Derivatives and Other Financial Instruments - Schedule of Gains and Losses on Derivative Excluded from Assessment of Effectiveness Recognized in Current Earnings (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Offsetting [Abstract]
Amount of loss expected to be recognized into earnings over the next 12 months			$ 14
Earnings recognized in relation to ineffective portion of the hedging relationships	0	1	0	10
Amount of gain or (loss) recognized in earnings related amount excluded from the assessment of hedge effectiveness	$ (2)	$ 1	$ (2)	$ (1)