Fair Value Measurements (Reconciliations For Change In Net Fair Value Of Derivative Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Unobservable Inputs (Level 3)) (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
Fair Value Measurements [Abstract]
Balance at beginning of period	$ (55)	$ (28)	$ (19)
Included in earnings	18	5	(27)	(22)
Included in other comprehensive income
Purchases, issuances, and settlements:
Purchases
Issuances
Settlements	(9)	(2)		(3)
Transfers into/out of Level 3
Balance at end of period	(46)	(25)	(46)	(25)
Change in gains (losses) included in earnings relating to derivatives still held as of September 30	$ 9	$ 3	$ (27)	$ (25)

Fair Value Measurements (Reconciliations For Change In Net Fair Value Of Derivative Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Significant Unobservable Inputs (Level 3)) (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

Fair Value Measurements [Abstract]

Balance at beginning of period

$ (55)

$ (28)

$ (19)

Included in earnings

(27)

(22)

Included in other comprehensive income

Purchases, issuances, and settlements:

Purchases

Issuances

Settlements

(9)

(2)

(3)

Transfers into/out of Level 3

Balance at end of period

(46)

(25)

(46)

(25)

Change in gains (losses) included in earnings relating to derivatives still held as of September 30

$ 9

$ 3

$ (27)

$ (25)

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Amount of gain (loss) recognized in the income statement of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB

-Name Accounting Standards Codification

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-Section 50

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Amount of gain (loss) recognized in other comprehensive income (loss) of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of issuances of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a derivative asset (liability) after deduction of derivative liability, measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfers of financial instrument classified as a derivative asset (liability) after deduction of derivative liability (asset) into (out of) level 3 of the fair value hierarchy.

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