Amount of asset retirement obligations, assumed at the acquisition date.

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Acreage is considered to be both developed and undeveloped. Developed acres are acres spaced or assigned to productive wells. Undeveloped acreage are those lease acres on which wells have not been drilled or completed to a point that would permit the producing.

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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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Amount of tangible or intangible assets, including a business or subsidiary of the acquirer transferred by the entity to the former owners of the acquiree. Excludes cash.

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Amount of assets acquired at the acquisition date.

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Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of liabilities incurred for goods and services received that are used in an entity's business and related party payables, assumed at the acquisition date.

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- Definition

The amount of inventory recognized as of the acquisition date.

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Amount of liabilities assumed at the acquisition date.

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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

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

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

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Acquisitions Business Combination (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			3 Months Ended	1 Months Ended	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2012	Jul. 31, 2013	Sep. 30, 2012
Business Combination, Consideration Transferred [Abstract]
Payments to Acquire Businesses, Net of Cash Acquired	$ 21	$ 74	$ 1,033
Eagle Ford Paloma [Member]
Business Acquisition [Line Items]
Fair Value Inputs, Discount Rate				10.00%
Gas and oil acreages undeveloped and developed net			25,000
Business Combination, Consideration Transferred [Abstract]
Payments to Acquire Businesses, Net of Cash Acquired				768
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents				8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables				22
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory				1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets				31
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment				822
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets				853
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable				78
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities				78
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities,Asset Retirement Obligations				7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities				85
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net				768
Eagle Ford [Member]
Business Acquisition [Line Items]
Fair Value Inputs, Discount Rate						10.00%
Business Combination, Consideration Transferred [Abstract]
Payments to Acquire Businesses, Net of Cash Acquired					74	232
Business Combination, Consideration Transferred, Other					23
Business Combination, Consideration Transferred					97
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents						0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables						8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory						0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets						8
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment						248
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets						256
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable						23
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities						23
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities,Asset Retirement Obligations						1
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities						24
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net						$ 232