Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Number of Options
Outstanding, beginning balance	9,778,539
Granted	1,233,086
Exercised	(661,909)
Cancelled	(1,418,133)
Outstanding, ending balance	8,931,583
Exercisable, ending balance	5,885,363	6,033,858	4,983,088
Weighted average exercise price
Outstanding, beginning balance	$ 15.53
Granted	$ 17.02
Exercised	$ 9.67
Cancelled	$ 18.47
Outstanding, ending balance	$ 15.71
Exercisable, ending balance	$ 17.20	$ 18.13	$ 18.60