Fair Value Measurements (Reconciliations Of Level 3 Fair Value Measurements) (Details) - Collar [Member] - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Beginning of period		$ 857	$ (4,464)	$ 3,355	$ (2,595)
Included in earnings	[1]	111	(4,401)	888	(7,829)
Settlements		(761)	2,784	(4,036)	4,343
End of period		207	(6,081)	207	(6,081)
Total losses for the period included in earnings attributable to the change in unrealized loss relating to assets still held at end of period		$ (650)	$ (1,617)	$ (3,148)	$ (3,486)

[1] Commodity collars are reported in the Unaudited Condensed Consolidated Statements of Operations in gain (loss) on derivatives not designated as hedges.