Stock Based Compensation - Employee Stock Option Activity and Related Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares outstanding, beginning balance	1,686,179
Shares, granted	669,030
Shares, cancelled	(65,410)
Shares, exercised	(177,165)
Shares outstanding, ending balance	2,112,632	1,686,179
Shares, options vested and expected to vest	2,087,810
Shares, options exercisable	872,414
Outstanding weighted-average exercise price per share, beginning balance	$ 2.28
Weighted-average exercise price per share, granted	$ 9.17
Weighted-average exercise price per share, cancelled	$ 2.24
Weighted-average exercise price per share, exercised	$ 2.16
Weighted-average exercise price per share, ending balance	$ 4.47	$ 2.28
Options vested and expected to vest	$ 4.46
Options exercisable	$ 2.48
Outstanding weighted-average remaining contractual life	8 years 1 month 13 days	8 years 7 months 2 days
Weighted-average remaining contractual term, options vested and expected to vest	8 years 1 month 10 days
Weighted-average remaining contractual term, options exercisable	7 years 4 months 21 days
Outstanding aggregate intrinsic value, ending balance	$ 26,968	$ 7,486
Aggregate intrinsic value, options vested and expected to vest	26,687
Aggregate intrinsic value, options exercisable	$ 12,875