Change in the Fair Value for Interest Rate Contracts and the Related Hedged Items (Detail) (Fair Value Hedging, Interest Rate Contract, USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Fair Value Hedging \| Interest Rate Contract
Derivatives, Fair Value
Change in fair value of interest rate swaps hedging long-term debt	$ 35	$ (67)
Change in fair value of hedged long-term debt	$ (37)	$ 66

Amount of unrealized gain (loss) included in earnings related to the fair value of the hedged item in an interest rate fair value hedge, offset by the gain (loss) on the hedging instrument to the extent that the fair value hedge is determined to be effective.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration