Derivative Financial Instruments Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fair value of derivative assets and liabilities
Fair Value: Derivative Assets	$ 55,813	$ 43,491
Fair Value: Derivative Liabilities	42,806	82,044
Derivative Instruments and Hedges, Noncurrent	31,062	18,841
Derivative Liabilities, Noncurrent	12,875	32,557
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Not Designated as Hedging Instrument [Member]
Fair value of derivative assets and liabilities
Fair Value: Derivative Assets	86,875
Fair Value: Derivative Liabilities	55,681
Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member] \| Designated as Hedging Instrument [Member]
Fair value of derivative assets and liabilities
Fair Value: Derivative Assets		62,332
Fair Value: Derivative Liabilities		$ 114,601

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be extinguished or otherwise disposed of after one year or beyond the normal operating cycle, if longer, net of the effects of master netting arrangements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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+ Details