Derivative Instruments Volume of Derivative Activity (Details) gal in Millions, Mcf in Millions	12 Months Ended
	Dec. 31, 2018 gal Mcf
Not Designated as Hedging Instrument [Member] | Natural Gas Futures [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume | Mcf	3.8
Sharp Energy Inc [Member] | Swap [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	9.7
Sharp Energy Inc [Member] | Put Option
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount, Volume	0.3