Oil and Gas Reserves (unaudited) (Details)	12 Months Ended
	Dec. 31, 2012 Mcfe	Dec. 31, 2011 Mcfe	Dec. 31, 2010 Mcfe
QUANTITIES OF PROVED RESERVES:
Balance (in Mcfe)	200,369	166,498
Revisions (in Mcfe)	(96,738)	(19,625)
Extensions, discoveries and additions (in Mcfe)	27,544	69,890
Sales (in Mcfe)		170
Production (in Mcfe)	(14,126)	(16,564)
Balance (in Mcfe)	117,049	200,369	166,498
Proved developed reserves (in Mcfe)	63,732	73,913	80,130
Proved undeveloped reserves (in Mcfe)	53,317	126,456	86,368
Crude Oil (MBbls)
QUANTITIES OF PROVED RESERVES:
Balance	3,734	2,164
Revisions	134	2
Extensions, discoveries and additions	3,088	1,943
Sales		22
Production	(754)	(397)
Balance	6,202	3,734
Proved developed reserves	2,343	1,845	1,403
Proved undeveloped reserves	3,859	1,890	761
Natural Gas (MMcf)
QUANTITIES OF PROVED RESERVES:
Balance	162,700	135,675
Revisions	(98,683)	(18,645)
Extensions, discoveries and additions	5,666	57,311
Sales		35
Production	(7,799)	(11,676)
Balance	61,884	162,700
Proved developed reserves	39,554	53,024	60,325
Proved undeveloped reserves	22,330	109,676	75,350
Natural Gas Liquids (MBbls)
QUANTITIES OF PROVED RESERVES:
Balance	2,544	2,973
Revisions	189	(165)
Extensions, discoveries and additions	559	154
Production	(300)	(418)
Balance	2,992	2,544
Proved developed reserves	1,686	1,637	1,898
Proved undeveloped reserves	1,306	907	1,075