Derivative Instruments (Commodity Derivatives) (Details) (USD $)	6 Months Ended
	Jun. 30, 2012 MMBTU
Derivative [Line Items]
Fair Value Asset	$ 42,400
Production Period Ending December 31, 2012 [Member] | Natural Gas Put Options [Member]
Derivative [Line Items]
Volumes (mmbtu)	14,522	[1]
Average Strike (per mmbtu)	2.80	[1]
Fair Value Asset	2,515	[2]
Production Period Ending December 31, 2013 [Member] | Natural Gas Put Options [Member]
Derivative [Line Items]
Volumes (mmbtu)	21,782	[1]
Average Strike (per mmbtu)	3.45	[1]
Fair Value Asset	8,718	[2]
Production Period Ending December 31, 2014 [Member] | Natural Gas Put Options [Member]
Derivative [Line Items]
Volumes (mmbtu)	18,152	[1]
Average Strike (per mmbtu)	3.80	[1]
Fair Value Asset	9,408	[2]
Production Period Ending December 31, 2015 [Member] | Natural Gas Put Options [Member]
Derivative [Line Items]
Volumes (mmbtu)	14,522	[1]
Average Strike (per mmbtu)	4.00	[1]
Fair Value Asset	9,860	[2]
Production Period Ending December 31, 2016 [Member] | Natural Gas Put Options [Member]
Derivative [Line Items]
Volumes (mmbtu)	14,522	[1]
Average Strike (per mmbtu)	4.15	[1]
Fair Value Asset	$ 11,881	[2]

[1] (1) "Mmbtu" represents million British Thermal Units.

[2] (2) Fair value based on forward NYMEX natural gas prices, as applicable.