Supplemental Oil And Gas Disclosures (Results Of Operations For Producing Activities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Oil and Gas Disclosures [Abstract]
Revenues	$ 371,335	$ 723,566	$ 633,792
Production costs	(152,560)	(165,315)	(162,822)
Depreciation, depletion, amortization, and impairment	(1,844,726)	(347,220)	(222,672)
Results of operations, income before income taxes	(1,625,951)	211,031	248,298
Income tax (expense) benefit	612,496	(82,028)	(96,091)
Results of operations for producing activities (excluding corporate overhead and financing costs)	$ (1,013,455)	$ 129,003	$ 152,207