Derivative Activities (Fair Value Of Derivative Contracts) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Current asset derivatives	$ 30,399	$ 45,522
Noncurrent asset derivatives	63,070	76,621
Asset derivative instruments	93,469	122,143
Current liability derivatives	15,306	8,727
Noncurrent liability derivatives	9,247	16,993
Liability derivative instruments	24,553	25,720
Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Current asset derivatives	30,399	45,522
Noncurrent asset derivatives	63,070	76,621
Asset derivative instruments	93,469	122,143
Current liability derivatives	9,982	4,130
Noncurrent liability derivatives	3,346	9,354
Liability derivative instruments	13,328	13,484
Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Current liability derivatives	5,324	4,597
Noncurrent liability derivatives	5,901	7,639
Liability derivative instruments	$ 11,225	$ 12,236

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.

+ References+ Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or 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.

+ References+ Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or 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.

+ References+ Details

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or 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.

+ References+ Details