Summary of Stock Option Activity (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014
Shares Available for Grant
Beginning balance	81,948
Options authorized	2,045,785
Options granted	(1,003,013)
Options canceled	52,470
Ending balance	1,177,190
Shares Subject to Outstanding Options
Beginning balance	3,708,773
Options granted	1,003,013
Options exercised	(433,146)
Options canceled	(52,470)
Ending balance	4,226,170
Weighted-Average Exercise Price Per Share
Beginning balance	$ 9.43
Options granted	$ 25.47
Options exercised	$ 6.34
Options canceled	$ 11.77
Ending balance	$ 13.53