Supplemental Oil And Gas Disclosures (Schedule Of The Oil And Natural Gas Property Costs Not Being Amortized) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unproved properties acquired and wells in progress	$ 252,874	$ 330,216	$ 296,764
2019
Unproved properties acquired and wells in progress	22,621
2018
Unproved properties acquired and wells in progress	54,780
2017
Unproved properties acquired and wells in progress	47,646
2016 and prior
Unproved properties acquired and wells in progress	$ 127,827