Supplemental Oil And Gas Disclosures (Results Of Operations For Producing Activities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Oil and Gas Disclosures [Abstract]
Revenues	$ 633,792	$ 557,003	$ 505,450
Production costs	(162,822)	(131,389)	(115,400)
Depreciation, depletion, amortization and impairment	(222,672)	(492,475)	(181,960)
Results of operations, income before income taxes	248,298	(66,861)	208,090
Income tax (expense) benefit	(96,091)	27,533	(80,323)
Results of operations for producing activities (excluding corporate overhead and financing costs)	$ 152,207	$ (39,328)	$ 127,767