Stock Option Activity and Related Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Options Outstanding
Outstanding at beginning of period	6,730,520
Granted	725,720
Exercised	(1,224,287)
Forfeited	(186,041)
Outstanding at end of period	6,045,912
Weighted average exercise price
Outstanding at beginning of period	$ 5.10
Granted	$ 24.82
Exercised	$ 3.20
Forfeited	$ 9.71
Outstanding at end of period	$ 7.72
Options Exercisable
Outstanding at beginning of period	3,352,116
Outstanding at end of period	3,195,701
Exercisable Weighted Average Exercise Price per Share
Outstanding at beginning of period	$ 2.20
Outstanding at end of period	$ 3.64