Summary of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Shares Available for Grant
Beginning balance	593,011
Options authorized	150,000
Options granted	(1,022,601)
Options canceled	361,538
Ending balance	81,948
Shares Subject to Outstanding Options
Beginning balance	3,451,178
Options granted	1,022,601
Options exercised	(403,468)
Options canceled	(361,538)
Ending balance	3,708,773
Weighted-Average Exercise Price Per Share
Beginning balance	$ 6.35
Options granted	$ 18.31
Options exercised	$ 6.40
Options cancelled	$ 8.58
Ending balance	$ 9.43