Summary of Fair Value of Derivative Instruments Not Designated as Hedging Instruments in Consolidated Balance Sheets (Detail) (Not Designated as Hedging Instrument, USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Note Hedge | Note Hedge
Asset Derivatives:
Derivative asset	$ 79	$ 78
Cash Conversion Option | Long-Term Debt, Current Portion [Member]
Liability Derivatives:
Derivative liability	79	78
Contingent interest features of the 3.25% Notes and Debentures | Other noncurrent liabilities
Liability Derivatives:
Derivative liability	$ 0	$ 0