Fair Value Of Assets And Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Financial assets (liabilities)
Long-term debt, including current portion	$ (3,908)		$ (3,909)
Carrying (Reported) Amount, Fair Value Disclosure
Financial assets (liabilities)
Other investments	149	[1]	150	[1]
Derivatives	1	[1]	22	[1]
Long-term debt, including current portion	(3,908)	[1]	(3,909)	[1]
Estimate of Fair Value, Fair Value Disclosure
Financial assets (liabilities)
Other investments	149	[1]	150	[1]
Derivatives	1	[1]	22	[1]
Long-term debt, including current portion	(3,775)	[1]	(3,966)	[1]
Fair Value, Inputs, Level 1
Financial assets (liabilities)
Other investments	100	[1]	96	[1]
Derivatives	0	[1]	0	[1]
Long-term debt, including current portion	0	[1]	0	[1]
Fair Value, Inputs, Level 2
Financial assets (liabilities)
Other investments	49	[1],[2]	54	[1],[2]
Derivatives	1	[1],[2]	22	[1],[2]
Long-term debt, including current portion	$ (3,775)	[1],[2]	$ (3,966)	[1],[2]

[1] We had no Level 3 financial instruments on December 31, 2012, or June 30, 2013.

[2] Determined under a market approach using valuation models that incorporate observable inputs such as interest rates, bond yields and quoted prices for similar assets and liabilities.