Derivative Instruments (Commodity Derivatives) (Details)		9 Months Ended
		Sep. 30, 2015 USD ($) MMBTU $ / MMBTU	Dec. 31, 2014 USD ($)
Derivative [Line Items]
Fair Value Asset		$ 14,000	$ 15,700
Natural Gas Put Options
Derivative [Line Items]
Fair Value Asset	[1]	$ 14,000
Natural Gas Put Options | Production Period Ending December 31, 2015
Derivative [Line Items]
Volumes | MMBTU	[2]	2,100
Average Fixed Price (per MMBtu) | $ / MMBTU	[2]	4.00
Fair Value Asset	[1]	$ 2,900
Natural Gas Put Options | Production Period Ending December 31, 2016
Derivative [Line Items]
Volumes | MMBTU	[2]	8,200
Average Fixed Price (per MMBtu) | $ / MMBTU	[2]	4.15
Fair Value Asset	[1]	$ 11,100

[1] Fair value based on forward NYMEX natural gas prices, as applicable.

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