Schedule of Derivative Instruments not Designated as Hedges Losses (Detail) $ in Millions	3 Months Ended
Mar. 31, 2015 USD ($)
Not Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss recognized in Nonoperating income (expense): Miscellaneous, net	$ (43)

Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of price risk derivatives not designated as hedging instruments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

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