Derivative Activities (Fair Value Of Derivative Contracts) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Current asset derivatives	$ 27,485	$ 45,522
Noncurrent asset derivatives	62,131	76,621
Asset derivative instruments	89,616	122,143
Current liability derivatives	11,233	8,727
Noncurrent liability derivatives	6,251	16,993
Liability derivative instruments	17,484	25,720
Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Current asset derivatives	27,485	45,522
Noncurrent asset derivatives	62,131	76,621
Asset derivative instruments	89,616	122,143
Current liability derivatives	5,651	4,130
Noncurrent liability derivatives	1,442	9,354
Liability derivative instruments	7,093	13,484
Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Current liability derivatives	5,582	4,597
Noncurrent liability derivatives	4,809	7,639
Liability derivative instruments	$ 10,391	$ 12,236