Derivative Instruments (Commodity Derivatives) (Details) (USD $)					3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Natural Gas Put Options		Mar. 31, 2014 Natural Gas Put Options Production Period Ending December 31, 2014 MMBTU		Mar. 31, 2014 Natural Gas Put Options Production Period Ending December 31, 2015 MMBTU		Mar. 31, 2014 Natural Gas Put Options Production Period Ending December 31, 2016 MMBTU
Derivative [Line Items]
Volumes (MMBtu)					59,700	[1]	63,700	[1]	63,700	[1]
Average Fixed Price (per MMBtu)					3.80	[1]	4.00	[1]	4.15	[1]
Fair Value Asset	$ 50,600	$ 60,700	$ 50,600	[2]	$ 3,700	[2]	$ 19,800	[2]	$ 27,100	[2]

[1] “MMBtu” represents million British Thermal Units.

[2] Fair value based on forward New York Mercantile Exchange (“NYMEX”) natural gas prices, as applicable.