Derivatives and Other Financial Instruments - Schedule of Carrying Values and Fair Values of Other Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Cash and Cash Equivalents [Member]
Derivative [Line Items]
Carrying value	$ 1,861	$ 1,939
Fair value	1,861	1,939
Restricted Cash [Member]
Derivative [Line Items]
Carrying value	189	25
Fair value	189	25
Noncurrent Receivables [Member]
Derivative [Line Items]
Carrying value	20	30
Fair value	20	30
Available-for-sale securities [Member]
Derivative [Line Items]
Carrying value	67	92
Fair value	67	92
Short-term Debt [Member]
Derivative [Line Items]
Carrying value	53	62
Fair value	53	62
Commercial Paper [Member]
Derivative [Line Items]
Carrying value		224
Fair value		224
Long-Term Debt Due Within One Year [Member]
Derivative [Line Items]
Carrying value	465	445
Fair value	465	445
Long-Term Debt, Less Amount Due Within One Year [Member]
Derivative [Line Items]
Carrying value	8,311	8,640
Fair value	$ 9,028	$ 9,274