Fair Value Measurements (Reconciliations Of Level 3 Fair Value Measurements) (Details) - Level 3 [Member] - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Beginning of period		$ 207	$ (6,081)	$ 3,355	$ (2,595)
Included in earnings	[1]	4,436	5,785	5,324	(2,043)
Settlements		(2,161)	887	(6,197)	5,229
End of period		2,482	591	2,482	591
Total gains (losses) for the period included in earnings attributable to the change in unrealized loss relating to assets still held at end of period		$ 2,275	$ 6,672	$ (873)	$ 3,186

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