Derivative Instruments And Hedging Activities Notional Contracts by Derivative Type (Details)	6 Months Ended
	Jun. 30, 2016 MMBTU bbl
Economic Hedges [Member] | Commodity Contract [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net | bbl	6,983,000
Economic Hedges [Member] | Commodity Contract [Member] | Maturing in Next Twelve Months [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net | bbl	5,888,000
Economic Hedges [Member] | Commodity Contract [Member] | Maturing in Year Two [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net | bbl	1,095,000
Economic Hedges [Member] | Natural Gas Liquids [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	15,462,000
Economic Hedges [Member] | Natural Gas Liquids [Member] | Maturing in Next Twelve Months [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	5,154,000
Economic Hedges [Member] | Natural Gas Liquids [Member] | Maturing in Year Two [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	10,308,000
Economic Hedges [Member] | Natural Gas - long [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	14,400,000
Economic Hedges [Member] | Natural Gas - long [Member] | Maturing in Next Twelve Months [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	4,800,000
Economic Hedges [Member] | Natural Gas - long [Member] | Maturing in Year Two [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Economic Hedges [Member] | Natural Gas - Short [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	14,400,000
Economic Hedges [Member] | Natural Gas - Short [Member] | Maturing in Next Twelve Months [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	4,800,000
Economic Hedges [Member] | Natural Gas - Short [Member] | Maturing in Year Two [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Economic Hedges [Member] | NYMEX WTI short [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net | bbl	910,000
Economic Hedges [Member] | NYMEX WTI short [Member] | Maturing in Next Twelve Months [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net | bbl	710,000
Economic Hedges [Member] | NYMEX WTI short [Member] | Maturing in Year Two [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net | bbl	200,000
Price Risk Derivative [Member] | Natural Gas - long [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	14,400,000
Price Risk Derivative [Member] | Natural Gas - long [Member] | Maturing in Next Twelve Months [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	4,800,000
Price Risk Derivative [Member] | Natural Gas - long [Member] | Maturing in Year Two [Member]
Economic hedges by derivative type [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure	9,600,000
Price Risk Derivative [Member] | Forward Contracts [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net | bbl	75,000
Price Risk Derivative [Member] | Forward Contracts [Member] | Maturing in Next Twelve Months [Member]
Economic hedges by derivative type [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net | bbl	75,000