Property And Equipment (Schedule Of Property And Equipment) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Oil and gas properties under the full cost method	$ 1,473,777	$ 1,453,329
Computers, furniture and fixtures	8,733	8,734
Total property and equipment	1,482,510	1,462,063
Accumulated depreciation, depletion and amortization	(428,735)	(389,912)
Net property and equipment	1,053,775	1,072,151
Subject To Amortization [Member]
Property, Plant and Equipment [Line Items]
Oil and gas properties under the full cost method	1,102,962	1,084,669
Not Subject To Amortization [Member] | Incurred in 2014 [Member]
Property, Plant and Equipment [Line Items]
Oil and gas properties under the full cost method	23,041
Not Subject To Amortization [Member] | Incurred in 2013 [Member]
Property, Plant and Equipment [Line Items]
Oil and gas properties under the full cost method	37,936	52,748
Not Subject To Amortization [Member] | Incurred in 2012 [Member]
Property, Plant and Equipment [Line Items]
Oil and gas properties under the full cost method	134,287	138,641
Not Subject To Amortization [Member] | Incurred prior to 2012 [Member]
Property, Plant and Equipment [Line Items]
Oil and gas properties under the full cost method	$ 175,551	$ 177,271