Financial Instruments - Summary of Notional Amounts of Derivative Contracts (Detail) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2013
Interest rate caps [Member]
 
Derivatives, Fair Value [Line Items]  
Derivative contracts, notional amounts $ 2,330
Foreign currency options [Member]
 
Derivatives, Fair Value [Line Items]  
Derivative contracts, notional amounts 219
Foreign Currency Forwards [Member]
 
Derivatives, Fair Value [Line Items]  
Derivative contracts, notional amounts $ 158