Common Stock - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012	Dec. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Decrease in basic and diluted earnings per share	$ 0.02	$ 0.01	$ 0.07	$ 0.04
Share based compensation	$ 2	$ 2	$ 9	$ 6
Weighted average grant-date fair value of options granted			$ 17.49	$ 26.11
Total fair value of shares vested			4	3
Stock Repurchased during Period, Shares			600,000
2012 authorized outstanding common stock for repurchase over a 12 month period					600,000
Stock repurchase duration in 2012			12 months
Payment for repurchase of Common Stock			18
Average price of share repurchase program			$ 29.22
Treasury stock, shares	2,294,692		2,294,692			1,694,692
Stock Option [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Compensation expense related to nonqualified stock options	1	1	4	2
Unrecognized compensation costs	6		6
Unrecognized compensation costs, weighted average period			1 year 3 months 18 days
Cash received from stock option exercises			3	4
Unrecorded tax benefit from stock options exercised			1	3
Restricted Stock, Restricted Stock Units, Long Term Performance Units, SARs [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized compensation costs	10		10
Unrecognized compensation costs, weighted average period			1 year 9 months 18 days
Share based compensation	3	1	11	8
Restricted Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Unrecognized compensation costs	6		6
Unrecognized compensation costs, weighted average period			1 year 9 months 18 days
Total fair value of restricted shares vested			$ 5	$ 2