Related Party Transactions - Genesis (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009
Former Related Party Transactions (Textuals) [Abstract]
Ownership percentage in equity method investments		12.00%
Cash distribution received from Genesis		$ 11.6
Settlement in Cash for Incentive Compensation Agreement	14.9
Deferred compensation in sale of Genesis equity interest	1.9
Change of control redemption amounts related to Genesis awards	13.0
Compensation expense included in "General and administrative" expense	1.1	14.2
Transportation Expenses for Crude Oil Production and Sale		7.9
Sales volume of CO2 to Genesis (In Bcf)		we sold 280.5 Bcf of CO2 to Genesis under three separate volumetric production payment agreements
Number of separate volumetric production payment agreements		3
Deferred revenue recognized		4.2
Revenues recognized from processing and transportation services provided to Genesis		$ 5.5

Cash distribution received from Genesis

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Change of control redemption payment amount related to Genesis awards.

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Compensation expense included in general and administrative expense related to incentive compensation arrangements with Genesis management

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Deferred compensation under Genesis management incentive agreement.

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Number of separate volumetric production payment agreements.

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Settlement in Cash for Incentive Compensation Agreement.

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Amount of previously reported deferred or unearned revenue that was recognized as revenue during the period. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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A description of the related party transaction, including transactions to which no amounts or nominal amounts were ascribed and such other information deemed necessary to an understanding of the effects of the transactions on the financial statements. Examples of common related party transactions are, sales, purchases and transfers of realty and personal property, services received or furnished, loans and leases to and from top management and affiliates.

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Expenses recognized during the period resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party during the period.

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Revenues, net of returns and allowances, realized from sales and other transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party during the period.

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