Supplemental Oil And Gas Disclosures (Standardized Measure Of Discounted Future Cash Flows Relating To Proved Reserves Disclosure) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Future Net Cash Flows Relating to Proved Oil and Gas Reserves, Net Cash Flows [Abstract]
Future cash flows	$ 1,386,777	$ 3,980,369	$ 3,347,396
Future production costs	(698,357)	(1,479,744)	(1,308,244)
Future development costs	0	(442,984)	(369,560)
Future income tax expenses	(321)	(307,916)	(234,152)
Future net cash flows	688,099	1,749,725	1,435,440
10% annual discount for estimated timing of cash flows	(226,390)	(766,047)	(628,270)
Standardized measure of discounted future net cash flows relating to proved oil, NGLs and natural gas reserves	$ 461,709	$ 983,678	$ 807,170	$ 518,210
Percentage of annual discount for estimated timing of cash flows	10.00%	10.00%	10.00%