Supplemental Oil And Natural Gas Disclosures (Capitalized Costs Relating To Oil And Natural Gas Producing Activities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Capitalized costs:
Proved properties	$ 2,110,346
Unproved properties	816,282
Total	2,926,628
Accumulated depreciation, depletion, amortization and impairment	(2,163,291)
Net capitalized costs	$ 763,337
Predecessor
Capitalized costs:
Proved properties		$ 1,545,963
Unproved properties		116,787
Total		1,662,750
Accumulated depreciation, depletion, amortization and impairment		(711,275)
Net capitalized costs		$ 951,475