Summary of Stock Option Activity (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
Shares Available for Grant
Beginning balance	81,948
Options authorized	2,045,785
Options granted	(671,613)
Options canceled	19,732
Ending balance	1,475,852
Shares Subject to Outstanding Options
Beginning balance	3,708,773
Options granted	671,613
Options exercised	(157,833)
Options canceled	(19,732)
Ending balance	4,202,821
Weighted-Average Exercise Price Per Share
Beginning balance	$ 9.43
Options granted	$ 25.14
Options exercised	$ 6.39
Options canceled	$ 17.76
Ending balance	$ 12.02