Company's Stock Option Activity (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011
Option shares outstanding, January 1	36		37
Weighted average exercise price	$ 21		$ 21
Option shares granted, including restoration options	1		2
Weighted average exercise price	$ 12		$ 13
Option shares exercised	1
Aggregate intrinsic value on date of exercise	$ 4	[1]	$ 1	[1]
Weighted average exercise price	$ 9		$ 8
Option shares forfeited	3		3
Weighted average exercise price	$ 18		$ 22
Option shares outstanding, September 30	33		36
Weighted average exercise price	$ 21		$ 21
Weighted average remaining option term (in years)	5 years		6 years
Option shares vested and expected to vest, September 30	33		36
Weighted average exercise price	$ 21		$ 21
Aggregate intrinsic value	39	[1]
Weighted average remaining option term (in years)	5 years		6 years
Option shares exercisable (vested), September 30	25		24
Weighted average exercise price	$ 24		$ 24
Aggregate intrinsic value	$ 17	[1]
Weighted average remaining option term (in years)	4 years		4 years

[1] Aggregate intrinsic value is calculated using the Company's stock price at each respective date, less the exercise price (grant date price) multiplied by the number of shares.