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, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss)	$ 2,267	$ (1,026)	$ 2,266	$ (2,036)
Realized Gain - Contract Settlements [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss)	493	39	2,056	28
Unrealized (Gain) Loss [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, gain (loss)	$ 1,774	$ (1,065)	$ 210	$ (2,064)