Supplemental Oil And Gas Information (Schedule Of Results Of Operations From Oil And Gas Producing Activities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Supplemental Oil And Gas Information [Abstract]
Revenues	$ 5,871	$ 4,683
Production costs and taxes	(3,591)	(3,444)
Depreciation, depletion and amortization	(722)	(796)
Income (loss) from oil and gas producing activities	$ 1,558	$ 443