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)

v3.20.2
Derivatives and Fair Value (Effect of Derivative Instruments on the Condensed Consolidated Statements of Operations) (Details) - Crude Oil Swaps [Member] - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]      
Derivative instruments gain (loss), net $ 2,267 $ 6,583 $ 2,266
Realized Gain - Contract Settlements [Member]      
Derivative Instruments, Gain (Loss) [Line Items]      
Derivative instruments gain (loss), net 493 7,216 2,056
Unrealized Gain (Loss) [Member]      
Derivative Instruments, Gain (Loss) [Line Items]      
Derivative instruments gain (loss), net $ 1,774 $ (633) $ 210