Energy Commodity Price Risk Managment (Details) (Hedge Funds, Equity Long (Short) [Member], Forward Contracts [Member])	Sep. 30, 2014 Bcf
Natural Gas Basis [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	(23,500,000,000)
Natural Gas Basis [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	(4,100,000,000)
Crude Oil Basis [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	(3,300,000)
Crude Oil Fixed Price [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	(22,300,000)
Crude Oil Fixed Price [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	(200,000)
Natural Gas Fixed Price [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	(25,300,000,000)
Natural Gas Fixed Price [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	(4,500,000,000)
Natural Gas Liquids Fixed Price [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	(400,000)