Derivative Instruments And Hedging Activities Notional Contracts by Derivative Type (Details)	6 Months Ended
	Jun. 30, 2018 USD ($) MMBTU bbl
Designated as Hedging Instrument [Member] | Natural Gas [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	6,300,000
Designated as Hedging Instrument [Member] | Crude Oil [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	180,000
Designated as Hedging Instrument [Member] | Maturing in Next Twelve Months [Member] | Natural Gas [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	900,000
Designated as Hedging Instrument [Member] | Maturing in Next Twelve Months [Member] | Crude Oil [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	180,000
Designated as Hedging Instrument [Member] | Maturing in Year Two [Member] | Natural Gas [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	1,800,000
Designated as Hedging Instrument [Member] | Maturing in Year Three [Member] | Natural Gas [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	1,800,000
Designated as Hedging Instrument [Member] | Maturing in Year Four [Member] | Natural Gas [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	1,800,000
Not Designated as Hedging Instrument [Member]
Economic hedges by derivative type [Line Items]
Foreign Currency Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net | $	$ 451,027,063
Not Designated as Hedging Instrument [Member] | NYMEX WTI short [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	1,315,000
Not Designated as Hedging Instrument [Member] | WTI Crude Oil [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	300,000
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	675,000
Not Designated as Hedging Instrument [Member] | Maturing in Next Twelve Months [Member]
Economic hedges by derivative type [Line Items]
Foreign Currency Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net | $	$ 227,169,087
Not Designated as Hedging Instrument [Member] | Maturing in Next Twelve Months [Member] | NYMEX WTI short [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	1,315,000
Not Designated as Hedging Instrument [Member] | Maturing in Next Twelve Months [Member] | WTI Crude Oil [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	300,000
Not Designated as Hedging Instrument [Member] | Maturing in Next Twelve Months [Member] | Commodity Contract [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	675,000
Not Designated as Hedging Instrument [Member] | Maturing in Year Two [Member]
Economic hedges by derivative type [Line Items]
Foreign Currency Derivative Instruments Not Designated as Hedging Instruments at Fair Value, Net | $	$ 223,857,976