Derivatives (Effect Of Derivative Instruments Recognized In Statement Of Operations, Not Designated As Hedging Instruments) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives		$ (3,184)	$ 14,732
Cash receipts (payments) on derivatives settled		(22,803)	173
Commodity Contract
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives	[1]	$ (3,184)	$ 14,732

[1] Amounts settled during the periods are a loss of $22,803 and a gain of $173, respectively.