Ownership interest

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- Definition

Ownership interest purchased

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- Definition

The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.

+ References

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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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- Definition

Income (expense) and gain (loss) recognized from the settlement of a preexisting relationship between the acquirer and the acquiree.

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- Definition

Amount of goodwill arising from a business combination, which is the excess of the cost of the acquired entity over the amounts assigned to assets acquired and liabilities assumed.

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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- Definition

The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

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- Definition

In a business combination achieved in stages, this element represents the acquisition-date percentage of equity in the acquiree held by the acquirer immediately before the acquisition date.

+ Details

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- Definition

In a business combination achieved in stages, this element represents the amount of gain recognized by the entity as a result of remeasuring to fair value the equity interest in the acquiree it held before the business combination.

+ References

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- Definition

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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Acquisitions - Additional Information (Detail) (USD $) In Millions, unless otherwise specified				9 Months Ended
	Sep. 30, 2011	May 31, 2011	Dec. 31, 2010	Sep. 30, 2011 Wattenberg Natural-Gas Processing Plant [Member]	May 31, 2011 Wattenberg Natural-Gas Processing Plant [Member]	May 31, 2011 Wattenberg Natural-Gas Processing Plant [Member] Oil and Gas Exploration and Production Reporting Segment [Member]	Feb. 28, 2011 Platte Valley Natural-Gas Processing Plant and Related Gathering Systems [Member] Western Gas Partners Limited Partnership [Member]	Sep. 30, 2011 Oil and Gas Exploration and Production Reporting Unit [Member] Excluding Other Intangible Assets [Member]	Sep. 30, 2011 Other Gathering and Processing Reporting Unit [Member] Excluding Other Intangible Assets [Member]	Sep. 30, 2011 WES Gathering and Processing Reporting Unit [Member] Excluding Other Intangible Assets [Member]	Sep. 30, 2011 Transportation Reporting Unit [Member] Excluding Other Intangible Assets [Member]	Sep. 30, 2011 Excluding Other Intangible Assets [Member]
Business Acquisition [Line Items]
Ownership interest purchased					93.00%
Business acquisition, cost of acquired entity, purchase price		$ 878			$ 576		$ 302
Ownership interest					100.00%
Business acquisition, purchase price allocation, goodwill		362				335
Business acquisition, purchase price allocation, goodwill, amortizable for tax purposes					469
Goodwill	5,832		5,311					5,400	102	59	5	5,600
Loss on Anadarko's preexisting contracts with the previous Wattenberg Plant owner		76		76
Gain related to the fair-value remeasurement of Anadarko's pre-acquisition 7% equity interest in the Wattenberg Plant				$ 21
Business combination, equity interest in acquiree, percentage					7.00%