Derivatives (Effect Of Derivative Instruments Recognized In Statement Of Operations, Not Designated As Hedging Instruments) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives		$ (22,813)	$ 26,345
Cash receipts (payments) on derivatives settled		9,658	46,615
Commodity Contract
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives	[1]	$ (22,813)	$ 26,345

[1] Amount settled during the period is a gain of $9,658 and a gain of $46,615, respectively.