Dispositions (Details) (USD $)	6 Months Ended			12 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2011 Barnett Shale Properties [Member]	Dec. 31, 2011 Barnett Shale Properties [Member]	Mar. 31, 2012 East Texas [Member]	Mar. 31, 2011 Low pressure pipeline [Member]	Jun. 30, 2012 Marcellus Shale Properties [Member]
Dispositions and Acquisitions (Textual) [Abstract]
Proceeds from sale of oil and gas properties	$ 15,620,000	$ 23,409,000			$ 8,600,000		$ 2,500,000
Loss on sale of oil and gas properties	(13,653,000)	(1,483,000)			(10,900,000)		(2,500,000)
Proceeds from the sale of natural gas properties				889,300,000
Proceeds from sale of pipeline						14,700,000
Sale of oil and gas properties					75.00%
Overriding royalty in the prospect minimum					2.50%
Overriding royalty in the prospect maximum					5.00%
Gain from sale of pipeline						0
Loss on derivative contracts			$ (1,700,000)