Stock Option Activity (Detail)	12 Months Ended
	Dec. 31, 2015 $ / shares shares
Number of Shares
Options outstanding, January 1, 2015 | shares	10,148,087
Granted | shares	1,534,425
Forfeited | shares	(780,914)
Exercised | shares	(668,629)
Options outstanding, December 31, 2015 | shares	10,232,969
Weighted Average Exercise Price Per Share
Options outstanding, January 1, 2015 | $ / shares	$ 10.09
Granted | $ / shares	7.49
Forfeited | $ / shares	9.90
Exercised | $ / shares	5.78
Options outstanding, December 31, 2015 | $ / shares	$ 10.00