Derivative Instruments and Other Financial Instruments Used For Hedging - Schedule of Derivatives Designated as Cash Flow Hedges (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
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Amount recognized relates to interest expenses	$ 1	$ 1	$ 1	$ 1