Acquisitions and Divestitures - (Schedule of Merger Related Costs) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Montage merger-related expenses	$ 41	$ 0	$ 0
Montage Resources Corporation
Business Acquisition [Line Items]
Bank, legal and consulting fees	18
Employee severance and related costs	17
Contract buyouts	5
Other	1
Montage merger-related expenses	$ 41

Business Combination, Acquisition Related Costs, Other

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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Gain (loss) related to the termination of a contract between the parties. The termination may be due to many causes including early termination of a lease by a lessee, a breach of contract by one party, or a failure to perform.

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A fee charged for services from professionals such as doctors, lawyers and accountants. The term is often expanded to include other professions, for example, pharmacists charging to maintain a medicinal profile of a client or customer.

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Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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