Price Risk Management Assets And Liabilities Fair Value of Derivatives, Netting Basis (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Income, Net	$ 5	$ (34)	$ (66)	$ 11
Derivative Asset, Fair Value, Gross Asset	131		131		316
Derivative Liability, Fair Value, Gross Liability	(211)		(211)		(360)
Derivative Asset, Fair Value, Amount Offset Against Collateral	(14)		(14)		(37)
Derivative Liability, Fair Value, Amount Offset Against Collateral	39		39		91
Netting [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	142		142		306
Derivative Liability, Fair Value, Gross Liability	164		164		356
Derivative Asset, Fair Value, Gross Liability	(9)		(9)		(36)
Derivative Liability, Fair Value, Gross Asset	9		9		36
Derivative Asset, Fair Value, Net	128		128		269
Derivative Liability, Fair Value, Net	(125)		(125)		(265)
Bi-lateral contracts [Member] | Netting [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	12		12		41
Derivative Liability, Fair Value, Gross Liability	12		12		38
Broker cleared derivative contracts [Member] | Netting [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset	130		130		265
Derivative Liability, Fair Value, Gross Liability	152		152		318
Asset Fair Value, Netting Offset [Member] | Netting [Member]
Derivative [Line Items]
Payments on Margin Deposits	(5)		(5)		(1)
Other Derivatives Not Designated as Hedging Instruments Assets at Fair Value	3		3		47
Liability Fair Value, Netting Offset [Member] | Netting [Member]
Derivative [Line Items]
Payments on Margin Deposits	30		30		55
Other Derivatives Not Designated as Hedging Instruments Liabilities at Fair Value	$ (86)		$ (86)		$ (95)