Supplemental Oil And Gas Information (Schedule Of Reserve Value By Category And The Respective Present Values, Before Income Taxes, Discounted At 10% As A Percentage Of Total Proved Reserves) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reserve Quantities [Line Items]
Total proved reserves year-end reserve report	$ 13,976	$ 8,170	$ 5,815
Proved developed producing reserves (PDP)	$ 12,534	$ 7,065	$ 5,397
% of PDP reserves to total proved reserves	90.00%	87.00%	93.00%
Proved developed non-producing reserves	$ 739	$ 1,082	$ 418
% of PDNP reserves to total proved reserves	5.00%	13.00%	7.00%
Proved undeveloped reserves (PUD)	$ 703	$ 23
% of PUD reserves to total proved reserves	5.00%
Oil [Member]
Reserve Quantities [Line Items]
Total proved reserves year-end reserve report	$ 13,976	8,170	$ 5,815
Proved developed producing reserves (PDP)	$ 12,534	$ 7,065	$ 5,397
% of PDP reserves to total proved reserves	90.00%	87.00%	93.00%
Proved developed non-producing reserves	$ 739	$ 1,082	$ 418
% of PDNP reserves to total proved reserves	5.00%	13.00%	7.00%
Proved undeveloped reserves (PUD)	$ 703	$ 23
% of PUD reserves to total proved reserves	5.00%