Derivatives Derivatives (Subsequent Schedule of Derivatives Outstanding) (Details) - Basis swap [Member] - Natural Gas [Member] - PEPL [Member] - Jan'19 - Dec'19 [Member]	1 Months Ended	6 Months Ended
	Aug. 07, 2018 $ / Unit MMBTU	Jun. 30, 2018 $ / Unit MMBTU
Derivative [Line Items]
Weighted average price | $ / Unit		(0.728)
Hedged volume (MMBtu/day) | MMBTU		10,000
Subsequent Event [Member]
Derivative [Line Items]
Weighted average price | $ / Unit	(0.590)
Hedged volume (MMBtu/day) | MMBTU	10,000