Derivatives And Fair Value Measurements (Changes In Level 3 Fair Values) (Details) (Fair Value Inputs, Level 3 [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Balance at beginning of period	$ (4,931)	$ 150,989
Unrealized gain on derivatives	(40,398)	19,451
Transfers out of Level 3	0	(180,732)
Unrealized gains reported in OCI	0	(34,302)
Balance at end of period	23,485	(4,931)
Total gains included in net derivative gains attributable to the change in unrealized gains related to assets still held at the reporting date	41,909	19,451
Production Revenue [Member]
Settlements	0	(3,738)
Derivative gains (losses) [Member]
Settlements	$ (11,982)	$ (25,203)