Price Risk Management Assets And Liabilities Table - Fair Value of Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Total derivatives assets	$ 193	$ 320
Total derivatives liabilities	331	389
Designated as Hedging Instrument [Member]
Total derivatives assets	1	3
Total derivatives liabilities	12	18
Designated as Hedging Instrument [Member] | Commodity Derivatives (Margin Deposits) [Member]
Total derivatives assets	1	3
Total derivatives liabilities	12	18
Not Designated as Hedging Instrument [Member]
Total derivatives assets	192	317
Total derivatives liabilities	319	371
Not Designated as Hedging Instrument [Member] | Commodity Derivatives (Margin Deposits) [Member]
Total derivatives assets	128	227
Total derivatives liabilities	139	209
Not Designated as Hedging Instrument [Member] | Commodity Derivatives [Member]
Total derivatives assets	60	43
Total derivatives liabilities	64	48
Not Designated as Hedging Instrument [Member] | Interest Rate Derivatives [Member]
Total derivatives assets	4	47
Total derivatives liabilities	96	95
Not Designated as Hedging Instrument [Member] | Embedded Derivatives [Member]
Total derivatives assets	0	0
Total derivatives liabilities	$ 20	$ 19