The change in capitalized costs during the reporting period relating to proceeds.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM format.

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Firm transportation capacity assumed, per day.

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Net production per day of acreage sold in MMcf.

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Number of miles of natural gas gathering pipeline.

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Number Of Wells

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Pipeline capacity per day.

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The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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Area of land held.

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Short-Term financing which is expected to be paid back relatively quickly, such as by a subsequent longer-term loan. Also called swing loan or bridge financing.

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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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Percentage of voting equity interests acquired at the acquisition date in the business combination.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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The amount of property, plant, and equipment recognized as of the acquisition date.

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Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

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Amount of gain (loss) on sale or disposal of oil and gas property or timber property.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of all notes and loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

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Oil and gas properties, net of depletion, carried under the full cost method.

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The cash outflow to purchase of mineral interests in oil and gas properties for use in the normal oil and gas operations and not intended for resale.

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The cash inflow to dispose of long-lived, physical assets and mineral interests in oil and gas properties used for normal oil and gas operations.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Acquisitions And Divestitures (Narrative) (Details) $ in Millions	1 Months Ended					3 Months Ended	12 Months Ended
	Nov. 30, 2015 USD ($)	May. 31, 2015 USD ($)	Apr. 30, 2015 USD ($) mi MMcf	Jan. 31, 2015 USD ($) a MMcf	Dec. 31, 2014 USD ($) a MMcf	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) a item MMcf
Business Acquisition [Line Items]
Area of land purchased \| a					413,000			413,000
Bridge Loan [Member]
Business Acquisition [Line Items]
Bridge loan				$ 4,500	$ 4,500		$ 4,500	$ 4,500
Debt instrument, term				364 days			364 days	364 days
Debt issuance costs				$ 47
Unsecured Debt [Member] \| Term Loan due November 2018 [Member]
Business Acquisition [Line Items]
Loans payable	$ 750				$ 500			$ 500
Maturity date, month and year								2016-12
Debt instrument, term	3 years							2 years
WPX Property Acquisition [Member]
Business Acquisition [Line Items]
Area of land purchased \| a				46,700
Cash consideration				$ 270
Net production per day of acreage sold in MMcf \| MMcf					50			50
Number of horizontal wells operated \| item								63
Firm transportation capacity assumed, per day \| MMcf				260
Firm transportation, useful life				19 years
Amortization						$ 10	$ 8
Statoil Property Acquisition [Member]
Business Acquisition [Line Items]
Area of land purchased \| a				30,000
Percentage of interest acquired				20.00%
Cost to acquire property				$ 357
Allocated to natural gas and oil properties				$ 357
Chesapeake Property Acquisition [Member]
Business Acquisition [Line Items]
Cash consideration					$ 5,000
East Texas and Arkoma Basin [Member]
Business Acquisition [Line Items]
Proceeds from sale of oil and gas property and equipment		$ 211
Reduction in capitalized costs relating to proceeds		$ (205)
Bradford And Lycoming Counties, Pennsylvania [Member]
Business Acquisition [Line Items]
Proceeds from sale of oil and gas property and equipment			$ 489
Net book value			206
Gain on sale of property			$ 283
Number of miles of natural gas gathering pipeline \| mi			100
Pipeline capacity per day \| MMcf			600