Supplemental Information On Oil And Natural Gas Producing Activities (Change Standardized Measure) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Supplemental Information On Oil And Natural Gas Producing Activities
Beginning of the period	$ 52,246	$ 56,697
Sales and transfers of oil and natural gas, net of production costs	(8,006)	(14,795)
Net changes in prices and production costs related to future production	(7,330)	17,392
Changes in development costs	35	207
Revisions of previous quantity estimates	(1,942)	(4,203)
Purchases and sales of reserves in place		(5,423)
Accretion discount	5,225	5,670
Change in production rates, timing, and other	(1,878)	(3,299)
Standardized measure of discounted future net cash flows related to proved oil and natural gas reserves	$ 38,350	$ 52,246