Fair Value Hedges (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2014
Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Gain / (loss) recognized in income on fair value of hedges	$ (13)	$ 1
Long-term Debt
Derivative Instruments, Gain (Loss) [Line Items]
Gain / (loss) recognized in income on fair value of hedges	$ 13	$ (1)

Amount of the increase (decrease) in fair value of the hedged item in a fair value hedge recognized in the income statement.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 25

-Section 50

-Paragraph 1

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

Name:	us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration