Supplementary Oil And Natural Gas Disclosures (Unaudited) (Capitalized Costs Relating To Oil And Gas Producing Activities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Capitalized Costs, Oil and Gas Producing Activities, Net [Abstract]
Proved oil and gas properties	$ 44,109	$ 34,336
Accumulated depreciation, depletion and amortization	(8,215)	(3,038)
Capitalized costs, net	35,894	31,298
Equity Method Investments [Member]
Capitalized Costs, Oil and Gas Producing Activities, Net [Abstract]
Unproved oil and gas properties	13,559	24,097
Proved oil and gas properties	159,527	144,324
Accumulated depreciation, depletion and amortization	(52,764)	(49,849)
Capitalized costs, net	$ 120,322	$ 118,572