Debt (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Total debt	$ 3,909	$ 3,930
Less current portion	1	23
Long-term debt	3,908	3,907
Fixed-Rate Notes Due May 2013
Debt Instrument [Line Items]
Total debt	0	1,000
Interest Rate	4.25%
Fixed-Rate Notes Due February 2014
Debt Instrument [Line Items]
Total debt	0	998
Interest Rate	5.25%
Fixed-Rate Notes Due January 2015
Debt Instrument [Line Items]
Total debt	500	499
Interest Rate	1.375%
Fixed-Rate Notes Due August 2015
Debt Instrument [Line Items]
Total debt	0	400
Interest Rate	5.375%
Fixed-Rate Notes Due July 2016
Debt Instrument [Line Items]
Total debt	500	499
Interest Rate	2.25%
Fixed-Rate Notes Due November 2017
Debt Instrument [Line Items]
Total debt	895	0
Interest Rate	1.00%
Fixed-Rate Notes Due July 2021
Debt Instrument [Line Items]
Total debt	499	499
Interest Rate	3.875%
Fixed-Rate Notes Due November 2022
Debt Instrument [Line Items]
Total debt	990	0
Interest Rate	2.25%
Fixed-Rate Notes Due November 2042
Debt Instrument [Line Items]
Total debt	498	0
Interest Rate	3.60%
Other Debt Securities
Debt Instrument [Line Items]
Total debt	$ 27	$ 35
Other	Various