Derivative Instruments And Hedging Activities Notional Contracts by Derivative Type (Details)	9 Months Ended
	Sep. 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	5,850,000
Designated as Hedging Instrument [Member] | Price Risk Derivative [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	4,388,000
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	450,000
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 Two [Member] | Price Risk Derivative [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	1,460,000
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 Three [Member] | Price Risk Derivative [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	2,928,000
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 | $	$ 446,361,369
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	2,303,000
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	400,000
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	25,000
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 | $	$ 113,632,223
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	2,102,000
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	400,000
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	25,000
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 | $	$ 332,729,146
Not Designated as Hedging Instrument [Member] | Maturing in Year Two [Member] | NYMEX WTI short [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	201,000