Stock Option Activity (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014
Number of Shares
Options outstanding, January 1, 2014	10,379,668
Granted	1,493,560
Forfeited	(1,036,902)
Exercised	(368,446)
Options outstanding, June 30, 2014	10,467,880
Weighted Average Exercise Price Per Share
Options outstanding, January 1, 2014	$ 10.83
Granted	$ 7.35
Forfeited	$ 14.25
Exercised	$ 4.20
Options outstanding, June 30, 2014	$ 10.23