Derivative And Financial Instruments (Effect On Statement Of Operations) (Details) - Commodity Contract - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Embedded Derivative [Line Items]
Net gain (loss) on derivatives	$ (3,772)	$ 1,316
Oil reserves
Embedded Derivative [Line Items]
Net gain (loss) on derivatives	(4,031)	1,400
Natural gas
Embedded Derivative [Line Items]
Net gain (loss) on derivatives	$ 259	$ (84)