Fair Value Measurements (Fair Value Hierarchy Table) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Current	$ 421,702us-gaap_DerivativeAssetsCurrent	$ 440,359us-gaap_DerivativeAssetsCurrent
Derivative Asset, Long-term	19,456us-gaap_DerivativeAssetsNoncurrent	66,187us-gaap_DerivativeAssetsNoncurrent
Total Derivative Assets	441,158us-gaap_DerivativeAssets	506,546us-gaap_DerivativeAssets
Quoted Prices in Active Markets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Current	0	0
Derivative Asset, Long-term	0	0
Total Derivative Assets	0	0
Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Current	270,126	283,238
Derivative Asset, Long-term	6,017	34,862
Total Derivative Assets	276,143	318,100
Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative Asset, Current	151,576	157,121
Derivative Asset, Long-term	13,439	31,325
Total Derivative Assets	$ 165,015	$ 188,446

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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