Quarterly report pursuant to Section 13 or 15(d)

Derivatives And Fair Value (Effect Of Derivative Instruments On The Condensed Consolidated Statements Of Operations) (Details)

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Derivatives And Fair Value (Effect Of Derivative Instruments On The Condensed Consolidated Statements Of Operations) (Details) - Other, net [Member] - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Crude Oil Puts [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss) on Derivative, Net   $ (921)   $ (971)
Crude Oil Swaps [Member]        
Derivative Instruments, Gain (Loss) [Line Items]        
Derivative, Gain (Loss) on Derivative, Net $ (1,026)   $ (2,036)