Derivatives And Risk Management (Balance Sheet Classification Of Derivative Financial Instruments) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivative [Line Items]
Derivative assets	$ 78	$ 79
Derivative liabilities	116	41
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative assets	27	21
Derivative liabilities	24	4
Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Derivative Assets [Member]
Derivative [Line Items]
Derivative assets	11	21
Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Other Long-Term Assets [Member]
Derivative [Line Items]
Derivative assets	16
Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	24	4
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative assets	51	58
Derivative liabilities	92	37
Not Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Derivative Assets [Member]
Derivative [Line Items]
Derivative assets	10	37
Not Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Other Long-Term Assets [Member]
Derivative [Line Items]
Derivative assets	16
Not Designated as Hedging Instrument [Member] | Fixed Price Swaps [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	9
Not Designated as Hedging Instrument [Member] | Basis Swaps [Member] | Derivative Assets [Member]
Derivative [Line Items]
Derivative assets	19	13
Not Designated as Hedging Instrument [Member] | Basis Swaps [Member] | Other Long-Term Assets [Member]
Derivative [Line Items]
Derivative assets	3
Not Designated as Hedging Instrument [Member] | Basis Swaps [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	20	2
Not Designated as Hedging Instrument [Member] | Basis Swaps [Member] | Other Long-Term Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	4
Not Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member] | Other Long-Term Assets [Member]
Derivative [Line Items]
Derivative assets	3	8
Not Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	3	2
Not Designated as Hedging Instrument [Member] | Interest Rate Swaps [Member] | Other Long-Term Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	3	3
Not Designated as Hedging Instrument [Member] | Fixed Price Call Options [Member] | Derivative Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	16
Not Designated as Hedging Instrument [Member] | Fixed Price Call Options [Member] | Other Long-Term Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	$ 37	$ 30