Segment Information - Reconciliation of Consolidated Adjusted EBITDAX to Income (Loss) Before Income Taxes (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting [Abstract]
Income (loss) before income taxes	$ (736)	$ 142	$ (474)	$ 442
Interest expense	249	237	502	465
DD&A	1,161	1,003	2,242	1,993
Exploration expense	90	94	139	262
(Gains) losses on divestitures, net	(6)	(52)	(1)	(28)
Impairments	0	128	0	147
Total (gains) losses on derivatives, net, less net cash from settlement of commodity derivatives	255	267	571	240
Reorganization-related charges	15	0	33	0
Merger transaction costs	1,042	0	1,042	0
Less net income (loss) attributable to noncontrolling interests	80	(12)	191	41
Consolidated Adjusted EBITDAX	$ 1,990	$ 1,831	$ 3,863	$ 3,480

Business Combination, Termination Fee And Acquisition Related Costs

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Adjusted EBITDAX provides information useful in assessing the Company's financial condition and results of operations. Adjusted EBITDAX is a widely accepted financial indicator of a company's ability to incur and service debt, fund capital expenditures, and make distributions to stockholders.

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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments less the cash received (paid) on commodity derivative instruments not designated or qualifying as hedging instruments as a result of settlement of derivative instruments during the period.

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Total amount before tax of gain (loss) on the sale or disposal and write down of a disposal group.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Exploration expenses (including prospecting) related to oil and gas producing entities and would be included in operating expenses of that entity. Costs incurred in identifying areas that may warrant examination and in examining specific areas that are considered to have prospects of containing oil and gas reserves, including costs of drilling exploratory wells and exploratory-type stratigraphic test wells. Exploration costs may be incurred both before acquiring the related property (sometimes referred to in part as prospecting costs) and after acquiring the property. Principal types of exploration costs, which include depreciation and applicable operating costs of support equipment and facilities and other costs of exploration activities, are: (i) Costs of topographical, geographical and geophysical studies, rights of access to properties to conduct those studies, and salaries and other expenses of geologists, geophysical crews, and others conducting those studies. Collectively, these are sometimes referred to as geological and geophysical or "G&G" costs. (ii) Costs of carrying and retaining undeveloped properties, such as delay rentals, ad valorem taxes on properties, legal costs for title defense, and the maintenance of land and lease records. (iii) Dry hole contributions and bottom hole contributions. (iv) Costs of drilling and equipping exploratory wells. (v) Costs of drilling exploratory-type stratigraphic test wells.

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Interest and debt related expenses associated with nonoperating financing activities of the entity.

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