Fair Value Measuremen (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	6 Months Ended
Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Fair Value Measurements [Abstract]
Balance at beginning of period	$ (56)	$ (60)	$ (19)
Included in earnings	6	32	(46)	(27)
Included in other comprehensive income
Purchases, issuances, and settlements:
Purchases
Issuances
Settlements	(5)		10	(1)
Transfers into/out of Level 3
Balance at end of period	(55)	(28)	(55)	(28)
Change in losses included in earnings relating to derivatives still held as of June 30	$ 1	$ 32	$ (36)	$ (28)

Fair Value Measuremen (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

6 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Fair Value Measurements [Abstract]

Balance at beginning of period

$ (56)

$ (60)

$ (19)

Included in earnings

(46)

(27)

Included in other comprehensive income

Purchases, issuances, and settlements:

Purchases

Issuances

Settlements

(5)

(1)

Transfers into/out of Level 3

Balance at end of period

(55)

(28)

(55)

(28)

Change in losses included in earnings relating to derivatives still held as of June 30

$ 1

$ 32

$ (36)

$ (28)

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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.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 3

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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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.

+ References

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-Name Accounting Standards Codification

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Amount of increase (decrease) 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.

+ References

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Amount of purchases 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.

+ References

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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.

+ References

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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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