27 2021 26 2022 5 Later years 4 Sublease rentals — Total minimum lease payments $ 119 * Future minimum commitments for capital lease obligations are nil as of December 31, 2017.

Summary of Principal Accounti52

Summary of Principal Accounting Policies DDA (Details)	12 Months Ended
	Dec. 31, 2017
Office furniture, equipment and computer hardwareWells and Related Equipment and Facilities [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	4 years
Office furniture, equipment and computer hardwareWells and Related Equipment and Facilities [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	15 years
Pipelines [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Pipelines [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Plants, facilities, mine equipment and infrastructure [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Plants, facilities, mine equipment and infrastructure [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years

Accounting Standards Accounting

Accounting Standards Accounting Standards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Marketing Revenues (Expense) [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gross Billings	$ 130	$ 100

Income per Common Share (Detail

Income per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Income (loss) from continuing operations	$ (830)	$ (2,087)	$ (1,701)
Income (loss) from discontinued operations	(4,893)	(53)	(503)
Net income (loss)	$ (5,723)	$ (2,140)	$ (2,204)
Weighted average common shares outstanding, basic	850	819	677
Weighted average common shares outstanding, diluted	850	819	677
Basic:
Income from continuing operations (in dollars per basic share)	$ (0.97)	$ (2.55)	$ (2.51)
Discontinued operations (in dollars per basic share)	(5.76)	(0.06)	(0.75)
Net income (in dollars per basic share)	(6.73)	(2.61)	(3.26)
Diluted:
Income from continuing operations (in dollars per diluted share)	(0.97)	(2.55)	(2.51)
Discontinued operations (in dollars per diluted share)	(5.76)	(0.06)	(0.75)
Net income (in dollars per diluted share)	$ (6.73)	$ (2.61)	$ (3.26)
Antidilutive securities excluded from computation of earnings per share	11	13	13

Acquisitions Acquisitions Asset

Acquisitions Acquisitions Asset (Details) a in Thousands, Boe in Thousands, $ in Millions	Jun. 01, 2017USD ($)a	May 01, 2017USD ($)aBoe	Aug. 01, 2016USD ($)a	Dec. 31, 2017USD ($)	Jun. 30, 2017a	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Business Combination, Consideration Transferred | $			$ 904
Payments to Acquire Businesses, Net of Cash Acquired | $						$ 1,891	$ 902	$ 0
Permian Basin [Member]
Business Acquisition [Line Items]
Gas and Oil Acres, Undeveloped and Developed, Net | a					91
Payments to Acquire Businesses, Net of Cash Acquired | $				$ 63
Permian Basin [Member] | BC Operating Transaction [Member]
Business Acquisition [Line Items]
Gas and Oil Acres, Undeveloped and Developed, Net | a		70
Production, Barrels of Oil Equivalents | Boe		5
Payments to Acquire Businesses, Net of Cash Acquired | $		$ 1,100
Permian Basin [Member] | Black Mountain Oil and Gas Transaction [Member]
Business Acquisition [Line Items]
Gas and Oil Acres, Undeveloped and Developed, Net | a	21
Payments to Acquire Businesses, Net of Cash Acquired | $	$ 700
Northern Delaware - Permian Basin [Member] | BC Operating Transaction [Member]
Business Acquisition [Line Items]
Gas and Oil Acres, Undeveloped and Developed, Net | a					70
Anadarko Basin STACK Play [Member]
Business Acquisition [Line Items]
Gas and Oil Acres, Undeveloped and Developed, Net | a			61

Dispositions (Details)

Dispositions (Details)

May 31, 2017USD ($)

Sep. 30, 2017USD ($)

Nov. 30, 2016USD ($)

Oct. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Aug. 31, 2015USD ($)

Apr. 30, 2016USD ($)

Mar. 31, 2018USD ($)

Sep. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Sep. 30, 2016USD ($)

Jun. 30, 2016USD ($)

Mar. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Sep. 30, 2015USD ($)

Jun. 30, 2015USD ($)

Dec. 31, 2017USD ($)notes_receivable

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 1,787,000,000

$ 1,219,000,000

$ 225,000,000

Impairment of Oil and Gas Properties

229,000,000

67,000,000

721,000,000

Oil Sands Mining Segment [Member]

Dispositions Detail [Line Items]

Impairment of Oil and Gas Properties

$ 6,600,000,000

6,636,000,000

0

31,000,000

Net gain (loss) on disposal of assets

(43,000,000)

0

0

GOM Producing Properties [Member]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 111,000,000

Neptune Field [Member]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 4,000,000

East Texas/North Louisiana and Wilburton Assets [Member]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 100,000,000

Net gain (loss) on disposal of assets

$ (1,000,000)

Kenya and Ethiopia Assets [Member]

Dispositions Detail [Line Items]

Net gain (loss) on disposal of assets

$ (109,000,000)

Oil Sands Mining Segment [Member]

Dispositions Detail [Line Items]

Impairment of Oil and Gas Properties

$ 4,960,000,000

East Texas/North Louisiana and Wilburton Assets [Member]

Dispositions Detail [Line Items]

Impairment of Oil and Gas Properties

44,000,000

Fair Value, Measurements, Nonrecurring [Member]

Dispositions Detail [Line Items]

Impairment of Oil and Gas Properties

$ 229,000,000

Assets, Fair Value Adjustment

67,000,000

$ 386,000,000

Fair Value, Measurements, Nonrecurring [Member] | East Texas/North Louisiana and Wilburton Assets [Member] | Fair Value, Inputs, Level 3 [Member]

Dispositions Detail [Line Items]

Assets, Fair Value Adjustment

$ (44,000,000)

Discontinued Operations, Disposed of by Sale [Member] | Oil Sands Mining Segment [Member]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 2,500,000,000

Number of notes receivable

2

2

Net gain (loss) on disposal of assets

$ (43,000,000)

Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Oklahoma Resource Basin [Member]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 25,000,000

Net gain (loss) on disposal of assets

$ 21,000,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | West Texas and New Mexico [Domain]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 235,000,000

$ 67,000,000

Net gain (loss) on disposal of assets

$ 63,000,000

$ 55,000,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Wyoming Upstream and Midstream Assets Sold [Member]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 155,000,000

$ 690,000,000

Net gain (loss) on disposal of assets

$ 38,000,000

$ 266,000,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Shenandoah in Gulf of Mexico, Piceance in Colorado, and West Texas [Member]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 80,000,000

Net gain (loss) on disposal of assets

$ 32,000,000

$ (48,000,000)

Working capital interest to be disposed of

10.00%

Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | GOM Producing Properties [Member]

Dispositions Detail [Line Items]

Net gain (loss) on disposal of assets

$ 228,000,000

Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Non-core [Member]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 53,000,000

Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Non-core [Member]

Dispositions Detail [Line Items]

Assets held for sale

66,000,000

Liabilities held for sale

$ 2,000,000

Variable Interest Entity, Not Primary Beneficiary [Member] | Oil Sands Mining Segment [Member]

Dispositions Detail [Line Items]

Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage

20.00%

Note Receivable 1 [Member] | Discontinued Operations, Disposed of by Sale [Member] | Oil Sands Mining Segment [Member]

Dispositions Detail [Line Items]

Accounts, Notes, Loans and Financing Receivable, Net, Current

$ 375,000,000

Subsequent Event [Member] | Discontinued Operations, Disposed of by Sale [Member] | Oil Sands Mining Segment [Member]

Dispositions Detail [Line Items]

Proceeds from Sale of Oil and Gas Property and Equipment

$ 1,800,000,000

Dispositions Discontinued Opera

Dispositions Discontinued Operations - Reported in Consolidated Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Impairments			$ 229	$ 67	$ 721
Oil Sands Mining Segment [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Total sales and other revenues and other income			431	863	908
Net gain (loss) on disposal of assets			(43)	0	0
Total revenues and other income			388	863	908
Production expenses			254	601	715
Exploration expenses			0	7	347
Depreciation, depletion and amortization			40	239	236
Impairments		$ 6,600	6,636	0	31
Other			25	87	98
Total costs and expenses			6,955	934	1,427
Pretax income (loss) from discontinued operations			(6,567)	(71)	(519)
Provision (benefit) for income taxes			(1,674)	(18)	(16)
Income (loss) from discontinued operations			$ (4,893)	$ (53)	$ (503)
Discontinued Operations, Disposed of by Sale [Member] | Oil Sands Mining Segment [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Net gain (loss) on disposal of assets	$ (43)

Dispositions Discontinued Ope58

Dispositions Discontinued Operations - Reflected as Held-For-Sale in Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Total current assets held for sale	$ 11	$ 227
Total current assets held for sale—continuing operations	11	1
Noncurrent assets:
Other	55	9,098
Current liabilities:
Total current liabilities held for sale	0	121
Total current liabilities held for sale—continuing operations	0	0
Discontinued Operations, Held-for-sale [Member]
Noncurrent liabilities:
Total noncurrent liabilities held for sale	2	1,791
Oil Sands Mining Segment [Member] | Discontinued Operations, Held-for-sale [Member]
Current assets:
Cash and cash equivalents	0	2
Accounts receivables	0	129
Inventories	0	91
Other	0	4
Total current assets held for sale	0	226
Noncurrent assets:
Property, plant and equipment, net	0	8,991
Other	0	106
Total noncurrent assets held for sale—discontinued operations	0	9,097
Total noncurrent assets held for sale—continuing operations	55	1
Total noncurrent assets held for sale	55	9,098
Current liabilities:
Accounts payable	0	111
Other	0	10
Total current liabilities held for sale	0	121
Noncurrent liabilities:
Asset retirement obligations	0	95
Deferred tax liabilities	0	1,669
Other	0	20
Total noncurrent liabilities held for sale—discontinued operations	0	1,784
Total noncurrent liabilities held for sale—continuing operations	$ 2	$ 7

Segment Information (Details)

Segment Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)segment	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	2
Sales and other operating revenues	$ 4,211	$ 2,930	$ 4,136
Marketing revenues	162	240	499
Total revenues	4,373	3,170	4,635
Income from equity method investments	256	175	145
Net gain (loss) on disposal of assets and other income	136	442	173
Production expenses	706	712	979
Marketing costs	168	245	500
Other Cost and Expense, Operating	431	484	410
Exploration expenses	409	323	971
Depreciation, depletion and amortization	2,372	2,156	2,721
Impairment of Oil and Gas Properties	229	67	721
Taxes other than income	183	151	216
General and Administrative Expense	400	481	588
Net interest and other	270	332	286
Gain (Loss) on Extinguishment of Debt	(51)	0	0
Provision for income taxes	376	923	(738)
Income from continuing operations	(830)	(2,087)	(1,701)
Property, Plant and Equipment, Additions	2,150	1,036	2,946
Derivative, Gain (Loss) on Derivative, Net	(36)	(66)	128
Deferred Foreign Income Tax Expense (Benefit)	(104)	(16)	(102)
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Severance Costs		8	55
Valuation Allowances and Reserves, Period Increase (Decrease)		1,346
Loss on Contract Termination		113
Pension Plan [Member]
Segment Reporting Information [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	(32)	(103)	(119)
Net Interest and Other [Member] | Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Segment Reporting Information [Line Items]
Derivative, Gain (Loss) on Derivative, Net	47
Operating Segments [Member] | United States Exploration and Production [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	3,138	2,375	3,358
Marketing revenues	29	135	396
Total revenues	3,167	2,510	3,754
Income from equity method investments	0	0	0
Net gain (loss) on disposal of assets and other income	13	28	24
Production expenses	476	486	724
Marketing costs	36	142	401
Other Cost and Expense, Operating	354	328	335
Exploration expenses	154	127	314
Depreciation, depletion and amortization	2,011	1,835	2,377
Impairment of Oil and Gas Properties	4	20	2
Taxes other than income	173	149	215
General and Administrative Expense	119	94	127
Net interest and other	0	0	0
Gain (Loss) on Extinguishment of Debt	0
Provision for income taxes	1	(228)	(265)
Income from continuing operations	(148)	(415)	(452)
Property, Plant and Equipment, Additions	2,081	936	2,553
Operating Segments [Member] | International Exploration and Production [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	1,154	665	728
Marketing revenues	133	105	103
Total revenues	1,287	770	831
Income from equity method investments	256	175	157
Net gain (loss) on disposal of assets and other income	6	32	27
Production expenses	229	226	255
Marketing costs	132	103	99
Other Cost and Expense, Operating	77	43	48
Exploration expenses	5	17	101
Depreciation, depletion and amortization	328	276	295
Impairment of Oil and Gas Properties	0	0	0
Taxes other than income	0	0	0
General and Administrative Expense	32	35	44
Net interest and other	0	0	0
Gain (Loss) on Extinguishment of Debt	0
Provision for income taxes	372	49	61
Income from continuing operations	374	228	112
Property, Plant and Equipment, Additions	42	82	368
Not Allocated to Segments [Member] | Corporate and Other [Member]
Segment Reporting Information [Line Items]
Sales and other operating revenues	(81)	(110)	50
Marketing revenues	0	0	0
Total revenues	(81)	(110)	50
Income from equity method investments	0	0	(12)
Net gain (loss) on disposal of assets and other income	117	382	122
Production expenses	1	0	0
Marketing costs	0	0	0
Other Cost and Expense, Operating	0	113	27
Exploration expenses	250	179	556
Depreciation, depletion and amortization	33	45	49
Impairment of Oil and Gas Properties	225	47	719
Taxes other than income	10	2	1
General and Administrative Expense	249	352	417
Net interest and other	270	332	286
Gain (Loss) on Extinguishment of Debt	(51)
Provision for income taxes	3	1,102	(534)
Income from continuing operations	(1,056)	(1,900)	(1,361)
Property, Plant and Equipment, Additions	$ 27	$ 18	$ 25

Segment Information (Geographic

Segment Information (Geographical)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$ 4,373	$ 3,170	$ 4,635
Long-Lived Assets	18,512	17,658
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	3,086	2,400	3,804
Long-Lived Assets	15,971	14,272
EQUATORIAL GUINEA
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	530	444	444
Long-Lived Assets	1,582	1,794
LIBYAN ARAB JAMAHIRIYA
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	431	54	0
UNITED KINGDOM
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	289	263	380
Other International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	37	9	$ 7
Long-Lived Assets	$ 959	$ 1,592

Segment Information (Products a

Segment Information (Products and Services)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue from External Customer by Product Line [Line Items]
Revenue, Net	$ 4,373	$ 3,170	$ 4,635
Crude oil and condensate [Member]
Revenue from External Customer by Product Line [Line Items]
Revenue, Net	3,477	2,605	3,963
Natural Gas Liquids [Member]
Revenue from External Customer by Product Line [Line Items]
Revenue, Net	338	198	203
Natural gas [Member]
Revenue from External Customer by Product Line [Line Items]
Revenue, Net	510	356	464
Miscellaneous other [Member]
Revenue from External Customer by Product Line [Line Items]
Revenue, Net	$ 48	$ 11	$ 5

Segment Information (Narrative)

Segment Information (Narrative)(Details) - Sales Revenue, Net [Member]	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Vitol [Member]
Entity-Wide Revenue, Major Customer, Percent [Line Items]
Concentration Risk, Percentage	10.00%
Valero Marketing and Supply [Member]
Entity-Wide Revenue, Major Customer, Percent [Line Items]
Concentration Risk, Percentage		13.00%
Tesoro Petroleum [Member]
Entity-Wide Revenue, Major Customer, Percent [Line Items]
Concentration Risk, Percentage		11.00%
Flint Hills Resources [Member]
Entity-Wide Revenue, Major Customer, Percent [Line Items]
Concentration Risk, Percentage		10.00%
Shell Oil [Member]
Entity-Wide Revenue, Major Customer, Percent [Line Items]
Concentration Risk, Percentage			10.00%

Income Taxes (Schedule of Incom

Income Taxes (Schedule of Income (Loss) Before Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
United States	$ (783)	$ (1,449)	$ (2,384)
Foreign	329	285	(55)
Income from continuing operations before income taxes	$ (454)	$ (1,164)	$ (2,439)

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	$ (454)	$ (1,164)	$ (2,439)
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	(159)	(407)	(854)
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount	140	47	(55)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	446	1,270	95
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount	(19)	9	(15)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	(35)	6	(3)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount	0	0	94
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	3	(2)	0
Income Tax Expense (Benefit)	$ 376	$ 923	$ (738)
Libya Statutory Income Tax Rate	93.50%
Effective income tax rate excluding Libya	5.00%	79.00%	29.00%
Federal
Current	$ (32)	$ 2	$ (41)
Deferred	41	836	(684)
Total	9	838	(725)
State and local
Current	(14)	2	(8)
Deferred	2	8	(18)
Total	(12)	10	(26)
Foreign
Current	483	91	115
Deferred	(104)	(16)	(102)
Total	379	75	13
Current Income Tax Expense (Benefit)	437	95	66
Deferred Income Tax Expense (Benefit)	$ (61)	$ 828	$ (804)
Effective Tax Rate Reconciliation [Abstract]
Effective income tax rate on continuing operations	83.00%	79.00%	(30.00%)

Income Taxes Income Taxes (Sche

Income Taxes Income Taxes (Schedule of Net Deferred Tax Asset/Liability) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets, Gross [Abstract]
Employee benefits	$ 111	$ 228
Operating loss carryforwards	1,030	1,065
Capital loss carryforwards	3	4
Foreign tax credits	611	4,430
Other credit carryforwards	0	35
Investments in subsidiaries and affiliates	174	91
Other	69	86
Deferred Tax Assets, Gross	1,998	5,939
Deferred Tax Assets, Valuation Allowance	(926)	(4,301)
Deferred Tax Assets, Net of Valuation Allowance	1,072	1,638
Deferred Tax Liabilities, Gross [Abstract]
Property, plant and equipment	1,332	3,672
Accrued revenue	81	75
Other	3	(7)
Deferred Tax Liabilities, Gross	1,416	3,740
Deferred Tax Liabilities, Net	$ 344	$ 2,102

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Reduction in valuation allowance as a result of U.S. Tax Reform	$ 3,819
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	13
Valuation and Qualifying Accounts Disclosure [Line Items]
Increase in Unrecognized Tax Benefits is Reasonably Possible	83
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	446	$ 1,270	$ 95
Income tax benefit due to tax law change	35
Impairments and Exploration Expenses [Abstract]
Deferred Tax Liabilities, Net	344	2,102
Deferred Tax Assets, Valuation Allowance	926	4,301
Assets
Other noncurrent assets	489	336
Liabilities
Noncurrent deferred tax liabilities	833	769
Domestic Tax Authority [Member]
Impairments and Exploration Expenses [Abstract]
Deferred Tax Assets, Valuation Allowance	41
UNITED STATES
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	898
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	119
Internal Revenue Service (IRS) [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Additions for Charges to Cost and Expense	926	1,268	$ 99
UK Government [Member] | Foreign Tax Authority [Member]
Impairments and Exploration Expenses [Abstract]
Income Tax Examination, Penalties and Interest Expense	108
Discontinued Operations, Held-for-sale [Member] | Oil Sands Mining Segment [Member]
Liabilities
Noncurrent liabilities held for sale	$ 0	$ 1,669

Income Taxes (Unrecognized Tax

Income Taxes (Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unrecognized Tax Benefit Rollforward [Abstract]
Unrecognized Tax Benefits, Beginning Balance	$ 66	$ 65	$ 80
Additions for tax positions of prior years	83	6	1
Reductions for tax positions of prior years	(3)	(5)	0
Settlements	(20)	0	(7)
Statute of limitations	0	0	(9)
Unrecognized Tax Benefits, Ending Balance	126	66	65
Unrecognized Tax Benefits That Would Impact Effective Tax Rate	10
Increase in Unrecognized Tax Benefits is Reasonably Possible	83
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense [Abstract]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	2	1	$ 1
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 25	$ 15

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Crude oil and natural gas	$ 9	$ 6
Supplies and sundry items	117	130
Inventories at cost	$ 126	$ 136

Property, Plant and Equipment69

Property, Plant and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 17,665	$ 16,727
United States Exploration and Production [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	15,867	14,158
International Exploration and Production [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	1,710	2,470
Corporate [Member]
Segment Reporting Information [Line Items]
Property, plant and equipment, net	$ 88	$ 99

Property, Plant and Equipment70

Property, Plant and Equipment (Details 2) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)project	Dec. 31, 2016USD ($)project	Dec. 31, 2015USD ($)project
Property, Plant and Equipment [Abstract]
Amounts capitalized less than one year after completion of drilling				$ 263	$ 131	$ 352
Amounts capitalized greater than one year after completion of drilling				32	118	85
Total deferred exploratory well costs	$ 249	$ 437	$ 573	$ 295	$ 249	$ 437
Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects | project				1	3	2
Increase (Decrease) in Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]
Beginning balance	249	437	573
Additions	212	299	610
Charges to expense	(64)	(23)	(111)
Transfers to development	(102)	(388)	(635)
Dispositions	0	(76)	0
Ending balance	$ 295	$ 249	$ 437

Property, Plant and Equipment71

Property, Plant and Equipment (Details 3) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)project	Dec. 31, 2016USD ($)project	Dec. 31, 2015USD ($)project
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized Exploratory Well Cost, Charged to Expense	$ 64	$ 23	$ 111
Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects | project	1	3	2
Amounts capitalized greater than one year after completion of drilling	$ 32	$ 118	$ 85
Diaba [Member]
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized Exploratory Well Cost, Charged to Expense	$ 64

Impairment and Exploration Ex72

Impairment and Exploration Expenses Impairments (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties			$ 229	$ 67	$ 721
Goodwill, Impairment Loss			0	0
Oklahoma and Gulf of Mexico [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties				67
East Texas/North Louisiana and Wilburton Assets [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties					44
Colorado and Gulf of Mexico [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties					335
United States Exploration and Production [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Goodwill, Impairment Loss			0	0	340
Oil Sands Mining Segment [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties		$ 6,600	6,636	$ 0	$ 31
Fair Value, Measurements, Nonrecurring [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties			229
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | International Exploration and Production [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of Oil and Gas Properties	$ 136		136
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Gulf of Mexico Assets [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment Expense - Proved Properties	$ 65		$ 89

Impairment and Exploration Ex73

Impairment and Exploration Expenses Exploration Expenses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Exploration Expenses [Line Items]
Exploration expenses	$ 409	$ 323	$ 971
Exploration Abandonment and Impairment Expense	323	220	867
Capitalized Exploratory Well Cost, Charged to Expense	64	23	111
Unproved Property Impairments [Member]
Exploration Expenses [Line Items]
Exploration expenses	246	195	655
Dry Well Costs [Member]
Exploration Expenses [Line Items]
Exploration expenses	77	25	212
Geological and Geophysical [Member]
Exploration Expenses [Line Items]
Exploration expenses	25	5	31
Other Exploration Expenses [Member]
Exploration Expenses [Line Items]
Exploration expenses	61	$ 98	$ 73
Tchicuate [Member] | Unproved Property Impairments [Member]
Exploration Expenses [Line Items]
Exploration Abandonment and Impairment Expense	43
Diaba [Member]
Exploration Expenses [Line Items]
Capitalized Exploratory Well Cost, Charged to Expense	64
Diaba [Member] | Unproved Property Impairments [Member]
Exploration Expenses [Line Items]
Exploration expenses	159
Exploration Abandonment and Impairment Expense	$ 95

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset Retirement Obligation Beginning Balance	$ 1,652	$ 1,544
Incurred, including acquisitions	25	14
Settled, including dispositions	(50)	(74)
Accretion expense (included in depreciation, depletion and amortization)	85	79
Revisions to previous estimates	(227)	96
Held for sale	(2)	(7)
Asset Retirement Obligation Ending Balance	1,483	1,652
Asset Retirement Obligation, Current	$ 55	$ 50

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2017
Goodwill [Line Items]
Goodwill, gross		$ 115	$ 115
Less: accumulated impairment		0	0
Goodwill [Roll Forward]
Beginning balance, net	$ 115	115
Dispositions	0	0
Impairment	0	0
Ending balance, net	115	115	115
United States Exploration and Production [Member]
Goodwill [Line Items]
Goodwill, gross		0	0
Less: accumulated impairment		0	0
Goodwill [Roll Forward]
Beginning balance, net	0	0
Dispositions	0	0
Impairment	0	0	340
Ending balance, net	0	0	0
International Exploration and Production [Member]
Goodwill [Line Items]
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount				40.00%
Goodwill, gross		115	115
Less: accumulated impairment		0	0
Goodwill [Roll Forward]
Beginning balance, net	115	115
Dispositions	0	0
Impairment	0	0
Ending balance, net	$ 115	$ 115	$ 115

Derivatives (Balance Sheet) (De

Derivatives (Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		$ 68
Derivative Asset, Fair Value, Gross Liability		60
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		8
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Instruments in Hedges, Assets, at Fair Value		68
Derivative Instruments in Hedges, Liabilities, at Fair Value		0
Derivative Instruments in Hedges, at Fair Value, Net		68
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 0	0
Derivative Asset, Fair Value, Gross Liability	140	60
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(140)	(60)
Derivative Liability, Fair Value, Gross Liability	140
Other Current Assets [Member] | Interest rate [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		3
Derivative Asset, Fair Value, Gross Liability		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		3
Other Noncurrent Assets [Member] | Interest rate [Member] | Fair Value Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset		1
Derivative Asset, Fair Value, Gross Liability		0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		1
Other Noncurrent Assets [Member] | Interest rate [Member] | Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		64
Interest Rate Cash Flow Hedge Asset at Fair Value		64
Interest Rate Cash Flow Hedge Liability at Fair Value		0
Other Current Liabilities [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Asset, Fair Value, Gross Liability	138	60
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(138)	$ (60)
Other Noncurrent Liabilities [Member] | Commodity Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0
Derivative Asset, Fair Value, Gross Liability	2
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	$ (2)

Derivatives (Fair Value Hedges)

Derivatives (Fair Value Hedges) (Details) - Interest Rate Contract [Member] - Fair Value Hedging [Member] - Designated as Hedging Instrument [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debentures Due 2017 [Member]
Derivatives, Fair Value [Line Items]
Aggregate Notional Amount	$ 0	$ 600
Weighted-average, LIBOR-based, floating rate	0.00%	5.10%
Notes Due 2018 [Member]
Derivatives, Fair Value [Line Items]
Aggregate Notional Amount	$ 0	$ 300
Weighted-average, LIBOR-based, floating rate	0.00%	5.04%

Derivatives (Fair Value Hedges

Derivatives (Fair Value Hedges IS & OCI) (Details) - Net interest and other [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Change in unrealized gain (loss) on hedged item in fair value hedge	$ 0	$ 4	$ 0
Interest rate [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments	$ 0	$ (4)	$ 0

Derivatives Derivatives (Schedu

Derivatives Derivatives (Schedule of Cash Flow Hedges Rollforward) (Details) - Interest Rate Swap [Member] - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Cash Flow Hedges Derivative Instruments at Fair Value, Net	$ 0	$ 60	$ 0	$ 0
Change in fair value recognized in other comprehensive income	(13)	64	0
Reclassification from other comprehensive income	(47)	(4)	$ 0
Notes Due 2018 [Member]
Derivatives, Fair Value [Line Items]
Aggregate Notional Amount - Interest Rate Swap Agreements	$ 0	$ 750
Derivative, Fixed Interest Rate	0.00%	1.57%

Derivatives (Non Hedges Commodi

Derivatives (Non Hedges Commodity) (Details)	Feb. 12, 2018Bbls_per_day$ / bbl	Dec. 31, 2017MMBTUMMBTU_per_dayBBL / DaysBbls_per_day$ / MMBTU$ / bbl
Crude Oil Three-Way Collars for the First Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | BBL / Days		85,000
Derivative, Average Cap Price		56.38
Derivative, Average Floor Price		51.65
Derivatives, Average Sold Put Price		45
Crude Oil Three-Way Collars for the Second Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | BBL / Days		85,000
Derivative, Average Cap Price		56.38
Derivative, Average Floor Price		51.65
Derivatives, Average Sold Put Price		45
Crude Oil Three-Way Collars for Third Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | BBL / Days		85,000
Derivative, Average Cap Price		56.96
Derivative, Average Floor Price		51.53
Derivatives, Average Sold Put Price		44.65
Crude Oil Three-Way Collars for the Fourth Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | BBL / Days		85,000
Derivative, Average Cap Price		56.96
Derivative, Average Floor Price		51.53
Derivatives, Average Sold Put Price		44.65
Crude Oil Three-Way Collars For First Quarter of Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | BBL / Days		10,000
Derivative, Average Cap Price		60
Derivative, Average Floor Price		55
Derivatives, Average Sold Put Price		47
Crude Oil Three-Way Collars For Second Quarter of Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | BBL / Days		10,000
Derivative, Average Cap Price		60
Derivative, Average Floor Price		55
Derivatives, Average Sold Put Price		47
Crude Oil Swaps For the First Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU_per_day		20,000
Derivative, Average Price Risk Option Strike Price | $ / MMBTU		55.12
Crude Oil Swaps For the Second Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU_per_day		20,000
Derivative, Average Price Risk Option Strike Price | $ / MMBTU		55.12
Crude Oil Swaps For the Third Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU_per_day		0
Derivative, Average Price Risk Option Strike Price | $ / MMBTU		0
Crude Oil Swaps For the Fourth Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU_per_day		0
Derivative, Average Price Risk Option Strike Price | $ / MMBTU		0
Crude Oil Swaps For the First Quarter of Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU_per_day		0
Derivative, Average Price Risk Option Strike Price | $ / MMBTU		0
Crude Oil Swaps For the Second Quarter of Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU_per_day		0
Derivative, Average Price Risk Option Strike Price | $ / MMBTU		0
Crude Oil Basis Swaps For the First Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day		5,000
Weighted Average Differential To WTI Midland and WTI Cushing		(0.60)
Crude Oil Basis Swaps For the Second Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day		5,000
Weighted Average Differential To WTI Midland and WTI Cushing		(0.60)
Crude Oil Basis Swaps For the Third Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day		10,000
Weighted Average Differential To WTI Midland and WTI Cushing		(0.67)
Crude Oil Basis Swaps For the Fourth Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day		10,000
Weighted Average Differential To WTI Midland and WTI Cushing		(0.67)
Crude Oil Basis Swaps For the First Quarter of Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day		0
Weighted Average Differential To WTI Midland and WTI Cushing		0
Crude Oil Basis Swaps For the Second Quarter of Year 2 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day		0
Weighted Average Differential To WTI Midland and WTI Cushing		0
Natural Gas Three-Way Collars for the First Quarter in Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU_per_day		200,000
Derivative, Average Cap Price | $ / MMBTU		3.79
Derivative, Average Floor Price | $ / MMBTU		3.08
Derivatives, Average Sold Put Price | $ / MMBTU		2.55
Natural Gas Three-Way Collars For the Second Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU_per_day		160,000
Derivative, Average Cap Price | $ / MMBTU		3.61
Derivative, Average Floor Price | $ / MMBTU		3
Derivatives, Average Sold Put Price | $ / MMBTU		2.50
Natural Gas Three-Way Collars For the Third Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU		160,000
Derivative, Average Cap Price | $ / MMBTU		3.61
Derivative, Average Floor Price | $ / MMBTU		3
Derivatives, Average Sold Put Price | $ / MMBTU		2.50
Natural Gas Three-Way Collars For the Fourth Quarter of Year 1 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | MMBTU		160,000
Derivative, Average Cap Price | $ / MMBTU		3.61
Derivative, Average Floor Price | $ / MMBTU		3
Derivatives, Average Sold Put Price | $ / MMBTU		2.50
Subsequent Event [Member] | Crude Oil Three-Way Collars for July - December 2018 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day	10,000
Derivative, Average Cap Price	63.51
Derivative, Average Floor Price	57
Derivatives, Average Sold Put Price	50
Subsequent Event [Member] | Crude Oil Three-Way Collars for January - June 2019 [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount | Bbls_per_day	20,000
Derivative, Average Cap Price	67.92
Derivative, Average Floor Price	53.50
Derivatives, Average Sold Put Price	46.50

Derivatives (Non Hedges - Narra

Derivatives (Non Hedges - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		$ (36)	$ (66)	$ 128
Derivative Net Settlements Received - Commodity		45	$ 44	$ 78
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Proceeds Received from Derivatives	$ 54	54
Interest Rate Swap [Member] | Net Interest and Other [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net		$ 47
Unsecured Debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Debt Instrument, Face Amount	$ 1,000

Fair Value Measurements (Detail

Fair Value Measurements (Details-Recurring) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Assets	$ 0	$ 68
Derivative Liability	(140)	60
Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Liability	(140)	60
Interest rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Assets	0	68
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Assets	0	0
Derivative Liability	(20)	0
Fair Value, Inputs, Level 1 [Member] | Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Liability	(20)	0
Fair Value, Inputs, Level 1 [Member] | Interest rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Assets	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Assets	0	68
Derivative Liability	(120)	60
Fair Value, Inputs, Level 2 [Member] | Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Liability	(120)	60
Fair Value, Inputs, Level 2 [Member] | Interest rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Assets	0	68
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Assets	0	0
Derivative Liability	0	0
Fair Value, Inputs, Level 3 [Member] | Commodity Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Liability	0	0
Fair Value, Inputs, Level 3 [Member] | Interest rate [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis, Financial Statement [Line Items]
Derivative Assets	$ 0	$ 0

Fair Value Measurements (Deta83

Fair Value Measurements (Details 2-Nonrecurring) - USD ($) $ in Millions	3 Months Ended						12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Impairment of Oil and Gas Properties							$ 229	$ 67	$ 721
Colorado and Gulf of Mexico [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Impairment of Oil and Gas Properties									335
East Texas/North Louisiana and Wilburton Assets [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Impairment of Oil and Gas Properties									44
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure			$ 15	$ 15			179	15		$ 56
Impairment of Oil and Gas Properties							229
Assets, Fair Value Adjustment								67	386
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Oklahoma Resource Basin [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Impairment Expense - Proved Properties				$ 47
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Colorado and Gulf of Mexico [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure					$ 41
Assets, Fair Value Adjustment					333
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | East Texas/North Louisiana and Wilburton Assets [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Assets, Fair Value Adjustment						$ (44)
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | International Exploration and Production [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	$ 103
Impairment of Oil and Gas Properties	136						136
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Gulf of Mexico Assets [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Impairment Expense - Proved Properties	65						89
Property, Plant, and Equipment, Fair Value Disclosure	$ 66
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Assets Held and Used Ozona [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Assets, Fair Value Adjustment			$ 17
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | EG Equity Method Investment [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure					604
Assets, Fair Value Adjustment					$ 12
Oil Sands Mining Segment [Member]
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Financial Statement [Line Items]
Impairment of Oil and Gas Properties		$ 6,600					$ 6,636	$ 0	$ 31

Fair Value Measurements (Deta84

Fair Value Measurements (Details 3-Reported)	May 31, 2017USD ($)	Dec. 31, 2017USD ($)notes_receivable	Dec. 31, 2016USD ($)
Estimate of Fair Value Measurement [Member]
Financial assets
Other current assets		$ 762,000,000	$ 7,000,000
Other noncurrent assets		159,000,000	105,000,000
Total financial assets		921,000,000	112,000,000
Financial liabilities
Other current liabilities		32,000,000	68,000,000
Long-term debt, including current portion(a)		5,976,000,000	7,449,000,000
Deferred credits and other liabilities		110,000,000	114,000,000
Total financial liabilities		6,118,000,000	7,631,000,000
Reported Value Measurement [Member]
Financial assets
Other current assets		761,000,000	7,000,000
Other noncurrent assets		161,000,000	108,000,000
Total financial assets		922,000,000	115,000,000
Financial liabilities
Other current liabilities		43,000,000	75,000,000
Long-term debt, including current portion(a)		5,526,000,000	7,292,000,000
Deferred credits and other liabilities		103,000,000	107,000,000
Total financial liabilities		$ 5,672,000,000	$ 7,474,000,000
Oil Sands Mining Segment [Member] | Discontinued Operations, Disposed of by Sale [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Number of notes receivable	2	2

Debt Revolver (Details)

Debt Revolver (Details)	1 Months Ended	12 Months Ended
	Jul. 31, 2017USD ($)	Dec. 31, 2017USD ($)extension	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jun. 30, 2017USD ($)	May 31, 2015
Debt Instrument [Line Items]
Other Long-term Debt, Noncurrent		$ 5,536,000,000	$ 7,301,000,000
Line of Credit Facility, Expiration Date		May 31, 2020
Ratio of Indebtedness to Net Capital		0.32
Derivative, Gain (Loss) on Derivative, Net		$ (36,000,000)	$ (66,000,000)	$ 128,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 3,400,000,000	3,400,000,000			$ 3,300,000,000
Line of Credit Facility, Increase (Decrease), Net	$ 93,000,000
Line of Credit Facility, Maximum Borrowing Capacity		$ 0
Line of Credit Facility, Number of One Year Extensions | extension		2
Line of Credit, Period of Extension Options		1 year
Line of Credit Facility, Remaining Borrowing Capacity		$ 107,000,000
Bridge Loan [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		100,000,000
Letter of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 500,000,000
Maximum [Member]
Debt Instrument [Line Items]
Ratio of Indebtedness to Net Capital						0.65

Debt (Details)

Debt (Details) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jul. 24, 2017
Debt Instrument [Line Items]
Gain (Loss) on Extinguishment of Debt			$ (51,000,000)	$ 0	$ 0
Other Long-term Debt, Noncurrent	$ 5,536,000,000		5,536,000,000	7,301,000,000
Unamortized Discount	(10,000,000)		(10,000,000)	(9,000,000)
Fair value adjustments	0		0	7,000,000
Unamortized Debt Issuance Expense	(32,000,000)		(32,000,000)	(35,000,000)
Amounts due within one year	0		0	(683,000,000)
Total long-term debt due after one year	5,494,000,000		5,494,000,000	6,581,000,000
Debt Immediately Due If Change In Control	236,000,000		236,000,000
Proceeds from Issuance of Debt		$ 990,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2,015	0		0
2,016	0		0
2,017	600,000,000		600,000,000
2,018	0		0
2,019	1,035,000,000		1,035,000,000
Thereafter	3,901,000,000		3,901,000,000
Other Long-term Debt, Noncurrent	$ 5,536,000,000		$ 5,536,000,000	7,301,000,000
Senior Unsecured Notes Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage						4.40%
Other Long-term Debt, Noncurrent						$ 1,000,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent						$ 1,000,000,000
Senior Unsecured Notes Due 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.00%		6.00%
Other Long-term Debt, Noncurrent	$ 0		$ 0	682,000,000
Unsecured Debt, Current	682,000,000		682,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 0		$ 0	682,000,000
Senior Unsecured Notes Due 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.90%		5.90%
Other Long-term Debt, Noncurrent	$ 0		$ 0	854,000,000
Unsecured Debt, Current	854,000,000		854,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 0		$ 0	854,000,000
Senior Unsecured Notes Due 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	7.50%		7.50%
Other Long-term Debt, Noncurrent	$ 0		$ 0	228,000,000
Unsecured Debt, Current	228,000,000		228,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 0		$ 0	228,000,000
Senior Unsecured Notes Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.70%		2.70%
Other Long-term Debt, Noncurrent	$ 600,000,000		$ 600,000,000	600,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 600,000,000		$ 600,000,000	600,000,000
Senior Unsecured Notes Due 2022 [A] [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.80%		2.80%
Other Long-term Debt, Noncurrent	$ 1,000,000,000		$ 1,000,000,000	1,000,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 1,000,000,000		$ 1,000,000,000	1,000,000,000
Senior Unsecured Notes Due 2022 [B] [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	9.375%		9.375%
Other Long-term Debt, Noncurrent	$ 32,000,000		$ 32,000,000	32,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	32,000,000		32,000,000	32,000,000
Series Medium Term Notes Due 2022 [Member]
Debt Instrument [Line Items]
Other Long-term Debt, Noncurrent	3,000,000		3,000,000	3,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 3,000,000		$ 3,000,000	3,000,000
Senior Unsecured Notes Due 2023 [A] [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.50%		8.50%
Other Long-term Debt, Noncurrent	$ 70,000,000		$ 70,000,000	70,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 70,000,000		$ 70,000,000	70,000,000
Senior Unsecured Notes Due 2023 [B] [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	8.125%		8.125%
Other Long-term Debt, Noncurrent	$ 131,000,000		$ 131,000,000	131,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 131,000,000		$ 131,000,000	131,000,000
Senior Unsecured Notes Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	3.85%		3.85%
Other Long-term Debt, Noncurrent	$ 900,000,000		$ 900,000,000	900,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 900,000,000		$ 900,000,000	900,000,000
Senior Unsecured Notes Due 2032 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.80%		6.80%
Other Long-term Debt, Noncurrent	$ 550,000,000		$ 550,000,000	550,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 550,000,000		$ 550,000,000	550,000,000
Notes Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.40%		4.40%
Other Long-term Debt, Noncurrent	$ 1,000,000,000		$ 1,000,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 1,000,000,000		$ 1,000,000,000
Senior Unsecured Notes Due 2037 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	6.60%		6.60%
Other Long-term Debt, Noncurrent	$ 750,000,000		$ 750,000,000	750,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 750,000,000		$ 750,000,000	750,000,000
Senior Unsecured Notes Due 2045 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.20%		5.20%
Other Long-term Debt, Noncurrent	$ 500,000,000		$ 500,000,000	500,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	500,000,000		500,000,000	500,000,000
Capital Lease Obligation of Consolidated Subsidiary due 2016 - 2049 [Member]
Debt Instrument [Line Items]
Other Long-term Debt, Noncurrent	0		0	1,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	$ 0		$ 0	1,000,000
Obligation Relating To Revenue Bonds Due 2037 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.125%		5.125%
Extinguishment of Debt, Amount	$ 1,000,000,000
Other Long-term Debt, Noncurrent	0		$ 0	1,000,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
Other Long-term Debt, Noncurrent	0		0	$ 1,000,000,000
Unsecured Debt [Member]
Debt Instrument [Line Items]
Gain (Loss) on Extinguishment of Debt			(46,000,000)
Extinguishment of Debt, Amount			1,760,000,000
Municipal Revenue Bonds Due 2037 [Member] | The Parish [Member]
Debt Instrument [Line Items]
Long-term Debt, Excluding Current Maturities	$ 1,000,000,000		$ 1,000,000,000
Debt Instrument, Interest Rate, Stated Percentage	3.75%		3.75%

Incentive Based Compensation 87

Incentive Based Compensation Plans (Details-All) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	55,000,000
Maximum award for options or stock appreciation rights	2.41
Granted, stock option awards (in shares)	799,591
Allocated stock-based compensation expense	$ 50,000,000	$ 51,000,000	$ 57,000,000
Tax benefit from compensation expense		19,000,000	20,000,000
Proceeds from stock options exercised		1,000,000	9,000,000
Tax benefit realized from exercise of stock options	$ 0	$ 0	$ 0
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award contractual period	10 years
Stock Appreciation Rights (SARs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, stock option awards (in shares)	0
Restricted Stock [Member] | Granted Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Restricted Stock [Member] | Non Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Stock Compensation Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	0.00%
Stock Compensation Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage	200.00%
Restricted Stock Units (RSUs) [Member] | Non Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Share-based Compensation Plans Prior to the 2016 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, stock option awards (in shares)	0

Incentive Based Compensation 88

Incentive Based Compensation Plans - Stock Option Award Assumptions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Incentive Based Compensation Plans [Abstract]
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	$ 0	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Exercise price per share (in dollars per share)	$ 15.80	$ 7.22	$ 29.06
Expected annual dividend yield	1.30%	2.80%	2.90%
Expected life in years	6 years 4 months 24 days	6 years 3 months 26 days	6 years 2 months 12 days
Expected volatility	42.00%	36.00%	32.00%
Risk-free interest rate	2.10%	1.40%	1.70%
Weighted average grant date fair value of stock option awards granted (in dollars per share)	$ 6.07	$ 1.97	$ 6.84

Incentive Based Compensation 89

Incentive Based Compensation Plans - Stock Option Award Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Beginning of year, stock option awards (in shares)	11,915,533
Granted, stock option awards (in shares)	799,591
Exercised, stock option awards (in shares)	(8,666)
Canceled, stock option awards (in shares)	(2,375,682)
End of year, stock option awards (in shares)	10,330,776	11,915,533
Exercisable at end of year, stock option awards (in shares)	8,661,893
Expected to vest, stock option awards (in shares)	1,650,737
Weighted Average Exercise Price
Beginning of year, weighted average exercise price (in dollars per share)	$ 27.71
Granted, weighted average exercise price (in dollars per share)	15.80	$ 7.22	$ 29.06
Exercises, weighted average exercise price (in dollars per share)	7.22
Canceled, weighted average exercise price (in dollars per share)	33.31
End of year, weighted average exercise price (in dollars per share)	25.52	$ 27.71
Exercisable at end of year, weighted average exercise price (in dollars per share)	27.91
Expected to vest, weighted average exercise price (in dollars per share)	$ 13.08
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding at end of year, Weighted Average Remaining Contractual Term	4 years
Exercisable at end of year, Weighted Average Remaining Contractual Term	3 years
Expected to vest, Weighted Average Remaining Contractual Term	9 years
Outstanding at end of year, Average Intrinsic Value	$ 13
Exercisable at end of year, Average Intrinsic Value	5
Expected to vest, Average Intrinsic Value	8
Stock option awards, intrinsic value			$ 6
Unrecognized compensation costs	$ 4
Unrecognized compensation costs, period for recognition	1 year

Incentive Based Compensation 90

Incentive Based Compensation Plans - Restricted Stock Awards and RSUs (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted Average Grant Date Fair Value
Unrecognized compensation costs	$ 4
Unrecognized compensation costs, period for recognition	1 year
Restricted Stock [Member]
Awards
Unvested at beginning of year (in shares)	6,933,533
Granted (in shares)	4,198,624
Vested & Exercised (in shares)	(2,472,367)
Canceled (in shares)	(1,086,945)
Unvested at end of year (in shares)	7,572,845	6,933,533
Weighted Average Grant Date Fair Value
Unvested at beginning of year (in dollars per share)	$ 14.44	$ 30.76
Granted (in dollars per share)	16.13
Vested & Exercised (in dollars per share)	17.67
Canceled (in dollars per share)	15.03
Unvested at end of year (in dollars per share)	$ 14.24	$ 14.44	$ 30.76
Vested in period, total fair value	$ 30	$ 16	$ 26
Unrecognized compensation costs	$ 67
Unrecognized compensation costs, period for recognition	1 year

Incentive Based Compensation 91

Incentive Based Compensation Plans - Performance Unit Awards (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	$ 0	$ 0	$ 0
Allocated stock-based compensation expense	$ 50,000,000	$ 51,000,000	$ 57,000,000
Expected annual dividend yield	1.30%	2.80%	2.90%
Expected volatility	42.00%	36.00%	32.00%
Risk-free interest rate	2.10%	1.40%	1.70%
Performance Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested units (in shares)	1,510,823
Allocated stock-based compensation expense	$ 8,000,000	$ 6,000,000	$ 0
Valuation date stock price (in dollars per share)	$ 16.93	$ 16.93	$ 16.93
Expected annual dividend yield	1.20%	1.20%	1.20%
Expected volatility	54.00%	34.00%	33.00%
Risk-free interest rate	1.90%	1.70%	1.40%
Fair value of stock-based performance units outstanding	$ 21.63	$ 19.86	$ 0
Granted Officer [Member] | Performance Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	563,631	1,205,517	382,335
2015 [Member] | Performance Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested units (in shares)	0

Defined Benefit Postretiremen92

Defined Benefit Postretirement Plans and Defined Contribution Plan (Obligations and Funded Status)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
UNITED STATES
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Accumulated benefit obligation	$ 378	$ 386
Change in benefit obligations:
Benefit obligations at January 1	397	525
Service cost	22	25
Interest cost	13	16
Plan amendment	0	0
Actuarial loss	42	78
Foreign currency exchange rate changes	0	0
Divestiture	0	0
Settlements paid	(84)	(240)
Benefits paid	(6)	(7)
Benefit obligations at December 31	384	397
Change in fair value of plan assets:
Fair value of plan assets at January 1	227	354
Actual return on plan assets	27	25
Employer contributions	52	95
Foreign currency exchange rate changes	0	0
Divestiture	0	0
Settlements paid	(84)	(240)
Benefits paid	(6)	(7)
Fair value of plan assets at December 31	216	227
Funded status of plans at December 31
Funded status of plans at December 31	(168)	(170)
Amounts recognized in the consolidated balance sheets:
Noncurrent assets	0	0
Current liabilities	(6)	(4)
Noncurrent liabilities	(162)	(166)
Accrued benefit cost	(168)	(170)
Pretax amounts in accumulated other comprehensive loss:
Net loss (gain)	122	130
Prior service cost (credit)	(45)	(55)
Foreign Plan [Member]
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Accumulated benefit obligation	599	583
Change in benefit obligations:
Benefit obligations at January 1	583	579
Service cost	0	0
Interest cost	17	23
Plan amendment	0	1
Actuarial loss	(7)	139
Foreign currency exchange rate changes	52	(108)
Divestiture	0	0
Settlements paid	(31)	(36)
Benefits paid	(15)	(15)
Benefit obligations at December 31	599	583
Change in fair value of plan assets:
Fair value of plan assets at January 1	595	608
Actual return on plan assets	47	129
Employer contributions	17	18
Foreign currency exchange rate changes	57	(109)
Divestiture	0	0
Settlements paid	(31)	(36)
Benefits paid	(15)	(15)
Fair value of plan assets at December 31	670	595
Funded status of plans at December 31
Funded status of plans at December 31	71	12
Amounts recognized in the consolidated balance sheets:
Noncurrent assets	71	12
Current liabilities	0	0
Noncurrent liabilities	0	0
Accrued benefit cost	71	12
Pretax amounts in accumulated other comprehensive loss:
Net loss (gain)	58	81
Prior service cost (credit)	3	4
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets [Abstract]
Accumulated benefit obligation	221	227
Change in benefit obligations:
Benefit obligations at January 1	227	260
Service cost	2	2
Interest cost	8	11
Plan amendment	0	(38)
Actuarial loss	5	11
Foreign currency exchange rate changes	0	0
Divestiture	0	0
Settlements paid	0	0
Benefits paid	(21)	(19)
Benefit obligations at December 31	221	227
Change in fair value of plan assets:
Fair value of plan assets at January 1	0	0
Actual return on plan assets	0	0
Employer contributions	21	20
Foreign currency exchange rate changes	0	0
Divestiture	0	0
Settlements paid	0	0
Benefits paid	(21)	(20)
Fair value of plan assets at December 31	0	0
Funded status of plans at December 31
Funded status of plans at December 31	(221)	(227)
Amounts recognized in the consolidated balance sheets:
Noncurrent assets	0	0
Current liabilities	(21)	(21)
Noncurrent liabilities	(200)	(206)
Accrued benefit cost	(221)	(227)
Pretax amounts in accumulated other comprehensive loss:
Net loss (gain)	30	25
Prior service cost (credit)	$ (56)	$ (63)

Defined Benefit Postretiremen93

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, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018
Foreign Plan [Member]
Components of net periodic benefit cost:
Service cost	$ 0	$ 0	$ 14
Interest cost	17	23	25
Expected return on plan assets	(30)	(35)	(37)
Depreciation, Depletion and Amortization [Abstract]
- prior service cost (credit)	0	1	1
- actuarial loss	1	0	2
Net curtailment loss (gain)	0	0	4
Net settlement loss	4	6	0
Net periodic benefit cost	(8)	(5)	9
Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax):
Actuarial loss (gain)	(26)	41	(25)
Amortization of actuarial (loss) gain	(4)	(6)	(2)
Prior service cost	0	1	1
Amortization of prior service credit (cost)	0	(1)	(5)
Total recognized in other comprehensive (income) loss	(30)	35	(31)
Total recognized in net periodic benefit cost and other comprehensive (income) loss	(38)	30	(22)
UNITED STATES
Components of net periodic benefit cost:
Service cost	22	25	29
Interest cost	13	16	25
Expected return on plan assets	(13)	(18)	(30)
Depreciation, Depletion and Amortization [Abstract]
- prior service cost (credit)	(10)	(10)	(7)
- actuarial loss	8	14	22
Net curtailment loss (gain)	0	0	(5)
Net settlement loss	28	97	119
Net periodic benefit cost	48	124	153
Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax):
Actuarial loss (gain)	28	70	30
Amortization of actuarial (loss) gain	(36)	(111)	(134)
Prior service cost	0	0	(89)
Amortization of prior service credit (cost)	10	10	7
Total recognized in other comprehensive (income) loss	2	(31)	(186)
Total recognized in net periodic benefit cost and other comprehensive (income) loss	50	93	(33)
Other Postretirement Benefit Plans, Defined Benefit [Member]
Components of net periodic benefit cost:
Service cost	2	2	3
Interest cost	8	11	11
Expected return on plan assets	0	0	0
Depreciation, Depletion and Amortization [Abstract]
- prior service cost (credit)	(7)	(3)	(4)
- actuarial loss	0	0	1
Net curtailment loss (gain)	0	0	(7)
Net settlement loss	0	0	0
Net periodic benefit cost	3	10	4
Other changes in plan assets and benefit obligations recognized in other comprehensive (income) loss (pretax):
Actuarial loss (gain)	5	11	(21)
Amortization of actuarial (loss) gain	0	0	(1)
Prior service cost	0	(38)	0
Amortization of prior service credit (cost)	7	3	13
Total recognized in other comprehensive (income) loss	12	(24)	(9)
Total recognized in net periodic benefit cost and other comprehensive (income) loss	$ 15	$ (14)	$ (5)
Scenario, Forecast [Member]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Defined Benefit Plan, Amortization of Net Gains (Losses)				$ 13
Defined Benefit Plan, Amortization of Net Prior Service Cost (Credit)				10
Scenario, Forecast [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Defined Benefit Plan, Amortization of Net Gains (Losses)				1
Defined Benefit Plan, Amortization of Net Prior Service Cost (Credit)				$ 7

Defined Benefit Postretiremen94

Defined Benefit Postretirement Plans and Defined Contribution Plan (Plan Assumptions)(Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
UNITED STATES
Weighted average assumptions used to determine benefit obligation:
Discount rate	3.55%	4.02%	4.04%
Rate of compensation increase	4.00%	4.00%	4.00%
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate	3.86%	3.66%	3.79%
Expected long-term return on plan assets	6.50%	6.75%	6.75%
Rate of compensation increase	4.00%	4.00%	4.00%
Foreign Plan [Member]
Weighted average assumptions used to determine benefit obligation:
Discount rate	2.50%	2.70%	3.90%
Rate of compensation increase	0.00%	0.00%	0.00%
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate	2.70%	3.90%	3.70%
Expected long-term return on plan assets	4.50%	5.50%	5.70%
Rate of compensation increase	0.00%	0.00%	3.60%
Other Postretirement Benefit Plans, Defined Benefit [Member]
Weighted average assumptions used to determine benefit obligation:
Discount rate	3.54%	3.98%	4.36%
Rate of compensation increase	4.00%	4.00%	4.00%
Weighted average assumptions used to determine net periodic benefit cost:
Discount rate	3.98%	4.36%	3.93%
Expected long-term return on plan assets	0.00%	0.00%	0.00%
Rate of compensation increase	4.00%	4.00%	4.00%

Defined Benefit Postretiremen95

Defined Benefit Postretirement Plans and Defined Contribution Plan (Health Care Cost Trends Table and Narrative)(Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Initial health care trend rate	8.00%	8.25%	8.00%
Ultimate trend rate	4.70%	4.50%	4.50%
Year ultimate trend rate is reached	2,025	2,025	2,024
Foreign Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Target allocation percentage	55.00%
Foreign Plan [Member] | Fixed Income Securities [Member]
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Target allocation percentage	45.00%
UNITED STATES | Equity Securities [Member]
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Target allocation percentage	55.00%
UNITED STATES | Fixed Income Securities [Member]
Defined Benefit Plan Assumed Health Care Cost Trend Rates [Line Items]
Target allocation percentage	45.00%

Defined Benefit Postretiremen96

Defined Benefit Postretirement Plans and Defined Contribution Plan (Fair Value of Defined Benefit Pension Plan Assets)(Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 216	$ 227	$ 354
Defined Benefit Plan, Fair Value of Plan Assets, Before Commingled Funds	157	213
UNITED STATES | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6	8
UNITED STATES | Common And Preferred Stock [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	81	82
UNITED STATES | Private Equity And Reit [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	16	20
UNITED STATES | Mutual And Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
UNITED STATES | Corporate Bond Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6	52
UNITED STATES | Exchange Traded Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	5	5
UNITED STATES | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	24	25
UNITED STATES | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
UNITED STATES | MRO Other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	19	21
UNITED STATES | Commingled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	59	14
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0	0
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	670	595	$ 608
Defined Benefit Plan, Fair Value of Plan Assets, Before Commingled Funds	670	595
Foreign Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1	5
Foreign Plan [Member] | Common And Preferred Stock [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Foreign Plan [Member] | Private Equity And Reit [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Foreign Plan [Member] | Mutual And Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	266	360
Foreign Plan [Member] | Corporate Bond Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Foreign Plan [Member] | Exchange Traded Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Foreign Plan [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Foreign Plan [Member] | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	403	230
Foreign Plan [Member] | MRO Other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	111	101
Defined Benefit Plan, Fair Value of Plan Assets, Before Commingled Funds	111	101
Fair Value, Inputs, Level 1 [Member] | UNITED STATES | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6	8
Fair Value, Inputs, Level 1 [Member] | UNITED STATES | Common And Preferred Stock [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	81	82
Fair Value, Inputs, Level 1 [Member] | UNITED STATES | Private Equity And Reit [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | UNITED STATES | Mutual And Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | UNITED STATES | Corporate Bond Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | UNITED STATES | Exchange Traded Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	5	5
Fair Value, Inputs, Level 1 [Member] | UNITED STATES | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	19	6
Fair Value, Inputs, Level 1 [Member] | UNITED STATES | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | UNITED STATES | MRO Other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	152	206
Defined Benefit Plan, Fair Value of Plan Assets, Before Commingled Funds	152	206
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1	5
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member] | Common And Preferred Stock [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member] | Private Equity And Reit [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member] | Mutual And Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	151	201
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member] | Corporate Bond Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member] | Exchange Traded Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member] | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 1 [Member] | Foreign Plan [Member] | MRO Other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8	71
Defined Benefit Plan, Fair Value of Plan Assets, Before Commingled Funds	8	71
Fair Value, Inputs, Level 2 [Member] | UNITED STATES | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | UNITED STATES | Common And Preferred Stock [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | UNITED STATES | Private Equity And Reit [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | UNITED STATES | Mutual And Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | UNITED STATES | Corporate Bond Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6	52
Fair Value, Inputs, Level 2 [Member] | UNITED STATES | Exchange Traded Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | UNITED STATES | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2	19
Fair Value, Inputs, Level 2 [Member] | UNITED STATES | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | UNITED STATES | MRO Other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	518	389
Defined Benefit Plan, Fair Value of Plan Assets, Before Commingled Funds	518	389
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member] | Common And Preferred Stock [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member] | Private Equity And Reit [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member] | Mutual And Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	115	159
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member] | Corporate Bond Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member] | Exchange Traded Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member] | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	403	230
Fair Value, Inputs, Level 2 [Member] | Foreign Plan [Member] | MRO Other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	38	41
Defined Benefit Plan, Fair Value of Plan Assets, Before Commingled Funds	38	41
Fair Value, Inputs, Level 3 [Member] | UNITED STATES | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | UNITED STATES | Common And Preferred Stock [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | UNITED STATES | Private Equity And Reit [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	16	20
Fair Value, Inputs, Level 3 [Member] | UNITED STATES | Mutual And Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | UNITED STATES | Corporate Bond Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | UNITED STATES | Exchange Traded Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | UNITED STATES | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	3	0
Fair Value, Inputs, Level 3 [Member] | UNITED STATES | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | UNITED STATES | MRO Other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	19	21
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Defined Benefit Plan, Fair Value of Plan Assets, Before Commingled Funds	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member] | Common And Preferred Stock [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member] | Private Equity And Reit [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member] | Mutual And Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member] | Corporate Bond Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member] | Exchange Traded Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member] | Pooled Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Fair Value, Inputs, Level 3 [Member] | Foreign Plan [Member] | MRO Other investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 0	$ 0

Defined Benefit Postretiremen97

Defined Benefit Postretirement Plans and Defined Contribution Plan (Cash Flows)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Employer discretionary contribution amount	$ 20	$ 20	$ 20
Scenario, Forecast [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Estimated future employer contributions in 2018				$ 65
UNITED STATES
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
2,018	43
2,019	40
2,020	37
2,021	33
2,022	30
2023 through 2027	123
Foreign Plan [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
2,018	17
2,019	18
2,020	17
2,021	19
2,022	21
2023 through 2027	118
Unfunded Plans [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Estimated future employer contributions in 2018				6
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
2,018	21
2,019	20
2,020	20
2,021	19
2,022	18
2023 through 2027	$ 74
Other Postretirement Benefit Plans, Defined Benefit [Member] | Scenario, Forecast [Member]
Defined Benefit Plan Estimated Future Benefit Payments [Line Items]
Estimated future employer contributions in 2018				$ 21

Reclassifications Out of Accu98

Reclassifications Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Provision for income taxes	$ (376)	$ (923)	$ 738
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amortization of actuarial loss	(9)	(14)
Net settlement loss	(32)	(103)
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion	46	0
Derivative Instruments, Income Statement Location of Gain (Loss) Reclassified from Accumulated OCI	1	4
Income from operations before income taxes	6	(113)
Provision for income taxes	(40)	41
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax	(34)	(72)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	(30)	0
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent	$ (64)	$ (72)

Supplemental Cash Flow Inform99

Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities:
Interest paid (net of amounts capitalized)	$ (379)	$ (375)	$ (325)
Income taxes paid to taxing authorities	(391)	(84)	(171)
Commercial paper:
Asset Retirement Obligation, Period Increase (Decrease)	(202)	110	(95)
Noncash investing and financing activities:
Increase in capital expenditure accrual	176	0	0
Asset Retirement Obligation, Liabilities Transferred	14	40	251
Notes, Loans and Financing Receivable, Net, Current	748	0
Receivable Related To Disposal Of Assets		$ 0	$ 0
Foreign Tax Authority [Member] | UK Government [Member]
Income Tax Examination [Line Items]
Income Tax Examination, Penalties and Interest Expense	$ 108

Other Items (Details)

Other Items (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Interest and Other Financing [Abstract]
Interest income	$ 34	$ 14	$ 9
Interest expense(a)	(380)	(398)	(350)
Income on interest rate swaps	53	13	11
Interest capitalized	3	18	19
Total interest	(290)	(353)	(311)
Net foreign currency gains (losses)	8	6	4
Other	12	15	21
Total other	20	21	25
Net interest and other	(270)	(332)	(286)
Aggregate foreign currency gains losses [Abstract]
Net interest and other	8	6	4
Provision for income taxes	57	(32)	(11)
Aggregate foreign currency gains (losses)	$ 65	$ (26)	$ (7)

Equity Method Investments an101

Equity Method Investments and Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity Method Investments Disclosure [Abstract]
Proceeds from Equity Method Investment, Distribution	$ 276	$ 192	$ 178
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	847	931
Equity Method Investment, Summarized Financial Information [Abstract]
Revenues and other income	1,294	770	769
Income from operations	631	346	313
Net income	508	313	280
Current assets	586	525
Noncurrent assets	1,044	1,173
Current liabilities	221	218
Noncurrent liabilities	94	47
Related Party Transactions [Abstract]
Revenue from Related Parties	60	54	51
Related Party Transaction, Purchases from Related Party	132	103	$ 207
Accounts Receivable, Related Parties, Current	24	23
Accounts Payable, Related Parties, Current	$ 14	11
EG Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	60.00%
Equity Method Investments	$ 456	550
Alba Plant LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	52.00%
Equity Method Investments	$ 214	215
AMPCO [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	45.00%
Equity Method Investments	$ 177	165
Other Equity Method Investees [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 0	$ 1

Stockholders Equity (Details)

Stockholders Equity (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity, Class of Treasury Stock [Line Items]
Stock Issued During Period, Shares, New Issues	166,750,000
Treasury Stock, Value, Acquired, Cost Method		$ 11	$ 5	$ 8
Common stock, par value per share	$ 1	$ 1	$ 1
Shares Issued, Price Per Share	$ 7.65
Stock Issued	$ 1,236
Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 1,500

Leases (Details)

Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Year 1 Operating	$ 29
Year 2 Operating	28
Year 3 Operating	27
Year 4 Operating	26
Year 5 Operating	5
Later years, Operating Leases	4
Sublease rentals	0
Operating Leases, Future Minimum Payments Due	119
Operating Leases, Rent Expense, Net [Abstract]
Operating Leases, Rent Expense	$ 87	$ 87	$ 99

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Override Royalty - GOM Future Abandonment	$ 70
Payments to Acquire Property, Plant, and Equipment [Abstract]
Commitments to acquire property, plant and equipment	102	$ 144
Other Guarantee [Member]
Guarantor Obligations [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	35
UK Government [Member] | Foreign Tax Authority [Member]
Guarantor Obligations [Line Items]
Income Tax Examination, Penalties and Interest Expense	$ 108