Derivatives and Other Financial Instruments - Schedule of Carrying Values and Fair Values of Other Financial Instruments (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Cash and Cash Equivalents [Member]
Derivative [Line Items]
Carrying value	$ 1,202	$ 1,861
Fair value	1,202	1,861
Restricted Cash [Member]
Derivative [Line Items]
Carrying value	84	189
Fair value	84	189
Noncurrent Receivables [Member]
Derivative [Line Items]
Carrying value	20	20
Fair value	20	20
Available-for-Sale Securities [Member]
Derivative [Line Items]
Carrying value	94	67
Fair value	94	67
Short-Term Borrowings [Member]
Derivative [Line Items]
Carrying value	55	53
Fair value	55	53
Commercial Paper [Member]
Derivative [Line Items]
Carrying value
Fair value
Long-Term Debt Due within One Year [Member]
Derivative [Line Items]
Carrying value	604	465
Fair value	773	477
Long-Term Debt, Less Amount Due within One Year [Member]
Derivative [Line Items]
Carrying value	7,700	8,311
Fair value	$ 7,730	$ 9,028