Stock Option Activity (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014
Number of Shares
Options outstanding, January 1, 2014	10,379,668
Granted	1,493,560
Forfeited	(1,333,975)
Exercised	(632,521)
Options outstanding, September 30, 2014	9,906,732
Weighted Average Exercise Price Per Share
Options outstanding, January 1, 2014	$ 10.83
Granted	$ 7.35
Forfeited	$ 13.83
Exercised	$ 4.44
Options outstanding, September 30, 2014	$ 10.31