Derivatives (Schedule Of Fair Value Of Derivative Assets And Liabilities) (Details) - Other Current Assets [Member] - Commodity Derivatives [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 23	$ 0
Derivative Liability, Fair Value, Gross Asset	23	0
Derivative Liability	0	0
Not Designated As Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	1,703	16,383
Derivative Liability, Fair Value, Gross Liability	388	2,310
Derivative Liability, Fair Value, Gross Asset	388	2,310
Derivative Asset, Fair Value, Gross Liability	388	2,310
Derivative Asset	1,315	14,073
Derivative Liability	$ 0	$ 0