Supplemental Disclosures About Natural Gas, Oil and NGL Producing Activities (Reserve Audits Estimate of Aggregate Reserves (Table) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reserve Quantities [Line Items]
Proved Reserves Volume Percentage	89.00%	77.00%	78.00%
Ryder Scott Company L P [Member]
Reserve Quantities [Line Items]
Proved Reserves Volume Percentage	44.00%	19.00%	6.00%
PetroTechnical Services, Division Of Schlumberger Technology Corporation [Member]
Reserve Quantities [Line Items]
Proved Reserves Volume Percentage	24.00%	7.00%	7.00%
Netherland Sewell And Associates Inc [Member]
Reserve Quantities [Line Items]
Proved Reserves Volume Percentage	21.00%	42.00%	58.00%
Lee Keeling And Associates Inc [Member]
Reserve Quantities [Line Items]
Proved Reserves Volume Percentage	0.00%	9.00%	7.00%