Derivative Instruments And Hedging Activities Volumes related to price risk purchase derivatives (Details) - Price Risk Derivative [Member]	9 Months Ended
	Sep. 30, 2015 MMBTU bbl
Natural Gas - long [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	21,600,000
Natural Gas - long [Member] | Maturing in Next Twelve Months [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	2,400,000
Natural Gas - long [Member] | Maturing in Year Two [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	9,600,000
Natural Gas - long [Member] | Maturing in Year Three [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Derivative, Nonmonetary Notional Amount, Energy Measure | MMBTU	9,600,000
WTI Crude Oil [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	2,760,000
WTI Crude Oil [Member] | Maturing in Next Twelve Months [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	2,760,000
Ultra Low Sulfur Diesel [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	2,760,000
Ultra Low Sulfur Diesel [Member] | Maturing in Next Twelve Months [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	2,760,000
Forward Contracts [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	225,000
Forward Contracts [Member] | Maturing in Next Twelve Months [Member]
Price Risk Derivatives for Future Purchases Notional Contract Volumes [Line Items]
Price Risk Fair Value Hedge Derivative, at Fair Value, Net	225,000