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Fair Value Measurements - Included in Earnings (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value Disclosures [Abstract]
Gains (losses) on derivative and hedging activities, net	$ (27)	$ 37	$ (298)
Interest expense	77	120	224
Total	$ 50	$ 157	$ (74)

X

- Definition

Amount of gain (loss) recognized in the income statement in the gains (losses) on derivative and hedging activities line item for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

No definition available.

+ Details

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X

- Definition

Amount of gain (loss) recognized in the income statement in the interest expense line item for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

No definition available.

+ Details

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- Details

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X

- Definition

Amount of gain (loss) recognized in the income statement for financial instrument classified as an 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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

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