Derivative Activities (Fair Value Of Derivative Contracts) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Current asset derivatives	$ 33,744	$ 27,485
Noncurrent asset derivatives	29,681	62,131
Asset derivative instruments	63,425	89,616
Current liability derivatives	7,378	11,233
Noncurrent liability derivatives	5,283	6,251
Liability derivative instruments	12,661	17,484
Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Current asset derivatives	33,744	27,485
Noncurrent asset derivatives	29,365	62,131
Asset derivative instruments	63,109	89,616
Current liability derivatives	1,911	5,651
Noncurrent liability derivatives	3,017	1,442
Liability derivative instruments	4,928	7,093
Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Noncurrent asset derivatives	316
Asset derivative instruments	316
Current liability derivatives	5,467	5,582
Noncurrent liability derivatives	2,266	4,809
Liability derivative instruments	$ 7,733	$ 10,391